| The repaire of completely transected peripheral nerve is a challenging problem in clinical medicine, therefor, a study of new repairing method is necessory. It is widely known that thyroid hormone is one of the most important physiological regulator of peripheral nerve systerm development, maturation and function. In recently, with the development of material technology, more and more bioresorbable material have been used in the nerve tissue engineering. Combined the two ideas, the study designed to fabricate the PDLLA-T3 with triiodiothyronine and PDLLA, in order to repaire the gap of sciatic nerve of rats. the study have two parts, the first one is to fabricate the PDLLA-T3, the second is observation of effects of PDLLA-T3 in peripheral nerve regeneration.There are four experiments in part one. In the first experiment, a thermally induced phase separetion(TIPS) has been used in this work to fabricate the PDLLA-T3, then, 50μg/ml solution of Fn in PBS have been addited dropwise at the upper surface of the scaffolds, oriented porous structure were seen by scanning eletron microscopy, and special equipments have been applied to measure the pore radius, porosity, polymer density, et al. the second experiment, the releasing rate of T3 in PDLLA-T3have been tested, it is stabely and didn't influenc the systerm blood density of T3, the density of T3 have been assayed by radio-immuno(one-step) method. The purpose of experiment 3 is in order to observe the effects of PDLLA-T3 to cultured Schwann cells, the more cells, the upper percentage of cell survivals measured by MTT spectrophotometric assay and the higher content of NGF have been tested when cultures were in the presence of foams. In experiment 4, Schwann cells were seeded on PDLLA-T3 with the density of 2×106cells/ml, the foams were sterilized by infrared and removed air from the pore to facilitate the infiltration of cell suspension. The Schwann cells density on the PDLLA-T3 were observed by scanning electron microscopy, cells clearly survivaled, there are cells in the inner of the foam too.In part 2, the effects of PDLLA-T3 in repairing the 1.0cm gap of sciatic nerve of rats have been observed. The animal model of nerve injury have been set up, the PDLLA and the nerve homotransplantation have been compared as contral, the samples collected in2weeks, 1month and 2months respectivly. Firstly, The contacts have beeen set up between the new regeneration nerves and spinal cord tested by a HRP retrograde tracing. In experiment 2, the electron microscopy, HE, Bielschowsky staining and S-100 immunostaining have been applied to assess the effects of new regeneration nerve, including the number of nerves and myelin sheath nerve, the thickness of myelin sheath, et al. the pictures were analysed by image analysis systerm, and the data were processed by SPSS10.0. it is concluded that the effects of PDLLA-T3 is satisfied than that of the PDLLA, but inferior to that of the normal. In experiment 3, Motornerve conduction velocity, latend period, tibialis anterior muscle recovery rate and Sciatic nerve function index have been used to evaluated the effects of nerve regeneration, all of these index have directed that the PDLLA-T3 is a good scaffold in nerve regeneration and is better than PDLLA.According to the experiments, the main results and conclusions are as follows:1. We have successfully fabricated PDLLA-T3, which have a three-dimensional structure with oriented pore morphology, the pore radium is 60-100μm, the porosity is 91%, there are 35ng T3 in per mg PDLLA. It could release T3 stably with a long-term, and the similar results haven't reported ever before.2. The time of PDLLA-T3 degradation completely is 2 months in vitro or in vivo of rats. There is no influrence in systerm blood density of T3 after placing it in vivo of rats.3. the more cells, the upper percentage of cell survivals and the higher content of NGF have benn tested when cultures were in the presence of foams. Cells attachment in PDLLA-T3 are tested by scanning electron microscopy,...
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