TGF-β1 affinity peptides incorporated within a chitosan sponge scaffold can significantly enhance cartilage regeneration
Growth factors, such as TGF-β and BMPs, play key roles in the chondrogenic differentiation of mesenchymal stem cells (MSCs) and cartilage regeneration in vivo. Nevertheless, there are some technical challenges in delivering exogenous growth factors in vivo, such as burst release and loss of bioactivity. In this study, TGF-β1 affinity peptides were incorporated within porous chitosan scaffolds to enhance cartilage regeneration. Significant upregulation of gene expression levels of Sox9, Col II and AGG during chondrogenic differentiation of MSCs in vitro, were positively correlated with increasing amounts of TGF-β1 affinity peptides incorporated within the chitosan scaffolds. The results of ectopic implantation of scaffolds in nude mice showed that incorporation of TGF-β1 affinity peptides and preloading of TGF-β1 synergistically enhanced ectopic cartilage formation at both high and low cell densities. Furthermore, in a rabbit osteochondral defect model, implantation of chitosan scaffolds incorporated with TGF-β1 affinity peptides (CHI-PEP) could significantly promote cartilage regeneration, even in the absence of exogenous growth factors and seeded cells. Notably, inflammation and cartilage degeneration were markedly alleviated in the CHI-PEP group. Hence, incorporation of TGF-β1 affinity peptide within the chitosan sponge scaffold significantly enhanced articular cartilage regeneration.