Mesenchymal Stem Cells for the Treatment of Spinal Arthrodesis: From Preclinical Research to Clinical Scenario. Stem Cells Int. 2017;2017:3537094. [PMID: 28286524 PMCID: PMC5327761 DOI: 10.1155/2017/3537094]

Efficacy of using autologous cells with graft substitutes for spinal fusion surgery: A systematic review and meta-analysis of clinical outcomes and imaging features

Over the past several decades, there has been a notable increase in the total number of spinal fusion procedures worldwide. Advanced spinal fusion techniques, surgical approaches, and new alternatives in grafting materials and implants, as well as autologous cellular therapies, have been widely employed for treating spinal diseases. While the potential of cellular therapies to yield better clinical results is appealing, supportive data are needed to confirm this claim. This meta-analysis aims to compare the radiographic and clinical outcomes between graft substitutes with autologous cell therapies and graft substitutes alone. PubMed, Scopus, Web of Science, ClinicalTrials.gov, and the Cochrane Central Register of Controlled Trials were searched for studies comparing graft substitutes with autologous cell therapies and graft substitutes alone up to February 2024. The risk of bias of the included studies was evaluated using the Downs and Black checklist. The following outcomes were extracted for comparison: fusion success, complications/adverse events, Visual Analog Scale (VAS) score, and Oswestry Disability Index (ODI) score. Thirteen studies involving 836 patients were included, with 7 studies considered for the meta-analysis. Results indicated that the use of graft substitutes with autologous cell therapies demonstrated higher fusion success rates at 3, 6, and 12 months, lower VAS score at 6 months, and lower ODI score at 3, 6, and 12 months. The complication rate was similar between graft substitutes with autologous cell therapies and graft substitutes alone. Although the current literature remains limited, this meta-analysis suggests that the incorporation of cellular therapies such as bone marrow and platelet derivatives with graft substitutes is associated with a higher fusion rate and significant improvements in functional status and pain following spinal fusion. Future well-designed randomized clinical trials are needed to definitively assess the clinical effectiveness of cellular therapies in spinal fusion.

Safety and efficacy of autologous bone marrow clot as a multifunctional bioscaffold for instrumental posterior lumbar fusion: a 1-year follow-up pilot study

Background

Bone marrow aspirate (BMA), when combined with graft substitutes, has long been introduced as a promising alternative to iliac crest bone graft in spinal fusion. However, the use of BMA is limited by the absence of a standardized procedure, a structural texture, and the potential for diffusion away from the implant site. Recently, the potential use of a new formulation of BMA, named BMA clot, has been preclinically described. In this report, we present the results of a prospective pilot clinical study aimed at evaluating the safety and efficacy of autologous vertebral BMA (vBMA) clot as a three-dimensional and multifunctional bioscaffold in instrumented posterior lumbar fusion.

Methods

Ten consecutive patients with an indication of multilevel (≤5) posterior spinal fusion due to lumbar spine degenerative diseases were included in the study and treated with vBMA. Clinical outcomes were assessed using the Visual Analog Scale (VAS), Oswestry Disability Index (ODI), and EuroQoL-5L (EQ-5L) preoperatively and at 3 months and 12 months after spinal fusion. Bone fusion quality was evaluated at the 12-month follow-up using the Brantigan classification on radiography (XR) imaging. Bone density was measured on computed tomography (CT) scans at 6 and 12 months of follow-up visits at the intervertebral arches and intervertebral joint areas and expressed in Hounsfield unit (HU).

Results

The results indicate a successful posterolateral fusion rate of approximately 100% (considering levels with C, D, and E grades according to the Brantigan classification) at the 12-month follow-up, along with an increase in bone density from 6 to 12 months of follow-up. An improvement in the quality of life and health status following surgery, as assessed by clinical scores (ODI, VAS, and EQ-5L), was also observed as early as 3 months postsurgery. No adverse events related to the vBMA clot were reported.

