Human chondrocyte-conditioned medium promotes chondrogenesis of bone marrow stem cells

Abstract

Cell-based therapy for osteoarthritis requires culturing of good quality cells, especially with a chondrogenic lineage, for implantation. To investigate the ability of chondrocyte-conditioned medium (CCM) to induced chondrogenesis. Bone marrow mesenchymal stem cells (BMSCs) were subjected to chondrogenic induction using CCM and chondrocyte induction medium (CIM). The optimal condition for the collection of CCM was evaluated by quantifying the concentration of secreted proteins. The chondrogenic efficiency of BMSCs induced by CCM (iCCM) was evaluated using immunocytochemical analysis, Safranin-O staining, and gene expression. Protein quantification revealed that CCM obtained from cells at passage 3 at the 72 h collection point had the greatest amount of protein. Supplementation of CCM results in the aggregation of BMSCs; however, no clumping was visible as in iCIM. The expression of collagen type 2 was detected as early as day 7 for all groups except for non-induced BMSCs; however, the level of expression decreased with culture time. Similarly, all tested groups showed positive staining for Safranin-O as early as day 7. The induction of BMSCs by CCM caused the down-regulation of collagen type 1, along with the up-regulation of the collagen type 2, ACP and SOX9 genes. The optimum CCM to induce BMSC into chondrocytes was collected at passage 3 after 72 h and was used in a 50:50 ratio of CCM to fresh medium.