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Alini M, Diwan AD, Erwin WM, Little CB, Melrose J. An update on animal models of intervertebral disc degeneration and low back pain: Exploring the potential of artificial intelligence to improve research analysis and development of prospective therapeutics. JOR Spine 2023; 6:e1230. [PMID: 36994457 PMCID: PMC10041392 DOI: 10.1002/jsp2.1230] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/13/2022] [Revised: 08/31/2022] [Accepted: 09/11/2022] [Indexed: 02/03/2023] Open
Abstract
Animal models have been invaluable in the identification of molecular events occurring in and contributing to intervertebral disc (IVD) degeneration and important therapeutic targets have been identified. Some outstanding animal models (murine, ovine, chondrodystrophoid canine) have been identified with their own strengths and weaknesses. The llama/alpaca, horse and kangaroo have emerged as new large species for IVD studies, and only time will tell if they will surpass the utility of existing models. The complexity of IVD degeneration poses difficulties in the selection of the most appropriate molecular target of many potential candidates, to focus on in the formulation of strategies to effect disc repair and regeneration. It may well be that many therapeutic objectives should be targeted simultaneously to effect a favorable outcome in human IVD degeneration. Use of animal models in isolation will not allow resolution of this complex issue and a paradigm shift and adoption of new methodologies is required to provide the next step forward in the determination of an effective repairative strategy for the IVD. AI has improved the accuracy and assessment of spinal imaging supporting clinical diagnostics and research efforts to better understand IVD degeneration and its treatment. Implementation of AI in the evaluation of histology data has improved the usefulness of a popular murine IVD model and could also be used in an ovine histopathological grading scheme that has been used to quantify degenerative IVD changes and stem cell mediated regeneration. These models are also attractive candidates for the evaluation of novel anti-oxidant compounds that counter inflammatory conditions in degenerate IVDs and promote IVD regeneration. Some of these compounds also have pain-relieving properties. AI has facilitated development of facial recognition pain assessment in animal IVD models offering the possibility of correlating the potential pain alleviating properties of some of these compounds with IVD regeneration.
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Affiliation(s)
- Mauro Alini
- AO Research Institute Davos Platz Switzerland
| | - Ashish D. Diwan
- Spine Service, Department of Orthopedic Surgery, St. George & Sutherland Campus, Clinical School University of New South Wales Sydney New South Wales Australia
| | - W. Mark Erwin
- Department of Surgery University of Toronto Ontario Canada
| | - Chirstopher B. Little
- Raymond Purves Bone and Joint Research Laboratory Kolling Institute, Sydney University Faculty of Medicine and Health, Northern Sydney Area Health District, Royal North Shore Hospital St. Leonards New South Wales Australia
| | - James Melrose
- Raymond Purves Bone and Joint Research Laboratory Kolling Institute, Sydney University Faculty of Medicine and Health, Northern Sydney Area Health District, Royal North Shore Hospital St. Leonards New South Wales Australia
- Graduate School of Biomedical Engineering The University of New South Wales Sydney New South Wales Australia
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How annulus defects can act as initiation sites for herniation. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2022; 31:1487-1500. [PMID: 35174401 DOI: 10.1007/s00586-022-07132-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 01/13/2022] [Accepted: 01/25/2022] [Indexed: 10/19/2022]
Abstract
PURPOSE Both posture and loading rate are key factors in the herniation process and can determine the mechanism of disc failure. The aim of this study was to test the hypothesis that disruption visible with HR-MRI post-testing corresponds with microstructural features and further elucidate the mechanism by which this disruption weakens the disc. This will enable us to gain new insights into the herniation process. METHODS Thirty ovine lumbar spinal segments were subjected to combinations of four loading conditions (0-12° flexion, 0-9° lateral bending, 0-4° axial rotation, 0-1500 N axial compression) for 1000 loading cycles at 2 Hz in a dynamic disc loading simulator. The discs were scanned in an ultra-high field MRI (11.7 T) then examined using brightfield microscopy to examine their microstructure. RESULTS Four discs herniated and seven discs suffered nucleus displacement. These discs contained pre-existing defects in the central posterior annulus. Generally, following testing discs contained more posterior annulus disruption, Microstructural investigation revealed there was clear correspondence between HR-MRI and microstructural observations, and that the mid-outer annular-endplate junction had failed in all discs examined in this study. CONCLUSIONS While all discs suffered outer annulus damage, only the discs containing pre-existing defects herniated. These pre-existing defects weakened the inner and mid annulus, allowing herniation to occur once the mid and outer annular wall was compromised. We propose this can occur during the degenerative cascade.
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Constant C, Hom WW, Nehrbass D, Carmel E, Albers CE, Deml MC, Gehweiler D, Lee Y, Hecht A, Grad S, Iatridis JC, Zeiter S. Comparison and optimization of sheep in vivo intervertebral disc injury model. JOR Spine 2022; 5:e1198. [PMID: 35783908 PMCID: PMC9238284 DOI: 10.1002/jsp2.1198] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 03/08/2022] [Accepted: 03/16/2022] [Indexed: 11/09/2022] Open
Abstract
Background The current standard of care for intervertebral disc (IVD) herniation, surgical discectomy, does not repair annulus fibrosus (AF) defects, which is partly due to the lack of effective methods to do so and is why new repair strategies are widely investigated and tested preclinically. There is a need to develop a standardized IVD injury model in large animals to enable comparison and interpretation across preclinical study results. The purpose of this study was to compare in vivo IVD injury models in sheep to determine which annulus fibrosus (AF) defect type combined with partial nucleus pulposus (NP) removal would better mimic degenerative human spinal pathologies. Methods Six skeletally mature sheep were randomly assigned to one of the two observation periods (1 and 3 months) and underwent creation of 3 different AF defect types (slit, cruciate, and box-cut AF defects) in conjunction with 0.1 g NP removal in three lumbar levels using a lateral retroperitoneal surgical approach. The spine was monitored by clinical CT scans pre- and postoperatively, at 2 weeks and euthanasia, and by magnetic resonance imaging (MRI) and histology after euthanasia to determine the severity of degeneration (disc height loss, Pfirrmann grading, semiquantitative histopathology grading). Results All AF defects led to significant degenerative changes detectable on CT and MR images, produced bulging of disc tissue without disc herniation and led to degenerative and inflammatory histopathological changes. However, AF defects were not equal in terms of disc height loss at 3 months postoperatively; the cruciate and box-cut AF defects showed significantly decreased disc height compared to their preoperative height, with the box-cut defect creating the greatest disc height loss, while the slit AF defect showed restoration of normal preoperative disc height. Conclusions The tested IVD injury models do not all generate comparable disc degeneration but can be considered suitable IVD injury models to investigate new treatments. Results of the current study clearly indicate that slit AF defect should be avoided if disc height is used as one of the main outcomes; additional confirmatory studies may be warranted to generalize this finding.
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Affiliation(s)
| | - Warren W. Hom
- Department of OrthopaedicsIcahn School of Medicine, Mount Sinai Health SystemNew YorkNew YorkUSA
| | | | - Eric‐Norman Carmel
- Département de sciences cliniques, Faculté de médecine vétérinaireUniversité de MontréalSaint‐HyacintheCanada
| | - Christoph E. Albers
- Department of Orthopaedic Surgery & TraumatologyInselspital, University Hospital BernBernSwitzerland
| | - Moritz C. Deml
- Department of Orthopaedic Surgery & TraumatologyInselspital, University Hospital BernBernSwitzerland
| | | | - Yunsoo Lee
- Department of OrthopaedicsIcahn School of Medicine, Mount Sinai Health SystemNew YorkNew YorkUSA
| | - Andrew Hecht
- Department of OrthopaedicsIcahn School of Medicine, Mount Sinai Health SystemNew YorkNew YorkUSA
| | | | - James C. Iatridis
- Department of OrthopaedicsIcahn School of Medicine, Mount Sinai Health SystemNew YorkNew YorkUSA
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Liu T, Wang Y, Xu Z, Wu T, Zang X, Li M, Li J. Application study of 3D LAVA-Flex on lumbar intervertebral disc degeneration. Eur J Med Res 2021; 26:43. [PMID: 33962698 PMCID: PMC8106152 DOI: 10.1186/s40001-021-00512-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Accepted: 04/22/2021] [Indexed: 11/29/2022] Open
Abstract
Background Degeneration of the intervertebral discs are very common diseases, indicating the specific or malignant changes in intervertebral disc component, structure and function. Imaging examination is currently used to evaluate the severity of lumbar intervertebral disc degeneration. This study was designed to investigate the diagnostic value of 3D LAVA-Flex in lumbar intervertebral disc degeneration. Material and methods Sagittal 3D LAVA-Flex and T2WI scans were performed in 45 patients with lumbar intervertebral disc degeneration. On T2WI, the degenerated intervertebral disc in every patient was evaluated using Pfirrmann grade. Then, the patients were re-evaluated using 3D LAVA-Flex with considerations of the distinction of nucleus pulposus and annulus fibrosus, hypointense signal of intervertebral disc and height of intervertebral disc. The evaluation results were compared between 3D LAVA-Flex and T2WI. Virtual endoscopy was also performed to evaluate the degenerated intervertebral disc. Results The intermediate–intense signal of nucleus pulposus and complete ring-shaped hyperintense signal of annulus fibrosus were found and the distinction of nucleus pulposus and annulus fibrosus was clear in the normal intervertebral disc on 3D LAVA-Flex. The incidence of linear hypointensity of narrowed intervertebral space (65/91) was higher than that of normal intervertebral space (4/134) (P = 0.000). A good consistency was shown between the LAVA-Flex grade and T2WI-based Pfirrmann grade. Virtual endoscopy based on 3D LAVA-Flex could help clearly show the anatomic relationship between the degenerated disc and intervertebral foramen. Conclusions 3D LAVA-Flex and T2WI show similar efficacy in evaluating lumbar intervertebral disc degeneration. 3D LAVA-Flex-based virtual endoscopy possesses great potential in the study of intervertebral disc abnormalities.
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Affiliation(s)
- Tiefang Liu
- Department of Radiology, The First Medical Center of PLA General Hospital, Beijing, 100853, China
| | - Yonghao Wang
- Department of Ultrasound, The Eighth Medical Center of PLA General Hospital, Beijing, 100091, China
| | - Zhengyang Xu
- Department of Radiology, The First Medical Center of PLA General Hospital, Beijing, 100853, China
| | - Tao Wu
- MR Enhanced Application Team, GE Healthcare, Beijing, 100176, China
| | - Xiao Zang
- Department of Radiology, The First Medical Center of PLA General Hospital, Beijing, 100853, China
| | - Meng Li
- Department of Radiology, The First Medical Center of PLA General Hospital, Beijing, 100853, China
| | - Jinfeng Li
- Department of Radiology, The First Medical Center of PLA General Hospital, Beijing, 100853, China.
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Newton MD, Marek AA, Planalp M, Park DK, Baker KC, Maerz T. Longitudinal characterization of intervertebral disc remodeling following acute annular injury in a rat model of degenerative disc disease. Connect Tissue Res 2020; 61:568-576. [PMID: 31232119 DOI: 10.1080/03008207.2019.1635589] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Objective: Characterize 3D remodeling of the rat intervertebral disc (IVD) following acute annular injury via in vivo micro-computed tomography (µCT), ex vivo contrast-enhanced (CE)-µCT, and histology. Design: Female Lewis rats (N = 4/group) underwent either sham surgery or anterior annular puncture to L3-L4 and L5-L6 (n = 8 IVDs/group) to induce IVD degeneration. Rats were allowed ad libidum cage activity before and after surgery and underwent in vivo µCT scanning at baseline and every 2 weeks post-op for 12 weeks to characterize longitudinal changes in IVD height. At 12 weeks, lumbar spines were dissected and underwent CE-µCT scanning to characterize endpoint glycosaminoglycan distribution and nucleus pulposus (NP) volume ratio. Spines were processed for safranin-O-stained sagittal histology, and IVD degeneration was graded via the Rutges scale. Results: Puncture IVDs exhibited loss of IVD height at all time points from 4 weeks onward compared to Sham-the most severe height loss occurred posteriorly, with significant changes also occurring in the NP and laterally. Puncture IVDs exhibited higher CE-µCT attenuation, indicative of lower glycosaminoglycan content, and reduced NP volume ratio compared to Sham. Histologically, Puncture IVDs had higher Rutges damage scores and exhibited reduced NP cellularity and hydration, disorganized annulus fibrosus (AF) lamellae with evidence of the stab tract, and indistinct AF-NP border compared to Sham. Conclusions: Characterization of the complex, 3D alterations involved in the onset and early progression of IVD degeneration can foster greater understanding of the pathoetiology of IVD degeneration and may inform future studies assessing more sensitive diagnostic techniques or novel therapies.