Conclusion

This prospective pilot study demonstrates the effectiveness and safety profile of vBMA clot as an advanced bioscaffold capable of achieving posterior lumbar fusion in the treatment of degenerative spine diseases. This lays the groundwork for a larger randomized clinical study.

Autologous mesenchymal stem cell transplantation for spinal fusion: 10 years follow-up of a phase I/II clinical trial

Posterolateral spinal fusion is the standard surgical approach for patients with degenerative disc disease. In our previously published article, we reported a 5-years follow-up of a phase I/II clinical trial in patients undergoing spinal fusion with autologous mesenchymal stem cells (MSCs) embedded in tricalcium phosphate. In the current manuscript, we have updated the results with a 10-year follow-up, the longest reported to date in this setting. After clinical and radiological evaluation, safety of the procedure was further confirmed in all 11 treated patients, with no evidence of tumor, infection, inflammatory reaction, or heterotopic ossification related to the administration of MSCs. Regarding clinical efficacy, low back pain and radicular pain (both assessed by the visual analogue scale-VAS), and the Owestry Disability Index remained significantly lower compared to pre-intervention. Radiologic evaluation demonstrated spinal fusion in all cases, improving over time. Finally, quality of life improved significantly also during follow-up. In summary, the use of tricalcium phosphate-embedded autologous MSCs with lumbar posterolateral arthrodesis is safe and potentially provides long-term benefits for 10 years.

Preclinical Study of Human Bone Marrow-Derived Mesenchymal Stem Cells Using a 3-Dimensional Manufacturing Setting for Enhancing Spinal Fusion

Spinal fusion surgery is a surgical technique that connects one or more vertebrae at the same time to prevent movement between the vertebrae. Although synthetic bone substitutes or osteogenesis-inducing recombinant proteins were introduced to promote bone union, the rate of revision surgery is still high due to pseudarthrosis. To promote successful fusion after surgery, stem cells with or without biomaterials were introduced; however, conventional 2D-culture environments have resulted in a considerable loss of the innate therapeutic properties of stem cells. Therefore, we conducted a preclinical study applying 3D-spheroids of human bone marrow-dewrived mesenchymal stem cells (MSCs) to a mouse spinal fusion model. First, we built a large-scale manufacturing platform for MSC spheroids, which is applicable to good manufacturing practice (GMP). Comprehensive biomolecular examinations, which include liquid chromatography-mass spectrometry and bioinformatics could suggest a framework of quality control (QC) standards for the MSC spheroid product regarding the identity, purity, viability, and potency. In our animal study, the mass-produced and quality-controlled MSC spheroids, either undifferentiated or osteogenically differentiated were well-integrated into decorticated bone of the lumbar spine, and efficiently improved angiogenesis, bone regeneration, and mechanical stability with statistical significance compared to 2D-cultured MSCs. This study proposes a GMP-applicable bioprocessing platform and QC directions of MSC spheroids aiming for their clinical application in spinal fusion surgery as a new bone graft substitute.

Autologous mesenchymal stem cells in the treatment of spinal aneurysmal bone cyst

PURPOSE

We retrospectively analyzed a cohort of patients treated at our Centre with bone marrow concentrated (BMC) injection for aneurysmal bone cyst (ABC) of the spine, in order to propose this treatment as a valid alternative for the management of ABCs.

METHODS

Fourteen patients (6 male, 8 female) were treated between June 2014 to December 2019 with BMC injection for ABC of the spine. The mean age was 15.5 years. The mean follow up was 37.4 months (range 12-60 months). The dimension of the cyst and the degree of ossification were measured by Computed Tomography (CT) scans before the treatment and during follow-up visits.

