Evaluation of the effect of mesenchymal stromal cells from different sources on human chondrocyte proliferation

Abstract

Objective: to study the effect of a conditioned medium of mesenchymal stromal cells (MSCs) from different sources on human chondrocyte proliferation.Materials and methods. To confirm functional activity, chondrocytes were cultured in a cartilage cell-engineered construct (CEC), including 5 × 105 cells and 5 mg of tissue-specific matrix from decellularized cartilage. The conditioned medium was obtained after culturing MSCs derived from human adipose tissue (AT), MSCs derived from the pulp of primary teeth and MSCs isolated from umbilical cord-derived Wharton’s jelly in a complete cell growth medium (CCGM). To evaluate the effect of MSC-derived secretome on chondrocyte proliferation, the conditioned medium, diluted 1 : 1 with CCGM, was added to wells containing chondrocytes. The effect of MSCs on human chondrocyte proliferation was studied by indirectly coculturing cells in CCGM using Transwell inserts. 5 × 104 MSCs were applied to the bottom of the lower chamber, and 5 × 104 human chondrocytes and 5 mg of matrix were placed in the upper chamber. Chondrocyte proliferation was assessed at days 7 and 14 by DNA quantification. Interleukin-6 content was determined as a marker of secretory activity of MSCs in the conditioned medium. The morphology of the samples was studied using histological staining methods.Results. The ability of chondrocytes to produce cartilage-specific extracellular matrix was confirmed when forming cartilage CEC with tissue-specific matrix in a chondrogenic differentiation medium. When comparing the effect of the conditioned medium of MSCs obtained from different sources on the growth of human chondrocytes in vitro, increased proliferation was observed in all samples compared to controls. Indirect co-culture of MSCs with chondrocytes as part of CEC showed increased DNA amount in all samples at day 14, with the amount of DNA in the sample with MSC conditioned medium significantly higher than the control.Conclusion. Studies on the effect of MSC conditioned medium on chondrocyte proliferation in 2D culture indicate a possible regenerative potential of MSCs for cartilage tissue repair. Within the scope of this work, we did not identify significant differences in the effect of secretome derived from MSCs that were obtained from different sources on chondrocyte proliferation. However, additional in vivo studies are warranted in the future.