Enhancement of chondrogenesis of human adipose derived stem cells in a hyaluronan-enriched microenvironment

Microenvironment plays a critical role in guiding stem cell differentiation. We investigated the enhancing effect of a hyaluronan (HA)-enriched microenvironment on human adipose derived stem cell (hADSC) chondrogenesis for articular cartilage tissue engineering. The hADSCs were obtained from patients undergoing hip replacement. HA-coated wells and HA-modified poly-(lactic-co-glycolic acid) (HA/PLGA) scaffolds were used as the HA-enriched microenvironment. The mRNA expressions of chondrogenic (SOX-9, aggrecan and collagen type II), fibrocartilage (collagen type I), and hypertrophic (collagen type X) marker genes were quantified by real-time polymerase chain reaction. Sulfated glycosaminoglycan (sGAG) deposition was detected by Alcian blue, safranin-O staining, and dimethylmethylene blue (DMMB) assays. Localized collagen type II was detected by immunohistochemistry. The hADSCs cultured in HA-coated wells (0.005–0.5 mg/cm2) showed enhanced aggregation and mRNA expressions (SOX-9, collagen type II, and aggrecan) after 24 h, and sGAG content was also significantly increased after 9 days of culture. The HA-modified PLGA did not change the cell adherence and viability of hADSCs. The mRNA expressions of chondrogenic marker genes were significantly enhanced in hADSCs cultured in HA/PLGA rather than those cultured in the PLGA scaffold after 1, 3, and 5 days of culture. The hADSCs cultured in HA/PLGA produced higher levels of sGAG and collagen type II, compared to those in the PLGA scaffold after 4 weeks of cultures. Our results suggest that HA-enriched microenvironment induces chondrogenesis in hADSCs, which may be beneficial in articular cartilage tissue engineering.