Implantation of bone marrow-derived buffy coat can supplement bone marrow stimulation for articular cartilage repair

Effect of Systemic Administration of Granulocyte Colony-Stimulating Factor on a Chronic Partial-Thickness Cartilage Defect in a Rabbit Knee Joint

OBJECTIVE

Cartilage lesions in the knee joint can lead to joint mechanics changes and cause knee pain. Bone marrow stimulation (BMS) promotes cartilage regeneration by perforating the subchondral bone just below the injury and inducing bone marrow cells. This study aimed to investigate whether systemic administration of granulocyte colony-stimulating factor (G-CSF) with BMS improves repair of chronic partial-thickness cartilage defects (PTCDs).

DESIGN

Eighteen 6-month-old New Zealand white rabbits were divided into 3 groups: control (C, n = 6), BMS alone (n = 6), and BMS + G-CSF (n = 6). Partial cartilage defects with 5 mm diameter were created in the trochlear region of both knees; after 4 weeks, the BMS alone and BMS + G-CSF groups underwent BMS; G-CSF (50 µg/kg) or saline was administered subcutaneously for 5 days starting from 3 days before BMS. At 8 and 16 weeks after cartilage defect creation, the area of cartilage defects was macroscopically and histologically evaluated.

RESULTS

International Cartilage Repair Society (ICRS) grades for macroscopic assessment were 0, 0.7, and 0.7 at 8 weeks and 0, 1.2, and 1.3 at 16 weeks in the C, BMS, and BMS + G-CSF groups, respectively. Wakitani scores for histological assessment were 9.8, 8.7, and 8.2 at 8 weeks and 9.5, 9, and 8.2 at 16 weeks in the C, BMS, and BMS + G-CSF groups, respectively. The BMS + G-CSF group showed significantly more repair than the C group, but there was no difference from the BMS group.

CONCLUSIONS

The effect of BMS and G-CSF on chronic PTCDs in mature rabbit knees was limited.

Diagnostic and Therapeutic Role of Extracellular Vesicles in Articular Cartilage Lesions and Degenerative Joint Diseases

Two leading contributors to the global disability are cartilage lesions and degenerative joint diseases, which are characterized by the progressive cartilage destruction. Current clinical treatments often fail due to variable outcomes and an unsatisfactory long-term repair. Cell-based therapies were once considered as an effective solution because of their anti-inflammatory and immunosuppression characteristics as well as their differentiation capacity to regenerate the damaged tissue. However, stem cell-based therapies have inherent limitations, such as a high tumorigenicity risk, a low retention, and an engraftment rate, as well as strict regulatory requirements, which result in an underwhelming therapeutic effect. Therefore, the non-stem cell-based therapy has gained its popularity in recent years. Extracellular vesicles (EVs), in particular, like the paracrine factors secreted by stem cells, have been proven to play a role in mediating the biological functions of target cells, and can achieve the therapeutic effect similar to stem cells in cartilage tissue engineering. Therefore, a comprehensive review of the therapeutic role of EVs in cartilage lesions and degenerative joint diseases can be discussed both in terms of time and favorability. In this review, we summarized the physiological environment of a joint and its pathological alteration after trauma and consequent changes in EVs, which are lacking in the current literature studies. In addition, we covered the potential working mechanism of EVs in the repair of the cartilage and the joint and also discussed the potential therapeutic applications of EVs in future clinical use.

The Use of Peripheral Blood-Derived Stem Cells for Cartilage Repair and Regeneration In Vivo: A Review

Background

Peripheral blood (PB) is a potential source of chondrogenic progenitor cells that can be used for cartilage repair and regeneration. However, the cell types, isolation and implantation methods, seeding dosage, ultimate therapeutic effect, and in vivo safety remain unclear.

Methods

PubMed, Embase, and the Web of Science databases were systematically searched for relevant reports published from January 1990 to December 2019. Original articles that used PB as a source of stem cells to repair cartilage in vivo were selected for analysis.

Results

A total of 18 studies were included. Eight human studies used autologous nonculture-expanded PB-derived stem cells (PBSCs) as seed cells with the blood cell separation isolation method, and 10 animal studies used autologous, allogenic or xenogeneic culture-expanded PB-derived mesenchymal stem cells (PB-MSCs), or nonculture-expanded PBSCs as seed cells. Four human and three animal studies surgically implanted cells, while the remaining studies implanted cells by single or repeated intra-articular injections. 121 of 130 patients (in 8 human clinical studies), and 230 of 278 animals (in 6 veterinary clinical studies) using PBSCs for cartilage repair achieved significant clinical improvement. All reviewed articles indicated that using PB as a source of seed cells enhances cartilage repair in vivo without serious adverse events.

