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The response of nucleus pulposus cell senescence to static and dynamic compressions in a disc organ culture. Biosci Rep 2018; 38:BSR20180064. [PMID: 29437905 PMCID: PMC5843747 DOI: 10.1042/bsr20180064] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 01/27/2018] [Accepted: 01/31/2018] [Indexed: 01/08/2023] Open
Abstract
Mechanical stimuli obviously affect disc nucleus pulposus (NP) biology. Previous studies have indicated that static compression exhibits detrimental effects on disc biology compared with dynamic compression. To study disc NP cell senescence under static compression and dynamic compression in a disc organ culture, porcine discs were cultured and subjected to compression (static compression: 0.4 MPa for 4 h once per day; dynamic compression: 0.4 MPa at a frequency of 1.0 Hz for 4 h once per day) for 7 days using a self-developed mechanically active bioreactor. The non-compressed discs were used as controls. Compared with the dynamic compression, static compression significantly promoted disc NP cell senescence, reflected by the increased senescence-associated β-galactosidase (SA-β-Gal) activity, senescence-associated heterochromatic foci (SAHF) formation and senescence markers expression, and the decreased telomerase (TE) activity and NP matrix biosynthesis. Static compression accelerates disc NP cell senescence compared with the dynamic compression in a disc organ culture. The present study provides that acceleration of NP cell senescence may be involved in previously reported static compression-mediated disc NP degenerative changes.
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Han X, Leng X, Zhao M, Wu M, Chen A, Hong G, Sun P. Resveratrol increases nucleus pulposus matrix synthesis through activating the PI3K/Akt signaling pathway under mechanical compression in a disc organ culture. Biosci Rep 2017; 37:BSR20171319. [PMID: 29074559 PMCID: PMC5700294 DOI: 10.1042/bsr20171319] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 10/20/2017] [Accepted: 10/25/2017] [Indexed: 11/17/2022] Open
Abstract
Disc nucleus pulposus (NP) matrix homeostasis is important for normal disc function. Mechanical overloading seriously decreases matrix synthesis and increases matrix degradation. The present study aims to investigate the effects of resveratrol on disc NP matrix homeostasis under a relatively high-magnitude mechanical compression and the potential mechanism underlying this process. Porcine discs were perfusion-cultured and subjected to a relatively high-magnitude mechanical compression (1.3 MPa at a frequency of 1.0 Hz for 2 h once per day) for 7 days in a mechanically active bioreactor. The non-compressed discs were used as controls. Resveratrol was added along with culture medium to observe the effects of resveratrol on NP matrix synthesis under mechanical load respectively. NP matrix synthesis was evaluated by histology, biochemical content (glycosaminoglycan (GAG) and hydroxyproline (HYP)), and expression of matrix macromolecules (aggrecan and collagen II). Results showed that this high-magnitude mechanical compression significantly decreased NP matrix content, indicated by the decreased staining intensity of Alcian Blue and biochemical content (GAG and HYP), and the down-regulated expression of NP matrix macromolecules (aggrecan and collagen II). Further analysis indicated that resveratrol partly stimulated NP matrix synthesis and increased activity of the PI3K/Akt pathway in a dose-dependent manner under mechanical compression. Together, resveratrol is beneficial for disc NP matrix synthesis under mechanical overloading, and the activation of the PI3K/Akt pathway may participate in this regulatory process. Resveratrol may be promising to regenerate mechanical overloading-induced disc degeneration.