RESULTS

Six patients received a single dose of BMC, five patients received two doses and in three patients three doses of BMC were administered. The mean ossification of the cyst (expressed in Hounsfield units) increased statistically from 43.48 ± 2.36 HU to 161.71 ± 23.48 HU during follow-up time and the ossification was associated to an improvement of the clinical outcomes. The mean ossification over time was significantly higher in patients treated with a single injection compared to patients treated with multiple injections. No significant difference in ossification was found between cervical and non-cervical localization of the cyst. Moreover, the initial size of the cyst was not statistically associated with the degree of ossification during follow-up CONCLUSIONS: Results of this paper reinforce our previous evidence on the use of BMC as a valid alternative for spinal ABC management when SAE treatment is contraindicated or ineffective.

ADSC-Based Cell Therapies for Musculoskeletal Disorders: A Review of Recent Clinical Trials

Recently published clinical trials involving the use of adipose-derived stem cells (ADSCs) indicated that approximately one-third of the studies were conducted on musculoskeletal disorders (MSD). MSD refers to a wide range of degenerative conditions of joints, bones, and muscles, and these conditions are the most common causes of chronic disability worldwide, being a major burden to the society. Conventional treatment modalities for MSD are not sufficient to correct the underlying structural abnormalities. Hence, ADSC-based cell therapies are being tested as a form of alternative, yet more effective, therapies in the management of MSDs. Therefore, in this review, MSDs subjected to the ADSC-based therapy were further categorized as arthritis, craniomaxillofacial defects, tendon/ligament related disorders, and spine disorders, and their brief characterization as well as the corresponding conventional therapeutic approaches with possible mechanisms with which ADSCs produce regenerative effects in disease-specific microenvironments were discussed to provide an overview of under which circumstances and on what bases the ADSC-based cell therapy was implemented. Providing an overview of the current status of ADSC-based cell therapy on MSDs can help to develop better and optimized strategies of ADSC-based therapeutics for MSDs as well as help to find novel clinical applications of ADSCs in the near future.

Pseudarthrosis rate following anterior cervical discectomy with fusion using an allograft cellular bone matrix: a multi-institutional analysis

OBJECTIVE

The use of osteobiologics, engineered materials designed to promote bone healing by enhancing bone growth, is becoming increasingly common for spinal fusion procedures, but the efficacy of some of these products is unclear. The authors performed a retrospective, multi-institutional study to investigate the clinical and radiographic characteristics of patients undergoing single-level anterior cervical discectomy with fusion performed using the osteobiologic agent Osteocel, an allograft mesenchymal stem cell matrix.

METHODS

The medical records across 3 medical centers and 12 spine surgeons were retrospectively queried for patients undergoing single-level anterior cervical discectomy and fusion (ACDF) with the use of Osteocel. Pseudarthrosis was determined based on CT or radiographic imaging of the cervical spine. Patients were determined to have radiographic pseudarthrosis if they met any of the following criteria: 1) lack of bridging bone on CT obtained > 300 days postoperatively, 2) evidence of instrumentation failure, or 3) motion across the index level as seen on flexion-extension cervical spine radiographs. Univariate and multivariate analyses were then performed to identify independent preoperative or perioperative predictors of pseudarthrosis in this population.

RESULTS

A total of 326 patients met the inclusion criteria; 43 (13.2%) patients met criteria for pseudarthrosis, of whom 15 (34.9%) underwent revision surgery. There were no significant differences between patients with and those without pseudarthrosis, respectively, for patient age (54.1 vs 53.8 years), sex (34.9% vs 47.4% male), race, prior cervical spine surgery (37.2% vs 33.6%), tobacco abuse (16.3% vs 14.5%), chronic kidney disease (2.3% vs 2.8%), and diabetes (18.6% vs 14.5%) (p > 0.05). Presence of osteopenia or osteoporosis (16.3% vs 3.5%) was associated with pseudarthrosis (p < 0.001). Implant type was also significantly associated with pseudarthrosis, with a 16.4% rate of pseudarthrosis for patients with polyetherethereketone (PEEK) implants versus 8.4% for patients with allograft implants (p = 0.04). Average lengths of follow-up were 27.6 and 23.8 months for patients with and those without pseudarthrosis, respectively. Multivariate analysis demonstrated osteopenia or osteoporosis (OR 4.97, 95% CI 1.51-16.4, p < 0.01) and usage of PEEK implant (OR 2.24, 95% CI 1.04-4.83, p = 0.04) as independent predictors of pseudarthrosis.

