Outcome of wound healing process was mainly determined by the presence and concentration of the healing‐associated factors such as MMPs, TGF‐β, VEGF and IGF1.45, 46, 47 Overproduction or high activity of MMP9 and suppressed expression of TGF‐β were identified as indicators of poor healing in skin samples of chronic ulcers.46, 48 In our study, H2 promoted the expression of pro‐healing factors (TGF‐β, VEGF and IGF1) and inhibited the production of MMP9 in wound tissue of pressure ulcer, accompanied by acceleration of dermal collagen synthesis. The gene discussed is MMP9; the disease is decubitus ulcer.