The Relationship Between VEGF, TGF-β₁,bFGF Expression And Wound Age In The Healing Process Of Mouse Skin Wounds

Wound healing is a complex biological response, which is spatially and temporally controlled by many repair factors. Various kinds of biological substances are involved in different stages of wound healing and are closely related to wound age. The predominant expression of cytokines in wound healing process, which is a kind of molecular vital reaction, may be a new mark in wound age estimation.VEGF, TGF-β1, bFGF are cytokines involved in late inflammatory and proliferating stage of wound healing process and play an important role in granulation tissue formation, angiogenesis and collagen synthesis. Immunohistochemical method was used to detect VEGF, TGF-β1 bFGF in the mouse skin wounds with different wound ages in order to explore the relationship between expression of cytokines and wound age. Furthermore, real-time PCR was employed to detect the dynamic expression of TGF-β1 mRNA and to explore the value of cytokine mRNA detection in wound age estimation.The results indicated that persistent positive expression of VEGFwas seen in the epidermal cells and sebaceous gland cells. The expression of TGF-β1 and bFGF in the epidermal cells enhanced at 3h after incision and persisted to 48h and 12h respectively (Kruskal-Wallis test, P<0.01). There was a similar distribution in the positive amount of inflammation and repair cells among VEGF, TGF-β1 and bFGF. At 6h, some of neutrophils showed positive reactions. In 24-96h, macrophages and fibroblasts were main positive cells. The amount of positive cells was increased with wound age, and the peak was occurred at 48h ( VEGF ) and 96h ( TGF-β1, bFGF ) respectively(Dunnet t test, P<0.01). There were still some positive macrophages and fibroblasts at 1w and 2w after incision.TGF-β1 mRNA level in vital wounds elevated apparently at 24h after wounding(Dunnet t test, P<0.01) and persisted at a high level at 48h and 72h. In postmortem wounds, TGF-β1 mRNA was in a increasing manner at 1h and 3h(plh, p3h), and decreased to control level at 6h(p6h).We can conclude that there is a time-related expression of TGF-β1 and bFGF in the epidermal cells in mouse skin wounds; The amount and distribution of inflammation and repair cells that express VEGF, TGF-β1and bFGF is changed in a time-related manner in the healing process of mouse skin wounds; The dynamic expression of TGF-B 1mRNA is closely related to wound age and it can be used as a representative cytokine mark in dating vital skin wounds with a survival interval of more than 6h. Using the expression level of TGF-β1 mRNA alone can not draw any clue to wound vitality with a woundage less than 6h and other cytokines expressed at earlier stage after wounding, such as bFGF, should be used. For the first time, real-time PCR was used to detect the dynamic expression of TGF-β1 imRNA in wound healing process and compared with other methods, we consider that it is at present the most valid method for cytokine qualitative and quantitative analysis in forensic wound age estimation. Detection of VEGF, TGF-β1 bFGF protein and TGF-β1 mRNA is of value in wound age estimation. But in forensic practice, the differences between animal and human specimens and the differences of individuality should cause interference to the wound age estimation. So more research should be done on human specimens and the factors above should be considered.