| Adult wound healing always end with scar, but in fetal, cutaneous wounds made before the trimester of gestation heal rapidly, effectively and without the formation of scar. It indicates that the mechanism of fetal scarless wound healing is different from that of adult. Lots of researches have showed that many growth factors and inflammatory mediums have participated in the scar formation of adult wound. Fetal scarless wound healing is related to the changes in connective tissue matrix deposition,different growth factor expression and cellular migration into the wound site. Recently, it is believed that peripheral nerve and neuropeptide have important effects on adult wound healing, which are related to the healing speed, the regeneration of epithelia and the formation of scar. However,whether the peripheral nerve and neuropeptide play the same role in fetal scarless wound healing as which do in adult,which remains unknown.Therefore, it is necessary to explore the role of the peripheral nerve and neuropeptide in fetal scarless wound healing, to provide theoretical bases for the method of promote wound healing by ameliorate the nerve function and regulate the secretion of neuropeptides.In the present study, an animal model was replicated in which rabbit fetuses at 22 days gestation (term=31 days) were subjected to a full thickness skin wound on the back. Fetal control, adult trauma, and adult control were designed as control groups respectively. The progress of wound healing was observed on micro-and macro-levels at the 1st, 2nd, 3rd, 5th ,7th, 14th days post-injury respectively.Skin innervation during wound healing was investigated with protein gene product (PGP) 9.5 immunofluorescence stain which labels the entire innervation of the skin throughout the development and in the adult. The expression level of substance p (SP), calcitonin geng-related peptide (CGRP )during wound healing was also detected by the immunohistochemistry stain.Moreover, we placed subcutaneous wound implants containing SP(0.01M) in fetal rabbits at 22 days gestation,to investigate the influence of which on fetal wound healing.The main results are as follows:1. The cutaneous wounds in fetal rabbits heal more rapidly than that in adult and without the formation of scar.2. The skin nerve fibers were detected in the fetal rabbits at 22 days gestation.3. Skin innervation density of wound decreased significantly in fetal rabbit at the early stage post-injury,then increase gradually, up to the nomal levels. Skin innervation density of wound also decreased significantly in adult rabbit at the early stage post-injury, then increased quickly ,up to the higher level than nomal group,which reached a peak at the 7th days post-injury(186%,vs adult control), then returned to the normal levels.4. The expression of SP and CGRP of wound decreased significantly in fetal rabbit at the early stage post-injury , down to the lowest levels at the 2nd day post-injury(75%,80%. vs fetal control), then increased gradually, up to the nomal levels.The expression of SP and CGRP of wound decreased in adult rabbit at the early stage post-injury , down to the lowest levels at the 1st day post-injury(60%,77%, vs adult control), then increased quickly ,up to the higher level than nomal group,which reach a peak at the 7th days post-injury(168%,131%, vs adult control ),then return to the normal levels.5. Exogenous SP induced acute inflammation, followed by fibroblast proliferation and collagen synthesis, resulted in a large amout of scar in fetal wound healing.These results indicate that:1. The skin nerve fiber proliferation of wound is limited in fetal rabbit, on the contrary , the skin nerve fiber of wound proliferate significantly in adult rabbit.2. The expression of SP and CGRP of wound decrease at the early stage post-injury . then increase gradually and reture to the nomal levels. The expression of SP and CGRP of wound decrease in adult rabbit at the early stage post-injury , then increase significantly.3. Exogenous SP...
|
PDF Full Text Request