CONCLUSIONS

In patients who underwent single-level ACDF, rates of pseudarthrosis associated with the use of the osteobiologic agent Osteocel are higher than the literature-reported rates associated with the use of alternative osteobiologics. This is especially true when Osteocel is combined with a PEEK implant.

Comparison of Freshly Isolated Adipose Tissue-derived Stromal Vascular Fraction and Bone Marrow Cells in a Posterolateral Lumbar Spinal Fusion Model

STUDY DESIGN

Rat posterolateral lumbar fusion model.

OBJECTIVE

The aim of this study was to compare the efficacy of freshly isolated adipose tissue-derived stromal vascular fraction (A-SVF) and bone marrow cells (BMCs) cells in achieving spinal fusion in a rat model.

SUMMARY OF BACKGROUND DATA

Adipose tissue-derived stromal cells (ASCs) offer advantages as a clinical cell source compared to bone marrow-derived stromal cells (BMSCs), including larger available tissue volumes and reduced donor site morbidity. While pre-clinical studies have shown that ex vivo expanded ASCs can be successfully used in spinal fusion, the use of A-SVF cells better allows for clinical translation.

METHODS

A-SVF cells were isolated from the inguinal fat pads, whereas BMCs were isolated from the long bones of syngeneic 6- to 8-week-old Lewis rats and combined with Vitoss (Stryker) bone graft substitute for subsequent transplantation. Posterolateral spinal fusion surgery at L4-L5 was performed on 36 female Lewis rats divided into three experimental groups: Vitoss bone graft substitute only (VO group); Vitoss + 2.5 × 106 A-SVF cells/side; and, Vitoss + 2.5 × 106 BMCs/side. Fusion was assessed 8 weeks post-surgery via manual palpation, micro-computed tomography (μCT) imaging, and histology.

RESULTS

μCT imaging analyses revealed that fusion volumes and μCT fusion scores in the A-SVF group were significantly higher than in the VO group; however, they were not significantly different between the A-SVF group and the BMC group. The average manual palpation score was highest in the A-SVF group compared with the BMC and VO groups. Fusion masses arising from cell-seeded implants yielded better bone quality than nonseeded bone graft substitute.

CONCLUSION

In a rat model, A-SVF cells yielded a comparable fusion mass volume and radiographic rate of fusion to BMCs when combined with a clinical-grade bone graft substitute. These results suggest the feasibility of using freshly isolated A-SVF cells in spinal fusion procedures.Level of Evidence: N/A.

Randomized clinical trial: expanded autologous bone marrow mesenchymal cells combined with allogeneic bone tissue, compared with autologous iliac crest graft in lumbar fusion surgery

BACKGROUND CONTEXT

Although autogenous iliac crest bone graft (AICBG) is considered the gold-standard graft material for spinal fusion, new bone substitutes are being developed to avoid associated complications and disadvantages. By combining autologous bone marrow mesenchymal stromal cells (MSCs) expanded ex vivo and allogenic cancellous bone graft, we obtain a tissue-engineered product that is osteoconductive and potentially more osteogenic and osteoinductive than AICBG, owing to the higher concentration of MSCs.

PURPOSE

This study aimed to evaluate the feasibility and safety of implanting a tissue-engineered product consisting of expanded bone marrow MSCs loaded onto allograft bone (MSC+allograft) for spinal fusion in degenerative spine disease, as well as to assess its clinical and radiological efficacy.

STUDY DESIGN/SETTING

A prospective, multicenter, open-label, blinded-reader, randomized, parallel, single-dose phase I-II clinical trial.

