Irradiation of muscle precursor cells impairs the proliferative and angiogenic functions of their extracellular vesicles.

Ionizing radiation exposure, whether from accidental incidents, radiation therapy, or radiological weapons, poses a significant risk to public health and military personnel. Survivors experience both acute and chronic physiological effects, including tissue dysfunction, fibrosis, and impaired organ function. Among affected tissues, skeletal muscle is particularly vulnerable, as radiation damages muscle precursor cells (MPCs), impairing their ability to regenerate and maintain muscle homeostasis. Extracellular vesicles (EVs), nano-sized lipid-bound vesicles released by cells, mediate intercellular communication by transferring bioactive molecules such as proteins, lipids, and microRNAs. EVs derived from MPCs have shown promise in promoting muscle regeneration, yet their role in radiation injury remains unclear. This study investigated whether EVs from healthy MPCs (NoRad-EVs) could improve cell function in irradiated cells compared to EVs from irradiated MPCs (Rad-EVs). Our findings demonstrated that viability and proliferation are improved in irradiated MPCs receiving NoRad-EVs whereas Rad-EVs fail to mitigate radiation-induced damage. Specifically, NoRad-EVs increased MPC viability from 52 ± 5.7% to 71 ± 4.9% and improved BrdU-measured proliferation by ~ 16% compared to untreated irradiated controls. NoRad-EVs also enhanced angiogenesis in human umbilical vein endothelial cells (HUVECs) and microvascular fragments (MVFs). HUVECs treated with NoRad-EVs showed significantly greater tube branching length (~ 1.5-fold increase) compared to cells exposed to Rad-EVs. Similarly, MVFs receiving NoRad-EVs treatment exhibited a ~ 3-fold increase in vessel density after 7 days as opposed to the group cultured with Rad-EVs. Differential miRNA expression analysis revealed significant alterations in Rad-EVs compared to NoRad-EVs, affecting key pathways related to muscle repair, angiogenesis, and oxidative stress response. Thirteen miRNAs were downregulated and seven were upregulated in Rad-EVs compared to NoRad-EVs (fold change ≥ 1.3, p < 0.05), including targets involved in VEGF, PI3K-Akt, and FoxO signaling. This research underscores the need for effective countermeasures against radiation-induced injuries, which have detrimental effects on the pro-angiogenic and proliferative functions of MPCs and their secreted EVs. Overall, these promising in vitro findings support the restorative impacts of NoRad-EVs as a potential therapeutic, including miRNA-enriched vesicles, in mitigating radiation-induced muscle injury, particularly in the context of military medicine and radiological emergencies.