Hydrogen-Generating Silica Material Prevents UVA-ray-Induced Cellular Oxidative Stress, Cell Death, Collagen Loss and Melanogenesis in Human Cells and 3D Skin Equivalents.

Ultraviolet-A (UVA) irradiation induces harmful effects on skin cells and accelerates skin aging through oxidative stress. In this study, the effects of a hydrogen-generating silica material named ULH-002 against UVA injuries in human cells and 3D skin equivalents were investigated. The oxygen radical absorption capacity (ORAC) assay showed that both freshly prepared ULH-002 solutions and 7-day-old solutions exhibited equal peroxyl radical (ROO·) scavenging activities concentration-dependently. CellROX® green/orange staining showed that ULH-002 could reduce UVA-induced oxidative stress in human keratinocytes HaCaT and human gingival fibroblasts (HGFs). ULH-002 significantly prevented UVA-induced apoptotic/necrotic cell death and cell-viability decline in HGFs and keratinocytes, as shown by Annexin V/PI apoptosis assay and PrestoBlue assay, respectively. Immunostaining showed that ULH-002 prevented the UVA-induced deterioration of expression of both type IV and I collagens in the 3D skin equivalents, and similarly in monolayer HGFs. UVA-enhanced melanogenesis was observed in human melanocytes HMV-II and HMV-II cell-containing 3D skin equivalents, but markedly prevented by ULH-002 as demonstrated by Fontana–Masson’s staining. In conclusion, our data suggested that ULH-002 could protect human keratinocytes and fibroblasts from UVA-induced injuries, prevent the loss of type IV and I collagens, as well as reduce melanogenesis. ULH-002 might be developed as a skin care reagent in the cosmetic industry.