Conclusion

Autologous nonculture-expanded PBSCs are currently the most commonly used cells among all stem cell types derived from PB. Allogeneic, autologous, and xenogeneic PB-MSCs are more widely used in animal studies and are potential seed cell types for future applications. Improving the mobilization and purification technology, and shortening the culture cycle of culture-expanded PB-MSCs will obviously promote the researchers' interest. The use of PBSCs for cartilage repair and regeneration in vivo are safe. PBSCs considerably warrant further investigations due to their superiority and safety in clinical settings and positive effects despite limited evidence in humans.

[Research progress in treatment of knee osteoarthritis by paracrine effect of stem cells]

OBJECTIVE

To review the advances in utilizing paracrine effect of stem cells in knee osteoarthritis (OA) treatment.

METHODS

The researches in applying stem cells derived conditioned medium, extracellular matrix, exosomes, and microvesicles in knee OA treatment and cartilage repair were reviewed and analyzed.

RESULTS

The satisfying outcomes of using different products of stem cells paracrine effect in knee OA condition as well as cartilage defect is revealed in studies in vitro and in vivo. The mechanism including suppressing the intraarticular inflammation, the apoptosis of chondrocytes, and the degradation of cartilage matrix, while enhancing the synthesis of cartilage matrix, the differentiation of in-situ stem cells into chondrocytes and the migration to the affected area. The effectiveness can be further improved supplemented with the tissue engineering methods or gene modification.

CONCLUSION

Compared with the traditional stem cell therapy, applying the products from paracrine effect of stem cells in knee OA treatment is more economical and safer, presenting great potential in clinical practice.

Evaluation of an Autologous Bone Mesenchymal Stem Cell-Derived Extracellular Matrix Scaffold in a Rabbit and Minipig Model of Cartilage Repair

Background

This study aimed to evaluate an autologous bone mesenchymal stem cell (MSC)-derived extracellular matrix (ECM) scaffold in two animal models of cartilage repair.

Material/Methods

A rabbit model (n=16) and a minipig model (n=8) of cartilage repair were created with cartilage defects of the knee joints treated with bone marrow stimulation (BMS). In the ECM group, autologous bone MSC-derived ECM scaffolds were implanted into the cartilage defects after bone marrow stimulation. In the BMS group, the cartilage defects were treated by bone marrow stimulation only. The renewal capacity of bone MSCs was measured with a colony-forming unit fibroblast (CFU-F) in vitro assay. The extent of cartilage repair was as-sessed at 6 months after surgery.

Results

In the rabbit model, the macroscopic appearance of the exudate of the healing wounds in the ECM group showed less fibrosis, and the histology showed more evenly distributed chondrocytes compared with the BMS group. The CFU-F assay showed that the number of bone MSCs in the ECM group was approximately was twice that of the BMS group. In the minipig model, the macroscopic appearance and magnetic resonance imaging (MRI) findings of the ECM group were improved when compared with the BMS group. The repaired tissue in ECM group had similar histological characteristics and biochemical content to normal hyaline cartilage.

Conclusions

In two animal models of knee joint cartilage repair, the use of an ECM scaffold increased the number of bone MSCs and improved the extent of cartilage repair.

Granulocyte macrophage - colony stimulating factor (GM-CSF) significantly enhances articular cartilage repair potential by microfracture

OBJECTIVE

To investigate whether granulocyte macrophage-colony stimulating factor (GM-CSF) can be used to increase the number of mesenchymal stem cells (MSCs) in blood clots formed by microfracture arthroplasty (MFX) and whether it can improve the therapeutic outcome for cartilage repair.

METHODS

Thirty-six New Zealand white rabbits were divided into four groups: (1) control, (2) GM-CSF, (3) MFX, and (4) GM-CSF + MFX. GM-CSF was administrated intravenously (IV) at 10 μg/kg body weight 20 min before the MFX surgery. The repaired tissues were retrieved and examined by histological observation, quantitative assessment, and biochemical assays at 4, 8, and 12 weeks after treatment. The number of MSCs was measured in the blood clots by the colony forming unit-fibroblast (CFU-F) assay. The kinetic profile and distribution of GM-CSF in vivo was also evaluated by near-Infrared (NIR) fluorescence imaging and enzyme-linked immune sorbent assay.

