Dynamic Proteinaceous Hydrogel Enables In-Situ Recruitment of Endogenous TGF-1 and Stem Cells for Cartilage Regeneration

Articular cartilage is a tissue with relatively poor self-regeneration capacity due to insufficient blood vessels and chondrocytes in the region. Biomaterial-assisted tissue engineering has shown great potential in cartilage regeneration. However, there are still many worries over the uses of exogenous growth factors, stem cells and scaffolds. To address these concerns, here a dynamic proteinaceous hydrogel with a self-recruiting ability of cartilage-inducing factor for in situ cartilage regeneration is reported. The dynamic hydrogel (Pep-GelSH) is prepared by using thiol-modified gelatin and thiol-capped TGF-beta 1-affinity peptide through the Au-S coordination. The injectability and self-recovery of Pep-GelSH hydrogel enabled not only minimally invasive implantation but also the adaptability of the scaffold to irregular defect shapes. Meanwhile, the dynamic hydrogel showed improved adherence to the host tissue and allowed quick infiltration of host cells. More importantly, the hydrogel significantly enhanced local enrichment of endogenous TGF-beta 1 and led to the recruitment of stem cells in vivo. After implantation, the hydrogel scaffold triggered the innate repair capacity of cartilage defects by successively promoting stem cells recruitment, infiltration and differentiation, resulting in significantly enhanced chondrogenesis and improved cartilage repair. Therefore, the study in this work may provide a feasible and promising approach for in situ cartilage regeneration.