Regulating Schwann cells and endothelial cells by YIGSR functionalized porous chitosan scaffolds for nerve regeneration

Abstract

Numerous artificial nerve implants for repair of peripheral nerve injury has been developed while their performance still needs to be further improved. In this study, the Tyr-Ile-Gly-Ser-Arg (YIGSR, YR) functionalized porous chitosan scaffolds were prepared by freeze-drying technique and surface biomodification for simultaneous regulation of Schwann cells (SCs) and endothelial cells (ECs), which play important role in nerve regeneration. The physicochemical properties were characterized, including morphology, composition, wettability, mechanical properties, porosity, etc. The culture of SCs and ECs were used to evaluate the pro-neural and endothelial cell growth effects of the grafts, as well as the constitutive relationship between YR-regulated SCs and ECs. Then, the mechanisms involved were explored using molecular biology experiments. The results showed that the YR-grafted chitosan scaffolds could be successfully prepared with aggregated dopamine and YR particles on the surface of the scaffolds. The scaffolds showed a uniform porous structure, YR grafting decreased the porosity of the scaffolds but increased the mechanical properties of the scaffolds, and YR displayed a relatively stable release behavior. Further on, all YR-grafted scaffolds were proven no cytotoxicity and significantly promoted the proliferation and spreading of SCs and ECs, up-regulated the gene expression of Tumor Necrosis Factor-alpha (TNF-α) and Recombinant Contactin 2 (Cntn2), and facilitated the release of growth factors such as brain derived neurotrophic factor (BDNF), nerve growth factor (NGF), and vascular endothelial growth factor (VEGF). Thus, this YR-functionalized scaffold is expected to simultaneously promote both neuronal cell growth and vascularization in peripheral nerve regeneration. This study provides a strategy for the development of biofunctionalized nerve grafts.