RESULTS

In the histological observations and chemical assays examined at 4, 8, and 12 weeks, the MFX after GM-CSF administration showed better cartilage repair than the one without GM-CSF. The CFU-F assay showed a significantly larger amount of MSCs present in the blood clots of the GM-CSF + MFX group than in the blood clots of the other groups. The blood concentration of GM-CSF peaked at 10 min and decreased back to almost the initial level after a couple of hours. GM-CSF was distributed in many organs including the bone marrow but was not observed clearly in the joint cavity.

CONCLUSION

Intravenous administration of GM-CSF together with MFX could be a promising therapeutic protocol to enhance the repair of cartilage defects.

Difference between biomarkers of tibial bone marrow and adipose tissue

BACKGROUND

Stem cells, with their regeneration capacity, long-term viability, and differentiation characteristics, have indispensable biological properties. As described by Hauner and Grigoradis et al., mesenchymal stem cell originating from adipose or bone marrow can be differentiated into many tissues such as adipocyte, chondrocyte, myeloblast, and osteoblast. The aim of our study is to compare the use of adipose and tibial bone marrow derived stem cells for therapeutic purposes in orthopedic surgery, which has not been clearly evaluated in the literature to our knowledge and to also evaluate their use.

MATERIAL AND METHOD

Our study was performed between May 2014 and December 2016 in our clinic (Istanbul Medipol University, Department of Orthopedics and Traumatology) in 40 patients. Twelve patients were excluded. The ages of the 28 included patients ranged from 19 to 61 years, with a mean of 41.18 ± 13.39 years. The stem cell samples of these patients were analyzed by flow cytometry.

RESULTS

Tibial bone marrow stem cells were used in 15 cases and the mean age was 49.33 ± 9.15. Adipose-derived stem cells were used in 13 patients and the mean age was 31.77 ± 11.25. None of the patients had any minor/major complication in the areas where stem cells were collected.

DISCUSSION

Tibial-derived bone marrow has better results with regard to the complications, economic burden, and surgery time. Tibial-derived bone marrow harvesting and stem cell preparation time are one-fourth of the stem cell treatment prepared from adipose tissue and the surgical duration is shortened by 45 min.

CONCLUSION

If stem cell use is the preference of the surgeon, we have found that the tibial-derived stem cell system is more advantageous for ease of acquisition, cost analysis, and surgical time.

Extracellular Matrix (ECM) Multilayer Membrane as a Sustained Releasing Growth Factor Delivery System for rhTGF-β3 in Articular Cartilage Repair

Recombinant human transforming growth factor beta-3 (rhTGF-β₃) is a key regulator of chondrogenesis in stem cells and cartilage formation. We have developed a novel drug delivery system that continuously releases rhTGF-β₃ using a multilayered extracellular matrix (ECM) membrane. We hypothesize that the sustained release of rhTGF-β₃ could activate stem cells and result in enhanced repair of cartilage defects. The properties and efficacy of the ECM multilayer-based delivery system (EMLDS) are investigated using rhTGF-β₃ as a candidate drug. The bioactivity of the released rhTGF-ß3 was evaluated through chondrogenic differentiation of mesenchymal stem cells (MSCs) using western blot and circular dichroism (CD) analyses in vitro. The cartilage reparability was evaluated through implanting EMLDS with endogenous and exogenous MSC in both in vivo and ex vivo models, respectively. In the results, the sustained release of rhTGF-ß3 was clearly observed over a prolonged period of time in vitro and the released rhTGF-β₃ maintained its structural stability and biological activity. Successful cartilage repair was also demonstrated when rabbit MSCs were treated with rhTGF-β3-loaded EMLDS ((+) rhTGF-β3 EMLDS) in an in vivo model and when rabbit chondrocytes and MSCs were treated in ex vivo models. Therefore, the multilayer ECM membrane could be a useful drug delivery system for cartilage repair.