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Affiliation(s)
- Michael D Newton
- Orthopaedic Research Laboratories, Beaumont Health , Royal Oak, MI, USA
| | - Abigail A Marek
- Orthopaedic Research Laboratories, Beaumont Health , Royal Oak, MI, USA
| | - Michael Planalp
- Department of Orthopaedic Surgery, Beaumont Health , Royal Oak, MI, USA
| | - Daniel K Park
- Department of Orthopaedic Surgery, Beaumont Health , Royal Oak, MI, USA
| | - Kevin C Baker
- Orthopaedic Research Laboratories, Beaumont Health , Royal Oak, MI, USA
| | - Tristan Maerz
- Orthopaedic Research Laboratories, Beaumont Health , Royal Oak, MI, USA.,Department of Orthopaedic Surgery, University of Michigan , Ann Arbor, MI, USA
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Farrugia B, Smith SM, Shu CC, Melrose J. Spatiotemporal Expression of 3-B-3(-) and 7-D-4 Chondroitin Sulfation, Tissue Remodeling, and Attempted Repair in an Ovine Model of Intervertebral Disc Degeneration. Cartilage 2020; 11:234-250. [PMID: 31578084 PMCID: PMC7097983 DOI: 10.1177/1947603519876354] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
OBJECTIVE Examination of intervertebral disc (IVD) regeneration in an ovine annular lesion model. HYPOTHESIS Sulfation motifs are important functional determinants in glycosaminoglycans (GAGs). Previous studies have correlated 3-B-3(-) and 7-D-4 chondroitin sulfate (CS) motifs in tissues undergoing morphogenetic transition in development. We hypothesize that these motifs may also be expressed in degenerate IVDs and may represent a reparative response. DESIGN Induction of disc degeneration by 5 mm or 6 × 20 mm lesions in the annulus fibrosus (AF) over 6 or 3 to 6 months postoperation (PO). Tissue sections were stained with toluidine blue-fast green, 3-B-3(-) and 7-D-4 CS-sulfation motifs were immunolocalized in 3-month PO 6 × 20 mm lesion IVDs. Sulfated glycosaminoglycan (GAG), 3-B-3(-), and 7-D-4 epitopes were quantitated by ELISIA (enzyme-linked immunosorbent inhibition assay) in extracts of AF (lesion site and contralateral half) and nucleus pulposus (NP) 0, 3, and 6 months PO. RESULTS Collagenous overgrowth of lesions occurred in the outer AF. Chondroid metaplasia in ~20% of the 6 × 20 mm affected discs resulted in integration of an outgrowth of NP tissue with the inner AF lamellae preventing propagation of the lesion. 3-B-3(-) and 7-D-4 CS sulfation motifs were immunolocalized in this chondroid tissue. ELISIA quantified CS sulfation motifs demonstrating an increase 3 to 6 months PO in the AF lesion and a reduction in sulfated GAG not evident in the contralateral AF. CONCLUSIONS (1) Outer annular lesions underwent spontaneous repair. (2) Chondroid metaplasia of the inner 6 × 20 mm defect prevented its propagation suggesting an apparent reparative response.
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Affiliation(s)
- Brooke Farrugia
- Department of Biomedical Engineering, Melbourne School of Engineering, The University of Melbourne
| | - Susan M. Smith
- Raymond Purves Bone and Joint Research Laboratory, Kolling Institute of Medical Research, Northern Sydney Area Health Authority, Royal North Shore Hospital, St. Leonards, New South Wales, Australia
| | - Cindy C. Shu
- Raymond Purves Bone and Joint Research Laboratory, Kolling Institute of Medical Research, Northern Sydney Area Health Authority, Royal North Shore Hospital, St. Leonards, New South Wales, Australia
| | - James Melrose
- Raymond Purves Bone and Joint Research Laboratory, Kolling Institute of Medical Research, Northern Sydney Area Health Authority, Royal North Shore Hospital, St. Leonards, New South Wales, Australia
- Sydney Medical School, Northern, The University of Sydney, Royal North Shore Hospital, St. Leonards, New South Wales, Australia
- Graduate School of Biomedical Engineering, The University of New South Wales, Sydney, New South Wales, Australia
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Hom WW, Tschopp M, Lin HA, Nasser P, Laudier DM, Hecht AC, Nicoll SB, Iatridis JC. Composite biomaterial repair strategy to restore biomechanical function and reduce herniation risk in an ex vivo large animal model of intervertebral disc herniation with varying injury severity. PLoS One 2019; 14:e0217357. [PMID: 31136604 PMCID: PMC6538241 DOI: 10.1371/journal.pone.0217357] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 05/09/2019] [Indexed: 12/14/2022] Open
Abstract
Back pain commonly arises from intervertebral disc (IVD) damage including annulus fibrosus (AF) defects and nucleus pulposus (NP) loss. Poor IVD healing motivates developing tissue engineering repair strategies. This study evaluated a composite injectable IVD biomaterial repair strategy using carboxymethylcellulose-methylcellulose (CMC-MC) and genipin-crosslinked fibrin (FibGen) that mimic NP and AF properties, respectively. Bovine ex vivo caudal IVDs were evaluated in cyclic compression-tension, torsion, and compression-to-failure tests to determine IVD biomechanical properties, height loss, and herniation risk following experimentally-induced severe herniation injury and discectomy (4 mm biopsy defect with 20% NP removed). FibGen with and without CMC-MC had failure strength similar to discectomy injury suggesting no increased risk compared to surgical procedures, yet no biomaterials improved axial or torsional biomechanical properties suggesting they were incapable of adequately restoring AF tension. FibGen had the largest failure strength and was further evaluated in additional discectomy injury models with varying AF defect types (2 mm biopsy, 4 mm cruciate, 4 mm biopsy) and NP removal volume (0%, 20%). All simulated discectomy defects significantly compromised failure strength and biomechanical properties. The 0% NP removal group had mean values of axial biomechanical properties closer to intact levels than defects with 20% NP removed but they were not statistically different and 0% NP removal also decreased failure strength. FibGen with and without CMC-MC failed at super-physiological stress levels above simulated discectomy suggesting repair with these tissue engineered biomaterials may perform better than discectomy alone, although restored biomechanical function may require additional healing with the potential application of these biomaterials as sealants and cell/drug delivery carriers.
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Affiliation(s)
- Warren W. Hom
- Leni & Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Melanie Tschopp
- Leni & Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Huizi A. Lin
- Department of Biomedical Engineering, The City College of New York, New York, New York, United States of America
| | - Philip Nasser
- Leni & Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Damien M. Laudier
- Leni & Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Andrew C. Hecht
- Leni & Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
| | - Steven B. Nicoll
- Department of Biomedical Engineering, The City College of New York, New York, New York, United States of America
| | - James C. Iatridis
- Leni & Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, New York, New York, United States of America
- * E-mail:
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Shu CC, Dart A, Bell R, Dart C, Clarke E, Smith MM, Little CB, Melrose J. Efficacy of administered mesenchymal stem cells in the initiation and co-ordination of repair processes by resident disc cells in an ovine (Ovis aries) large destabilizing lesion model of experimental disc degeneration. JOR Spine 2018; 1:e1037. [PMID: 31463452 PMCID: PMC6686814 DOI: 10.1002/jsp2.1037] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Revised: 08/27/2018] [Accepted: 09/11/2018] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Forty percent of low back pain cases are due to intervertebral disc degeneration (IVDD), with mesenchymal stem cells (MSCs) a reported treatment. We utilized an ovine IVDD model and intradiscal heterologous MSCs to determine therapeutic efficacy at different stages of IVDD. METHODOLOGY Three nonoperated control (NOC) sheep were used for MSC isolation. In 36 sheep, 6 × 20 mm annular lesions were made at three spinal levels using customized blades/scalpel handles, and IVDD was allowed to develop for 4 weeks in the Early (EA) and late Acute (LA) groups, or 12 weeks in the chronic (EST) group. Lesion IVDs received injections of 10 × 106 MSCs or PBS, and after 8 (EA), 22 (LA) or 14 (EST) weeks recuperation the sheep were sacrificed. Longitudinal lateral radiographs were used to determine disc heights. IVD glycosaminoglycan (GAG) and hydroxyproline contents were quantified using established methods. An Instron materials testing machine and customized jigs analyzed IVD (range of motion, neutral zone [NZ] and stiffness) in flexion/extension, lateral bending and axial rotation. qRTPCR gene profiles of key anabolic and catabolic matrix molecules were undertaken. Toluidine blue and hematoxylin and eosin stained IVD sections were histopathologically scoring by two blinded observers. RESULTS IVDD significantly reduced disc heights. MSC treatment restored 95% to 100% of disc height, maximally improved NZ and stiffness in flexion/extension and lateral bending in the EST group, restoring GAG levels. With IVDD qRTPCR demonstrated elevated catabolic gene expression (MMP2/3/9/13, ADAMTS4/5) in the PBS IVDs and expession normalization in MSC-treated IVDs. Histopathology degeneracy scores were close to levels of NOC IVDs in MSC IVDs but IVDD developed in PBS injected IVDs. DISCUSSION Administered MSCs produced recovery in degenerate IVDs, restored disc height, composition, biomechanical properties, down regulated MMPs and fibrosis, strongly supporting the efficacy of MSCs for disc repair.
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Affiliation(s)
- Cindy C. Shu
- Raymond Purves Bone and Joint Research Laboratory, Kolling Institute, Northern Sydney Local Health DistrictSt. LeonardsNew South WalesAustralia
- Faculty of Medicine and HealthUniversity of Sydney, Royal North Shore HospitalSt. LeonardsNew South WalesAustralia
| | - Andrew Dart
- University of SydneyVeterinary Teaching HospitalCamdenNew South WalesAustralia
| | - Robin Bell
- University of SydneyVeterinary Teaching HospitalCamdenNew South WalesAustralia
| | - Christina Dart
- University of SydneyVeterinary Teaching HospitalCamdenNew South WalesAustralia
| | - Elizabeth Clarke
- Faculty of Medicine and HealthUniversity of Sydney, Royal North Shore HospitalSt. LeonardsNew South WalesAustralia
- Murray Maxwell Biomechanics Laboratory, Kolling Institute of Medical Research, The Royal North Shore HospitalUniversity of SydneySt LeonardsNew South WalesAustralia
| | - Margaret M. Smith
- Raymond Purves Bone and Joint Research Laboratory, Kolling Institute, Northern Sydney Local Health DistrictSt. LeonardsNew South WalesAustralia
- Faculty of Medicine and HealthUniversity of Sydney, Royal North Shore HospitalSt. LeonardsNew South WalesAustralia
| | - Christopher B. Little
- Raymond Purves Bone and Joint Research Laboratory, Kolling Institute, Northern Sydney Local Health DistrictSt. LeonardsNew South WalesAustralia
- Faculty of Medicine and HealthUniversity of Sydney, Royal North Shore HospitalSt. LeonardsNew South WalesAustralia
- Sydney Medical School, NorthernThe University of SydneySt LeonardsNew South WalesAustralia
| | - James Melrose
- Raymond Purves Bone and Joint Research Laboratory, Kolling Institute, Northern Sydney Local Health DistrictSt. LeonardsNew South WalesAustralia
- Faculty of Medicine and HealthUniversity of Sydney, Royal North Shore HospitalSt. LeonardsNew South WalesAustralia
- Sydney Medical School, NorthernThe University of SydneySt LeonardsNew South WalesAustralia
- Graduate School of Biomedical EngineeringUniversity of New South WalesSydneyNew South WalesAustralia
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Long RG, Zderic I, Gueorguiev B, Ferguson SJ, Alini M, Grad S, Iatridis JC. Effects of Level, Loading Rate, Injury and Repair on Biomechanical Response of Ovine Cervical Intervertebral Discs. Ann Biomed Eng 2018; 46:1911-1920. [PMID: 29926304 DOI: 10.1007/s10439-018-2077-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 06/13/2018] [Indexed: 12/15/2022]
Abstract
A need exists for pre-clinical large animal models of the spine to translate biomaterials capable of repairing intervertebral disc (IVD) defects. This study characterized the effects of cervical spinal level, loading rate, injury and repair with genipin-crosslinked fibrin (FibGen) on axial and torsional mechanics in an ovine cervical spine model. Cervical IVDs C2-C7 from nine animals were tested with cyclic tension-compression (- 240 to 100 N) and cyclic torsion (± 2° and ± 4°) tests at three rates (0.1, 1 and 2 Hz) in intact, injured and repaired conditions. Intact IVDs from upper cervical levels (C2-C4) had significantly higher torque range and torsional stiffness and significantly lower axial range of motion (ROM) and tensile compliance than IVDs from lower cervical levels (C5-C7). A tenfold increase in loading rate significantly increased torque range and torsional stiffness 4-8% (depending on amplitude) (p < 0.001). When normalized to intact, FibGen significantly restored torque range (FibGen: 0.96 ± 0.14, Injury: 0.88 ± 0.14, p = 0.03) and axial ROM (FibGen: 1.00 ± 0.05, Injury: 1.04 ± 0.15, p = 0.02) compared to Injury, with a values of 1 indicating full repair. Cervical spinal level must be considered for controlling biomechanical evaluations, and FibGen restored some torsional and axial biomechanical properties to intact levels.
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Affiliation(s)
- Rose G Long
- AO Research Institute Davos, Clavadelstrasse 8, 7270, Davos, Switzerland.,Leni & Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, 1 Gustave Levy Place, Box 1188, New York, NY, 10029-6574, USA
| | - Ivan Zderic
- AO Research Institute Davos, Clavadelstrasse 8, 7270, Davos, Switzerland
| | - Boyko Gueorguiev
- AO Research Institute Davos, Clavadelstrasse 8, 7270, Davos, Switzerland
| | | | - Mauro Alini
- AO Research Institute Davos, Clavadelstrasse 8, 7270, Davos, Switzerland
| | - Sibylle Grad
- AO Research Institute Davos, Clavadelstrasse 8, 7270, Davos, Switzerland
| | - James C Iatridis
- Leni & Peter W. May Department of Orthopaedics, Icahn School of Medicine at Mount Sinai, 1 Gustave Levy Place, Box 1188, New York, NY, 10029-6574, USA.
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Abstract
STUDY DESIGN Ovine in vivo study. OBJECTIVE To perform lateral approach lumbar surgery in an ovine model to administer an injectable riboflavin cross-linked high-density collagen (HDC) gel and to assess its ability to mitigate intervertebral disc (IVD) degeneration after induced annulus fibrosus (AF) injury. SUMMARY OF BACKGROUND DATA Biological-based injectable gels have shown efficacy in restoring biomechanical, radiographic, and histological parameters in IVD-injured animal models. Riboflavin cross-linked HDC gel has previously demonstrated retention of nucleus pulposus (NP) tissue, reduced loss of disc height, and prevention of terminal cellular degenerative changes in rat-tail spines. However, this biological therapy has never been tested in large animal models. METHODS Forty lumbar IVDs were accessed from eight sheep via lateral approach surgery. IVDs were randomly assigned to healthy control, injury and HDC treatment, or negative control with injury and no treatment. IVD injury was carried out using a drill-bit through the AF followed by needle puncture of the NP. Sheep were followed for 16 weeks and underwent qualitative/quantitative magnetic resonance imaging, x-ray, and histological analyses of collagen and proteoglycan content. RESULTS The lateral approach to the ovine lumbar spine to deliver HDC gel proved to be safe and reproducible. IVDs treated with the HDC gel revealed less degenerative changes at the microscopic level based on AF and NP histology. However, mean Pfirrmann grade, T2 relaxation time, NP voxel size, and disc height index were not significantly different between the two injury groups. CONCLUSION Injectable HDC gel can be administered safely via lateral approach surgery in an ovine AF injury model. IVDs treated with HDC gel demonstrated less degeneration at the microscopic level though radiographic changes were slight when comparing treated to untreated IVDs. Future studies will need to elucidate the role of injury technique and time frame for follow-up in correlating histological and radiographical outcomes. LEVEL OF EVIDENCE N /A.