PATIENT SAMPLE

A total of 73 adult patients from 5 hospitals, with Meyerding grade I-II L4-L5 degenerative spondylolisthesis and/or with L4-L5 degenerative disc disease who underwent spinal fusion through transforaminal lumbar interbody fusion (TLIF).

OUTCOME MEASURES

Spinal fusion was assessed by plain X-ray at 3, 6, and 12 months and by computed tomography (CT) at 6 and 12 months post-treatment. An independent radiologist performed blinded assessments of all images. Clinical outcomes were measured as change from baseline value: visual analog scale for lumbar and sciatic pain at 12 days, 3, 6, and 12 months posttreatment, and Oswestry Disability Index and Short Form-36 at 3, 6, and 12 months posttreatment.

METHODS

Patients who underwent L4-L5 TLIF were randomized for posterior graft type only, and received either MSC+allograft (the tissue-engineered product, group A) or AICBG (standard graft material, group B). Standard graft material was used for anterior fusion in all patients. Feasibility was measured primarily as the percentage of randomized patients who underwent surgery in each treatment group. Safety was assessed by analyzing treatment-emergent adverse events (AEs) for the full experimental phase and appraising their relationship to the experimental treatment. Outcome measures, both radiological and clinical, were compared between the groups.

RESULTS

Seventy-three patients were randomized in this study, 36 from the MSC+allograft group and 37 from the AICBG group, and 65 were surgically treated (31 group A, 34 group B). Demographic and comorbidity data showed no difference between groups. Most patients were diagnosed with grade I or II degenerative spondylolisthesis. MSC+allograft was successfully implanted in 86.1% of randomized group A patients. Most patients suffered treatment-emergent AEs during the study (88.2% in group A and 97.1% in group B), none related to the experimental treatment. X-ray-based rates of posterior spinal fusion were significantly higher for the experimental group at 6 months (p=.012) and 12 months (p=.0003). CT-based posterior fusion rates were significantly higher for MSC+allograft at 6 months (92.3% vs 45.7%; p=.0001) and higher, but not significantly, at 12 months (76.5% vs 65.7%; p=.073). CT-based complete response (defined as the presence of both posterior intertransverse fusion and anterior interbody fusion) was significantly higher at 6 months for MSC+allograft than for AICBG (70.6% vs 40%; p=.0038), and remained so at 12 months (70.6% vs 51.4%; p=.023). Clinical results including patient-reported outcomes improved postsurgery, although there were no differences between groups.

CONCLUSIONS

Compared with the current gold standard, our experimental treatment achieved a higher rate of posterior spinal fusion and radiographic complete response to treatment at 6 and 12 months after surgery. The treatment clearly improved patient quality of life and decreased pain and disability at rates similar to those for the control arm. The safety profile of the tissue-engineered product was also similar to that for the standard material, and no AEs were linked to the product. Procedural AEs did not increase as a result of BM aspiration. The use of expanded bone marrow MSCs combined with cancellous allograft is a feasible and effective technique for spinal fusion, with no product-related AEs found in our study.

Isolation and characterization of mesenchymal stem cells in orthopaedics and the emergence of compact bone mesenchymal stem cells as a promising surgical adjunct

The potential clinical and economic impact of mesenchymal stem cell (MSC) therapy is immense. MSCs act through multiple pathways: (1) as “trophic” cells, secreting various factors that are immunomodulatory, anti-inflammatory, anti-apoptotic, proangiogenic, proliferative, and chemoattractive; (2) in conjunction with cells native to the tissue they reside in to enhance differentiation of surrounding cells to facilitate tissue regrowth. Researchers have developed methods for the extraction and expansion of MSCs from animal and human tissues. While many sources of MSCs exist, including adipose tissue and iliac crest bone graft, compact bone (CB) MSCs have shown great potential for use in orthopaedic surgery. CB MSCs exert powerful immunomodulatory effects in addition to demonstrating excellent regenerative capacity for use in filling boney defects. CB MSCs have been shown to have enhanced response to hypoxic conditions when compared with other forms of MSCs. More work is needed to continue to characterize the potential applications for CB MSCs in orthopaedic trauma.

