Surface‐Anchored Nanogel Coating Endows Stem Cells with Stress Resistance and Reparative Potency via Turning Down the Cytokine‐Receptor Binding Pathways

Stem cell‐based therapy has great potential in regenerative medicine. However, the survival and engraftment rates of transplanted stem cells in disease regions are poor and limit the effectiveness of cell therapy due to the fragility of stem cells. Here, an approach involving a single‐cell coating of surface‐anchored nanogel to regulate stem cell fate with anti‐apoptosis capacity in the hypoxic and ischemic environment of infarcted hearts is developed for the first time. A polysialic acid‐based system is used to anchor microbial transglutaminase to the external surface of the cell membrane, where it catalyzes the crosslinking of gelatin. The single‐cell coating with surface‐anchored nanogel endows mesenchymal stem cells (MSCs) with stress resistance by blocking the activity of apoptotic cytokines including the binding of tumor necrosis factor α (TNFα) to tumor necrosis factor receptor, which in turn maintains mitochondrial integrity, function and protects MSCs from TNFα‐induces apoptosis. The administration of surface engineered MSCs to hearts results in significant improvements in engraftment, cardiac function, infarct size, and vascularity compared with using uncoated MSCs in treating myocardial infarction. The surface‐anchored, biocompatible cell surface engineering with nanogel armor provides a new way to produce robust therapeutic stem cells and may explore immense potentials in cell‐based therapy.