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Grunert P, Moriguchi Y, Grossbard BP, Ricart Arbona RJ, Bonassar LJ, Härtl R. Degenerative changes of the canine cervical spine after discectomy procedures, an in vivo study. BMC Vet Res 2017. [PMID: 28645289 PMCID: PMC5481861 DOI: 10.1186/s12917-017-1105-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Discectomies are a common surgical treatment for disc herniations in the canine spine. However, the effect of these procedures on intervertebral disc tissue is not fully understood. The objective of this study was to assess degenerative changes of cervical spinal segments undergoing discectomy procedures, in vivo. RESULTS Discectomies led to a 60% drop in disc height and 24% drop in foraminal height. Segments did not fuse but showed osteophyte formation as well as endplate sclerosis. MR imaging revealed terminal degenerative changes with collapse of the disc space and loss of T2 signal intensity. The endplates showed degenerative type II Modic changes. Quantitative MR imaging revealed that over 95% of Nucleus Pulposus tissue was extracted and that the nuclear as well as overall disc hydration significantly decreased. Histology confirmed terminal degenerative changes with loss of NP tissue, loss of Annulus Fibrosus organization and loss of cartilage endplate tissue. The bony endplate displayed sclerotic changes. CONCLUSION Discectomies lead to terminal degenerative changes. Therefore, these procedures should be indicated with caution specifically when performed for prophylactic purposes.
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Affiliation(s)
- Peter Grunert
- Department of Neurological Surgery, Weill Cornell Medicine, New York-Presbyterian Hospital, Weill Cornell Brain and Spine Institute
- , 525 East 68th Street, Box 99, New York, NY, 10065, USA.,Department of Neurological Surgery, Swedish Neuroscience Institute, Seattle, WA, USA
| | - Yu Moriguchi
- Department of Neurological Surgery, Weill Cornell Medicine, New York-Presbyterian Hospital, Weill Cornell Brain and Spine Institute
- , 525 East 68th Street, Box 99, New York, NY, 10065, USA
| | - Brian P Grossbard
- Department of Orthopedics and Neurosurgery VCA-Animal Specialty, Yonkers, NY, USA
| | - Rodolfo J Ricart Arbona
- Center of Comparative Medicine and Pathology, Memorial Sloan Kettering Cancer Center & Weill Cornell Medicine, New York City, NY, USA
| | | | - Roger Härtl
- Department of Neurological Surgery, Weill Cornell Medicine, New York-Presbyterian Hospital, Weill Cornell Brain and Spine Institute
- , 525 East 68th Street, Box 99, New York, NY, 10065, USA.
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12
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Shu CC, Smith MM, Smith SM, Dart AJ, Little CB, Melrose J. A Histopathological Scheme for the Quantitative Scoring of Intervertebral Disc Degeneration and the Therapeutic Utility of Adult Mesenchymal Stem Cells for Intervertebral Disc Regeneration. Int J Mol Sci 2017; 18:E1049. [PMID: 28498326 PMCID: PMC5454961 DOI: 10.3390/ijms18051049] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 04/28/2017] [Accepted: 05/08/2017] [Indexed: 12/12/2022] Open
Abstract
The purpose of this study was to develop a quantitative histopathological scoring scheme to evaluate disc degeneration and regeneration using an ovine annular lesion model of experimental disc degeneration. Toluidine blue and Haematoxylin and Eosin (H&E) staining were used to evaluate cellular morphology: (i) disc structure/lesion morphology; (ii) proteoglycan depletion; (iii) cellular morphology; (iv) blood vessel in-growth; (v) cell influx into lesion; and (vi) cystic degeneration/chondroid metaplasia. Three study groups were examined: 5 × 5 mm lesion; 6 × 20 mm lesion; and 6 × 20 mm lesion plus mesenchymal stem cell (MSC) treatment. Lumbar intervertebral discs (IVDs) were scored under categories (i-vi) to provide a cumulative score, which underwent statistical analysis using STATA software. Focal proteoglycan depletion was associated with 5 × 5 mm annular rim lesions, bifurcations, annular delamellation, concentric and radial annular tears and an early influx of blood vessels and cells around remodeling lesions but the inner lesion did not heal. Similar features in 6 × 20 mm lesions occurred over a 3-6-month post operative period. MSCs induced a strong recovery in discal pathology with a reduction in cumulative histopathology degeneracy score from 15.2 to 2.7 (p = 0.001) over a three-month recovery period but no recovery in carrier injected discs.
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Affiliation(s)
- Cindy C Shu
- Raymond Purves Bone and Joint Research Laboratory, Kolling Institute, Northern Sydney Local Health District, St. Leonards, NSW 2065, Australia.
| | - Margaret M Smith
- Raymond Purves Bone and Joint Research Laboratory, Kolling Institute, Northern Sydney Local Health District, St. Leonards, NSW 2065, Australia.
| | - Susan M Smith
- Raymond Purves Bone and Joint Research Laboratory, Kolling Institute, Northern Sydney Local Health District, St. Leonards, NSW 2065, Australia.
| | - Andrew J Dart
- Faculty of Veterinary Science, University Veterinary Teaching Hospital, University of Sydney, Camden, NSW 2050, Australia.
| | - Christopher B Little
- Raymond Purves Bone and Joint Research Laboratory, Kolling Institute, Northern Sydney Local Health District, St. Leonards, NSW 2065, Australia.
- Sydney Medical School, Northern, The University of Sydney, Royal North Shore Hospital, St. Leonards, NSW 2065, Australia.
| | - James Melrose
- Raymond Purves Bone and Joint Research Laboratory, Kolling Institute, Northern Sydney Local Health District, St. Leonards, NSW 2065, Australia.
- Sydney Medical School, Northern, The University of Sydney, Royal North Shore Hospital, St. Leonards, NSW 2065, Australia.
- Graduate School of Biomedical Engineering, University of New South Wales, Kensington, NSW 2052, Australia.
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13
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Melrose J. Strategies in regenerative medicine for intervertebral disc repair using mesenchymal stem cells and bioscaffolds. Regen Med 2016; 11:705-24. [DOI: 10.2217/rme-2016-0069] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The intervertebral disc (IVD) is a major weight bearing structure that undergoes degenerative changes with aging limiting its ability to dissipate axial spinal loading in an efficient manner resulting in the generation of low back pain. Low back pain is a number one global musculoskeletal disorder with massive socioeconomic impact. The WHO has nominated development of mesenchymal stem cells and bioscaffolds to promote IVD repair as primary research objectives. There is a clear imperative for the development of strategies to effectively treat IVD defects. Early preclinical studies with mesenchymal stem cells in canine and ovine models have yielded impressive results in IVD repair. Combinatorial therapeutic approaches encompassing biomaterial and cell-based therapies promise significant breakthroughs in IVD repair in the near future.
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Affiliation(s)
- James Melrose
- Raymond Purves Bone & Joint Research Laboratory, Kolling Institute Northern Sydney Local Health District, St Leonards, NSW 2065, Australia
- Sydney Medical School, Northern, The University of Sydney, Royal North Shore Hospital, St Leonards, NSW 2065, Australia
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, NSW 2052, Australia
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14
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Kang YM, Hong SH, Yang JH, Oh JC, Park JO, Lee BH, Lee SY, Kim HS, Lee HM, Moon SH. Pamidronate Down-regulates Tumor Necrosis Factor-alpha Induced Matrix Metalloproteinases Expression in Human Intervertebral Disc Cells. J Bone Metab 2016; 23:165-73. [PMID: 27622181 PMCID: PMC5018610 DOI: 10.11005/jbm.2016.23.3.165] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Revised: 08/12/2016] [Accepted: 08/12/2016] [Indexed: 01/08/2023] Open
Abstract
Background N-containing bisphosphonates (BPs), such as pamidronate and risedronate, can inhibit osteoclastic function and reduce osteoclast number by inducing apoptotic cell death in osteoclasts. The aim of this study is to demonstrate the effect of pamidronate, second generation nitrogen-containing BPs and to elucidate matrix metallo-proteinases (MMPs) mRNA expression under serum starvation and/or tumor necrosis factor alpha (TNF-α) stimulation on metabolism of intervertebral disc (IVD) cells in vitro. Methods Firstly, to test the effect of pamidronate on IVD cells in vitro, various concentrations (10-12, 10-10, 10-8, and 10-6 M) of pamidronate were administered to IVD cells. Then DNA and proteoglycan synthesis were measured and messenger RNA (mRNA) expressions of type I collagen, type II collagen, and aggrecan were analyzed. Secondly, to elucidate the expression of MMPs mRNA in human IVD cells under the lower serum status, IVD cells were cultivated in full serum or 1% serum. Thirdly, to elucidate the expression of MMPs mRNA in IVD cells under the stimulation of 1% serum and TNF-α (10 ng/mL) In this study, IVD cells were cultivated in three dimensional alginate bead. Results Under the lower serum culture, IVD cells in alginate beads showed upregulation of MMP 2, 3, 9, 13 mRNA. The cells in lower serum and TNF-α also demonstrated upregulation of MMP-2, 3, 9, and 13 mRNA. The cells with various doses of pamidronate and lower serum and TNF-α were reveled partial down-regulation of MMPs. Conclusions Pamidronate, N-containing second generation BPs, was safe in metabolism of IVD in vitro maintaining chondrogenic phenotype and matrix synthesis, and down-regulated TNF-α induced MMPs expression.
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Affiliation(s)
- Young-Mi Kang
- The Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea
| | - Seong-Hwan Hong
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea
| | - Jae-Ho Yang
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea
| | - Jin-Cheol Oh
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea
| | - Jin-Oh Park
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea
| | - Byung Ho Lee
- Department of Orthopedic Surgery, Catholic Kwandong University College of Medicine, Incheon, Korea
| | - Sang-Yoon Lee
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea
| | - Hak-Sun Kim
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea
| | - Hwan-Mo Lee
- Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea
| | - Seong-Hwan Moon
- The Brain Korea 21 PLUS Project for Medical Science, Yonsei University College of Medicine, Seoul, Korea.; Department of Orthopaedic Surgery, Yonsei University College of Medicine, Seoul, Korea
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15
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Sitte I, Klosterhuber M, Lindtner RA, Freund MC, Neururer SB, Pfaller K, Kathrein A. Morphological changes in the human cervical intervertebral disc post trauma: response to fracture-type and degeneration grade over time. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2015; 25:80-95. [PMID: 26188769 DOI: 10.1007/s00586-015-4089-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 06/20/2015] [Accepted: 06/26/2015] [Indexed: 12/25/2022]
Abstract
PURPOSE In the first 24 h post-intervertebral disc (IVD) trauma, up to 75 % cell death has been reported. In addition, burst fractures cause post-traumatic disc degeneration by elevated pro-apoptotic and pro-inflammatory gene transcription. Moreover, some patients have pre-trauma degenerative disc disease. The aim of the study was to assess histological changes and cell-death over a time period of up to 1 year caused by mechanical and structural factors. METHODS 116 anterior portions of IVDs of the cervical spine were studied histologically by light microscopy and ultrastructurally by transmission electron microscopy (TEM). The group was investigated with regard to three main parameters: fracture mechanism (compressive vs. tensile/shear loads), degeneration grade (low vs. high) and endplate fracture (with vs. without). Disc architecture (e.g. ruptures) was studied histologically. Cell morphology was examined ultrastructurally to quantify cell-death, healthy and balloon cells. According to ultrastructural observations, two time-groups (up to 6 days vs. later) were established. Statistical analyses were carried out within and between time-groups. RESULTS Histological changes were obvious in the annulus fibrosus where ruptures with haematoma were replaced by granulation tissue. Significant differences in cell-death were seen in the first few days due to different loads. In contrast to the more degenerated segments, low degenerated ones revealed significantly less cell death with time post-trauma. Interestingly, no difference was found between groups after the sixth day. Cell-death (mean 44 % for all investigated groups) remained high after day 6 post-trauma. CONCLUSION IVDs retrieved from low grade degenerated segments revealed a significant recovery, with less cell-death and a partially restored disc matrix, although cell-death remained high. Long-term clinical studies of stabilized segments arising from different fracture mechanisms are required.