Repair of partial thickness cartilage defects using cartilage extracellular matrix membrane-based chondrocyte delivery system in human Ex Vivo model

Treatment options for partial thickness cartilage defects are limited. The purpose of this study was to evaluate the efficacy of the chondrocyte-seeded cartilage extracellular matrix membrane in repairing partial thickness cartilage defects. First, the potential of the membrane as an effective cell carrier was investigated. Secondly, we have applied the chondrocyte-seeded membrane in an ex vivo, partial thickness defect model to analyze its repair potential. After culture of chondrocytes on the membrane in vitro, cell viability assay, cell seeding yield calculation and cell transfer assay were done. Cell carrying ability of the membrane was also tested by seeding different densities of cells. Partial defects were created on human cartilage tissue explants. Cell-seeded membranes were applied using a modified autologous chondrocyte implantation technique on the defects and implanted subcutaneously in nude mice for 2 and 4 weeks. In vitro data showed cell viability and seeding yield comparable to standard culture dishes. Time dependent cell transfer from the membrane was observed. Membranes supported various densities of cells. Ex vivo data showed hyaline-like cartilage tissue repair, integrated on the defect by 4 weeks. Overall, chondrocyte-seeded cartilage extracellular membranes may be an effective and feasible treatment strategy for the repair of partial thickness cartilage defects.

Fetal Cartilage-Derived Cells Have Stem Cell Properties and Are a Highly Potent Cell Source for Cartilage Regeneration

Current strategies for cartilage cell therapy are mostly based on the use of autologous chondrocytes or mesenchymal stem cells (MSCs). However, these cells have limitations of a small number of cells available and of low chondrogenic ability, respectively. Many studies now suggest that fetal stem cells are more plastic than adult stem cells and can therefore more efficiently differentiate into target tissues. However, the characteristics and the potential of progenitor cells from fetal tissue remain poorly defined. In this study, we examined cells from human fetal cartilage at 12 weeks after gestation in comparison with bone marrow-derived MSCs or cartilage chondrocytes from young donors (8-25 years old). The fetal cartilage-derived progenitor cells (FCPCs) showed higher yields by approximately 24 times than that of chondrocytes from young cartilage. The morphology of the FCPCs was polygonal at passage 0, being similar to that of the young chondrocytes, but it changed later at passage 5, assuming a fibroblastic shape more akin to that of MSCs. As the passages advanced, the FCPCs showed a much greater proliferation ability than the young chondrocytes and MSCs, with the doubling times ranging from 2∼4 days until passage 15. The surface marker profile of the FCPCs at passage 2 was quite similar to that of the MSCs, showing high expressions of CD29, CD90, CD105, and Stro-1. When compared to the young chondrocytes, the FCPCs showed much less staining of SA-β-gal, a senescence indicator, at passage 10 and no decrease in SOX9 expression until passage 5. They also showed a much greater chondrogenic potential than the young chondrocytes and the MSCs in a three-dimensional pellet culture in vitro and in polyglycolic acid (PGA) scaffolds in vivo. In addition, they could differentiate into adipogenic and osteogenic lineages as efficiently as MSCs in vitro. These results suggest that FCPCs have stem cell properties to some extent and that they are more active in terms of proliferation and chondrogenic differentiation than young chondrocytes or MSCs.

Repair of articular cartilage defects in the knee with autologous iliac crest cartilage in a rabbit model

PURPOSE

To demonstrate that iliac crest cartilage may be used to repair articular cartilage defects in the knees of rabbits.

METHODS

Full-thickness cartilage defects were created in the medial femoral condyle on both knees of 36 New Zealand white rabbits. The 72 defects were randomly assigned to be repaired with ipsilateral iliac crest cartilage (Group I), osteochondral tissues removed at defect creation (Group II), or no treatment (negative control, Group III). Animals were killed at 6, 12, and 24 weeks post-operatively. The repaired tissues were harvested for magnetic resonance imaging (MRI), histological studies (haematoxylin and eosin and immunohistochemical staining), and mechanical testing.

RESULTS

At 6 weeks, the iliac crest cartilage graft was not yet well integrated with the surrounding articular cartilage, but at 12 weeks, the graft deep zone had partial ossification. By 24 weeks, the hyaline cartilage-like tissue was completely integrated with the surrounding articular cartilage. Osteochondral autografts showed more rapid healing than Group I at 6 weeks and complete healing at 12 weeks. Untreated defects were concave or partly filled with fibrous tissue throughout the study. MRI showed that Group I had slower integration with surrounding normal cartilage compared with Group II. The mechanical properties of Group I were significantly lower than those of Group II at 12 weeks, but this difference was not significant at 24 weeks.

CONCLUSION

Iliac crest cartilage autografts were able to repair knee cartilage defects with hyaline cartilage and showed comparable results with osteochondral autografts in the rabbit model.

