Overexpression of miRNA-216 in exosomes derived from umbilical cord mesenchymal stem cells promotes angiogenesis and improves functional recovery after spinal cord injury.

This study aimed to engineer miR-216-overexpressing umbilical cord mesenchymal stem cells (UCMSCs) to generate miR-216-enriched UCMSC-derived exosomes (UCMSC-Exos) and evaluate their therapeutic potential in Spinal cord injury (SCI). miR-216 overexpression was achieved in UCMSCs, and exosomes were subsequently isolated. The biological effects of miR-216-overexpressing UCMSC-Exos (UCMSC-miR-216OE-Exos) were assessed using in vitro migration, and tube formation assays with vascular endothelial cells. For in vivo evaluation, SCI mouse models were treated with either UCMSC-Exos or UCMSC-miR-216OE-Exos. Functional recovery was measured using the BMS scores, while angiogenesis, neuronal apoptosis, and proinflammatory cytokine expression were analyzed through immunohistochemistry and molecular assays. qPCR analysis confirmed successful miR-216 overexpression in UCMSCs and their derived exosomes. In vitro, UCMSC-miR-216OE-Exos significantly enhanced endothelial cell migration and tube formation compared to control UCMSC-Exos. In vivo, both UCMSC-Exos and UCMSC-miR-216OE-Exos improved BMS scores, promoted angiogenesis, and reduced neuronal apoptosis and proinflammatory cytokine expression in SCI mice. Notably, UCMSC-miR-216OE-Exos demonstrated superior therapeutic effects, including greater improvements in functional recovery, enhanced angiogenic responses, and more pronounced reductions in neuronal apoptosis and inflammation compared to control UCMSC-Exos. Additionally, in vitro experiments revealed that PTEN expression was down-regulated, and the AKT pathway was activated following treatment with UCMSC-miR-216OE-Exos. These findings demonstrate that miR-216-overexpressing UCMSC-Exos exhibits enhanced therapeutic efficacy in promoting angiogenesis, reducing inflammation and neuronal apoptosis, and improving functional recovery after SCI. This study demonstrates the promise of miR-216-enriched exosomes as a novel cell-free therapeutic approach for SCI, paving the way for clinical translation through their biologically translatable mechanisms.