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Affiliation(s)
- Ingrid Sitte
- Department of Traumatology, Medical University of Innsbruck, Anichstr. 35, 6020, Innsbruck, Austria.
| | - Miranda Klosterhuber
- Department of Traumatology, Medical University of Innsbruck, Anichstr. 35, 6020, Innsbruck, Austria
| | - Richard Andreas Lindtner
- Department of Traumatology, Medical University of Innsbruck, Anichstr. 35, 6020, Innsbruck, Austria
| | | | - Sabrina Barbara Neururer
- Department for Medical Statistics, Informatics and Health Economics, Medical University of Innsbruck, Innsbruck, Austria
| | - Kristian Pfaller
- Division of Histology and Embryology, Medical University of Innsbruck, Innsbruck, Austria
| | - Anton Kathrein
- Department of Traumatology and Sports Medicine, Sankt Vinzenz Krankenhaus Zams, Zams, Austria
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16
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Papadimitriou N, Thorfve A, Brantsing C, Junevik K, Baranto A, Barreto Henriksson H. Cell Viability and Chondrogenic Differentiation Capability of Human Mesenchymal Stem Cells After Iron Labeling with Iron Sucrose. Stem Cells Dev 2014; 23:2568-80. [DOI: 10.1089/scd.2014.0153] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Affiliation(s)
- Nikolaos Papadimitriou
- Department of Orthopaedics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Anna Thorfve
- Department for Biomaterials, Institute of Clinical Sciences, Sahlgrenska Academy, Gothenburg University of Gothenburg, Gothenburg, Sweden
| | - Camilla Brantsing
- Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Katarina Junevik
- Department of Clinical Chemistry and Transfusion Medicine, Institute of Biomedicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
| | - Adad Baranto
- Department of Orthopaedics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden
| | - Helena Barreto Henriksson
- Department of Orthopaedics, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden
- Department of Orthopaedics, Sahlgrenska University Hospital, Gothenburg, Sweden
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17
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Oehme D, Ghosh P, Shimmon S, Wu J, McDonald C, Troupis JM, Goldschlager T, Rosenfeld JV, Jenkin G. Mesenchymal progenitor cells combined with pentosan polysulfate mediating disc regeneration at the time of microdiscectomy: a preliminary study in an ovine model. J Neurosurg Spine 2014; 20:657-69. [PMID: 24702507 DOI: 10.3171/2014.2.spine13760] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECT Following microdiscectomy, discs generally fail to undergo spontaneous regeneration and patients may experience chronic low-back pain and recurrent disc prolapse. In published studies, formulations of mesenchymal progenitor cells combined with pentosan polysulfate (MPCs+PPS) have been shown to regenerate disc tissue in animal models, suggesting that this approach may provide a useful adjunct to microdiscectomy. The goal of this preclinical laboratory study was to determine if the transplantation of MPCs+PPS, embedded in a gelatin/fibrin scaffold (SCAF), and transplanted into a defect created by microdiscectomy, could promote disc regeneration. METHODS A standardized microdiscectomy procedure was performed in 18 ovine lumbar discs. The subsequent disc defects were randomized to receive either no treatment (NIL), SCAF only, or the MPC+PPS formulation added to SCAF (MPCs+PPS+SCAF). Necropsies were undertaken 6 months postoperatively and the spines analyzed radiologically (radiography and MRI), biochemically, and histologically. RESULTS No adverse events occurred throughout the duration of the study. The MPC+PPS+SCAF group had significantly less reduction in disc height compared with SCAF-only and NIL groups (p < 0.05 and p < 0.01, respectively). Magnetic resonance imaging Pfirrmann scores in the MPC+PPS+SCAF group were significantly lower than those in the SCAF group (p = 0.0213). The chaotropic solvent extractability of proteoglycans from the nucleus pulposus of MPC+PPS+SCAF-treated discs was significantly higher than that from the SCAF-only discs (p = 0.0312), and using gel exclusion chromatography, extracts from MPC+PPS+SCAF-treated discs also contained a higher percentage of proteoglycan aggregates than the extracts from both other groups. Analysis of the histological sections showed that 66% (p > 0.05) of the MPC+PPS+SCAF-treated discs exhibited less degeneration than the NIL or SCAF discs. CONCLUSIONS These findings demonstrate the capacity of MPCs in combination with PPS, when embedded in a gelatin sponge and sealed with fibrin glue in a microdiscectomy defect, to restore disc height, disc morphology, and nucleus pulposus proteoglycan content.
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Affiliation(s)
- David Oehme
- The Ritchie Centre, Monash Institute of Medical Research, Monash University, Clayton, Victoria
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18
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Sharifi S, Bulstra SK, Grijpma DW, Kuijer R. Treatment of the degenerated intervertebral disc; closure, repair and regeneration of the annulus fibrosus. J Tissue Eng Regen Med 2014; 9:1120-32. [PMID: 24616324 DOI: 10.1002/term.1866] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2013] [Revised: 09/19/2013] [Accepted: 11/25/2013] [Indexed: 12/25/2022]
Abstract
Degeneration of the intervertebral disc (IVD) and disc herniation are two causes of low back pain. The aetiology of these disorders is unknown, but tissue weakening, which primarily occurs due to inherited genetic factors, ageing, nutritional compromise and loading history, is the basic factor causing disc degeneration. Symptomatic disc herniation mainly causes radicular pain. Current treatments of intervertebral disc degeneration and low back pain are based on alleviating the symptoms and comprise administration of painkillers or surgical methods such as spinal fusion. None of these methods is completely successful. Current research focuses on regeneration of the IVD and particularly on regeneration of the nucleus pulposus. Less attention has been directed to the repair or regeneration of the annulus fibrosus, although this is the key to successful nucleus pulposus, and therewith IVD, repair. This review focuses on the importance of restoring the function of the annulus fibrosus, as well as on the repair, replacement or regeneration of the annulus fibrosus in combination with restoration of the function of the nucleus pulposus, to treat low back pain.
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Affiliation(s)
- Shahriar Sharifi
- University of Groningen, University Medical Center Groningen, W. J. Kolff Institute, Department of Biomedical Engineering, Groningen, The Netherlands
- MIRA Institute for Biomedical Technology and Technical Medicine, Department of Biomaterials Science and Technology, University of Twente, Enschede, The Netherlands
| | - Sjoerd K Bulstra
- University of Groningen, University Medical Center Groningen, Department of Orthopaedic Surgery, Groningen, The Netherlands
| | - Dirk W Grijpma
- University of Groningen, University Medical Center Groningen, W. J. Kolff Institute, Department of Biomedical Engineering, Groningen, The Netherlands
- MIRA Institute for Biomedical Technology and Technical Medicine, Department of Biomaterials Science and Technology, University of Twente, Enschede, The Netherlands
| | - Roel Kuijer
- University of Groningen, University Medical Center Groningen, W. J. Kolff Institute, Department of Biomedical Engineering, Groningen, The Netherlands
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Tang X, Richardson WJ, Fitch RD, Brown CR, Isaacs RE, Chen J. A new non-enzymatic method for isolating human intervertebral disc cells preserves the phenotype of nucleus pulposus cells. Cytotechnology 2013; 66:979-86. [PMID: 24101443 PMCID: PMC4235948 DOI: 10.1007/s10616-013-9650-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 09/20/2013] [Indexed: 01/05/2023] Open
Abstract
Cells isolated from intervertebral disc (IVD) tissues of human surgical samples are one of potential sources for the IVD cellular therapy. The purpose of this study was to develop a new non-enzymatic method, “tissue incubation”, for isolating human IVD cells. The IVD tissues of annulus fibrosus (AF) and nucleus pulposus (NP) were incubated separately in tissue culture flasks with culture medium. After 7–10 days incubation, cells were able to migrate out of IVD tissues and proliferate in vitro. After 3–4 weeks culture, expanded cells were harvested by trypsinization, and the remaining tissues were transferred to a new flask for another round of incubation. The molecular phenotype of IVD cells from juvenile and adult human samples was evaluated by both flow cytometry analysis and immunocytochemical staining for the expression of protein markers of NP cells (CD24, CD54, CD239, integrin α6 and laminin α5). Flow cytometry confirmed that both AF and NP cells of all ages positively expressed CD54 and integrin α6, with higher expression levels in NP cells than in AF cells for the juvenile group sample. However, CD24 expression was only found in juvenile NP cells, and not in AF or older disc cells. Similar expression patterns for NP markers were also confirmed by immunocytochemistry. In summary, this new non-enzymatic tissue incubation method for cell isolation preserves molecular phenotypic markers of NP cells and may provide a valuable cell source for the study of NP regeneration strategies.
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Affiliation(s)
- Xinyan Tang
- Department of Biomedical Engineering, Duke University, Durham, NC, USA
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Rainsford KD, Haynes DR. Professor Barrie Vernon-Roberts, AO, MD, BSc, PhD, FRCPath, FRCPA, FAOrthA (Hon), FRS.SA. Inflammopharmacology 2013; 21:269-77. [PMID: 23824627 DOI: 10.1007/s10787-013-0176-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 06/11/2013] [Indexed: 11/25/2022]
Abstract
This issue of Inflammopharmacology contains papers that have been submitted to commemorate the life and work of Professor Barrie Vernon-Roberts, an outstanding clinical scientist in the field of bone pathology and its pharmacological regulation. This review briefly summarizes his major works and achievements as well as a list of his publications.
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21
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Nisolle JF, Wang XQ, Squélart M, Hontoir F, Kirschvink N, Clegg P, Vandeweerd JM. Magnetic resonance imaging (MRI) anatomy of the ovine lumbar spine. Anat Histol Embryol 2013; 43:203-9. [PMID: 23668479 DOI: 10.1111/ahe.12063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 04/07/2013] [Indexed: 11/30/2022]
Abstract
Although the ovine spine is a useful research model for intervertebral disc pathology and vertebral surgery, there is little peer-reviewed information regarding the MRI anatomy of the ovine spine. To describe the lumbar spine MRI anatomy, 10 lumbar segments of cadaver ewes were imaged by 1.5-Tesla MR. Sagittal and transverse sequences were performed in T1 and T2 weighting (T1W, T2W), and the images were compared to gross anatomic sagittal and transverse sections performed through frozen spines. MRI was able to define most anatomic structures of the ovine spine in a similar way as can be imaged in humans. In both T1W and T2W, the signals of ovine IVDs were similar to those observed in humans. Salient anatomic features were identified: (1) a 2- to 3-mm linear zone of hypersignal was noticed on both extremities of the vertebral body parallel to the vertebral plates in sagittal planes; (2) the tendon of the crura of the diaphragm appeared as a hypointense circular structure between hypaxial muscles and the aorta and caudal vena cava; (3) dorsal and ventral longitudinal ligaments and ligamentum flavum were poorly imaged; (4) no ilio-lumbar ligament was present; (5) the spinal cord ended between S1-S2 level, and the peripheral white matter and central grey matter were easily distinguished on T1W and T2W images. This study provides useful reference images to researchers working with ovine models.
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Affiliation(s)
- J F Nisolle
- Department of Veterinary Medicine, Integrated Veterinary Research Unit-Namur Research Institute for Life Science (IRVU-NARILIS), University of Namur, Rue de Bruxelles, 61, 5000 Namur, Belgium; Centre Hospitalier Universitaire (CHU) de Mont Godinne, Université Catholique de Louvain, Avenue du Dr Gaston Thérasse, 1, 5530 Yvoir, Belgium
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Abstract
STUDY DESIGN Investigation of injectable nucleus pulposus (NP) implant. OBJECTIVE To assess the ability of a recently developed injectable hydrogel implant to restore nondegenerative disc mechanics through support of NP functional mechanics. SUMMARY OF BACKGROUND DATA Although surgical intervention for low back pain is effective for some patients, treated discs undergo altered biomechanics and adjacent levels are at increased risk for accelerated degeneration. One potential treatment as an alternative to surgery for degenerated disc includes the percutaneous delivery of agents to support NP functional mechanics. The implants are delivered in a minimally invasive fashion, potentially on an outpatient basis, and do not preclude later surgical options. One of the challenges in designing such implants includes the need to match key NP mechanical behavior and mimic the role of native nondegenerate NP in spinal motion. METHODS The oxidized hyaluronic acid gelatin implant material was prepared. In vitro mechanical testing was performed in mature ovine bone-disc-bone units in 3 stages: intact, discectomy, and implantation versus sham. Tested samples were cut axially for qualitative structural observations. RESULTS Discectomy increased axial range of motion (ROM) significantly compared with intact. Hydrogel implantation reduced ROM 17% (P < 0.05) compared with discectomy and returned ROM to intact levels (ROM intact 0.71 mm, discectomy 0.87 mm, postimplantation 0.72 mm). Although ROM for the hydrogel implant group was statistically unchanged compared with the intact disc, ROM for sham discs, which received a discectomy and no implant, was significantly increased compared with intact. The compression and tension stiffness were decreased with discectomy and remained unchanged for both implant and sham groups as expected because the annulus fibrosus was not repaired. Gross morphology images confirmed no ejection of NP implant. CONCLUSION An injectable implant that mimics nondegenerate NP has the potential to return motion segment ROM to normal subsequent to injury.
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Tissue engineering of the intervertebral disc with cultured nucleus pulposus cells using atelocollagen scaffold and growth factors. Spine (Phila Pa 1976) 2012; 37:452-8. [PMID: 22037529 DOI: 10.1097/brs.0b013e31823c8603] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN In vitro experiment using rabbit nucleus pulposus (NP) cells seeded in atelocollagen scaffolds under the stimulation of growth factors. OBJECTIVE To demonstrate the effect of anabolic growth factors in rabbit NP cells cultured in atelocollagen type I and type II. SUMMARY OF BACKGROUND DATA Atelocollagen provides intervertebral disc (IVD) cells for a biocompatible environment to produce extracellular matrix. IVD cells with exogenous transforming growth factor-beta 1 (TGF-β1) and bone morphogenetic protein-2 (BMP-2) also render an increase in matrix synthesis. However, the effect of anabolic growth factors in NP cells cultured in atelocollagens was not elucidated before. METHODS Rabbit NP cell was harvested, enzymatically digested, and cultured. The NP cells were seeded to atelocollagen type I and type II scaffolds, and then cultures were exposed to TGF-β1 (10 ng/mL) and/or BMP-2 (100 ng/mL). DNA synthesis was measured using [4H]-thymidine incorporation. Newly synthesized proteoglycan was measured using [35S]-sulfate incorporation. Reverse transcription-polymerase chain reactions (RT-PCRs) for mRNA expression of aggrecan, collagen type I, collagen type II, and osteocalcin were performed. RESULTS Rabbit NP cells cultured in atelocollagen type I scaffold showed an increase (1.7 to 2.4-fold) in DNA synthesis in response to TGF-β1 and/or BMP-2 (P < 0.05), whereas NP cultures in atelocollagen type II demonstrated a 30% increase in DNA synthesis only with combination of both growth factors compared with control (P < 0.05). Rabbit NP cells in atelocollagen type II scaffold with TGF-β1 and combination of both growth factors exhibited robust 5.3- and 5.4-fold increases in proteoglycan synthesis (P < 0.05), whereas any cultures in atelocollagen type I failed to show any significant increase compared with control. Rabbit NP cells in atelocollagen type I and type II scaffolds with TGF-β1 and/or BMP-2 demonstrated the upregulation of aggrecan, collagen type I, and collagen type II mRNA expression compared with saline control (P < 0.05). The response in transcriptional level was more robust in atelocollagen type II than in type I. In any event, there is no recognizable expression of osteocalcin (P < 0.05). CONCLUSION NP cells in atelocollagens under the stimulation of TGF-β1 and BMP-2 exhibited anabolic responses in transcriptional and translational levels. Hence, such an approach can provide a suitable engineered tissue for IVD regeneration with potential for robust refurbishment of matrix.
