Dynamic Hypoxia in Scar Tissue During Human Hypertrophic Scar Progression

BACKGROUND The skin color of human hypertrophic scar changes dynamically during scar progression. OBJECTIVE To investigate whether hypoxia is dynamic during scar progression. METHODS Thirty-five patients with early, proliferative, regressive, and mature scars were involved in this study. Tissue oxygen tension was measured before scar surgery. After surgery, the scar stage was further defined using hematoxylin and eosin staining, and microvessel density and hypoxia inducible factor-1 (HIF-1) expression were detected using immunohistochemistry to determine a correlation with oxygen level. RESULTS Mild hypoxia is present in early scars, moderate hypoxia in proliferative scars, and severe hypoxia in regressive scars. Oxygen levels then return to normal in mature scars, which was consistent with the dynamic change in microvessel density. Meanwhile, HIF-1 expression also changed dynamically along with alteration in oxygen levels. CONCLUSION Hypoxia is dynamic in scar tissue and is possibly correlated with scar formation and regression.