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Affiliation(s)
- Xiaorui Han
- Guangzhou First People’s Hospital, the Second Affiliated Hospital of South China University of Technology, Guangzhou, China
| | - Xiaoming Leng
- Universal Medical Imaging Diagnostic Center, Guangzhou, China
| | - Man Zhao
- Department of Radiography, The First Affiliated Hospital of Clinical Medicine of Guangdong Pharmaceutical University, Guangzhou, China
| | - Mei Wu
- Guangzhou First People’s Hospital, the Second Affiliated Hospital of South China University of Technology, Guangzhou, China
| | - Amei Chen
- Guangzhou First People’s Hospital, the Second Affiliated Hospital of South China University of Technology, Guangzhou, China
- Correspondence: Ping Sun () or Guoju Hong ()
| | - Guoju Hong
- Guangzhou University of Chinese Medicine, and Biomedical Science School, University of Western Australia, Australia
| | - Ping Sun
- Department of Orthopedic, The First Affiliated Hospital of Guangdong Pharmaceutical University, Guangzhou, ChinInsert Affiliation Text Here
- Correspondence: Ping Sun () or Guoju Hong ()
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Blanquer SBG, Grijpma DW, Poot AA. Delivery systems for the treatment of degenerated intervertebral discs. Adv Drug Deliv Rev 2015; 84:172-87. [PMID: 25451138 DOI: 10.1016/j.addr.2014.10.024] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2014] [Revised: 08/29/2014] [Accepted: 10/20/2014] [Indexed: 12/25/2022]
Abstract
The intervertebral disc (IVD) is the most avascular and acellular tissue in the body and therefore prone to degeneration. During IVD degeneration, the balance between anabolic and catabolic processes in the disc is deregulated, amongst others leading to alteration of extracellular matrix production, abnormal enzyme activities and production of pro-inflammatory substances like cytokines. The established treatment strategy for IVD degeneration consists of physiotherapy, pain medication by drug therapy and if necessary surgery. This approach, however, has shown limited success. Alternative strategies to increase and prolong the effects of bioactive agents and to reverse the process of IVD degeneration include the use of delivery systems for drugs, proteins, cells and genes. In view of the specific anatomy and physiology of the IVD and depending on the strategy of the therapy, different delivery systems have been developed which are reviewed in this article.
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Affiliation(s)
- S B G Blanquer
- MIRA Institute for Biomedical Technology and Technical Medicine, Department of Biomaterials Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands; Collaborative Research Partner Annulus Fibrosus Rupture Program of AO Foundation, Davos, Switzerland
| | - D W Grijpma
- MIRA Institute for Biomedical Technology and Technical Medicine, Department of Biomaterials Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands; Collaborative Research Partner Annulus Fibrosus Rupture Program of AO Foundation, Davos, Switzerland; University of Groningen, University Medical Center Groningen, W.J. Kolff Institute, Department of Biomedical Engineering, P.O. Box 196, 9700 AD Groningen, The Netherlands.
| | - A A Poot
- MIRA Institute for Biomedical Technology and Technical Medicine, Department of Biomaterials Science and Technology, University of Twente, P.O. Box 217, 7500 AE Enschede, The Netherlands; Collaborative Research Partner Annulus Fibrosus Rupture Program of AO Foundation, Davos, Switzerland
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Cheng KK, Berven SH, Hu SS, Lotz JC. Intervertebral discs from spinal nondeformity and deformity patients have different mechanical and matrix properties. Spine J 2014; 14:522-30. [PMID: 24246750 PMCID: PMC3944996 DOI: 10.1016/j.spinee.2013.06.089] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2012] [Revised: 06/01/2013] [Accepted: 06/24/2013] [Indexed: 02/03/2023]
Abstract
BACKGROUND CONTEXT It is well-established that disc mechanical properties degrade with degeneration. However, prior studies utilized cadaveric tissues from donors with undefined back pain history. Disc degeneration may present with pain at the affected motion segment, or it may be present in the absence of back pain. The mechanical properties and matrix quantity of discs removed and diagnosed for degeneration with patient chronic pain may be distinct from those with other diagnoses, such as spinal deformity. PURPOSE To test the hypothesis that discs from nondeformity segments have inferior mechanical properties than deformity discs owing to differences in matrix quality. STUDY DESIGN/SETTING In vitro study comparing the mechanical and matrix properties of discs from surgery patients with spinal nondeformity and deformity. METHODS We analyzed nucleus and annulus samples (8-11 specimens per group) from surgical discectomy patients as part of a fusion or disc replacement procedure. Tissues were divided into two cohorts: nondeformity and deformity. Dynamic indentation tests were used to determine energy dissipation, indentation modulus, and viscoelasticity. Tissue hydration at a physiologic pressure was assessed by equilibrium dialysis. Proteoglycan, collagen, and collagen cross-link content were quantified. Matrix structure was assessed by histology. RESULTS We observed that energy dissipation was significantly higher in the nondeformity nucleus than in the deformity nucleus. Equilibrium dialysis experiments showed that annulus swelling was significantly lower in the nondeformity group. Consistent with this, we observed that the nondeformity annulus had lower proteoglycan and higher collagen contents. CONCLUSIONS Our data suggest that discs from nondeformity discs have subtle differences in mechanical properties compared with deformity discs. These differences were partially explained by matrix biochemical composition for the annulus, but not for the nucleus. The results of this study suggest that compromised matrix quality and diminished mechanical properties are features that potentially accompany discs of patients undergoing segmental fusion or disc replacement for disc degeneration and chronic back pain. These features have previously been implicated in pain via instability or reduced motion segment stiffness.