An autologous bone marrow mesenchymal stem cell-derived extracellular matrix scaffold applied with bone marrow stimulation for cartilage repair

PURPOSE

It is well known that implanting a bioactive scaffold into a cartilage defect site can enhance cartilage repair after bone marrow stimulation (BMS). However, most of the current scaffolds are derived from xenogenous tissue and/or artificial polymers. The implantation of these scaffolds adds risks of pathogen transmission, undesirable inflammation, and other immunological reactions, as well as ethical issues in clinical practice. The current study was undertaken to evaluate the effectiveness of implanting autologous bone marrow mesenchymal stem cell-derived extracellular matrix (aBMSC-dECM) scaffolds after BMS for cartilage repair.

METHODS

Full osteochondral defects were performed on the trochlear groove of both knees in 24 rabbits. One group underwent BMS only in the right knee (the BMS group), and the other group was treated by implantation of the aBMSC-dECM scaffold after BMS in the left knee (the aBMSC-dECM scaffold group).

RESULTS

Better repair of cartilage defects was observed in the aBMSC-dECM scaffold group than in the BMS group according to gross observation, histological assessments, immunohistochemistry, and chemical assay. The glycosaminoglycan and DNA content, the distribution of proteoglycan, and the distribution and arrangement of type II and I collagen fibers in the repaired tissue in the aBMSC-dECM scaffold group at 12 weeks after surgery were similar to that surrounding normal hyaline cartilage.

CONCLUSIONS

Implanting aBMSC-dECM scaffolds can enhance the therapeutic effect of BMS on articular cartilage repair, and this combination treatment is a potential method for successful articular cartilage repair.

Histomorphochemical comparison of microfracture as a first-line and a salvage procedure: is microfracture still a viable option for knee cartilage repair in a salvage situation?

Microfracture is considered as the first-line procedure for knee cartilage repair, but the results of microfracture seem less predictable and rather controversial in a salvage situation. Thus, the purpose of the study was to histomorphochemically compare microfracture as a salvage procedure with microfracture as a first-line procedure in a rabbit model. We hypothesized that microfracture in a salvage situation would result in histomorphochemically inferior cartilage repair compared to microfracture as a first-line procedure, and the inferiority would be attributed to less migration of reparable marrow cells to the defect due to destruction of microarchitecture of the subchondral bone. Thirty-six New Zealand white rabbits were divided into three groups: (i) untreated full-thickness chondral defect, (ii) single microfracture treatment (first microfracture group), and (iii) repeated microfracture in 8 weeks after the first procedure (second microfracture group). In each group, rabbits were sacrificed at the end of 8 weeks, and osteochondral specimens at the repair sites were obtained for histomorphochemical analysis. Results showed that microfracture as a salvage procedure resulted in overall inferior cartilage repair histomorphochemically compared with microfracture as a first-line procedure, which correlated with deteriorative changes in the quality of underlying subchondral bone rather than intrinsic incapability to recruit the reparative cells in the defect area. In conclusion, although a comparable number of reparable cells and a mechanically weakened subchondral bone are anticipated, more study is necessary to clearly determine when a microfracture should be performed in a situation.

Cartilage extra-cellular matrix biomembrane for the enhancement of microfractured defects

PURPOSE

The purpose of the study was to evaluate whether the biomembrane made of cartilage extracellular matrix, designed to provide cartilage-like favourable environments as well as to prevent against washout of blood clot after microfracture, would enhance cartilage repair compared with the conventional microfracture technique.

METHODS

A prospective trial was designed to compare the biomembrane cover after microfracture with conventional microfracture among patients with grade III-IV symptomatic cartilage defect in the knee joint. Patients aged 18-60 years were assigned to either the microfracture/biomembrane (n = 45) or microfracture groups (n = 19). Among them, 24 knees in the microfracture/biomembrane and 12 knees in the microfracture were followed up for 2 years. Cartilage repair was assessed with magnetic resonance imagings taken 6 months, 1 year, and 2 years postoperatively, and the clinical outcomes were also recorded.

RESULTS

Compared with conventional microfracture, microfracture/biomembrane resulted in greater degree of cartilage repair (p = 0.043). In the intra-group analysis, while microfracture showed moderate to good degree of cartilage repair in nearly 50 % of the patients (47 % at 6 months to 50% at 2 years; n.s.), microfracture/biomembrane maintained an equivalent degree of repair up to 2 years (88% at 6 months to 75% at 2 years; n.s.). The clinical outcome at 2 years also showed improved knee score and satisfaction and decreased pain in each group, but the difference between the two groups was not statistically significant.

