An injectable macroporous hydrogel templated by gasification reaction for enhanced tissue regeneration

Owing to excellent biocompatibility, tunable modulus to match biological tissues, full of water environment, and wide range of constituents, injectable hydrogels have always been preferred as superior performers of regenerative medicine. In principle, the inclusion of macroporous structures in hydrogels facilitates the diffusion of oxygen and nutrients for cell survival and the removal of the metabolic waste, thus strengthening the integration between materials and host tissues. So far, it is still a challenge to construct macroporous structure in hydrogels in situ with preservation of mechanical strength after injecting hydrogel precursors into the biological tissues. In this study, we propose an innovative in situ gas-forming strategy for preparing a kind of bioactive injectable macroporous hydrogel with the assistance of Mg microparticles (MgMPs). Hydrogen gas as a product of MgMPs reacting with water acts as porous template during the gelation process. So the porosity is closely related to the amount of MgMPs, which is a crucial factor for improving cell viability and proliferation throughout the macroporous hydrogel. Referring to the in vivo wound care experiments, regenerated epidermis and extensive blood vessels are found in the macroporous hydrogel, indicating enhanced tissue regeneration. This in situ gas-templating strategy for preparing injectable macroporous hydrogels holds promise as a technique for providing improved biological scaffolds.