Effect of hyperbaric oxygen on human skin cells in culture and in human dermal and skin equivalents

A critical stage of cutaneous wound healing is the development and maturati on of the epidermis. In the aged, and in certain pathologies, this repair p rocess is compromised due to a variety of deficiencies, one of which is tis sue oxygenation. Several phases of wound healing are dependent on adequate tissue oxygen levels, and hyperbaric oxygenation has been shown to transien tly elevate these levels. The use of human cell monolayers, dermal equivale nts and human skin equivalents provide excellent opportunities for studying wound healing using in vivo relevant models. The goal of this study was to examine the effect of hyperbaric oxygen on cell proliferation, differentia tion, and matrix biosynthesis in monolayer cultures and epidermopoiesis in the developing skin equivalent. Normal human dermal fibroblasts, keratinocy tes and melanocytes, dermal equivalents and skin equivalents were exposed t o hyperbaric oxygen at pressures up to three atmospheres, for up to 10 cons ecutive daily treatments lasting 90 minutes each. Increase in fibroblast pr oliferation (cf., 30% at 1 atmosphere after 10 days treatment) was observed without a significant effect on proliferation of normal human melanocytes and glycosaminoglycan synthesis. Stimulation of collagen synthesis after tw o days of treatment was only significant at 1 atmosphere (about 20% increas e) but this differential was not observed after 5 days of treatment. Hyperb aric oxygenation above 2 atmospheres, inhibited proliferation of fibroblast s and keratinocytes in cell monolayer cultures (e.g., a 10 day treatment at 3 atmospheres appeared cytostatic to keratinocytes). In contrast, hyperbar ic treatment up to 3 atmospheres dramatically enhanced keratinocyte differe ntiation, and epidermopoiesis in the complete human skin equivalent. These results support the importance of hyperbaric oxygen therapy in wound healin g, and should provide an insight into oxygen utilization during repair of p eripheral human tissue. The results also show the utility of the human skin equivalent as a model for evaluation of parameters involved in wound heali ng.