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Affiliation(s)
- Kevin K Cheng
- Department of Orthopaedic Surgery, University of California, 513 Parnassus Ave., 11th Floor, San Francisco, CA 94143, USA
| | - Sigurd H Berven
- Department of Orthopaedic Surgery, University of California, 513 Parnassus Ave., 11th Floor, San Francisco, CA 94143, USA
| | - Serena S Hu
- Department of Orthopaedic Surgery, University of California, 513 Parnassus Ave., 11th Floor, San Francisco, CA 94143, USA
| | - Jeffrey C Lotz
- Department of Orthopaedic Surgery, University of California, 513 Parnassus Ave., 11th Floor, San Francisco, CA 94143, USA.
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Kuh SU, Kwon YM, Chin DK, Kim KS, Jin BH, Cho YE. Different Expression of Extracellular Matrix Genes : Primary vs. Recurrent Disc Herniation. J Korean Neurosurg Soc 2010; 47:26-9. [PMID: 20157374 DOI: 10.3340/jkns.2010.47.1.26] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2009] [Revised: 11/08/2009] [Accepted: 12/26/2009] [Indexed: 11/27/2022] Open
Abstract
OBJECTIVE Recurrent lumbar disc herniation has been reported to occur in 5% to 15% of surgically treated primary lumbar disc herniation cases. We investigated the molecular biologic characteristics of primary herniated discs and recurrent discs to see whether the recurrent discs has the similar biological features with primary herniated discs. METHODS Primary herniated disc and recurrent disc cells were obtained by discectomy of lumbar disc patients and cells were isolated and then taken through monolayer cultures. We compared chondrogenic and osteogenic mRNA gene expression, and western blot between the two groups. RESULTS The mRNA gene expression of recurrent disc cells were increased 1.47* times for aggrecan, 1.38 times for type I collagen, 2.04 times for type II collagen, 1.22 times for both Sox-9 and osteocalcin, and 1.31 times for alkaline phosphatase, respectively, compared with the primary herniated lumbar disc cells (*indicates p < 0.05). Western blot results for each aggrecan, type I collagen, type II collagen, Sox-9, osteocalcin, and alkaline phosphatase were similar between the primary herniated disc cells and recurrent disc cells. CONCLUSION These results indicate that the recurrent disc cells have similar chondrogenic and osteogenic gene expression compared to primary herniated disc cells. Therefore, we assumed that the regeneration of remaining discs could fill the previous discectomy space and also it could be one of the factors for disc recurrence especially in the molecular biologic field.
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Affiliation(s)
- Sung-Uk Kuh
- Department of Neurosurgery, Spine and Spinal Cord Institute, Yonsei University College of Medicine, Seoul, Korea
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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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Yang L, Kandel RA, Chang G, Santerre JP. Polar surface chemistry of nanofibrous polyurethane scaffold affects annulus fibrosus cell attachment and early matrix accumulation. J Biomed Mater Res A 2009; 91:1089-99. [DOI: 10.1002/jbm.a.32331] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Bron JL, Helder MN, Meisel HJ, Van Royen BJ, Smit TH. Repair, regenerative and supportive therapies of the annulus fibrosus: achievements and challenges. 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; 18:301-13. [PMID: 19104850 PMCID: PMC2899423 DOI: 10.1007/s00586-008-0856-x] [Citation(s) in RCA: 145] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2008] [Revised: 09/09/2008] [Accepted: 12/05/2008] [Indexed: 01/07/2023]
Abstract
Lumbar discectomy is a very effective therapy for neurological decompression in patients suffering from sciatica due to hernia nuclei pulposus. However, high recurrence rates and persisting post-operative low back pain in these patients require serious attention. In the past decade, tissue engineering strategies have been developed mainly targeted to the regeneration of the nucleus pulposus (NP) of the intervertebral disc. Accompanying techniques that deal with the damaged annulus fibrous are now increasingly recognised as mandatory in order to prevent re-herniation to increase the potential of NP repair and to confine NP replacement therapies. In the current review, the requirements, achievements and challenges in this quickly emerging field of research are discussed.
