| Mammalian fetal cutaneous wounds made before the third trimester of gestation heal without the formation of scar by using processes that are more akin to tissue regeneration than classic tissue repair. It is now well known that many animals undergo a transition late in development from scarless cutaneous healing to a scar-forming, adult-like phenotype, after the right developmental stage, the fetus begins to show increasing signs of adult-like wound healing, so that by birth all cutaneous wounds are repaired by creating a large amount of scar.Considerable researches have focused on the differences between fetal and adult wound healing, which range from changes in connective tissue matrix deposition to alteration in the type growth factor expression and cellular migrations into the wound site, yet why these differences exist and how these events are integrated remains unknown.It is suggested that there possibly exist some factors that orchestrates the regenerative repair likely to be present during the time of scarless healing. DesignThe remarkable phenotypic differences between fetal and adult healing guide us to explore their characteristics in genetics, which represent potentially important mechanisms to explain the differences in the quality of wound repair observed in fetal versus adult tissues.It's reasonable to speculate that there emerge some changes in the gene expression maps of fetal skin after trauma. During the process of scarless healing, some specific genes are open and other genes close. In addition, the expression level of opened genes may change at the same time. Thus the products of these genes possess biological effects, which results indifference in the reactions between the fetal and the adult, such as inflammation, cytokines maps and so on. The gene(s) which altered in scarless healing might be called "scarless healing-related gene(s)". It is very important and helpful to explore the unknown gene(s) for clarifying the molecular mechanism of scarless healing. Up to date, theDifferences Analysis of Gene Expression may be the best way for attaining this aim.In order to understand why the distinctions between adult and fetus healing exist and how they form, firstly, we have to know which specific gene(s) expressed or closed in the process of scarless healing besides the changes of gene(s) expression.Firstly, a fetal rabbit cutaneous wounds model was made, then the skin samples were processed with Suppression subtractive hybridization (SSH), a subtractive library was constructed by using differential expressed sequences which were gained from SSH. Finally, it is attempted to find scarless healing-related gene(s) after screened and homology comparisons in GenBank. This experiment includes two parts as follows. Methods and Strategies1. Construction of subtractive cDNA library from fetal rabbit skin scarless healing and screening(1) Fetal rabbit cutaneous wounds model 42 animals were selected carefully to meet the need of our experiments. Each pregnant rabbit carrying fetuses on 20 days of gestation underwent anesthesia. Body fluid was supplemented by intravenous 0.9% NaCl, while Aminobenzylpenicillin was applied for anti-infection. Middle laparotomy was performed and the gravid uterus was delivered into the operative field, then hysterotomy was made to expose the fetal back, with special care being taken to control the amnionic membrane. A longitudinal incision, which penetrated full skin, was made on the back of fetus. The fetal animal was replaced into uterus.All the rabbits were sacrificed 12 hours after operation; the fetal/adult skin samples were taken and submerged into RNAlater?immediately, then stored at -70癈 ready for use. The samples were labeled as: AT (adult trauma), FT (fetal trauma) and FC (fetal control).In the present study, more than 83% of the wounded fetal rabbits kept alive 12 hours after operation, some fetuses survived till birth. The evidence indicates that the animal model is successful, and the result of following RNA isolation is accord... |
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