Chondrogenesis by co-culture of adipose-derived stromal cells and chondrocytes in vitro.

Adipose-derived stromal cells (ADSCs) could be induced to differentiate into chondrocytes in the presence of cellular factors. In this study, we explored the feasibility of inducing the differentiation of ADSCs into chondrocytes in the presence of chondrocytes. Human ADSCs and porcine auricular chondrocytes were expanded in vitro and then were mixed at the ratio of 7:3. 5.0 × 10(7) mixed cells were seeded onto a polyglycolic acid/polylactic acid scaffold as co-culture group. Chondrocytes and ADSCs with the same cell number were seeded onto the scaffold as positive control group and negative control group. A total of 1.5 × 10(7) chondrocytes were seeded as low-concentration chondrocyte group. After culturing for 8 weeks, gross observation, wet weight, histology, glycosaminoglycan quantification, and collagen II expression were evaluated. Cells in all groups well adhered to the scaffold and could secrete extracellular matrices. In the co-culture group and positive control group, cell-scaffold constructs could maintain the original size and shape during the culture. At the 8th week, cartilage-like tissues were formed, and abundant type II collagen could be detected by immunohistochemistry and reverse transcription-polymerase chain reaction in co-culture and positive control groups. Wet weights and glycosaminoglycan contents of tissues in co-culture group were approximately onefold of those in the negative control group. In the negative control group, constructs shrunk gradually without mature cartilage lacuna formation. In low-concentration chondrocyte group, constructs also shrunk obviously with small amount of cartilage formation. Chondrocytes can provide chondrogenic microenvironment to induce chondrogenic differentiation of ADSCs and thus promote the chondrogenesis of ADSCs in vitro.