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Affiliation(s)
- Johannes Leendert Bron
- Department of Orthopaedic Surgery, VU University Medical Center, Amsterdam, The Netherlands.
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Evaluation criteria for musculoskeletal and craniofacial tissue engineering constructs: a conference report. Tissue Eng Part A 2008; 14:2089-104. [PMID: 19093294 PMCID: PMC2809981 DOI: 10.1089/ten.tea.2007.0383] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2007] [Accepted: 06/26/2008] [Indexed: 01/24/2023] Open
Abstract
Over the past 20 years, tissue engineering (TE) has evolved into a thriving research and commercial development field. However, applying TE strategies to musculoskeletal (MSK) and craniofacial tissues has been particularly challenging since these tissues must also transmit loads during activities of daily living. To address this need, organizers invited a small group of bioengineers, surgeons, biologists, and material scientists from academia, industry, and government to participate in a two and half-day conference to develop general and tissue-specific criteria for evaluating new concepts and tissue-engineered constructs, including threshold values of success. Participants were assigned to four breakout groups representing commonly injured tissues, including tendon and ligament, articular cartilage, meniscus and temporomandibular joint, and bone and intervertebral disc. Working in multidisciplinary teams, participants first carefully defined one or two important unmet clinical needs for each tissue type, including current standards of care and the potential impact of TE solutions. The groups then sought to identify important parameters for evaluating repair outcomes in preclinical studies and to specify minimally acceptable values for these parameters. The importance of in vitro TE studies was then discussed in the context of these preclinical studies. Where data were not currently available from clinical, preclinical, or culture studies, the groups sought to identify important areas of preclinical research needed to speed the development process. This report summarizes the findings of the conference.
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Le Maitre CL, Hoyland JA, Freemont AJ. Interleukin-1 receptor antagonist delivered directly and by gene therapy inhibits matrix degradation in the intact degenerate human intervertebral disc: an in situ zymographic and gene therapy study. Arthritis Res Ther 2008; 9:R83. [PMID: 17760968 PMCID: PMC2206387 DOI: 10.1186/ar2282] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2007] [Revised: 08/20/2007] [Accepted: 08/30/2007] [Indexed: 02/07/2023] Open
Abstract
Data implicate IL-1 in the altered matrix biology that characterizes human intervertebral disc (IVD) degeneration. In the current study we investigated the enzymic mechanism by which IL-1 induces matrix degradation in degeneration of the human IVD, and whether the IL-1 inhibitor IL-1 receptor antagonist (IL-1Ra) will inhibit degradation. A combination of in situ zymography (ISZ) and immunohistochemistry was used to examine the effects of IL-1 and IL-1Ra on matrix degradation and metal-dependent protease (MDP) expression in explants of non-degenerate and degenerate human IVDs. ISZ employed three substrates (gelatin, collagen, casein) and different challenges (IL-1β, IL-1Ra and enzyme inhibitors). Immunohistochemistry was undertaken for MDPs. In addition, IL-1Ra was introduced into degenerate IVD explants using genetically engineered constructs. The novel findings from this study are: IL-1Ra delivered directly onto explants of degenerate IVDs eliminates matrix degradation as assessed by multi-substrate ISZ; there is a direct relationship between matrix degradation assessed by ISZ and MDP expression defined by immunohistochemistry; single injections of IVD cells engineered to over-express IL-1Ra significantly inhibit MDP expression for two weeks. Our findings show that IL-1 is a key cytokine driving matrix degradation in the degenerate IVD. Furthermore, IL-1Ra delivered directly or by gene therapy inhibits IVD matrix degradation. IL-1Ra could be used therapeutically to inhibit degeneration of the IVD.