Safety and Tolerability of Stromal Vascular Fraction Combined with β-Tricalcium Phosphate in Posterior Lumbar Interbody Fusion: Phase I Clinical Trial

The rates of pseudarthrosis remain high despite recent advances in bone graft substitutes for spinal fusion surgery. The aim of this single center, non-randomized, open-label clinical trial was to determine the feasibility of combined use of stromal vascular fraction (SVF) and β-tricalcium phosphate (β-TCP) for patients who require posterior lumbar interbody fusion (PLIF) and pedicle screw fixation. Two polyetheretherketone (PEEK) cages were inserted into the intervertebral space following complete removal of the intervertebral disc. The PEEK cage (SVF group) on the right side of the patient was filled with β-TCP in combination with SVF, and the cage on the left side (control group) was filled with β-TCP alone. Fusion rate and cage subsidence were assessed by lumbar spine X-ray and CT at 6 and 12 months postoperatively. At the 6-month follow-up, 54.5% of the SVF group (right-sided cages) and 18.2% of the control group (left-sided cages) had radiologic evidence of bone fusion (p = 0.151). The 12-month fusion rate of the right-sided cages was 100%, while that of the left-sided cages was 91.6% (p = 0.755). Cage subsidence was not observed. Perioperative combined use of SVF with β-TCP is feasible and safe in patients who require spinal fusion surgery, and it has the potential to increase the early bone fusion rate following spinal fusion surgery.

Substantial Overview on Mesenchymal Stem Cell Biological and Physical Properties as an Opportunity in Translational Medicine

Mesenchymal stem cells (MSC) have piqued worldwide interest for their extensive potential to treat a large array of clinical indications, their unique and controversial immunogenic and immune modulatory properties allowing ample discussions and debates for their possible applications. Emerging data demonstrating that the interaction of biomaterials and physical cues with MSC can guide their differentiation into specific cell lineages also provide new interesting insights for further MSC manipulation in different clinical applications. Moreover, recent discoveries of some regulatory molecules and signaling pathways in MSC niche that may regulate cell fate to distinct lineage herald breakthroughs in regenerative medicine. Although the advancement and success in the MSC field had led to an enormous increase in the amount of ongoing clinical trials, we still lack defined clinical therapeutic protocols. This review will explore the exciting opportunities offered by human and animal MSC, describing relevant biological properties of these cells in the light of the novel emerging evidence mentioned above while addressing the limitations and challenges MSC are still facing.

Allogenic Stem Cells in Spinal Fusion: A Systematic Review

STUDY DESIGN

Systematic review.

OBJECTIVES

To review, critically appraise, and synthesize evidence on the use of allogenic stem cell products for spine fusion compared with other bone graft materials.

METHODS

Systematic searches of PubMed/MEDLINE, through October 31, 2018 and of EMBASE and ClinicalTrials.gov through April 13, 2018 were conducted for literature comparing allogenic stem cell sources for fusion in the lumbar or cervical spine with other fusion methods. In the absence of comparative studies, case series of ≥10 patients were considered.

RESULTS

From 382 potentially relevant citations identified, 6 publications on lumbar fusion and 5 on cervical fusion met the inclusion criteria. For lumbar arthrodesis, mean Oswestry Disability Index (ODI), visual analogue scale (VAS) pain score, and fusion rates were similar for anterior lumbar interbody fusion (ALIF) using allogenic multipotent adult progenitor cells (Map3) versus recombinant human bone morphogenetic protein-2 (rhBMP-2) in the one comparative lumbar study (90% vs 92%). Across case series of allogenic stem cell products, function and pain were improved relative to baseline and fusion occurred in ≥90% of patients at ≥12 months. For cervical arthrodesis across case series, stem cell products improved function and pain compared with baseline at various time frames. In a retrospective cohort study fusion rates were not statistically different for Osteocel compared with Vertigraft allograft (88% vs 95%). Fusion rates varied across time frames and intervention products in case series.

