Lipoaspirate-derived secretome restores redox homeostasis to attenuate pathological scar formation

Pathological scars are characterized by persistent fibroblast activation and excessive extracellular matrix (ECM) deposition. Although oxidative stress and dysregulated NRF2 signaling contribute to TGF-β1-mediated fibrosis in internal organs, their roles in cutaneous pathological scarring remain unclear. Secretome-based cell-free therapies have shown regenerative and antifibrotic potential, but whether lipoaspirate-derived secretome can restore fibroblast redox homeostasis and thereby attenuate pathological scarring is unknown.

Lipoaspirate fluid obtained during standard tumescent liposuction was processed by 100-kDa ultrafiltration to generate lipoaspirate-derived secretome (LA), while secretome from adipose-derived stromal cell (ADSC) culture supernatant served as a comparator (CS). LA and CS were characterized by nanoparticle tracking analysis, transmission electron microscopy, and immunoblotting for EV markers. In vivo efficacy was evaluated in a rabbit ear scar model with weekly intradermal LA injection, followed by gross, histological, collagen, and qPCR assessments. Comparative proteomic profiling of LA and CS was performed using data-independent acquisition LC-MS/MS with enrichment analysis, and paired human scar and normal skin samples were analyzed by single-cell RNA sequencing. In vitro, TGF-β1-stimulated fibroblasts were treated with LA or CS, and NRF2 involvement was assessed using the inhibitor ML385 or Nrf2-targeting siRNA. Redox balance, NRF2 signaling, and profibrotic responses were assessed by fluorometric assays, qPCR, and immunoblotting.

LA showed a substantially higher particle yield than CS and contained abundant extracellular vesicles. Weekly intradermal LA injections reduced scar formation and improved collagen organization in the rabbit ear model. Comparative proteomics of LA versus CS highlighted cytoprotective pathways, including glutathione metabolism and NRF2-associated antioxidant signaling. Analyses of human scar tissues revealed elevated NOX4 expression, increased 4-HNE, and impaired NRF2-associated antioxidant signaling in scar fibroblasts. In vitro, both LA and CS attenuated TGF-β1-driven profibrotic fibroblast activation, whereas LA showed greater antioxidant activity, including stronger suppression of oxidative stress-related responses and improved GSH/GSSG balance. Pharmacological inhibition and genetic silencing of NRF2 partially reversed the antioxidant and antifibrotic effects of LA.

Lipoaspirate-derived secretome (LA) is a clinically accessible cell-free therapeutic candidate for pathological scarring. LA restores redox homeostasis, in part through NRF2-associated antioxidant signaling, attenuates TGF-β1-driven profibrotic fibroblast activation, and improves scar remodeling in vivo. These findings support LA as a promising cell-free strategy for attenuating pathological scar formation.