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Ghosh P, Moore R, Vernon-Roberts B, Goldschlager T, Pascoe D, Zannettino A, Gronthos S, Itescu S. Immunoselected STRO-3+ mesenchymal precursor cells and restoration of the extracellular matrix of degenerate intervertebral discs. J Neurosurg Spine 2012; 16:479-88. [PMID: 22404141 DOI: 10.3171/2012.1.spine11852] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
OBJECT Chronic low-back pain of discal origin is linked strongly to disc degeneration. Current nonsurgical treatments are palliative and fail to restore the disc extracellular matrix. In this study the authors examined the capacity of ovine mesenchymal precursor cells (MPCs) to restore the extracellular matrix of degenerate discs in an ovine model. METHODS Three adjacent lumbar discs of 24 adult male sheep were injected intradiscally with chondroitinase-ABC (cABC) to initiate disc degeneration. The remaining lumbar discs were used as normal controls. Three months after cABC injection, the L3-4 discs of all animals were injected with either a high dose (4 × 10(6) cells, in 12 sheep) or low dose (0.5 × 10(6) cells, in 12 sheep) of MPCs suspended in hyaluronic acid (HA). The adjacent L4-5 degenerate discs remained untreated; the L5-6 discs were injected with HA only. The animals were euthanized at 3 or 6 months after MPC injections (6 sheep from each group at each time point), and histological sections of the lumbar discs were prepared. Radiographs and MR images were obtained prior to cABC injection (baseline), 3 months after cABC injection (pretreatment), and just prior to necropsy (posttreatment). RESULTS Injection of cABC decreased the disc height index (DHI) of target discs by 45%-50%, confirming degeneration. Some recovery in DHI was observed 6 months after treatment in all cABC-injected discs, but the DHI increased to within baseline control values only in the MPC-injected discs. This improvement was accompanied by a reduction in MRI degeneration scores. The histopathology scores observed at 3 months posttreatment for the high-dose MPC-injected discs and at 6 months posttreatment for the low-dose MPC-injected discs were significantly different from those of the noninjected and HA-injected discs (p <0.001) but not from the control disc scores. CONCLUSIONS On the basis of the findings of this study, the authors conclude that the injection of MPCs into degenerate intervertebral discs can contribute to the regeneration of a new extracellular matrix.
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Mechanical destabilization induced by controlled annular incision of the intervertebral disc dysregulates metalloproteinase expression and induces disc degeneration. Spine (Phila Pa 1976) 2012; 37:18-25. [PMID: 22179320 DOI: 10.1097/brs.0b013e31820cd8d5] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN An investigation of mechanical destabilization of the lumbar ovine intervertebral disc (IVD) inducing IVD degeneration (IVDD) as determined by multiparameter outcome measures (magnetic resonance imaging [MRI], IVD composition, biomechanical testing, gene profiling, immunohistochemistry, and immunoblotting). OBJECTIVE To assess the effect of IVD mechanical destabilization on matrix protein and metalloproteinase gene expression to investigate the pathophysiological mechanisms of lumbar IVDD. SUMMARY OF BACKGROUND DATA Several earlier studies have used annular transection to induce IVDD in sheep, but none have optimized or validated the most appropriate lesion size. METHODS The annulus fibrosus (AF) incision inducing maximal change in IVD biomechanics was applied to L1-L2, L3-L4, and L5-L6 discs in vivo to compare with a sham procedure at 3 months post operation. IVDs were evaluated by MRI, biomechanics, histopathology, proteoglycan and collagen content, gene expression, and aggrecan proteolysis by Western blotting. RESULTS Significant changes were observed in lesion (6 × 20 mm(2)) compared with sham IVDs at 3 months post operation: reduced disc height on MRI; increased neutral zone in biomechanical testing; depleted proteoglycan and collagen content in the nucleus pulposus (NP) and lesion half of the AF but not in the contralateral AF; increased messenger RNA for collagen I and II, aggrecan, versican, perlecan, matrix metalloproteinase (MMP)-1 & 13, and ADAMTS-5, in the lesion-site AF and NP but not in the contralateral AF. ADAMTS-4 messenger RNA was increased in the lesion-site AF but decreased in the NP. Despite an upregulation in MMPs, there was no change in MMP- or ADAMTS-generated aggrecan neoepitopes in any region of the IVD in lesion or sham discs. CONCLUSION Lumbar IVDD was reproducibly induced with a 6 × 20 mm(2) annular lesion, with focal dysregulation of MMP gene expression, cell cloning in the inner AF, loss of NP aggrecan, and disc height. Loss of aggrecan from the NP was not attributable to increased proteolysis in the interglobular domain by MMPs or ADAMTS.
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Pike FS, Kumar MSA, Boudrieau RJ. Reduction and fixation of cranial cervical fracture/luxations using screws and polymethylmethacrylate (PMMA) cement: a distraction technique applied to the base of the skull in thirteen dogs. Vet Surg 2011; 41:235-47. [PMID: 22188100 DOI: 10.1111/j.1532-950x.2011.00916.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE To (1) describe a surgical distraction technique for C1-2 cervical fractures/luxations or atlantoaxial (AA) subluxations using the base of the skull (basion of the foramen magnum) and either C2-3 or C3-4 for the purchase points of intraoperative axial distraction and (2) report outcome in 13 dogs. STUDY DESIGN Retrospective case series. ANIMALS Dogs (n = 13). MATERIALS AND METHODS Medical records (September 1995-December 2005) of dogs with fracture/luxation of the cervical spine, or AA subluxations, were reviewed. Only dogs that had intraoperative linear distraction using the base of the skull as a purchase point for a self-retaining retractor were included. Signalment, presenting neurologic deficits, fracture location, and concurrent injury were recorded. Both short-term in-hospital follow-up, including healing and any complications, and long-term telephone follow-up were obtained. RESULTS Realignment of the spinal vertebrae, reestablishing the normal properties of the spinal canal, was achieved after distraction in all dogs. Screws and small pins incorporated into polymethylmethacrylate cement were used to span the fracture ventrally and achieve rigid internal fixation. Eight dogs had a complete neurologic recovery, 2 dogs had slight residual ataxia, 2 dogs died, and 1 dog was lost to follow-up. Healing was good (mean, 7.5 weeks) or excellent (mean, 5.1 months) based on in-hospital follow-up (mean, 5.1 months). On final telephone follow-up (mean, 7.7 years), no dogs were reported to have had any associated problems or additional surgery. CONCLUSIONS This surgical distraction technique was a reliable, relatively simple method to obtain reduction of fracture/luxations of C1-2 to re-align the spinal canal. Mortality in this series appears lower than that previously reported and supports surgical management of these injuries.
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Affiliation(s)
- Fred S Pike
- Department of Clinical Sciences, Cummings School of Veterinary Medicine at Tufts University, North Grafton, MA 01536, USA
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Cho H, Park SH, Lee S, Kang M, Hasty KA, Kim SJ. Snapshot of degenerative aging of porcine intervertebral disc: a model to unravel the molecular mechanisms. Exp Mol Med 2011; 43:334-40. [PMID: 21499012 DOI: 10.3858/emm.2011.43.6.036] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Larger animal models, such as porcine, have been validated as appropriate models of the human disc with respect to biomechanics and biochemistry. They are advantageous for research as the models are relatively straightforward to prepare and easily obtainable for research to perform surgical techniques. The intention of this study was to quantitatively analyze gene expression for collagen and proteoglycan components of the extracellular matrix and for collagenase (MMP-1) in porcine discs of varying ages (Newborn; 2-3weeks, Mature; 6-9 month, Older; 2-3 years). In this study, we observed that the cell number and GAG (glycosaminoglycan) formation dramatically decreased with aging. Also, gene expression in the annulus fibrosus (AF) and nucleus pulposus (NP) cells changed with aging. The level of MMP-1 mRNA increased with age and both type I, II collagens decreased with age. The level of aggrecan mRNA was highest in the mature group and decreased significantly with aging. In the mature group, MMP-1 expression was minimal compared to the newborn group. In AF cells, type II collagen was expressed at a high level in the mature group with a higher level of aggrecan, when aged NP showed a decrease in type II collagen. The model of IVD degeneration in the porcine disc shows many changes in gene expression with age that have been previously documented for human and may serve as a model for studying changes in IVD metabolism with age. We concluded that the porcine model is excellent to test hypotheses related to disc degeneration while permitting time-course study in biologically active systems.
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Affiliation(s)
- Hongsik Cho
- University of Tennessee Health Science Center Memphis, TN, U.S.A
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Bae WC, Masuda K. Emerging technologies for molecular therapy for intervertebral disk degeneration. Orthop Clin North Am 2011; 42:585-601, ix. [PMID: 21944594 PMCID: PMC4029337 DOI: 10.1016/j.ocl.2011.07.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Intervertebral disks are biologically regulated by the maintenance of a balance between the anabolic and catabolic activities of disk cells. Therapeutic agents, initially evaluated using in vitro studies on disk cells and explants, have been used as intradiscal injections in preclinical settings to test in vivo efficacy. These include anabolic growth factors, other biostimulatory agents, and antagonistic agents against matrix-degrading enzymes and cytokines. Additional work is needed to identify patient populations, using methods such as MRI, and to better understand the mechanism of healing. Clinical trials are underway for a few of these agents and other promising candidates are on the horizon.
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Affiliation(s)
- Won C. Bae
- Department of Radiology, University of California, San Diego, San Diego, California
| | - Koichi Masuda
- Department of Orthopaedic Surgery, University of California, San Diego, La Jolla, California
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Abstract
STUDY DESIGN An in vivo study to develop a goat large-animal model for intervertebral disc (IVD) degeneration. OBJECTIVE To determine an optimal method for inducing goat IVD degeneration suitable for testing disc regeneration therapies. SUMMARY OF BACKGROUND DATA Although rodent, rabbit, and other small animal studies are useful, the narrow dimensions of IVDs in these species limit studies requiring injection of a relevant volume of therapeutics or implantation of engineered tissue constructs. For this study, the goat was selected because the size and shape of their IVDs are comparable with those of adult humans. METHODS A minimally invasive approach that did not cause significant morbidity or mortality to adult goats (n = 6) was used. Under fluoroscopic guidance, goat lumbar IVDs were injured with a 4.5-mm drill bit or #15 or #10 surgical blades. Two months postinjury, the goats were killed and their IVDs with adjacent end plates were isolated, decalcified, and stained. RESULTS.: A numerical histologic scale to categorize the degree of goat IVD degeneration was developed on the basis of the histologic features of rabbit IVDs previously described by Masuda et al, goat IVDs described by Hoogendoorn et al, and human IVDs described by Boos et al. The interrater agreement of our scoring system was assessed (weighted kappa value = 0.6646). Mann-Whitney U tests were used to compare the injured IVDs with uninjured control. A 4.5-mm drill bit inserted to a 15-mm depth resulted in a significantly higher histologic score than uninjured controls (P = 0.01). Injury with a #15 or #10 blade did not result in increased histologic scores compared with uninjured controls. CONCLUSION A comparison of the various injuries inflicted showed that the use of a 4.5-mm drill bit resulted in the most significant histologic changes.
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Abstract
STUDY DESIGN Surgically denucleated porcine intervertebral discs (IVD) were injected with BIOSTAT BIOLOGX Fibrin Sealant (FS), and the in vivo effects were assessed over time by histological, biochemical, and mechanical criteria. OBJECTIVE The objectives were to test whether the intradiscal injection of FS stimulates disc healing. SUMMARY OF BACKGROUND DATA Disc avascularity prevents the deposition of a provisional fibrin scaffold that typically facilitates soft tissue repair. Poor disc wound healing leads to disc damage accumulation and chronic inflammation characterized by overproduction of proinflammatory cytokines and proteolytic enzymes. METHODS Four lumbar IVDs from each of 31 Yucatan minipigs were randomized to untreated controls; degenerative injury (nucleotomy); and nucleotomy plus FS injection. Animals were killed at 1, 2, 3, 6, and 12 weeks postsurgery. IVDs were harvested to quantify (1) architecture using morphological and histological grading; (2) proteoglycan composition using DMMB assay; (3) cytokine content using ELISA; and (4) mechanical properties using quantitative pressure/volume testing. RESULTS There was progressive invasion of annular tissue into the nucleus of nucleotomy discs and concomitant reduction in proteoglycan content. By contrast, FS supplementation inhibited nuclear fibrosis and facilitated proteoglycan content recovery over time. FS discs synthesized significantly less TNF-α than degenerate discs (66% vs. 226%, P < 0.05) and had upregulation of IL-4 (310% vs. 166%) and TGF-β (400% vs. 117%) at 2 to 3 weeks posttreatment. At the third week postsurgery, the denucleated discs were less stiff than controls (pressure modulus 779.9 psi vs. 2754.8 psi; P < 0.05) and failed at lower pressures (250.5 psi vs. 492.5 psi; P < 0.05). The stiffness and leakage pressure of the FS-treated discs recovered to control values after 6 and 12 weeks, respectively. CONCLUSION FS facilitated structural, compositional, and mechanical repair of the surgically damaged IVD. These FS-derived benefits are likely due to its conductive scaffold properties and metabolically active constituents such as thrombin, factor XIII, and aprotinin acetate.
