| BackgroundExtensive deep burn has always been the emphases and difficulties on treatment of burn surgery.Large area naked wound often leads to a series of complications,such as high metabolism,sepsis,MOF(multiple organ falilure)and so on.Therefore,how to closed the wound as soon as possible is the key treatment measure of large area deep burns and improvement of successful cure rate.Conventional skingraft methods mainly include sheet graft,stamp autograft and mesh graft.The methods above present higher survival rate of the graft skin,lighter scar formation,better appearance and function after wound healing.However,it's hard to use the only auto-skin to repair the large area bare wound in a short time because of the small extension ratio.Now methods commonly used in the repair of large area burn wounds mainly includes cultured epithelial autograft(CEA),Meek skin graft,microskin graft and so on.CEA needs the least autoskin,and owns the highest extension ratio which is as high as 1000 ~ 10000 times.This method can extremely make use of the source of autoskin,and sovled the difficulty of lack of autoskin.But it is proved that after the cells have been transplanted to the wound,survival rate is low becasuse of lack of dermal,the wound is easy to burst again when wound healing,and the scar 's formation and contraction is easy to happen,for which appearance and function are seriously poor.Furthermore it's difficult that clinical needs can't be meet because of its' long culture time and high cost,.Meek skin graft is easy to operate,and it presents good appearance and function after wound healing.But its' extension ratio is small.Extensive ratio of microskin graft is high as 1: 10 ~ 1: 20 and it can make full use of the source of autoskin.Microskin graft has become one of the main methods to repair large area deep burn wounds since its' birth of 30 years.However,controlling the direction of the microskin after transplantation is very hard,so the survival rate is not stable,and various reports of which have significant differences.This study for the first time changed the direction of microskin by using the homemade collagen membrane and increased the survival rate,thus to provide a stable and reliable method to repair large area deep burn wounds in clinical.Methods1.Proving the influence of the direction of microskin on the survival rate1.1 Preparation of the cutting tool of microskinTen groups of circular blade were arranged parallelly,and the distance between the circular blades is 1mm.The skin can be cut into microskin of 1mm ? 1mm size after one cross cutting.1.2 Experiment of microskin graft on mude miceHuman skin(0.2mm ~ 0.3mm thickness)was obtained and cut into microskin skin(about 1mm ? 1mm size),which was then transplanted onto the wound of mude mice whose full-thickness skin have been excised.The effect of the direction of microskin on the survival rate was observed,HE staining was performed to observe the cells,Masson staining was performed to observe the collagen,and immunohistochemical HLA-Class?was also performed to observe the human source cells.2.Preparing collagen membrane,testing it's physical and biological characteristics,and improving the floating method2.1 preparation of collagen membrane and observation of it's organization structure featureCollagen was extracted from the skin of flatfish,and then made into collagen membrane by vacuum freeze drying.HE staining,scanning electron microscope and Masson staining were respectively made to watch it's structure characteristics.Also it's density and floating properties were measured.2.2 Toxicity experiment of the collagen membraneFibroblasts suspension mixed with leaching solution of the collagen membrane were cultured,the absorbance values were measured and the relative proliferation rate of cells was calculated.2.3 Floating experiment of microskinMicroskin with collagen membrane having been adhered to the epidermis were put and floating in isotonic saline,and then were transferred to the sheet allo-skin by the silk.Floating rate,positive floating(the epidermis facing up)rate and transfer rate with the same direction were calculated.3.Observing the effect of the improved method on improving the survival rate of graftMicroskin with collagen membrane having been adhered to the epidermis was transplanted to the wound of pig whose full-thickness skin were excised.The survival rate of graft was observed and rate of wound healing and contraction were also obtained.HE staining was made to see the survival cells and Masson staining were performed to observe collagen of the new skin.Results1.The wound healing rate in the 2nd,3rd and 4t h week after the microskin with their epidermis facing up were transplanted to the wound of nude mice was significantly higher than the group of epidermis half facing up and half facing down(54.75 ± 3.05% VS 44.85 ± 2.76% and 35.85 ± 2.87%?84.80 ± 3.17% VS 74.85 ± 2.80% and 45.25 ± 2.29%?94.80 ± 2.78% VS 84.95 ± 2.96% and 55.90 ± 2.00%)(P < 0.01).2.Floating rate,positive floating rate and transfer rate with the same direction were respectively 95.05 ± 2.09%?91.25 ± 2.88%,and were significantly higher than the group of pute pig microskin(52.20 ± 5.93%?68.05 ± 4.65%)(P < 0.01).3.Compared the group of microskin with collagen membrane being adhered to the epidermis to the group of pute microskin in the 4t h week after microskin graft,the wound contraction rate was significantly lower(12.45 ± 2.01% VS 20.05 ± 2.11%),and the wound healing rate was significantly higher(95.15 ± 2.28% VS 65.05 ± 2.33%)(P < 0.01).Conclusions1.The direction of microskin significantly afftect the survival rate of graft when their size is 1mm ? 1mm.2.With the collagen membrane being adhered on the epidermis of microskin,Floating rate,positive floating rate and transfer rate with the same direction were significantly improved and it presents perfect consistency of the direction when grafting.3.The improved method that collagen membrane changed the direction of microskin can significantly increase graft survival rate and quality after wound healing.Thus a stable and reliable method can be provided to repair large area deep burn wound in clinical. |
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