Injectable enzyme-crosslinking antioxidant hydrogel for stem cells protection and application in skeletal muscle regeneration

Abstract

Repair of large and irregular skeletal muscle defects by cell therapy has been one of the major challenges in tissue engineering and regenerative medicine because of some major hurdles including stem cell death, function decline rapidly, and low retention in situ. Commercially available hydrogels for encapsulating stem cells are usually not suitable for uses in deep and irregular defects due to the limitations of crosslinking approaches as well as that of antioxidant properties. In this work, an injectable and self-healing hydrogel was developed, which is composed of caffeic acid grafted-gelatin molecules cross-linked through laccase catalysis reaction. Mechanical properties, swelling and degradation rates, cell compatibility, ROS-scavenging ability, and anti-senescence potentials of the hydrogels were characterized and investigated with varying caffeic acid contents. Result showed that the hydrogels hold features of strong capacity of scavenging reactive oxygen species, appropriated mechanical modulus falling in the range of that for bone marrow, and relative low oxygen microenvironment, which enabled the hydrogels to reduce the senescence of bone marrow-derived mesenchymal stem cells (BMSCs) and preserved their stemness. When applied to a mouse model of large and deep skeletal muscle defects, the hydrogel encapsulation increased BMSC retention in situ, improved the cell viability, and differentiation function, promoting myofiber regeneration, vascularization, and M2 macrophage polarization. In conclusion, this study highlights the superior ability of the hydrogel to preserve BMSCs’ stemness and enhance their therapeutic potential, offering a promising strategy for BMSCs protection and application to the repair of deep and large skeletal muscle defects in situ.