A novel biodegradable self-healing hydrogel to induce blood capillary formation

A major challenge in tissue engineering is to generate a functional microvasculature that ensures proper blood perfusion and connection with surrounding tissues. Strategies such as the incorporation of growth factors have been proposed to induce the growth of new blood vessels into engineered tissue, but limitations remain. Herein a novel chitosan–fibrin (CF)-based self-healing hydrogel with a modulus of ~1.2 kPa was developed. The self-healing hydrogel was found to be injectable and to degrade ~70% in 2 weeks. Vascular endothelial cells seeded in the CF hydrogel were able to form capillary-like structures. Moreover, the injection of the CF hydrogel alone promoted angiogenesis in the perivitelline space of zebrafish and rescued the blood circulation in ischemic hindlimbs of mice. The excellent self-healing and angiogenic capacities of the hydrogel may be associated with the formation of an interpenetrating polymer network structure between chitosan and fibrin. This unique self-healing hydrogel offers new possibilities for future applications to vascular repair. Hydrogels: Ramping up regeneration A hydrogel that combines a cationic polymer and a protein could provide a useful scaffold for promoting blood vessel growth. Hydrogels have many properties, including biocompatibility and the capacity to dissolve over time, which makes them appealing for medical applications. Researchers led by Shan-hui Hsu at National Taiwan University have now developed a hydrogel based on chitosan and fibrin that potentially offers a uniquely effective medium for vascularization. Their hydrogel is injectable and self-healing–repairing itself within hours of being punctured. Furthermore, it disintegrates mere weeks after transplantation. By combining their gel with endothelial cells, Hsu and colleagues showed that such combination could produce vasculature in vitro . Critically, the angiogenic hydrogel without cells as the implant markedly improved circulation in mice with damaged blood vessels, suggesting that similar hydrogels could be useful for clinical vascular repair. A novel chitosan–fibrin (CF) injectable, self-healing hydrogel (modulus ~1.2 kPa) is developed. The CF hydrogel has excellent self-healing properties and induces vascular endothelial cells to form capillary-like structure. The self-healing and angiogenic capacities are associated with the interpenetrating network structure of the hydrogel. The hydrogel degrades ~70% in 2 weeks. Injection of the CF hydrogel alo