Sphingomonas olei Extracellular Vesicles Promote Hair-Growth Responses Linked to Wnt/β-Catenin Signalling.

Hair loss is a common condition with limited therapeutic options, and bacterial extracellular vesicles have recently emerged as potential bioactive mediators in skin biology. Here, we investigated whether an extracellular vesicle-enriched preparation obtained from Sphingomonas olei, a bacterium isolated from healthy human skin (hereafter SoEVs), influences human hair-growth-related responses and whether these effects are associated with Wnt/β-catenin-related signalling. SoEVs were non-cytotoxic to human dermal papilla (DP) cells and upregulated the hair-growth-related factors IGF1 and VEGFA. In DP cells, SoEV treatment was accompanied by increased levels of phosphorylated AKT and GSK-3β, and total β-catenin, alongside the induction of canonical Wnt readouts LEF1 and AXIN2. In ex vivo cultured human hair follicles, SoEVs promoted hair shaft elongation, counteracted shaft thinning and increased the number of Ki-67-positive cells around the DP. Together, these findings suggest that SoEVs may support human hair-growth-related responses in association with Wnt/β-catenin-related signalling, warranting further mechanistic and in vivo investigation.