Relationship Between Protein Expression of Endogenous Growth Factors on Fibroblasts and Sensory Nerve in Skin Wound Healing

Objective To study the effect of sensory nerves on the expression of epidermal growth factor(EGF), basic fibroblast growth factor(bFGF) by fibroblasts in the granulation tissues in skin wound healing. Methods In vivo and in vitro studies were conducted. Fifty wistar rats were randomly divided into capsaicin group and control group. The rats in the capsaicin group were subcutaneously injected with neurotoxin dose of capsaicin(50 mg/kg for 3 days) to chemically destroy the sensory nerves. Full thickness skin incisive wound was made on the rat′s back on 8th day after last injection. The contents of substance P(SP), which was mainly released from afferent sensory nerve terminal, and EGF, bFGF in granulation tissue of skin lesion were determined using immunohistochemistry combined with computerized imaging analysis on 3rd, 6th, 9th, 12th days after the incision. In the control group no capsaicin was injected. In the in vitro study the fibroblasts from granulation tissue of rats were cultured with different doses of SP(10-9 ~ 10-5 mol/L), and the protein expression of EGF, bFGF by cultured fibroblasts was determined using Western blot. Results Immunoreactive SP was not only found around the small blood vessels and in the intercellular space, but also in the cytoplasm of fibroblasts in granulation tissue. SP content and the protein expression of EGF, bFGF in granulation tissue decreased in the capsaicin group, compared with those in the control group, which indicated that SP(10-7 mol/L) added into the culture medium for fibroblasts could upregulate the levels of EGF, bFGF expression. Conclusions Protein expression of EGF and bFGF by fibroblasts in granulation tissue in skin wound healing might be related with the SP released from sensory nerves.