Contraction of collagen scaffolds in culture. Photographs of hMSCs cultured on C-GAG, XC-GAG, MC-GAG, and XMC-GAG scaffolds in osteogenic medium for 5 weeks. Photographs of representative scaffolds are shown and scaffolds at time 0 without cross-linking are shown for comparison. C-GAG, collagen-glycosaminoglycan scaffold; MC-GAG, mineralized collagen-glycosaminoglycan scaffold; XC-GAG, cross-linked collagen-glycosaminoglycan scaffold; XMC-GAG, cross-linked mineralized collagen-glycosaminoglycan scaffold.