Molecular hydrogen promotes wound healing by inducing early epidermal stem cell proliferation and extracellular matrix deposition

Abstract:

Background: Despite progress in developing wound care strategies, there is currently no treatment that promotes the self-tissue repair capabilities. H2 has been shown to effectively protect cells and tissues from oxidative and inflammatory damage. While comprehensive effects and how H2 functions in wound healing remains unknown, especially for the link between H2 and extracellular matrix (ECM) deposition and epidermal stem cells (EpSCs) activation.

Methods: Here, we established a cutaneous aseptic wound model and applied a high concentration of H2 (66% H2) in a treatment chamber. Molecular mechanisms and the effects of healing were evaluated by gene functional enrichment analysis, digital spatial profiler analysis, blood perfusion/oxygen detection assay, in vitro tube formation assay, enzyme-linked immunosorbent assay, immunofluorescent staining, non-targeted metabonomic analysis, flow cytometry, transmission electron microscope, and live-cell imaging.

Results: We revealed that a high concentration of H2 (66% H2) greatly increased the healing rate (3 times higher than the control group) on day 11 post-wounding. The effect was not dependent on O2 or anti-reactive oxygen species functions. Histological and cellular experiments proved the fast re-epithelialization in the H2 group. ECM components early (3 days post-wounding) deposition were found in the H2 group of the proximal wound, especially for the dermal col-I, epidermal col-III, and dermis-epidermis-junction col-XVII. H2 accelerated early autologous EpSCs proliferation (1-2 days in advance) and then differentiation into myoepithelial cells. These epidermal myoepithelial cells could further contribute to ECM deposition. Other beneficial outcomes include sustained moist healing, greater vascularization, less T-helper-1 and T-helper-17 cell-related systemic inflammation, and better tissue remodelling.

Conclusion: We have discovered a novel pattern of wound healing induced by molecular hydrogen treatment. This is the first time to reveal the direct link between H2 and ECM deposition and EpSCs activation. These H2-induced multiple advantages in healing may be related to the enhancement of cell viability in various cells and the maintenance of mitochondrial functions at a basic level in the biological processes of life.