| The early and rapid coverage of cutaneous defects is a primary goal of burn care.Xenoskin has been used as biological dressing to cover wounds for half of century.Pig Skin has been proven to be the first chose as the source of xenogeneic skin grafts.However, there is no established protocle for the storage of fresh pig skin in vitroprior to grafting operation until now. When stored in vitro, pig skin lacks blood andnutrition supply and the cells beginto reduce metabolism and die gradually. As aresult, the skin's viability and functionality as a wound dressing decreases.Therefore, it is necessary to performe detailed investigation about the viabilitychange of pig skin stored in vitro.It is uneasy to evaluate the viability of skin. There is no established criterion forviability evaluation until now. The currently available methods for viabilityevaluation include enzymology, oxygen consumption, protein metabolism, fatmetabolism, nucleic acid and glucose metabolism. At present, the most frequentlyused method in viability evaluation is by testing metabolism. Among all themethods, MTT test which is based on the reaction of Methylthiazalyl-tetrazalium(MTT) with Succinic Dehydrogenase is the most widely-used method in skin banks.Although it is not the simplest method, it has a better repeatablility and its result islinear with the whole bio-activity of both the cells and tissues. In this study, MTTtest was used to evaluate the skin viability. The results are the following:MTT tests were used to analysis the viability of BAMA miniature pigskin indifferent conditions in our research. The results are as follows:1. At 25℃, the viability of pig skins freshly ex vivo isolated decresed gradually when stored in sodium chloride. After. 10 h of storage, the viability remarkablydecreased to 53.15% of that of fresh pig skins. After 16 h, it decreased to 30% andfrom then on, the viability remained relatively constant until the end of the test(24hours). In contrast, when stored in DMEM meida, the skin viability increased in thefirst 4 hours instead, and from then on the viability decreased gradually to about58.53% of that of fresh pig skin after 24 hours of storage. It shows the effect ofDMEM is better than sodium chloride in room temperature.2. At 4℃, the skin viability decreased Steadily over time. When stored at 4℃,the viability decresed to 50% after 6 days of storage in sodium chloride and 20%after 15 days in DMEM. The viability of skins stored in DMEM was constantlyhigher than that in sodium chloride, except on the 15th day (the endtime of the test).3. The average viability of the cryopreserved skin samples was 77% of that offresh skin after one month of cryopreservation after it was immediately thawed. At25℃, the viability of the thawed cryopreserved samples decresed to 55.55% insodiumchloride after 6 h and to 52.61% in DMEM after 12 h. In contrast, theviability of shin grafts decresed to 49.68% in sodium chloride only after one day at4℃. However, it was below 50% until 4 day in DMEM. The viability decrease ofthawed cryopreserved skins is faster than fresh skin. To get good transplantation, itis suggested that the clinic use thawed skin as soon as possible.In conclusion, we used MTT test analysis the viability change of BAMAminiature pig skin exactly in different temperature and culture medium. The resultsshow skin grafts are better to store in DMEM if operation will be carried outimmediately. If operation will be processed within several days, the skin was put insodium Chloride at 4℃is ok. If the skin need to be preserved longer, it is better tostore in liquid nitrogen. According this character, it is helpful to preserve skin well forclinicians. Also, we hope the pig skin bank will be set up and viable biologicaldressing be provided for clinic.
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