Skin Nerve Regeneration And Burn Wound Healing Following Spinal Nerve Root Incision

Background:Burn Wound healing is a complex but orderly biological processes, including inflammation, cell proliferation, wound remodeling stages. There are many reports about inflammatory cells involved in wound healing, repair cells, inflammatory mediators, growth factors and extracellular matrix and other constituents. A lots of studies have shown nerves plays an important role in wound healing, the research focus on neuropeptides and wound healing, the neuropeptides were influenced by many factors, so they didn't exact prove the relationship between nerve fiber and wound healing; the regeneration of nerve and morphology three-dimensional structure in process of wound healing, the relationship between neural regulation and the formation of wound healing were rarely reported.Objective:Using an animal experiment, this study evaluated the effect of spinal nerve root broken on rat peripheral nerve regeneration and burn wound healing..Methods:Right T9-L1 stage spinal nerve root of 30 rats were cut off and prepared for denervation skin models; and then a diameter of 4 cm and a depth ofⅡdegree scalded wound was make on the right denervated skin area of rats (experiment group), the same wounds were made on the left normal skin as control group. The changes of wounds were continuously observed. continuous observation of the wound after injury,10 rats were randomly selected on days after burn 7d,14d,21d, firstly anesthetize the rats, then cut injury tissue in experimental group and control group, each sample is divided into two parts, one fixed in 4% neutral formaldehyde, dehydrated embedded into a wax block, the other save at-80℃freezer. After paraffin-embedded tissue sections by modified trichrome staining and immunohistochemical observate the secretion of type I and III collagen, vascular endothelial growth factor (VEGF) changes, and calculate I/III collagen ratio changes, the speed of wound healing and quality of wound healing.-80℃refrigerator preserved specimens made into frozen sections(5μm and 10μm), then use of protein gene product 9.5 (PGP9.5) to fluorescence immunohistochemistry,5μm thick sections were observed with ordinary fluorescence microscopy for the surface structure of regenerated nerve and the number of changes,5μm thick sections were observed with LSCM for three-dimensional structure of nerve. Protein gene product 9.5 (PGP9.5) is a ubiquitin hydrolase, widely used in the expression of nerve tissue in various stages of differentiation of nerve cells, is a known nerve markers.wo use PGP9.5 clearly show the nerve's change during wound healing changes in the distribution.Results:The experimental group I, III collagen secretion and I/III collagen ratio after injury were significantly lower than the control group (P<0.05). Experimental group:secretion of I collagen gradually increased with the tines(P <0.05), secretion of III collagen at 7 days and 14 days after injury have no significantly change, significantly higher at 21 days after injury (P<0.05),Ⅰ/Ⅲcollagen ratio significantly reduced at 21 days after injury (P<0.05); change of VEGF: VEGF are increase after injury in both experimental group and control group, at 7 days after injury the expression of VEGF between the two groups were significantly different (p<0.05), experimental group is higher then control group,14 days and 21 days after injury, there was no significant difference between the two groups (p> 0.05); changes of nerve regeneration:7 days after injury, the positive signal of PGP 9.5 is weak in experimental group, control group, the positive signal of PGP 9.5 can be seen in the base of injured, the NVF of two groups were no significant difference (p> 0.05); 14 days after injury, the experimental group still can not see the positive signal of PGP 9.5, the control group the positive signal of PGP 9.5 began to increase, mainly in the central base and organization, usually dot, short rod, the NVF of two groups were significant difference (p> 0.05); 21 days after injury, control group's positive signal of PGP 9.5 increased significantly, round point, rod-shaped or bean sprouts, the NVF of control group was significant higher than experiment group(p> 0.05).Conclusion:the skin nerve fibers in the injured area have a process of regeneration along with the process of wound healing, cut off the spinal nerve root, the skin nerve fibers was not found regeneration. In early stage of wound healing, strength the nerve factor can promote wound healing, in wound remodeling stage, reduced nerve function may improve the quality of wound remodeling.