CONCLUSIONS

The overall quality (strength) of evidence of effectiveness and safety of allogenic stem cells products for lumbar and cervical arthrodesis was very low, meaning that we have very little confidence that the effects seen are reflective of the true effects.

Effect of strontium substituted ß-TCP associated to mesenchymal stem cells from bone marrow and adipose tissue on spinal fusion in healthy and ovariectomized rat

Despite alternatives to autogenous bone graft for spinal fusion have been investigated, it has been shown that osteoconductive materials alone do not give a rate of fusion comparable with autogenous bone. This study analyzed a strontium substituted ß-tricalcium phosphate (Sr-ßTCP) associated with syngeneic, unexpanded, and undifferentiated mesenchymal stem cells from bone marrow (BMSC) or adipose tissue (ADSC) as a new tissue engineering approach for spinal fusion procedures. A posterolateral fusion was performed in 15 ovariectomized (OVX) and 15 sham-operated (SHAM) Inbred rats. Both SHAM and OVX animals were divided into three groups: Sr-ßTCP, Sr-ßTCP + BMCSs, and Sr-ßTCP + ADSCs. Animals were euthanized 8 weeks after surgery and the spines evaluated by manual palpation, micro-CT, and histology. For both SHAM and OVX animals, the fusion tissue in the Sr-ßTCP + BMSCs group was more solid. This effect was significantly higher in OVX animals by comparing the Sr-ßTCP + BMCSs group with Sr-ßTCP + ADSCs. Radiographical score, based on micro-CT 2D image, highlighted that the Sr-ßTCP + BMCSs group presented a similar fusion to Sr-ßTCP and higher than Sr-ßTCP + ADSCs in both SHAM and OVX animals. Micro-CT 3D parameters did not show significant differences among groups. Histological score showed significantly higher fusion in Sr-ßTCP + BMSCs group than Sr-ßTCP and Sr-ßTCP + ADSCs, for both SHAM and OVX animals. In conclusion, our results suggest that addition of BMSCs to a Sr-ßTCP improve bone formation and fusion, both in osteoporotic and nonosteoporotic animal, whereas spinal fusion is not enhanced in rats treated with Sr-ßTCP + ADSCs. Thus, for conducting cells therapy in spinal surgery BMSCs still seems to be a better choice compared with ADSCs.

Autologous mesenchymal stromal cells embedded in tricalcium phosphate for posterolateral spinal fusion: results of a prospective phase I/II clinical trial with long-term follow-up

BACKGROUND

Posterolateral spinal fusion with autologous bone graft is considered the "gold standard" for lumbar degenerative disc disease (DDD) when surgical treatment is indicated. The potential role of mesenchymal stromal cells (MSCs) to replace the bone graft in this setting has not been fully addressed.

OBJECTIVE

To analyze the safety, feasibility and potential clinical efficacy of the implantation of autologous MSCs embedded with tricalcium phosphate as a therapeutic alternative to bone graft in patients with DDD during posterolateral spine fusion.

STUDY DESIGN

Phase I/II single-arm prospective clinical trial.

METHODS

Eleven patients with monosegmental DDD at L4-L5 or L5-S1 level were included. Autologous bone marrow-derived MSC were expanded in our Good Manufacturing Practice (GMP) Facility and implanted during spinal surgery embedded in a tricalcium phosphate carrier. Monitoring of patients included a postoperative period of 12 months with four visits (after the 1st, 3rd, 6th, and 12th month), with clinical and radiological assessment that included the visual analog scale (VAS), the Oswestry disability index (ODI), the Short-Form Health Survey (SF-36), the vertebral fusion grade observed through a simple Rx, and the evaluation of possible complications or adverse reactions. In addition, all patients were further followed up to 5 years for outcome.

