mRNA samples were collected from cell-laden hydrogels before stiffening (day-1), as well as day-2 and day-6 post-stiffening using 1 kU/mL tyrosinase (i.e., day-3, day-7 culture time). Soft: Cell-laden hydrogels crosslinked by regular MMP-sensitive peptide (i.e., 0Y peptide). Stiffened: Cell-laden hydrogels crosslinked by 2Y peptide. GAPDH was used as the housekeeping gene and the expression levels of αSMA (A), CTGF (B), and HIF1α (C) in different samples were normalized to that in day-1 soft gel (1-fold). Experiments were repeated independently for three times with three samples in each group. (Data represent Mean ± SEM). **p<0.01, ***p<0.001.