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Affiliation(s)
- Christine L Le Maitre
- Tissue Injury and Repair Group, Research School of Clinical and Laboratory Sciences, The School of Medicine, University of Manchester, Manchester M13 9PT, UK
| | - Judith A Hoyland
- Tissue Injury and Repair Group, Research School of Clinical and Laboratory Sciences, The School of Medicine, University of Manchester, Manchester M13 9PT, UK
| | - Anthony J Freemont
- Tissue Injury and Repair Group, Research School of Clinical and Laboratory Sciences, The School of Medicine, University of Manchester, Manchester M13 9PT, UK
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Abstract
This review article describes anatomy, physiology, pathophysiology and treatment of intervertebral disc. The intervertebral discs lie between the vertebral bodies, linking them together. The components of the disc are nucleus pulposus, annulus fibrosus and cartilagenous end-plates. The blood supply to the disc is only to the cartilagenous end-plates. The nerve supply is basically through the sinovertebral nerve. Biochemically, the important constituents of the disc are collagen fibers, elastin fibers and aggrecan. As the disc ages, degeneration occurs, osmotic pressure is lost in the nucleus, dehydration occurs, and the disc loses its height. During these changes, nociceptive nuclear material tracks and leaks through the outer rim of the annulus. This is the main source of discogenic pain. While this is occurring, the degenerative disc, having lost its height, effects the structures close by, such as ligamentum flavum, facet joints, and the shape of the neural foramina. This is the main cause of spinal stenosis and radicular pain due to the disc degeneration in the aged populations. Diagnosis is done by a strict protocol and treatment options are described in this review. The rationale for new therapies are to substitute the biochemical constituents, or augment nucleus pulposus or regenerate cartilaginous end-plate or finally artificial disc implantation..
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Affiliation(s)
- P Prithvi Raj
- Department of Anesthesiology and Pain Management, Texas Tech University, Lubbock, Texas, USA.
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Kawakami M, Hashizume H, Matsumoto T, Enyo Y, Okada M, Yoshida M, Chubinskaya S. Safety of epidural administration of Osteogenic Protein-1 (OP-1/BMP-7): behavioral and macroscopic observation. Spine (Phila Pa 1976) 2007; 32:1388-93. [PMID: 17545905 DOI: 10.1097/brs.0b013e318060a6b0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN To assess the safety of epidural administration of Osteogenic Protein-1 (OP-1). OBJECTIVES To examine if epidural administration of OP-1 or administration into the nucleus pulposus (NP) resulted in ectopic bone formation and/or pain-related behavior. SUMMARY OF BACKGROUND DATA OP-1 has the potential for treatment of degenerative disc disease. However, OP-1's safety, when it is applied into the epidural space or herniated nucleus pulposus, is not well established. METHODS Forty rats were divided into 5 groups. Sham group: Left L4 and L5 nerve roots were exposed. NP group: The NP obtained from the tail was relocated onto the exposed nerve roots. NP+OP group: The NP obtained from the tail and injected with 0.2 microg of OP-1 in 1 microL of 5% lactose-buffered solution was placed on the nerve roots. GS group: A gelatin sponge was applied on the nerve roots. GS+OP group: A gelatin sponge soaked with 0.2 microg of OP-1 in 1 microL of 5% lactose-buffered solution was placed onto the nerve roots. Motor function and reflex responses to mechanical noxious stimuli were measured in all rats up to 3 weeks after surgery. Three weeks after surgery, all rats were killed for analysis of ectopic bone formation and magnitude of neural compression. RESULTS Motor paresis was not observed in any groups. Only rats in the NP group showed evidence of irreversible mechanical hyperalgesia after surgery. There were no differences in the mechanical stimuli response among all groups except the NP group. Macroscopic examination revealed no ectopic bone formation or differences in neural compression among the groups. CONCLUSION OP-1 application in the epidural space is safe based on behavioral measures and macroscopic observation on ectopic bone formation at 21 days after surgery.
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Affiliation(s)
- Mamoru Kawakami
- Department of Orthopaedic Surgery, Wakayama Medical University, Wakayama City, Wakayama, Japan.
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