Mesenchymal Stem Cell-Derived Exosomes Mitigate Cutaneous Radiation Injury Through Coordinated Modulation of DNA...

Background: Cutaneous radiation injury arises when ionizing radiation disrupts epidermal barrier integrity, triggering persistent DNA damage, oxidative stress, and senescence-associated inflammatory signaling that drive extracellular matrix degradation and impaired regeneration. Clinical burden is rising due to dose-intensified radiotherapy, but also due to an increased use of energy-based aesthetic procedures that elicit radiation-like dermal injury. Dermal fibroblasts exhibit marked sensitivity to ionizing radiation and rapidly acquire senescence-associated secretory phenotypes that suppress collagen biosynthesis and promote chronic inflammation, underpinning the need for regenerative treatments that restore tissue homeostasis and regenerative competence. Mesenchymal stem cell-derived exosomes have emerged as a promising therapeutic strategy in this setting, with increasing preclinical evidence demonstrating their capacity to attenuate oxidative stress, enhance DNA damage-repair pathways, and normalize fibroblast metabolic function. Methods: In this study, we examine the expression profiles for 14 radiation response-associated genes of irradiated human dermal fibroblasts that were treated with bone marrow and umbilical cord MSC-derived exosomes at different timepoints using quantitative RT-PCR analysis. We also explore functional relationships among these genes through interaction network analysis, and outline a framework to organize pathway-level transcriptional responses to irradiation and exosome treatment. Results: MSC-derived exosome treatment was associated with attenuated early damage response signaling at 24 h, followed by increased expression of genes associated with DNA repair and oxidative stress recovery at intermediate timepoints. Exosome-treated cells also exhibited transcriptional changes consistent with modulation of cell-cycle regulatory pathways and reduced expression of pro-inflammatory markers by 5 d. These findings suggest that MSC-derived exosomes influence the temporal organization of the fibroblast transcriptional response to ionizing radiation and may contribute to molecular programs associated with tissue recovery following ionizing radiation exposure.