Evaluation of in vitro chondrocytic differentiation: A stem cell research initiative at the King Abdulaziz University, Kingdom of Saudi Arabia.

Mesenchymal stem cells (MSCs) from various sources have been used in cartilage differentiation with variable success. Therefore, it is of interest to evaluate the in vitro differentiation potential of the hWJSCs derived from the human umbilical cords into chondrocytes at the stem cell research facility at the King Abdulaziz University. hWJSCs are an attractive choice for tissue engineering and regenerative medical applications including cartilage regeneration. We evaluated the hWJSCs using classical histological and cartilage related gene expression studies. Some of the known parameters were re-examined for consistency at the current laboratory conditions. Early passages (P1-P4) showed short fibroblastic morphology and high expression of MSC related surface markers namely CD29 (99.9%), CD44 (97.8%), CD73 (99.6%), CD90 (95.1%) and CD105 (98.9%). MTT assay showed time dependent increase in hWJSCs proliferation by 61.06% and 206.31% at 48h and 72h respectively. Toluidine blue histology showed that hWJSCs were successfully differentiated into chondrocytes in chondrocytic differentiation medium for 21 days. Differentiated hWJSCs also showed significantly increased expression of collagen type II, aggrecan and SOX9 compared to the undifferentiated control. It should be noted that the determination of the average cell yield, the population doubling time and histological staining wtih alcian blue and/or safronin O is required in future studies for improved evaluation of differentiation. Painless derivation, abundance of stem cells that are hypo-immunogenic and safety issues makes this method advantages to MSCs derived from other sources.