Study On The Repairing Effect Of Earthwom Black Fungus Powder (EBFP) On Deep Ⅱ Degree Scald In Rats

Objective:To establish successfully the rat model of deep Ⅱ degree scald.To observe the effect of Earthwom black fungus powder(EBFP)on repairing deep Ⅱdegree scald wound in rats,and to preliminaryly explore the mechanism of EBFP from the view of endothelial growth and inflammatory factors.Methods:Ninety-six healthy female Wistar rats were randomly divided into controlgroup,model group,EBFP group and Moisture burn ointment group(MBO)group with 24 rats in each group.The control group did not receive burns;The model group was treated with normal saline on the wound surface;The EBFP group was treated with EBFP for external application;MBO group was treated with MBO for external application.Each group was treated once a day for 21 days.(1)Establishment of deep Ⅱdegree scald model:The scald model was established by using temperature control scald apparatus.The time was 15 s,the pressure was 500 g,the scald area was 2 cm2,and the temperature was 70℃,80℃ and 90℃,respectively.24 h later,the whole skin of the scald site was cut,and the wound tissue was observed by hematoxylin-eosin(HE)staining method,confirming the conditions for establishing rat model of deep Ⅱ degree scald.(2)Study on the healing effect of EBFP group on deep Ⅱ degree scald wounds in rats:On the 3rd,7th,14th and 21st days after scald,the changes of scald wound were observed in each group.The wound healing rate was calculated.Histopathological changes of skin samples were detected by HE staining.The contents of vascular endothelial cell growth factor(VEGF),tumor necrosis factor-α(TNF-α)and interleukin-1β(IL-1β)in skin tissue and serum were determined by enzyme-linked immunosorbent assay(ELISA).Immunohistochemistry(IHC)was used to detect the expression of Collagen Ⅰ in skin samples.The content of hydroxyproline(Hyp)in wound tissue was determined.Results:In the scald model,sebaceous glands and other accessory structures were destroyed in the 80℃ scald group,and the amount of collagen fibers in dermis was reduced,resulting in deep Ⅱ degree scald.Confirm time 15 s,pressure 500 g,temperature 80℃ as the establishment conditions of deep Ⅱ degree scald model.On day 21,the wound healing rate of EBFP group increased to 81.70%(P<0.01),and that of MBO group increased to 86.07%(P<0.01).The healing area of both groups was better than that of the model group.By using HE staining,On day 14,new capillaries appeared in different degrees in each group.More new fibrocytes and collagen fiber bundles were observed in dermis of EBFP group and MBO group,and the inflammatory response was reduced.On day 21,the epidermal spinous layer in the model group was thickened,resulting in hyperkeratosis.Collagen fibers in the EBFP and MBO groups were arranged more neatly and closely,and the number of recovered appendages was more.On days 14,compared with the model group,The content of VEGF in wound tissue and serum was the highest in EBFP group and MBO group(370.99 pg/mL(P<0.01)and 163.81 pg/mL(P<0.01)in EBFP group,361.38 pg/mL(P<0.01)and 168.99 pg/mL(P<0.01)in MBO group),respectively,and the difference was statistically significant.On day 7,the contents of TNF-α and IL-1β in tissue and serum of all groups reached the highest level.Compared with model group,the levels of TNF-α and IL-1β in EBFP group were decreased,and the contents in serum of TNF-α and IL-1β in EBFP group were 397.20 pg/mL(P<0.01)and 126.49 pg/mL(P<0.01),respectively.The contents of that in tissue in EBFP group was 475,19 pg/mL(P<0.01)and 243.56 pg/mL(P<0.01),respectively,Compared with model group,the difference was statistically significant.Collagen Ⅰ level in wound tissue of EBFP group and MBO group was significantly increased,and the average optical density(AOD)of both groups was significantly higher than that of model group since the 7th day(P<0.01).On the 7th and 14th day,the Hyp content was 20.99μg/mg(P<0.01)and 28.49 μg/mg(P<0.01)in EBFP group,which was higher than that of model group,and the difference was statistically significant.Conclusion:Earthworm black fungus powder(EBFP)can obviously promote the healing of deep Ⅱ degree scald wound in rats,shorten the healing time,promote the epidermis and dermis tissue to return to normal morphology,increase the value of skin cells and significantly reduce the inflammatory reaction.The effect was related to up-regulation of Collagen Ⅰ and Hyp in skin tissue,up-regulation of VEGF,down-regulation of TNF-α and IL-1β in tissues and serum.This study provides an experimental basis for the treatment of deep Ⅱ degree scald with Earthworm black fungus powder(EBFP),and deserves further study.