Researchers treated human dermal fibroblasts with hyaluronic acid, polynucleotides or both before exposing them to UVA radiation. UVA reduced cell viability and proliferation, increased intracellular and mitochondrial reactive oxygen species, elevated inflammatory signalling and reduced expression of extracellular matrix genes including COL1A1 and FN1. 

While hyaluronic acid and polynucleotides each partially reduced these effects, combined treatment showed a stronger synergistic response. The combination improved fibroblast survival and proliferation, reduced oxidative stress to near-baseline levels, restored extracellular matrix gene expression and increased antioxidant enzyme activity, including GPX1 and SOD2. 

The combined treatment also increased fibroblast invasion, suggesting effects beyond cytoprotection and indicating potential relevance for dermal regenerative activity. Under non-irradiated conditions, neither hyaluronic acid nor polynucleotides showed cytotoxic or pro-oxidant effects at the tested concentrations. 

The authors conclude that hyaluronic acid and polynucleotides may act synergistically to counter UVA-induced oxidative stress and support dermal regeneration. The findings remain laboratory-based and further studies will be required to determine clinical relevance in photoaged skin.