FIG. 5.

PDLC ALP activity is elevated in MMP-degradable hydrogels. (A, B) ALP activity for hydrogels cultured in basal medium (A) and inductive medium (B). ALP activity was calculated by dividing the rate of phosphate substrate (p-nitrophenyl phosphate) cleavage by total hydrogel DNA content for each hydrogel using calf intestinal ALP as the standard. (C, D) Whole hydrogels were stained with nitro-blue tetrazolium chloride/5-bromo-4-chloro-3′-indolyphosphate p-toluidine salt (NBT/BCIP) to visualize PDLC ALP activity after 2 weeks culture in basal (C) or inductive medium (D). N = 6 hydrogels. (E) ALP activity for PDLCs cultured on tissue culture plates in basal or inductive medium. ****p < 0.0001 for between-group comparisons, ^%p < 0.0001 for within-group comparisons. ALP, alkaline phosphatase.