CONCLUSIONS

Compared with conventional microfracture, biomembrane cover after microfracture yielded superior outcome in terms of the degree of cartilage repair during 2 years of follow-up. This implies that initial protection of blood clot and immature repair tissue at the microfractured defect is important for the promotion of enhanced cartilage repair, which may be obtained by the application of a biomembrane.

LEVEL OF EVIDENCE

Prospective comparative study, Level II.

Utilizing tissue-engineered cartilage or BMNC-PLGA composites to fill empty spaces during autologous osteochondral mosaicplasty in porcine knees

The potential empty spaces between cylindrical plugs remaining after autologous osteochondral mosaicplasty rely on fibrous repair, which may constrain the quality and integrity of the repair. Thus, the empty spaces should be repaired, and how to fill the empty spaces is still a problem. In the present study, a standardized full-thickness defect (diameter, 6 mm) was created in the weight-bearing area of each medial femoral condyle in both knees of 18 miniature pigs. The 36 knees were randomly assigned to four groups with nine in each group. The defects were initially repaired by autologous osteochondral mosaicplasty. Simultaneously, any empty spaces between the multiple plugs were filled with cell-free poly(lactide-co-glycolide) (PLGA) scaffolds (the scaffold group), tissue-engineered cartilage (the TE group) or bone marrow mononuclear cell (BMNC)-PLGA composites (the composite group). The empty spaces were left untreated as control (the control group). Six months after surgery, the repair results were assessed via macroscopic observation, histological evaluation, magnetic resonance imaging, biomechanical assessment and glycosaminoglycan content. The results demonstrated that mosaicplasty combined with the treatment of the empty spaces could improve cartilage regeneration. The filling of empty spaces by tissue-engineered cartilage produced the best result in all the four groups. Meanwhile, utilizing BMNC-PLGA composites achieved a similar repair result. Considering the cost-effective, time-saving and convenient performance, the BMNC-PLGA composite could be an alternative option to fill the empty spaces combined with mosaicplasty. Copyright © 2014 John Wiley & Sons, Ltd.

Effect of different bone marrow stimulation techniques (BSTs) on MSCs mobilization

The therapeutic effect of bone marrow stimulation techniques (BSTs) is mainly attributed to the role of mesenchymal stem cells (MSCs) from the bone marrow. However, no studies have directly shown the amount of MSCs drained by BSTs. This study hypothesized that differences in the opening of subchondral bone affect the number of MSCs drained from the bone marrow. We purposed that as the exposed area and hole size of BSTs vary, the number of MSCs drained out was measured. Three groups of different BSTs were designed that have variations in the sizes of total exposed area and individual holes. Three different BSTs using a curette, 1.5- and 0.8-mm awls were carried out on the full-thickness femoral cartilage defect of young rabbits. After BST, the number of MSCs in the blood clot was measured by CFU-Fs assay. As the size of the total exposed area increased, so did the number of MSCs obtained. The number of MSCs drained from bone marrow may vary depending on different BSTs and this could affect therapeutic efficacy of cartilage defect. As current microfracture (MF) method cannot drain the most MSCs clinically, more improved surgery technique is needed.

Combination of bone marrow concentrate and PGA scaffolds enhance bone marrow stimulation in rabbit articular cartilage repair

Bone marrow stimulation (BMS) has been regarded as a first-line procedure for the repair of articular cartilage. However, cartilage repair using BMS alone has so far not been ideal because cell homing to the required area has not been sufficient. The aim of this study was to investigate the feasibility of autologous bone marrow concentrate transplantation for the repair of large, full-thickness cartilage defects. Thirty rabbits were divided into five groups: untreated (control); BMS only (BMS); BMS followed by PGA implantation (PGA); BMS followed by a combination of PGA and autologous bone marrow concentrate (BMC); and BMS together with a composite of PGA and cultured bone marrow stem cells (BME). The animals were sacrificed at week 8 after operation, and HE staining, toluidine blue staining and immunohistochemistry were used to assess the repair of defects. The results showed that improved repair, including more newly formed cartilage tissue and hyaline cartilage-specific extracellular matrix, was observed in BMC group relative to the first three groups, in addition similar results were found between BMC and BME groups, however it took longer time for in vitro cell expansion in the BME group. This study demonstrates that the transplantation of autologous bone marrow concentrate is an easy, safe and potentially viable method to contribute to articular cartilage repair.