Comparative Study of Collagen Hydrogels Modified in Two Ways Using the Model of Ectopic Cartilage Construction with Diffusion-chamber in Immunocompetent Host

Abstract

Purpose For scaffolds in cartilage tissue engineering, it is the principle to design the materials with both favorable mechanical and biological property. Methods In this article, collagen hydrogels modified by two ways to improve mechanical strength were applied for in vivo cartilage reconstruction: one is collagen-alginate hydrogel (CAH) representative of mixture, the other is collagen hydrogel crosslinked by genipin (CGH). To investigate the biological activities of the two materials, it was designed as: scaffolds loaded with allogenous chondrocytes were encased in diffusion chamber, and then implanted subcutaneously in SD rats for 8 weeks. Results Histologic, immunohistochemical, and RT-PCR results showed that collagen type II and GAG, indicator of cartilage extracellular matrix (ECM) was highly expressed in constructs of chondrocyte-CAH. Significantly lower cell density and expression of cartilage specific protein were shown in constructs of chondrocyte-CGH than that in chondrocyte-CAH. This demonstrated that CAH may provide a more favorable environment for cartilage reconstruction. In addition, the model with diffusion chamber technique was viable for evaluation of scaffolds for in vivo cartilage engineering in immunocompetent host. Instead, directly reconstruction of ectopic cartilage without diffusion chamber suffered from damaged tissue and less neo-cartilage matrix formed. Conclusions In conclusion, CAH is realistic as scaffold for in vivo cartilage tissue engineering with both satisfactory mechanical properties and biomimetic activity. Also, the model with diffusion chamber to reconstruct ectopic cartilage in immunocompetent animals is promising for evaluation of scaffolds. This study provided a new insight for in vivo cartilage tissue engineering.