Self-Assembling Copolymers Encapsulating Single Endothelial Cells Induce Endogenous ECM Deposition and Vascular Regeneration.

Cell therapy combined with biomimetic polymer engineering offers a promising strategy for cardiovascular regeneration. Compartmentalizing single cells in hydrogels creates three-dimensional (3D) micro-niches that enhance bio-responsiveness and the therapeutic efficacy of cell therapy. A non-microfluidic strategy for single-cell encapsulation using a stimuli-responsive amphiphilic copolymer, gelatin-poly(glycerol sebacate)-methacrylate (GPM) is developed. When incubated with cells at room temperature, GPM self-assembled into single-cell vesicles via ligand-receptor-mediated interactions, creating a nanoscale matrix around each cell with near 100% encapsulation efficiency. The presence of bioactive moieties, dynamic mechanical properties, and matrix metalloproteinase mediated degradability enabled reciprocal, cell-matrix interactions. Consequently, 3D cultures of GPM vesicles encapsulating single endothelial cell (GPM/EC vesicles) promoted deposition of thread-like extracellular matrix (ECM), which facilitated cell migration and served as a guidance scaffold for vessel-like network formation. For enhanced in vivo distribution and immunoprotection, GPM/reprogrammed EC vesicles were assembled into injectable microspheres, termed mGPM-rEC. Upon injection into a mouse hindlimb ischemia model, mGPM-rEC demonstrated robust cell survival and intramuscular migration with the deposition of dense ECM. This ECM functioned as a reservoir for growth factors and signaling molecules, recruiting host vasculature to promote neovascularization and providing structural and mechanical support for implanted cells to form de novo blood vessels.