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The effect of a new anular repair after discectomy in intervertebral disc degeneration: an experimental study using a porcine spine model. Spine (Phila Pa 1976) 2011; 36:761-9. [PMID: 20683387 DOI: 10.1097/brs.0b013e3181e08f01] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN In vitro and in vivo studies to assess the effect of direct anular repair on subsequent degeneration of intervertebral discs (IVDs). OBJECTIVE To assess whether a new suturing method could provide sealing effect on IVD after discectomy, and influence degenerative process of IVD. SUMMARY OF BACKGROUND DATA Recurrent disc herniation and subsequent disc degeneration are major problems after discectomy. Anular repair can reduce the risk of recurrence, but its effect on disc degeneration needs more investigation. METHODS A new suturing technique, the modified purse-string suture (MPSS), was designed for direct closure of anular incision. Intact motion segments of porcine lumbar spine were used to validate this technique in resisting disc pressure under mechanical loadings. A transverse slit incision was made in the anterior anulus of porcine cervical discs, with or without sealing of the anular defect by this suturing method. Magnetic resonance imaging grading was recorded before and after surgery. Anular healing was assessed histologically and gene expression of aggrecan, collagen type I, II, and matrix metalloproteinase-13 in nucleus pulposus were investigated. RESULTS The average failure force of axial compression was 1150.3 ± 121.1 N for a simple suture, and 2917.9 ± 627.6 N for a MPSS. Cyclic loading test showed that the repaired discs succeeded against repeated compression forces. Magnetic resonance imaging and gross appearances showed lesser degenerative changes in repaired discs than in injured discs at each time period. In repaired discs, mRNA expression of aggrecan and type II collagen downregulated slightly with time, whereas it decreased rapidly and persistently in unrepaired discs. Histologic findings showed primary healing of outer anular tract in repaired discs. CONCLUSION In this pilot study, the MPSS can provide effectively sealing for damaged anulus to withstand stresses. Direct repair of anular incision by this suturing method does significantly slow down degenerative process within discs after discectomy.
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A detailed microscopic examination of alterations in normal anular structure induced by mechanical destabilization in an ovine model of disc degeneration. Spine (Phila Pa 1976) 2010; 35:1965-73. [PMID: 20959777 DOI: 10.1097/brs.0b013e3181e0f085] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Microstructural investigation of anular structure. OBJECTIVE To reveal the effect of mechanical destabilization on the anular architecture both locally and distantly. SUMMARY OF BACKGROUND DATA Several longitudinal ovine-induced disc degeneration studies have documented degenerative changes in disc components using histologic, biomechanical, and biochemical approaches; however, changes in intervertebral disc (IVD) microstructure have largely remained neglected. In recent years, the use of structurally relevant section planes has improved our understanding of disc microstructure, including the presence of significant bridging structures radially linking the lamellae. It has been suggested that the translamellar cross-bridges offer a mechanism by which the anular wall can adaptively remodel itself in response to a changing biomechanical microenvironment. METHODS IVDs harvested from lesion and sham-operated groups of Merino wethers were subjected to en face oblique and vertical sectioning. The macrostructural effect of the destabilization was examined in the vertically sectioned group with conventional histologic techniques. The second group was serially sectioned into 30-μm slices allowing a global examination of the anular microstructure in its fully hydrated state using a differential interference contrast microscope. RESULTS The previously described induced disc degeneration in the mid-inner anulus fibrosus (AF) and a spontaneous repair process in the outer AF was confirmed. Increased translamellar bridging was observed contralaterally to the lesion in the mechanically destabilized IVD and development of atypical broad bridging elements in the outer lamellae. Structural alterations in the lamellar anchorages to the cartilaginous endplates in destabilized IVDs, including lamellar branching and discontinuities atypical of normal lamellar attachments were also observed. CONCLUSION The present investigation has offered a glimpse of an anular wall apparently capable of remodeling in response to perturbations in its normal mechanical environment. The translamellar cross-bridges undergo adaptations in structure, in response to altered stresses locally at the anular defect site but also distantly in the contralateral AF in the destabilized disc. It is currently not known whether such changes in anular microarchitecture, however, predispose the anulus to further mechanical damage or have a stabilizing role to play in this structure.
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Omlor GW, Bertram H, Kleinschmidt K, Fischer J, Brohm K, Guehring T, Anton M, Richter W. Methods to monitor distribution and metabolic activity of mesenchymal stem cells following in vivo injection into nucleotomized porcine intervertebral discs. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2009; 19:601-12. [PMID: 20039083 DOI: 10.1007/s00586-009-1255-7] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Revised: 11/25/2009] [Accepted: 12/10/2009] [Indexed: 12/17/2022]
Abstract
Intervertebral disc (IVD) degeneration involves a series of biochemical and morphological changes leading to loss of spinal stability and flexibility. Cell therapy is promising to reconstitute IVDs with new cells, however, sustained metabolic activity seems crucial for an active contribution to regeneration. The aim of the present study was to establish methods for separate follow up of persistence and activity of autologous porcine mesenchymal stem cells (pMSC) after implantation into IVDs of Goettingen minipigs in vivo in order to conclude about the potential of such an intervention strategy. For quantitative follow up, the transfer matrix was supplemented with Al(2)O(3) particles and pMSC which were retrovirally labeled with firefly luciferase (pMSC-Luc). Six mature Goettingen minipigs underwent matrix based cell transfer after partial nucleotomy of lumbar IVDs (n = 24). Day 0 and day 3 segments were analyzed for retained volume of Al(2)O(3) particles by micro-computed-tomography (muCT) and for cell activity by luciferase enzyme assessment. Three days after injection a reduction of Al(2)O(3) particles (P = 0.028) to about 9% and of pMSC-Luc activity to about 7% of initial values (P = 0.003) was detected, which suggests loss of 90% of the implant material under in vivo conditions without evidence for reduced pMSC-Luc metabolic activity (P = 0.887). In conclusion, separate follow up of implant material and cell activity was possible and unravels problems with in vivo implant persistence after annular puncture rather than quick loss of cell activity. Therefore, IVD-regeneration-strategies should increasingly focus on annulus reconstruction in order to reduce implant loss due to annular failure.
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Affiliation(s)
- G W Omlor
- Division of Experimental Orthopaedics, Orthopaedic University Hospital Heidelberg, Schlierbacher Landstrasse 200a, 69118 Heidelberg, Germany
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A new porcine in vivo animal model of disc degeneration: response of anulus fibrosus cells, chondrocyte-like nucleus pulposus cells, and notochordal nucleus pulposus cells to partial nucleotomy. Spine (Phila Pa 1976) 2009; 34:2730-9. [PMID: 19940730 DOI: 10.1097/brs.0b013e3181b723c9] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN In vivo animal study. OBJECTIVES To describe a new porcine disc degeneration model, and to analyze disc remodeling and degeneration after nucleotomy with special view to the different nucleus pulposus (NP) cell types. SUMMARY OF BACKGROUND DATA Thus far, predominantly smaller animals were used for disc degeneration models; however, such small discs were inappropriate to investigate cell implementation therapies. Though notochordal cells (NCs) are important for disc formation and maintenance, differences in the amount of NCs between human and animal discs have often been neglected. METHODS Twenty-four Goettingen minipigs underwent partial nucleotomy with a 16G biopsy cannula, to remove approximately 10% of total NP volume. Animals were followed up for 3, or 24 weeks and analyzed by radiographs, MRIs, (immuno)histology, gene expression analysis, and biomechanical testing. RESULTS Three weeks after nucleotomy disc height was reduced by 26%, and magnetic resonance imaging signal intensity by 40%. At 24 weeks disc height was decreased by 32%. Increased degenerative changes were found in a histodegeneration score 3 and 24 weeks after nucleotomy, as well as considerable NP scarification after 3 weeks. In controls, cytokeratin-8 immunohistochemistry identified NCs in proximity to chondrocyte-like NP cells at approximately equal ratio. After nucleotomy, NCs were considerably reduced to <10% of total NP cells. Matrix genes were upregulated, except for aggrecan that decreased to 35% of initial values 3 weeks after nucleotomy. Matrix degrading factors (matrix metalloproteinases 13 and 3) were continuously upregulated, whereas transcripts of their inhibitors (tissue inhibitors of matrix metalloproteinase 2 and 3) were downregulated. No significant changes in segmental spinal flexibility or bone density were found after nucleotomy. CONCLUSION We introduced a new disc degeneration model with relatively large discs that could be used for cell therapeutic approaches. The study gives further information about disc remodeling after nucleotomy and indicates the relevance of an altered cellular composition for the development of disc degeneration.
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Identification of cell proliferation zones, progenitor cells and a potential stem cell niche in the intervertebral disc region: a study in four species. Spine (Phila Pa 1976) 2009; 34:2278-87. [PMID: 19755937 DOI: 10.1097/brs.0b013e3181a95ad2] [Citation(s) in RCA: 154] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Descriptive experimental study in 4 different mammals. OBJECTIVE To investigate cell proliferation/regeneration and localize stem cells/progenitor cells within the intervertebral disc (IVD). SUMMARY OF BACKGROUND DATA Disc degeneration (DD) is believed to play a major role in patients with chronic lumbar pain. Lately, biologic treatment options for DD have gained increasing interest. Normal regeneration processes within the IVD and have previously been sparsely described and therefore it is of great interest to increase the knowledge about these processes. Methods. Detection of cell proliferations zones and label-retaining cells were done by in vivo 5-bromo-2-deoxyuridine (BrdU) labeling in 18 rabbits, killed after 4, 6, 10, 14, 28, or 56 days. Results were visualized with immunohistochemistry and fluorescence/confocal microscopy. Localization of progenitor cell were further investigated by immunohistochemistry using antibodies towards Notch1, Delta4, Jagged1, C-KIT, KI67, and Stro-1 in normal IVD from rabbits (n = 3), rats (n = 2), minipigs (n = 2), and in human degenerated IVD (n = 4). Further, flowcytometry analysis using progenitor markers were performed on additional human IVD cells (n = 3). RESULTS BrdU positive cells were found in comparable numbers at early and late time points in most regions of the anulus fibrosus (AF) and nucleus pulposus demonstrating slow ongoing cell proliferation. In the AF border to ligament zone (AFo) and the perichondrium region (P) a stem cell niche-like pattern was determined (a high number of BrdU positive cells at early time points vs. only a few label retaining cells at later time points). In normal and DD tissue from the 4 investigated species progenitor cell markers were detected. Conclusion. The IVD is a tissue with ongoing slow cell proliferation both in the AF and the nucleus pulposus. The stem cell niche pattern detected in AFo and P can be suggested to play a role for IVD morphology and function. These findings may be of importance for the development of biologic treatment strategies.
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Abstract
STUDY DESIGN In vitro experiment using bone morphogenetic protein-2 (BMP-2) and cells from the nucleus pulposus (NP), transitional zone (TZ), and anulus fibrosus (AF) of the human intervertebral disc (IVD). OBJECTIVE To demonstrate the differential effect of BMP-2 on DNA synthesis, proteoglycan synthesis, and osteocalcin mRNA expression in human IVD cells from the NP, TZ, and AF, respectively. SUMMARY OF BACKGROUND DATA BMP-2 has been proven to be effective in stimulating proteoglycan synthesis in articular chondrocytes and IVD cells from the NP. Nevertheless, the effect of BMP-2 on cells from different regions of the IVD has not yet been thoroughly elucidated. METHODS Human IVDs were harvested from surgical disc procedures and tissue from the NP, TZ, and AF was obtained. Disc tissue was enzymatically digested, and IVD cells were cultured three-dimensionally in alginate beads. Then IVD cell cultures from the NP, TZ, and AF were exposed to BMP-2. DNA synthesis and newly synthesized proteoglycan were measured. Reverse transcription-polymerase chain reaction for mRNA expression of bone sialoprotein, DLX5, osteocalcin, and collagen type I, was performed. RESULTS Cells from the AF responded to BMP-2 with mitogenesis. There was no significant increase in DNA synthesis in cultures from the NP and TZ treated with BMP-2. Only cells from the NP showed a significant increase in newly synthesized proteoglycan in response to BMP-2. IVD cells from all zones demonstrated no significant expression of bone sialoprotein, DLX5, osteocalcin mRNA after treatment with BMP-2. CONCLUSION BMP-2 clearly exerted a mitogenic effect on AF cells, and stimulated proteoglycan synthesis in NP cells. However, BMP-2 did not have an osteogenic effect in any IVD region. Taken together, these results confirm that BMP-2 can be used as an anabolic agent for mitogenesis in AF cells and NP cell matrix regeneration without the possibility of osteogenesis.
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Wei A, Williams LA, Bhargav D, Shen B, Kishen T, Duffy N, Diwan AD. BMP13 prevents the effects of annular injury in an ovine model. Int J Biol Sci 2009; 5:388-96. [PMID: 19521550 PMCID: PMC2695250 DOI: 10.7150/ijbs.5.388] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Accepted: 05/30/2009] [Indexed: 01/07/2023] Open
Abstract
Chronic back pain is a global health problem affecting millions of people worldwide and carries significant economic and social morbidities. Intervertebral disc damage and degeneration is a major cause of back pain, characterised by histological and biochemical changes that have been well documented in animal models. Recently there has been intense interest in early intervention in disc degeneration using growth factors or stem cell transplantation, to replenish the diseased tissues. Bone Morphogenetic Proteins (BMPs) have been approved for clinical use in augmenting spinal fusions, and may represent candidate molecules for intervertebral disc regeneration. BMP13 has an important role in embryonic development and recent genetic evidence shows a role in the development of the human spine. This study explores the effect of BMP13 on a damaged intervertebral disc in an ovine model of discal degeneration. We found that, when injected at the time of injury, BMP13 reversed or arrested histological changes that occurred in the control discs such as loss of extracellular matrix proteins. In addition, BMP13 injected discs retained greater hydration after 4months, and possessed more cells in the NP. Taken together, BMP13 may be a potent clinical therapeutic agent when used early in the degeneration cascade to promote healthy disc tissue.
