[Cell-based therapy options for osteochondral defects. Autologous mesenchymal stem cells compared to autologous chondrocytes]

Characterization of human articular chondrocytes and chondroprogenitors derived from non-diseased and osteoarthritic knee joints to assess superiority for cell-based therapy

PURPOSE

Cell based therapy is constantly underway since regeneration of genuine hyaline cartilage is under par. Much attention has been afforded to chondroprogenitors recently, as an alternative cell substitute for cartilage repair. Although single source derivation of chondrocytes and chondroprogenitors is advantageous, lack of a characteristic differentiating marker obscures clear identification, which is essential to create a biological profile and is also required to assess cell type superiority for cartilage repair.

METHODS

Cells obtained from three non-diseased/osteoarthritic human knee joints each, were expanded in culture up to passage 10. Characterization studies were performed using flow cytometry; gene expression was studied using RT-PCR; growth kinetics and tri-lineage differentiation was also studied to construct a better profile of chondroprogenitors as well as chondrocytes.

RESULTS AND CONCLUSION

Our results showed that both cell populations exhibited similar cell surface characteristics except for non-diseased chondroprogenitors, which showed markedly low expression of CD34 and high expression of CD166. Trilineage data was suggestive of multilineage potential for both cell types with chondroprogenitors showing notably higher glycosaminoglycan and lower calcified matrix deposition. Data acquired from this study aided in describing cellular behavior of human articular cartilage derived chondroprogenitors in conditions not reported earlier. Our comparative analysis suggests that sorting based on a combination of markers (CD34- and CD166+) would yield a population of cells with minimal contamination by chondrocytes, which may provide translatable results in terms of enhanced chondrogenesis and reduced hypertrophy; both indispensable for the field of cartilage regeneration.

Tissue-engineering strategies to repair chondral and osteochondral tissue in osteoarthritis: use of mesenchymal stem cells

Focal chondral or osteochondral lesions can be painful and disabling because they have insufficient intrinsic repair potential, and constitute one of the major extrinsic risk factors for osteoarthritis (OA). Attention has, therefore, been paid to regenerative therapeutic procedures for the early treatment of cartilaginous defects. Current treatments for OA are not regenerative and have little effect on the progressive degeneration of joint tissue. One major reason for this underrepresentation of regenerative therapy is that approaches to treating OA with cell-based strategies have to take into consideration the larger sizes of the defects, as compared with isolated focal articular-cartilage defects, and the underlying disease process. Here, we review current treatment strategies using mesenchymal stem cells (MSCs) for chondral and osteochondral tissue repair in trauma and OA-affected joints. We discuss tissue-engineering approaches, in preclinical large-animal models and clinical studies in humans, which use crude bone-marrow aspirates and MSCs from different tissue sources in combination with bioactive agents and materials.

The role of erythropoietin and bone marrow concentrate in the treatment of osteochondral defects in mini-pigs

Background

All available treatment options for osteochondral and chondral defects do not restore hyaline cartilage and are limited to decreasing associated pain, and maintaining or improving joint function. The purpose of this study was to evaluate the potential of erythropoietin (EPO) in combination with bone marrow aspiration concentrate (BMAC) in the treatment of osteochondral defects of mini-pigs.

Methods

14 Goettinger mini-pigs, in which a 6×10 mm osteochondral defect in the medial femoral condyle of both knee joints was created, were randomized into four groups: biphasic scaffold alone, scaffold with EPO, scaffold with BMAC and scaffold in combination with EPO and BMAC. After 26 weeks all animals were euthanized and histological slides were evaluated using a modified ÓDriscoll Score.

Results

In the therapy groups, areas of chondrogenic tissue that contained collagen II were present. Adding EPO (p = 0.245) or BMAC (p = 0.099) alone to the scaffold led to a non-significant increase in the score compared to the control group. However, the combination of EPO and BMAC in the implanted scaffold showed a significant improvement (p = 0.02) in the histological score.

Conclusion

The results of our study show that in mini-pigs, the combination of EPO and BMAC leads to an enhanced osteochondral healing. However, additional research is necessary to further improve the repair tissue and to define the role of MSCs and EPO in cartilage repair.

Regeneration of articular cartilage of the knee

Cartilage therapy for focal articular lesions of the knee has been implemented for more than a decade, and it is becoming increasingly available. What do we know on the healing response of cartilage lesions? What do we know on the treatment of focal cartilage lesions of the knee and the prognostic factors involved? PubMed articles related to articular cartilage regeneration of the knee in clinical studies were searched from January 2006 to November 2012, using the following key words: articular cartilage, regeneration, clinical studies, and knee. A total of 44 reports were found. They showed the following possibilities for the treatment of focal lesions of the articular cartilage of the knee: cartilage regeneration and repair including cartilage reparation with gene-activated matrices, autologous chondrocyte implantation (ACI) and matrix-induced ACI (MACI), microfracture, osteochondral autograft transfer (mosaicplasty), biological approaches (scaffolds, mesenchymal stem cells-MSCs, platelet-rich plasma, growing factors-GF, bone morphogenetic proteins-BMPs, magnetically labeled synovium-derived cells-M-SDCs, and elastic-like polypeptide gels), osteotomies, stem-cell-coated titanium implants, and chondroprotection with pulsed electromagnetic fields. Untreated cartilage lesions on the femoral condyles had a superior healing response compared to those on the tibial plateaus, and in the patellofemoral joint. Clinical outcome regarding the treatment of medial defects is better than that of the lateral defects. Improvement from baseline was better for patients < or = 30 years compared with patients > or = 30 years. ACI, MACI, and mosaicplasty have shown similar results. The results of comparative clinical studies using ACI have shown some superiority over conventional microfracturing in medium or large defects and in long-term durability. Some biological methods such as scaffolds, MSCs, GF, M-SDCs, BMPs, and elastic-like polypeptide gels still need more research.