Genipin-crosslinked cartilage-derived matrix as a scaffold for human adipose-derived stem cell chondrogenesis

Autologous cell-based tissue engineering using three-dimensional scaffolds holds much promise for the repair of cartilage defects. Previously, we reported on the development of a porous scaffold derived solely from native articular cartilage, which can induce human adipose-derived stem cells (ASCs) to differentiate into a chondrogenic phenotype without exogenous growth factors. However, this ASC-seeded cartilage-derived matrix (CDM) contracts over time in culture, which may limit certain clinical applications. The present study aimed to investigate the ability of chemical crosslinking using a natural biologic crosslinker, genipin, to prevent scaffold contraction while preserving the chondrogenic potential of CDM. CDM scaffolds were crosslinked in various genipin concentrations, seeded with ASCs, and then cultured for 4 weeks to evaluate the influence of chemical crosslinking on scaffold contraction and ASC chondrogenesis. At the highest crosslinking degree of 89%, most cells failed to attach to the scaffolds and resulted in poor formation of a new extracellular matrix. Scaffolds with a low crosslinking density of 4% experienced cell-mediated contraction similar to our original report on noncrosslinked CDM. Using a 0.05% genipin solution, a crosslinking degree of 50% was achieved, and the ASC-seeded constructs exhibited no significant contraction during the culture period. Moreover, expression of cartilage-specific genes, synthesis, and accumulation of cartilage-related macromolecules and the development of mechanical properties were comparable to the original CDM. These findings support the potential use of a moderately (i.e., approximately one-half of the available lysine or hydroxylysine residues being crosslinked) crosslinked CDM as a contraction-free biomaterial for cartilage tissue engineering.