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Affiliation(s)
- Aiqun Wei
- Orthopaedic Research Institute, Department of Orthopaedic Surgery, St George Hospital, University of New South Wales, Sydney, Australia
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Reliability of low-radiation dose CT in the assessment of screw placement after posterior scoliosis surgery, evaluated with a new grading system. Spine (Phila Pa 1976) 2009; 34:941-8. [PMID: 19532002 DOI: 10.1097/brs.0b013e31819b22a4] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN A retrospective study. OBJECTIVE To evaluate the reliability of computed tomography (CT) with low radiation dose in the assessment of implant status in patients with adolescent idiopathic scoliosis (AIS). SUMMARY OF BACKGROUND DATA The use of all-pedicle screw construct in scoliosis corrective surgery continues to gain increasing popularity since their introduction 1994 although their use in the thoracic spine carries a potential risk for neurovascular complications. CT is the method widely used to evaluate screw placement. METHODS Retrospective analysis of 46 consecutive low-dose spine CT in patients with AIS after posterior corrective surgery. Status of 809 titanium screws (642 thoracic) was evaluated. The degree of interobserver and intraobserver agreements about implant status was used as an indicator of the reliability of the low-dose spine CT in the assessment of accuracy of pedicle screw insertion. A new grading system has been developed for this purpose. Five types of misplacement have been evaluated: lateral, medial, and anterior cortical perforations; endplate perforation; and foraminal perforation. RESULTS The analysis has shown a substantial interobserver and intraobserver agreements (kappa: 0.69 and 0.76, respectively) in differentiating pedicle screws with acceptable placement from screws with partial or total cortical perforation. None of the examinations was subjectively classified as unreliable. CONCLUSION The study has shown that low-dose spine CT is a reliable method in evaluating screw placement in patients with AIS after posterior scoliosis surgery with titanium implants, using the here proposed grading system. The new grading system of screw misplacement was feasible and in line with the general agreement about the harmlessness of misplacement with minor pedicle breach. The reliability of low-dose spine CT in evaluation of lateral and medial cortical perforations was substantial. To reduce the radiation load, the postoperative assessment of titanium implants should be performed with low-dose CT.
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Melrose J, Burkhardt D, Taylor TKF, Dillon CT, Read R, Cake M, Little CB. Calcification in the ovine intervertebral disc: a model of hydroxyapatite deposition disease. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2009; 18:479-89. [PMID: 19165512 DOI: 10.1007/s00586-008-0871-y] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2008] [Revised: 10/20/2008] [Accepted: 12/22/2008] [Indexed: 01/02/2023]
Abstract
The study design included a multidisciplinary examination of the mineral phase of ovine intervertebral disc calcifications. The objective of the study was to investigate the mineral phase and its mechanisms of formation/association with degeneration in a naturally occurring animal model of disc calcification. The aetiology of dystrophic disc calcification in adult humans is unknown, but occurs as a well-described clinical disorder with hydroxyapatite as the single mineral phase. Comparable but age-related pathology in the sheep could serve as a model for the human disorder. Lumbar intervertebral discs (n = 134) of adult sheep of age 6 years (n = 4), 8 years (n = 12) and 11 years (n = 2) were evaluated using radiography, morphology, scanning and transmission electron microscopy, energy dispersive X-ray spectroscopy, X-ray powder diffraction, histology, immunohistology and proteoglycan analysis. Half of the 6-year, 84% of the 8-year and 86% of the 11-year-old discs had calcific deposits. These were not well delineated by plain radiography. They were either: (a) punctate deposits in the outer annulus, (b) diffuse deposits in the transitional zone or inner annulus fibrosus with occasional deposits in the nucleus, or (c) large deposits in the transitional zone extending variably into the nucleus. Their maximal incidence was in the lower lumbar discs (L4/5-L6/7) with no calcification seen in the lumbosacral or lower thoracic discs. All deposits were hydroxyapatite with large crystallite sizes (800-1,300 A) compared to cortical bone (300-600 A). No type X-collagen, osteopontin or osteonectin were detected in calcific deposits, although positive staining for bone sialoprotein was evident. Calcified discs had less proteoglycan of smaller hydrodynamic size than non-calcified discs. Disc calcification in ageing sheep is due to hydroxyapatite deposition. The variable, but large, crystal size and lack of protein markers indicate that this does not occur by an endochondral ossification-like process. The decrease in disc proteoglycan content and size suggests that calcification may precede or predispose to disc degeneration in ageing sheep.
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Affiliation(s)
- James Melrose
- Raymond Purves Research Laboratory, Institute of Bone and Joint Research, Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St. Leonards, Sydney, NSW, Australia.
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Age-related changes in the extracellular matrix of nucleus pulposus and anulus fibrosus of human intervertebral disc. Spine (Phila Pa 1976) 2009; 34:10-6. [PMID: 19127156 PMCID: PMC2837353 DOI: 10.1097/brs.0b013e31818e5ddd] [Citation(s) in RCA: 141] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN To characterize age-related changes in the matrix of human intervertebral disc (IVD) specimens, human specimens from the third to the eighth decade of life were collected and analyzed for collagen and proteoglycan (PG) composition. OBJECTIVE To identify age-related changes in the concentration of matrix macromolecules (collagen and PGs, including the small leucine-rich PGs biglycan, decorin, fibromodulin, and lumican) in human anulus fibrosus (AF) and nucleus pulposus (NP). SUMMARY OF BACKGROUND DATA IVD degeneration is associated with changes in the concentration and fragmentation of matrix molecules. Deciphering age-related matrix alterations may help us to better understand the regulatory mechanisms underlying IVD degeneration. METHODS Forty-six whole IVDs were obtained from the thoracolumbar spines (T11-L5) of humans aged between 32 and 80 years. All specimens were classified as Thompson grade 1 or 2 according to MRI criteria. Specimens were separated into (i) outer-and (ii) inner AF, and (iii) NP. DNA, collagen, and PG contents were measured using chemical assays, whereas small nonaggregating PG levels were analyzed by comparative Western blotting. RESULTS Total PG and collagen contents in both the AF and NP consistently decreased with aging. The concentrations of small nonaggregating PGs varied. In the outer anulus, decorin levels decreased, whereas biglycan and fibromodulin levels increased with age. In the inner anulus and nucleus, biglycan demonstrated a significant increase with aging. These changes differed in most cases from those previously reported for degenerating disc tissues. CONCLUSION Collagen and PGs appeared to undergo specific age-related changes in the human IVD. Although the total contents of these 2 families of molecules decreased during aging, individual species of small nonaggregating PGs showed species-specific age-related changes. Interestingly, the level of biglycan rose and remained elevated in all 3 compartments of the disc with aging. The functional significance of these alterations is yet to be determined.
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Kalson NS, Richardson S, Hoyland JA. Strategies for regeneration of the intervertebral disc. Regen Med 2008; 3:717-29. [DOI: 10.2217/17460751.3.5.717] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Low back pain resulting from degenerative disc disease is the most common cause of disability in the UK. Current low back pain treatments are aimed at either treating the symptoms of pain, or removing the source of pain itself, but do not address the biological basis of the disease. Our increasing understanding of the molecular biological basis for degenerative disc disease has enabled the development of strategies aimed at tackling the causes of degeneration. Here we review the progress that has been made in strategies using cells, biomaterials and growth factors aimed at regenerating the human intervertebral disc.
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Affiliation(s)
- NS Kalson
- Tissue Injury and Repair Group, School of Clinical & Laboratory Sciences, University of Manchester, Manchester, M13 9PT, UK
| | - S Richardson
- Tissue Injury and Repair Group, School of Clinical & Laboratory Sciences, University of Manchester, Manchester, M13 9PT, UK
| | - JA Hoyland
- Tissue Injury and Repair Group, School of Clinical & Laboratory Sciences, University of Manchester, Manchester, M13 9PT, UK
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Recent advances in annular pathobiology provide insights into rim-lesion mediated intervertebral disc degeneration and potential new approaches to annular repair strategies. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2008; 17:1131-48. [PMID: 18584218 DOI: 10.1007/s00586-008-0712-z] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2007] [Revised: 06/04/2008] [Accepted: 06/18/2008] [Indexed: 12/14/2022]
Abstract
The objective of this study was to assess the impact of a landmark annular lesion model on our understanding of the etiopathogenesis of IVD degeneration and to appraise current IVD repairative strategies. A number of studies have utilised the Osti sheep model since its development in 1990. The experimental questions posed at that time are covered in this review, as are significant recent advances in annular repair strategies. The ovine model has provided important spatial and temporal insights into the longitudinal development of annular lesions and how they impact on other discal and paradiscal components such as the NP, cartilaginous end plates, zygapophyseal joints and vertebral bone and blood vessels. Important recent advances have been made in biomatrix design for IVD repair and in the oriented and dynamic culture of annular fibrochondrocytes into planar, spatially relevant, annular type structures. The development of hyaluronan hydrogels capable of rapid in situ gelation offer the possibility of supplementation of matrices with cells and other biomimetics and represent a significant advance in biopolymer design. New generation biological glues and self-curing acrylic formulations which may be augmented with slow delivery biomimetics in microcarriers may also find application in the non-surgical repair of annular defects. Despite major advances, significant technical challenges still have to be overcome before the biological repair of this intractable connective tissue becomes a realistic alternative to conventional surgical intervention for the treatment of chronic degenerate IVDs.
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The effects of recombinant human bone morphogenetic protein-2, recombinant human bone morphogenetic protein-12, and adenoviral bone morphogenetic protein-12 on matrix synthesis in human annulus fibrosis and nucleus pulposus cells. Spine J 2008; 8:449-56. [PMID: 18455111 DOI: 10.1016/j.spinee.2006.11.006] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/24/2006] [Revised: 10/19/2006] [Accepted: 11/30/2006] [Indexed: 02/06/2023]
Abstract
BACKGROUND CONTEXT Bone morphogenetic proteins (BMPs) are potential therapeutic factors for degenerative discs, and BMP-12 does not have the osteogenic potential of BMP-2, making it better suited for intradiscal injection. However, no reports have compared the actions of BMP-2 and -12 on human annulus fibrosus (AF) and nucleus pulposus (NP) cells nor evaluated adenoviral-mediated gene therapy in human AF cells. PURPOSE To evaluate and compare the effects of recombinant human (rh) BMP-2, rhBMP-12, and adenoviral BMP-12 (Ad-BMP-12) on nucleus pulposus and annulus fibrosis cell matrix protein synthesis. STUDY DESIGN In vitro study using rhBMP-2 and -12 and adenoviral BMP-12 with human intervertebral disc (IVD) cells. METHODS Human NP and AF IVD cells were isolated, maintained in monolayer, and incubated with BMP-2 or -12 for 2 days. AF and NP cells were transduced with Ad-BMP-12, pellets formed, and incubated for 6 days. Growth factor-treated cells were labelled with either 35-S or 3H-proline to assay matrix protein synthesis. RESULTS rhBMP-2 increased NP proteoglycan, collagen, and noncollagen protein synthesis to 355%, 388%, and 234% of control. RhBMP-12 increased the same NP matrix proteins' synthesis to 140%, 143%, and 160% of control. Effects on AF matrix protein synthesis were minimal. Ad-BMP-12 significantly increased matrix protein synthesis and DNA content of AF and NP cells in pellet culture. NP synthesis of all matrix proteins and AF synthesis of proteoglycans was increased when the data were normalized to pellet DNA. AF synthesis of noncollagen protein and collagen was not modulated by Ad-BMP-12 if the data are normalized to pellet DNA content. CONCLUSIONS Both rhBMP-2 and -12 increase human NP cell matrix protein synthesis while having minimal effects on AF cells. However, Ad-BMP-12 did increase matrix protein synthesis in both NP and AF cells, making it a potential therapy for enhancing matrix production in the IVD. These responses plus the proliferative action of Ad-BMP-12 seen in the current studies, and the lack of an osteogenic action noted in other studies justifies future studies to determine if gene therapy with BMP-12 could provide protective and/or reparative actions in degenerating discs.
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Abstract
STUDY DESIGN A bovine intervertebral disc organ culture model was used to study the effect of needle puncture injury on short-term disc mechanics and biology. OBJECTIVE To test the hypothesis that significant changes in intervertebral disc structure, mechanics, and cellular response would be present within 1 week of needle puncture injury with a large-gauge needle but not with a small-gauge needle. SUMMARY OF BACKGROUND DATA Defects in anulus fibrosus induced by needle puncture injury can compromise mechanical integrity of the disc and lead to degeneration in animal models. The immediate and short-term mechanical and biologic response to anulus injury through needle puncture in a large animal model is not known. METHODS Bovine caudal intervertebral discs were harvested, punctured posterolaterally using 25G and 14G needles, and placed in organ culture for 6 days. Discs underwent a daily dynamic compression loading protocol for 5 days from 0.2 to 1 MPa at 1 Hz for 1 hour. Disc structure and function were assessed with measurements of dynamic modulus, creep, height loss, water content, proteoglycan loss to the culture medium, cell viability, and histology. RESULTS Needle puncture injury caused a rapid decrease in dynamic modulus and increase in creep during 1-hour loading, although no changes were detected in water content, disc height, or proteoglycan lost to the media. Cell viability was maintained except for localized cell death at the needle insertion site. An increase in cell number and possible remodeling response was seen in the insertion site in the nucleus pulposus. CONCLUSION Relatively minor disruption in the disc from needle puncture injury had immediate and progressive mechanical and biologic consequences with important implications for the use of discography, and repair-regeneration techniques. Results also suggest diagnostic techniques sensitive to mechanical changes in the disc may be important for early detection of degenerative changes in response to anulus injury.
