MSC-Encapsulating in Situ Cross-Linkable Gelatin Hydrogels to Promote Myocardial Repair

Current stem cell-based therapy for cardiac repair and regeneration after myocardial infarction (MI) is not readily translatable into clinical scenarios due to the low retention and survival of the transplanted cells. Here, we evaluated a simple and feasible design of gelatin-hydroxyphenyl propionic acid (GH) hydrogel as an in situ cross-linkable and injectable cell delivery platform for cardiac tissue regeneration. The GH hydrogel exhibited improved cell retention and survival in vitro and in vivo when encapsulating mouse bone marrow-derived mesenchymal stem cells (MSCs) that were used as promising therapeutic candidates for stem cell therapy. Moreover, we demonstrated that MSC-encapsulating GH hydrogels led to a significant improvement in cardiac functional metrics, such as the fractional shortening (FS), ejection fraction (EF), and end-systolic volume (ESV). Similarly, MSC-encapsulating GH hydrogels induced favorable effects in the cardiac structures of the infarcted heart, producing less fibrosis and thicker infarcted walls. These results suggest that GH hydrogels can be used as an instructive cell delivery platform to provide a suitable microenvironment for transplanted cells; therefore, their in vivo applications combined with MSCs may provide great potential for repair and regeneration of injured cardiac tissues after MI.