Cartilage injury is a very common joint disease, and cartilage repair is a great challenge in clinical treatment due to the specific structure of cartilage tissue and its microenvironment in vivo. The injectable self-healing hydrogel is a very promising candidate as a cartilage repair material because of its special network structure, high water retention and self-healing properties. In this work, a self-healing hydrogel cross-linked by host-guest interaction between cyclodextrin and cholic acid was developed. The host material was composed of β-cyclodextrin and 2-hydroxyethyl methacrylate-modified poly(l-glutamic acid) (P(LGA-co-GM-co-GC)), while the guest material was chitosan modified by cholic acid, glycidyl methacrylate, and (2,3-epoxypropyl)trimethylammonium chloride (EPTAC) (QCSG-CA). The host-guest interaction self-healing hydrogels, named as HG hydrogels (HG gel), exhibited excellent injectability and self-healable property, and the self-healing efficiency was greater than 90%. Furthermore, in order to enhance the mechanical properties and slow down the degradation of the HG gel in vivo, the second network was constructed by photo-cross-linking in situ. Biocompatibility tests showed that the enhanced multi-interaction hydrogel (MI gel) was extremely suitable for cartilage tissue engineering both in vitro and in vivo. In addition, the adipose derived stem cells (ASCs) in MI gel were able to differentiate cartilage effectively in vitro in the presence of inducing agents. Subsequently, the MI gel without ASCs was transplanted into rat cartilage defects in vivo for the regeneration of cartilage. After 3 months postimplantation, new cartilage tissue was successfully regenerated in a rat cartilage defect. All results indicated that the injectable self-healing host-guest hydrogels have important potential applications in cartilage injury repair.
Keywords: cartilage tissue engineering; chitosan; host−guest interactions; injectable hydrogels; poly(l-glutamic acid); self-healing.