Cell and Tissue Journal

Abstract Aim: Cartilage defects of the knee such as osteoarthritis disease (OA) are one of the most debilitating and public diseases that are related to high individual and socioeconomic problems. Many recent studies have applied mesenchymal stem cells (MSCs) incorporated with tissue engineering to repair articular cartilage defects or regeneration of OA.  So, the choice of the best cell type in this regard is one of the challenging issues of tissue engineering and OA cell therapy. This study aims to find the best cell source for the regeneration of critical size defects of cartilage knee using autologous chondrocytes and bone marrow-derived MSCs (Bm-MSCs), and adipose-derived MSCs (Ad-MSCs) that were isolated, cultured, and expanded in similar in vitro conditions.
Materials and Methods: In the current study, Najdi sheep were used at 12 months of age. After standard anesthesia, cartilage was isolated from the hyaline cartilage at the end of the ribs. The Bm-MSCs and Ad-MSCs were isolated from bone marrow and tails' adipose tissue, respectively. Following the enzymatic digestion of cartilage and adipose tissues, using collagenase I enzymes, the chondrocyte, Ad-MSCs, and Bm-MSCs were cultured in growth media at 37º C with similar conditions. Then, MSCs were identified by morphology analysis and also osteogenic/adipose/chondrogenic differentiation, in vitro. In addition, chondrocytes were identified by morphology and analysis of cartilage-related gene expression such as Aggrecan, Col II, and SOX9 genes by Real-time PCR technique. After that, an amount of 5×10⁶ cells/ml from each cell source was seeded in the type I collagen gel and transplanted into an experimentally created articular cartilage defect in the knee’s sheep model. Two months after transplantation, the animals were sacrificed in the standard ways and the implanted tissue was removed. The range of regeneration was investigated by macroscopic scoring and histological staining such as H&E and safranin o/fast green.
Results: MSCs showed spindle shape of morphology, and skeletal differentiation were confirmed the identity of MSCs and chondrocytes. The macroscopic observation showed that the defects in cell-treated groups of chondrocytes, Bm-MSCs, and Ad-MSCs were filled with hyaline cartilage-like tissue in contrast to the control groups of untreated and sham (without cell) groups. In addition, the surface of new cartilage formed in Bm-MSCs and chondrocyte groups appeared to be smoother than in the Ad-MSCs group and the hyaline cartilage of Bm-MSCs is more clearly than that of the Ad-MSCs group. Although histological scores (ranging from 1 to 4) were evaluated, there was no significant difference among the three experimental groups regarding newly formed cartilage repair tissues. Furthermore, the histological analysis of H&E and safranin O revealed that all defects were filled by chondrocyte-like cells that were enclosed in the secreted matrix (*P<0.05).
Conclusion: We used three prevalent and main autologous cell sources such as chondrocyte, BM-MSCs, and AD-MSCs cells in exactly equal conditions to find the most significant cell sources for critical size defect of cartilage in sheep’s knees. The results demonstrated that three cell sources are suitable for this purpose; Although the Ad-MSCs due to ease and more accessibility are further recommended.