This study also revealed that the hMSCs encapsulated in the Yunaconitine MMP-sensitive hydrogels displayed diminished hypertrophic behaviors leading to reduced matrix calcification. One likely explanation to this finding is the different amount of cartilaginous matrix deposition in the hydrogels. The MMP-sensitive hydrogels accumulated more GAG and collagen than the MMP-insensitive hydrogels. The two major cartilage ECM molecules, proteoglycans and type II collagen, are known to promote and stabilize chondrogenic phenotype and thereby suppress matrix calcification. Proteoglycans also bind and stabilize various growth factors and help maintain prolonged bioactivity of growth factors. Some of these growth factors such as TGFbs are inhibitors of hypertrophic differentiation. Therefore, the higher cartilage matrix content in the MMP-sensitive hydrogels may have contributed to the suppression of hMSC hypertrophy. A previous study by another group shows that longer therefore more complete chondrogenic induction actually expedites hypertrophy of chondrogenically induced MSCs compared to shorter chondrogenic induction. Our previously published work also indicates that compared to poorly Miglitol differentiated cells, more thoroughly differentiated hMSCs result in more significant hypertrophy after in vivo implantation. The correlation between the extent of MSCs chondrogenesis and the propensity of subsequent hypertrophy certainly warrants further investigation. Nevertheless, multiple factors can regulate hypertrophy at the same time. A study also shows that activated RhoA/ROCK signaling, which is associated with cell spreading and cytoskeletal tension, inhibits chondrocyte hypertrophy. We postulate that the spreading of the differentiated hMSCs in the MMP-sensitive hydrogels may have inhibited hypertrophy in this case. The MMP-cleavable peptide sequence used in this study is a target of multiple MMP species. Therefore, even though the MMP13 expression in the MMP-sensitive hydrogels was lower than that in the MMP-insensitive hydrogel, cells were still able to break down the MMP-cleavable crosslinks. However, the exact mechanisms underlying the observed effects of cell-mediated degradation on hMSC chondrogenesis remain to be elucidated. Future study is needed to better understand the mechanism of this regulation of hMSC chondrogenic differentiation by cell-mediated scaffold degradation. In the MMP-sensitive hydrogels, significant cell spreading was only observed after around 10 days of culture. The serum-free media used in this study likely induced less cell MMP synthesis than serum-supplemented media do, in which cell spreading in similar MMP-sensitive hydrogels were observed at earlier time points in an unpublished separate study. It should also be noted that significant variation in MMP expression exists among hMSCs from different donors. The hMSCs used in this study are from a healthy young donor. Our previous experiments revealed that hMSCs from osteoarthritic patients express significantly higher MMPs and would have degraded these HA hydrogels faster. Previous studies suggest that a round cell morphology and disrupted cell cytoskeletal structure is closely associated with chondrogenesis. This appears conflicting to our finding that the more spread hMSCs in the MMP-sensitive hydrogels exhibited better chondrogenesis than the rounded hMSCs in the control group.