Intravesicular gelation of mesenchymal stromal cell-derived microvesicles for enhanced therapeutic angiogenesis in lower limb ischemia

Mesenchymal stromal cell-derived artificial microvesicles (MSC-MVs) hold significant promise as a cell-free alternative to traditional stem cell therapy for the treatment of lower limb ischemia. However, their fragile plasma membrane is highly susceptible to oxidative damage, environmental fluctuations, and long-term storage, often leading to membrane rupture, vesicle disintegration, and leakage of bioactive cargoes. Additionally, MSC-MVs can be contaminated by nuclear genes, limiting their safety and therapeutic applicability. In this study, we developed gelated microvesicles (gel-MVs) derived from enucleated MSCs by incorporating a polyethylene glycol diacrylate (PEGDA) polymer network within the vesicular lumen. This intravesicular gelation process stabilized the structure of MSC-MVs, effectively preventing vesicle degradation and content leakage. <i>In vitro</i> experiments demonstrated that gelation preserved the integrity of bioactive components and maintained their functional activity. In a murine lower limb ischemia model, gel-MVs significantly enhanced angiogenesis, restored blood perfusion, reduced apoptosis, and promoted tissue regeneration in ischemic limbs. This study introduces a novel strategy that integrates artificial polymer networks with natural microvesicles, providing a promising platform for engineering robust and functional MSC-MVs with enhanced therapeutic potential for clinical translation.