Engineered Extracellular Vesicles from Antler Blastema Progenitor Cells: A Therapeutic Choice for Spinal Cord Injury.

Deer antler blastema progenitor cells (ABPCs) are promising for regenerative medicine due to their role in annual antler regeneration, the only case of complete organ regeneration in mammals. ABPC-derived signals show great potential for promoting regeneration in tissues with limited natural regenerative ability. Our findings demonstrate the capability of extracellular vesicles from ABPCs (EVs(ABPC)) to repair spinal cord injury (SCI), a condition with low regenerative capacity. EVs(ABPC) significantly enhanced the proliferation of neural stem cells (NSCs) and activated neuronal regenerative potential, resulting in a 5.2-fold increase in axonal length. Additionally, EVs(ABPC) exhibited immunomodulatory effects, shifting macrophages from M1 to M2. Engineered with activated cell-penetrating peptides (ACPPs), EVs(ABPC) significantly outperformed EVs from rat bone marrow stem cells (EVs(BMSC)) and neural stem cells (EVs(NSC)), promoting a 1.3-fold increase in axonal growth, a 30.6% reduction in neuronal apoptosis, and a 2.6-fold improvement in motor function recovery. These findings support ABPC-derived EVs as a promising therapeutic candidate for SCI repair.