RESULTS

Median age of patients included was 44 years (range 30-58 years), and male/female ratio was (6/5) L4-L5 and L5-S1 DDD was present five and six patients, respectively. Autologous MSCs were expanded in all cases. There were no adverse effects related to cell implantation. Regarding efficacy, both VAS and ODI scores improved after surgery. Radiologically, 80% of patients achieved lumbar fusion at the end of the follow-up. No adverse effects related to the procedure were recorded.

CONCLUSIONS

The use of autologous MSCs for spine fusion in patients with monosegmental degenerative disc disease is feasible, safe, and potentially effective.

TRIAL REGISTRATION

no. EudraCT: 2010-018335-17 ; code Identifier: NCT01513694 ( clinicaltrials.gov ).

A mouse model for the study of transplanted bone marrow mesenchymal stem cell survival and proliferation in lumbar spinal fusion

PURPOSE

Bone marrow aspirate has been successfully used alongside a variety of grafting materials to clinically augment spinal fusion. However, little is known about the fate of these transplanted cells. Herein, we develop a novel murine model for the in vivo monitoring of implanted bone marrow cells (BMCs) following spinal fusion.

METHODS

A clinical-grade scaffold was implanted into immune-intact mice undergoing spinal fusion with or without freshly isolated BMCs from either transgenic mice which constitutively express the firefly luciferase gene or syngeneic controls. The in vivo survival, distribution and proliferation of these luciferase-expressing cells was monitored via bioluminescence imaging over a period of 8 weeks and confirmed via immunohistochemistry. MicroCT imaging was performed 8 weeks to assess fusion.

RESULTS

Bioluminescence imaging indicated transplanted cell survival and proliferation over the first 2 weeks, followed by a decrease in cell numbers, with transplanted cell survival still evident at the end of the study. New bone formation and increased fusion mass volume were observed in mice implanted with cell-seeded scaffolds.

CONCLUSIONS

By enabling the tracking of transplanted bone marrow-derived cells during spinal fusion in vivo, this mouse model will be integral to developing a deeper understanding of the biological processes underlying spinal fusion in future studies. These slides can be retrieved under Electronic Supplementary Material.

Biological Rationale for the Use of Vertebral Whole Bone Marrow in Spinal Surgery

STUDY DESIGN

Laboratory study.

OBJECTIVE

Mesenchymal stem cells (MSCs) derived from whole bone marrow aspirate (BMA) and MSCs derived from density-gradient centrifugation were isolated from vertebral bodies and cultured under either hypoxic or normoxic conditions to evaluate their biological characteristics and HOX and TALE signature able to improve spinal surgery procedures.

SUMMARY OF BACKGROUND DATA

The use of spinal fusion procedures has increased over the last decades; however, failed fusion still remains an important problem. Clinician and researchers focused their attention on the therapeutic potential of bone marrow MSCs and several methods for their isolation and cultivation have been developed. However, the best source and techniques are still debated.

METHODS

MSCs morphology, surface markers, colony-forming-units, and three lineage differentiation through quantitative real-time PCR (qPCR) were evaluated. Additionally, gene expression analysis of HOX and TALE signatures during osteogenic differentiation were analyzed.

RESULTS

Our study showed that MSCs derived from whole BMA were successfully isolated and when cultured under hypoxic condition presented greater proliferation, larger colonies, and differentiated onto osteogenic and chondrogenic lineage with greater ability, while adipogenic differentiation was less efficient. Results also revealed that MSCs, differently isolated and cultured, expressed different level of HOX and TALE signatures and that HOXB8 were up-regulated with greater efficiency in MSCs derived from whole BMA under hypoxia.

CONCLUSION

Our data indicated that hypoxic preconditioning of MSCs derived from whole BMA exhibited more suitable biological characteristics and different level of HOX and TALE gene activation. We, therefore, concluded that vertebral body MSCs derived from whole BMA may provide alternative sources of MSCs for tissue engineering applications for spine surgery.

LEVEL OF EVIDENCE

N/A.