| Objective:The repair of peripheral nerve is a trouble problem for a surgeon. The traditional method of treating peripheral nerve defects is autogenous nerve grafting, it will inevitably cause a corresponding loss of function for the area although the effect is ideal, so it's not widely used in clinical. Therefore, the search for a new neural alternative to replace autogenous nerve grafting is of growing concern. In recent years, the emergence of tissue engineering has provided people with a new way of thinking. Tissue engineering is an edge of disciplines which rose in 80s of last century:to use science and engineering principles of the organization, to synthetic or natural biological materials as the carrier, the seeds of integration of separate cells in vitro pre-built living graft, and then implanted in the body to repair tissue defects, so as to maintain or improve the function of tissues and organs. The purpose of this study is that:The human umbilical cord mesenchymal stem cells were as seed cells and then co-cultured with acellular nerve basal lamina, so they were build into a composite tissue-engineered nerve for the repair of rat sciatic nerve defects 10mm in length. At the same time, autogenous nerve bridging group and pure acellular nerve basal lamina group were as control groups so as to explore its feasibility and to evaluate its surgical efficacy.Methods:1.Taking normal month-old fetus umbilical cord under sterile conditions, clean the fetus umbilical cord fully with phosphate buffer and clear off the umbilical artery and umbilical vein. Remaining of the umbilical cord was cut into about 1mm×1mm×1mm-sized pieces, which were inoculated in the culture medium especially for mesenchymal stem cells and were cultured in incubator box (37℃, the volume fraction of 5% CO2). After 2 weeks, removed tissue pieces and replaced culture medium. When cells grew to 80% confluence, digested the cells with 2.5 g/L trypsin and subcultured the cells. After the 5th generation of cells obtained by immunohistochemical identification confirmed as mesenchymal stem cells, induced cells into neuron-like cells with the astragalus (100μl/ml) and as seed cells for storing backup.2. Taking 10 healthy adult male SD rats to make acellular nerve basal lamina with Dument (1997) and Sondell's (1998) chemical extraction methods. Taking the induced umbilical cord mesenchymal stem cells into the neural tube with 100μl of stainless steel micro-needles to a certain concentration (107/ml) in the microscopic surgical microscope. Culturing the cells immediately after injection in DMEM-10% FBS fluid and to observe the cells in the bridge material by HE staining. When the seed cells crawling the basal lamina tube fully and then continued to culture two days so as to prepare for the transplantation.3. Taking another 30 healthy adult male SD rats to establish models of unilateral sciatic nerve defects (10mm) and dividing the rats into three groups randomly, ten rats of each group. Group A (experimental group): the umbilical cord mesenchymal stem cells combined with acellular nerve basal lamina tube group, with pre-built tissue-engineered nerve to bridge the defects of rat sciatic nerve. Group B (blank control group):pure acellular nerve basal lamina tube group, with non-composite seed cells neural basal lamina tubes to bridge nerve defects. Group C (standard control group):autogenous nerve bridging group. Evaluation of electrophysiological and histological results was carried out 10 weeks after operation.Results:All the detection of indicators showed that:the engineering nerve group had good result in nerve regeneration which was close to the effect of autogenous nerve transfer group(group A), and much better than the effect of pure acellular basal lamina tube group.Conclusions:1. Human umbilical cord mesenchymal stem cells can be purified, passaged and induced into neural-like cells in vitro under certain conditions.2. Engineering nerves from human umbilical cord derived mesenchymal stem cells can effectively repair 10mm defects of sciatic nerve.
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