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Melrose J, Smith SM, Fuller ES, Young AA, Roughley PJ, Dart A, Little CB. Biglycan and fibromodulin fragmentation correlates with temporal and spatial annular remodelling in experimentally injured ovine intervertebral discs. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2007; 16:2193-205. [PMID: 17899219 PMCID: PMC2140141 DOI: 10.1007/s00586-007-0497-5] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2007] [Revised: 05/29/2007] [Accepted: 09/03/2007] [Indexed: 01/07/2023]
Abstract
This study evaluated spatial and temporal extracellular matrix changes, induced by controlled surgical defects in the outer third of the annulus fibrosus (AF) of ovine intervertebral discs (IVDs). Thirty-two 4 year old sheep received a 4 mm deep x 10 mm wide standard annular surgical incision in the L1L2 and L3L4 IVDs (lesion group), 32 sheep were also subjected to the same surgical approach but the AF was not incised (sham-operated controls). Remodeling of the IVD matrix in the lesion and sham discs was assessed histochemically at 3, 6,12 and 26 month post operation (PO). Discs were also dissected into annular lesion site and contra-lateral AF and NP and equivalent zones in the sham sheep group, extracted with GuHCl, dialysed, freeze dried, digested with chondroitinase ABC/keratanase-I and aliquots examined for small leucine repeat proteoglycan (SLRP) core protein species by Western blotting using C-terminal antibodies to decorin, biglycan, lumican and fibromodulin and monoclonal antibody (Mab) 2B6 to unsaturated stub epitopes on chondroitin-4-sulphate generated by chondroitinase ABC. Masson Trichrome and Picrosirius red staining demonstrated re-organisation of the outermost collagenous lamellae in the incised discs 3-6 month PO. Toluidine blue staining also demonstrated a focal loss of anionic proteoglycan (PG) from the annular lesion 3-6 month PO with partial recovery of PG levels by 26 month. Specific fragments of biglycan and fibromodulin were associated with remodeling of the AF 12-26 month PO in the lesion IVDs but were absent from the NP of the lesion discs or all tissue zones in the sham animal group. Fragments of decorin were also observed in lesion zone extracts from 3 to 6 months but diminished after this. Isolation and characterization of the biglycan/fibromodulin fragments may identify them as prospective biomarkers of annular remodeling and characterization of the enzyme systems responsible for their generation may identify therapeutic target molecules.
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Affiliation(s)
- James Melrose
- Raymond Purves Laboratory, Institute of Bone and Joint Research, Kolling Institute of Medical Research, University of Sydney at Royal North Shore Hospital, St. Leonards, 2065, NSW, Australia.
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Alini M, Eisenstein SM, Ito K, Little C, Kettler AA, Masuda K, Melrose J, Ralphs J, Stokes I, Wilke HJ. Are animal models useful for studying human disc disorders/degeneration? EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2007; 17:2-19. [PMID: 17632738 PMCID: PMC2365516 DOI: 10.1007/s00586-007-0414-y] [Citation(s) in RCA: 496] [Impact Index Per Article: 29.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2006] [Revised: 04/24/2007] [Accepted: 05/28/2007] [Indexed: 12/11/2022]
Abstract
Intervertebral disc (IVD) degeneration is an often investigated pathophysiological condition because of its implication in causing low back pain. As human material for such studies is difficult to obtain because of ethical and government regulatory restriction, animal tissue, organs and in vivo models have often been used for this purpose. However, there are many differences in cell population, tissue composition, disc and spine anatomy, development, physiology and mechanical properties, between animal species and human. Both naturally occurring and induced degenerative changes may differ significantly from those seen in humans. This paper reviews the many animal models developed for the study of IVD degeneration aetiopathogenesis and treatments thereof. In particular, the limitations and relevance of these models to the human condition are examined, and some general consensus guidelines are presented. Although animal models are invaluable to increase our understanding of disc biology, because of the differences between species, care must be taken when used to study human disc degeneration and much more effort is needed to facilitate research on human disc material.
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Affiliation(s)
- Mauro Alini
- AO Research Institute, Clavadelerstrasse, 7270 Davos, Switzerland
| | | | - Keita Ito
- AO Research Institute, Clavadelerstrasse, 7270 Davos, Switzerland
| | - Christopher Little
- Raymond Purves Lab, Institute of Bone and Joint Research, Kolling Institute of Medical Research, University of Sydney at the Royal North Shore Hospital, St. Leonards, NSW Australia
| | - A. Annette Kettler
- Institute of Orthopaedic Research and Biomechanics, University of Ulm, Ulm, Germany
| | - Koichi Masuda
- Department of Orthopedic Surgery, Rush Medical College at Rush University Medical Center, Chicago, IL USA
| | - James Melrose
- Raymond Purves Lab, Institute of Bone and Joint Research, Kolling Institute of Medical Research, University of Sydney at the Royal North Shore Hospital, St. Leonards, NSW Australia
| | - Jim Ralphs
- School of Bioscience, Cardiff University, Cardiff, UK
| | - Ian Stokes
- Department of Orthopaedics and Rehabilitation, University of Vermont, Burlington, VA USA
| | - Hans Joachim Wilke
- Institute of Orthopaedic Research and Biomechanics, University of Ulm, Ulm, Germany
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Chung SA, Wei AQ, Connor DE, Webb GC, Molloy T, Pajic M, Diwan AD. Nucleus pulposus cellular longevity by telomerase gene therapy. Spine (Phila Pa 1976) 2007; 32:1188-96. [PMID: 17495775 DOI: 10.1097/brs.0b013e31805471a3] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Nonviral transfection of nucleus pulposus cells with a telomerase expression construct to assess the effects on cellular lifespan, function, karyotypic stability, and transformation properties. OBJECTIVES To investigate whether telomerase gene therapy can extend the cellular lifespan while retaining functionality of nucleus pulposus cells in a safe manner. SUMMARY OF BACKGROUND DATA Degeneration of the intervertebral disc is an age-related condition in which cells responsible for the maintenance and health of the disc deteriorate with age. Telomerase can extend the cellular lifespan and function of other musculoskeletal tissues, such as the heart, bones, and connective tissues. Therefore, extension of the cellular lifespan and matrix production of intervertebral disc cells may have the potential to delay the degeneration process. METHODS Ovine nucleus pulposus cells were lipofectamine transfected in vitro with a human telomerase reverse transcriptase (hTERT) expression construct. Cellular lifespan and matrix transcript levels were determined by cumulative population doublings and real-time RT-PCR, respectively. G1-cell cycle checkpoint, p53 functionality, growth of transfected cells in anchorage-independent or serum starvation conditions, and karyotypic analysis were performed. RESULTS Transfection was achieved successfully with 340% +/- 7% (mean +/- SD) relative telomerase activity in hTERT-transfected cells. hTERT transfection enabled a 50% extension in mean cellular lifespan and prolonged matrix production of collagen 1 and 2 for more than 282 days. Karyotypic instability was detected but G1-cell cycle checkpoint and p53 was functionally comparable to parental cells with no growth in serum starvation or anchorage-independent conditions. CONCLUSIONS Telomerase can extend the cellular lifespan of nucleus pulposus cells and prolong the production of extracellular matrix. Safety is still unresolved, as karyotypic instability was detected but no loss of contact inhibition, mitogen dependency, or G1-cell cycle checkpoint control was evident.
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Affiliation(s)
- Sylvia A Chung
- Orthopaedic Research Institute, University of New South Wales, St. George Hospital Campus, NSW, Australia
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Zhou H, Hou S, Shang W, Wu W, Cheng Y, Mei F, Peng B. A new in vivo animal model to create intervertebral disc degeneration characterized by MRI, radiography, CT/discogram, biochemistry, and histology. Spine (Phila Pa 1976) 2007; 32:864-72. [PMID: 17426630 DOI: 10.1097/01.brs.0000259835.31062.3d] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN A new in vivo sheep model was developed that produced disc degeneration through the injection of 5-bromodeoxyuridine (BrdU) into the intervertebral disc. This process was studied using magnetic resonance imaging (MRI), radiography, CT/discogram, histology, and biochemistry. OBJECTIVES To develop a sheep model of intervertebral disc degeneration that more faithfully mimics the pathologic hallmarks of human intervertebral disc degeneration. SUMMARY OF BACKGROUND DATA Recent studies have shown age-related alterations in proteoglycan structure and organization in human intervertebral discs. An animal model that involves the use of age-related changes in disc cells can be beneficial over other more invasive degenerative models that involves directly damaging the matrix of disc tissue. METHODS Twelve sheep were injected with BrdU or vehicle (phosphate-buffered saline) into the central region of separate lumbar discs. Intact discs were used as controls. At the 2-, 6-, 10-, and 14-week time points, discs underwent MRI, radiography, histology, and biochemical analyses. A CT/discogram study was performed at the 14-week time point. RESULTS MRI demonstrated a progressive loss of T2-weighted signal intensity at BrdU-injected discs over the 14-week study period. Radiograph findings included osteophyte and disc space narrowing formed by 10 weeks post-BrdU treatment. CT discography demonstrated internal disc disruption in several BrdU-treated discs at the 14-week time point. Histology showed a progressive loss of the normal architecture and cell density of discs from the 2-week time point to the 14-week time point. A progressive loss of cell proliferation capacity, water content, and proteoglycans was also documented. CONCLUSIONS BrdU injection into the central region of sheep discs resulted in degeneration of intervertebral discs. This progressive, degenerative process was confirmed using MRI, histology, and by observing changes in biochemistry. Degeneration occurred in a manner that was similar to that observed in human disc degeneration.
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Affiliation(s)
- HaoWei Zhou
- Department of Orthopaedics, First Affiliated Hospital of China People's Liberation Army General Hospital, Beijing, PR China
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Abstract
STUDY DESIGN Review and reinterpretation of existing literature. OBJECTIVE To suggest how intervertebral disc degeneration might be distinguished from the physiologic processes of growth, aging, healing, and adaptive remodeling. SUMMARY OF BACKGROUND DATA The research literature concerning disc degeneration is particularly diverse, and there are no accepted definitions to guide biomedical research, or medicolegal practice. DEFINITIONS The process of disc degeneration is an aberrant, cell-mediated response to progressive structural failure. A degenerate disc is one with structural failure combined with accelerated or advanced signs of aging. Early degenerative changes should refer to accelerated age-related changes in a structurally intact disc. Degenerative disc disease should be applied to a degenerate disc that is also painful. JUSTIFICATION Structural defects such as endplate fracture, radial fissures, and herniation are easily detected, unambiguous markers of impaired disc function. They are not inevitable with age and are more closely related to pain than any other feature of aging discs. Structural failure is irreversible because adult discs have limited healing potential. It also progresses by physical and biologic mechanisms, and, therefore, is a suitable marker for a degenerative process. Biologic progression occurs because structural failure uncouples the local mechanical environment of disc cells from the overall loading of the disc, so that disc cell responses can be inappropriate or "aberrant." Animal models confirm that cell-mediated changes always follow structural failure caused by trauma. This definition of disc degeneration simplifies the issue of causality: excessive mechanical loading disrupts a disc's structure and precipitates a cascade of cell-mediated responses, leading to further disruption. Underlying causes of disc degeneration include genetic inheritance, age, inadequate metabolite transport, and loading history, all of which can weaken discs to such an extent that structural failure occurs during the activities of daily living. The other closely related definitions help to distinguish between degenerate and injured discs, and between discs that are and are not painful.
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Affiliation(s)
- Michael A Adams
- Department of Anatomy, University of Bristol, Bristol, United Kingdom.
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Masuda K, Imai Y, Okuma M, Muehleman C, Nakagawa K, Akeda K, Thonar E, Andersson G, An HS. Osteogenic protein-1 injection into a degenerated disc induces the restoration of disc height and structural changes in the rabbit anular puncture model. Spine (Phila Pa 1976) 2006; 31:742-54. [PMID: 16582847 DOI: 10.1097/01.brs.0000206358.66412.7b] [Citation(s) in RCA: 207] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN In vivo study of the effect of injection of osteogenic protein-1 (OP-1) on a rabbit anular needle puncture model of intervertebral disc (IVD) degeneration. OBJECTIVE To study radiographic, magnetic resonance imaging (MRI), biochemical, and histologic changes in the rabbit IVD after injection of OP-1 into the nucleus pulposus in a needle puncture disc degeneration model. SUMMARY OF THE BACKGROUND DATA Growth factors, such as OP-1, have the ability to stimulate synthesis of proteoglycans and collagen in vitro. The in vivo injection of OP-1 into the normal rabbit IVD has increased disc height and proteoglycan content in the anulus fibrosus and nucleus pulposus. However, to our knowledge, no attempts have yet been made to determine the effects of these growth factors in an in vivo model of disc degeneration. METHODS New Zealand adolescent white rabbits (n = 90, 8 for baseline evaluation, 82 at 8 times) received an anular puncture in 2 noncontiguous discs with an 18-gauge needle to induce disc degeneration. Four weeks later, either 5% lactose (10 microL) or OP-1 (100 microg in 10 microL 5% lactose) was injected into the center of the nucleus pulposus. The disc height was followed radiographically for up to 24 weeks after the injections. At the 2, 4, 8, 12, and 24-week times after the injection, rabbits were euthanized, and MRI of the harvested spinal columns was obtained to grade the degeneration. The discs injected with OP-1 or lactose and noninjected discs were subjected to biochemical and histologic analysis. The specimens at the 24-week time were limited to histologic evaluation. RESULTS The anular puncture with a needle induced a consistent disc narrowing within 4 weeks. The injection of OP-1 induced a restoration of disc height at 6 weeks, which was sustained for the entire experimental period, up to 24 weeks after the injection. The injection of lactose alone did not change the course of disc narrowing over the same time. MRI grading score showed significant differences between the OP-1 and lactose groups at the 8, 12, and 24-week times, suggesting an increase in water content in the nucleus pulposus of the OP-1 group. The proteoglycan content of the nucleus pulposus and anulus fibrosus was significantly higher in the OP-1 group than in the control group. The degeneration grades of the punctured discs in the OP-1 group were significantly lower than those in the lactose group. CONCLUSION The results of this study show the feasibility of restoring degenerative rabbit discs by a single injection of OP-1 into the nucleus pulposus. Importantly, the effects of the OP-1 injection on disc height were sustained for up to 24 weeks. The metabolic changes in the cells, following a single injection, might be sustained and, thus, induce long-term changes in disc structure. An efficacy study in large animals is required to show further that the intradiscal injection of OP-1, or bone morphogenetic proteins or growth factors with similar properties would be useful for the structural restoration of the IVD in humans.
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Affiliation(s)
- Koichi Masuda
- Department of Orthopedic Surgery, Rush Medical College at Rush University Medical Center, Chicago, IL, USA.
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