Genipin-cross-linked type II collagen scaffold promotes the differentiation of adipose-derived stem cells into nucleus pulposus-like cells.

Adipose-derived stem cells (ADSCs)-based tissue engineering was a promising method to treat intervertebral disc degeneration. Type II collagen is a native component in the nucleus pulposus (NP), and has the ability to promote ADSCs to differentiate into NP-like cells. In this article, we aimed to establish a genipin-cross-linked three-dimensional (3D) type II collagen scaffold, and determine the biological effects of the scaffold on ADSCs differentiating into a NP-like phenotype. Different concentrations of genipin were used to cross-link the 3D type II collagen scaffold. Microstructure, surface topography, mechanical strength, porosity, swelling property, and biological stability of the scaffolds were detected to evaluate the scaffold properties. Cell proliferation, gene and protein expression were measured to access the biological effects of the scaffolds on ADSCs, and the related molecular mechanism was investigated. Cross-linking by genipin increased the stability of the type II collagen scaffolds, but deformed the configuration of scaffolds and changed the intrinsic properties of type II collagen. scaffold cross-linked with 0.1% genipin improved the biostability on the basis of maintaining the configuration of scaffold. In addition, the 0.1% genipin-cross-linked scaffold promoted ADSCs proliferation and differentiation into NP-like cells, along with the increasing gene and protein expressions of Sonic Hedgehog (Shh). All these results suggested that 0.1% genipin was the optimal concentration to establish a bio-stable 3D type II collagen scaffold, which inducing ADSC proliferation and differentiation toward a NP-like phenotype through the activation of Shh signaling pathway.