Riboflavin-induced photo-crosslinking of collagen hydrogel and its application in meniscus tissue engineering.

A meniscus tear is a common knee injury, but its regeneration remains a clinical challenge. Recently, collagen-based scaffolds have been applied in meniscus tissue engineering. Despite its prevalence, application of natural collagen scaffold in clinical setting is limited due to its extremely low stiffness and rapid degradation. The purpose of the present study was to increase the mechanical properties and delay degradation rate of a collagen-based scaffold by photo-crosslinking using riboflavin (RF) and UV exposure. RF is a biocompatible vitamin B2 that showed minimal cytotoxicity compared to conventionally utilized photo-initiator. Furthermore, collagen photo-crosslinking with RF improved mechanical properties and delayed enzyme-triggered degradation of collagen scaffolds. RF-induced photo-crosslinked collagen scaffolds encapsulated with fibrochondrocytes resulted in reduced scaffold contraction and enhanced gene expression levels for the collagen II and aggrecan. Additionally, hyaluronic acid (HA) incorporation into photo-crosslinked collagen scaffold showed an increase in its retention. Based on these results, we demonstrate that photo-crosslinked collagen-HA hydrogels can be potentially applied in the scaffold-based meniscus tissue engineering.