Cell Therapy Using Bone Marrow-Derived Stem Cell Overexpressing BMP-7 for Degenerative Discs in a Rat Tail Disc Model

Degenerative discs can cause low back pain. Cell-based transplantation or growth factors therapy have been suggested as a strategy to stimulate disc regeneration. Bone marrow-derived mesenchymal stem cells (BMDMSC) containing bone morphogenetic protein-7 (BMP-7) gene were constructed. We evaluated the effectiveness of these BMP-7 overexpressing cells on degenerative discs in rat tails. In vitro and in vivo studies were designed. In the first stage, the rats were divided into two group according to discs punctured by different needle gauges (18 gauge and 22 gauge). In the second stage, the ideal size of needle was used to induce rat tail disc degeneration. These animals are divided into three groups according to timing of treatment (zero-week, two-week, four-week). Each group was divided into three treating subgroups: control group, BMDMSC group, and Baculo-BMP-7-BMDMSC group. Each rat undergoes radiography examination every two weeks. After eight weeks, the discs were histologically examined with hematoxylin and eosin stain and Alcian blue stain. The 18-gauge group exhibited significant decrease in disc height index (%) than 22-gauge group at eight weeks at both Co6-7 (58.1% ± 2.8% vs. 63.7% ± 1.0%, p = 0.020) and Co8-9 discs (62.7% ± 2.8% vs. 62.8% ± 1.5%, p = 0.010). Baculo-BMP-7-BMDMSCs group showed significant difference in disc height index compared to the BMDMSCs group at both Co6-7 (93.7% ± 1.5% vs. 84.8% ± 1.0%, p = 0.011) and Co8-9 (86.0% ± 2.1% vs. 81.8% ± 1.7%, p = 0.012). In Baculo-BMP-7-BMDMSCs group, the zero-week treatment subgroup showed significant better in disc height index compared to two-week treatment group (p = 0.044), and four-week treatment group (p = 0.011). The zero-week treatment subgroup in Baculo-BMP-7-BMDMSCs group also had significant lower histology score than two-week treatment (4.3 vs. 5.7, p = 0.045) and four-week treatment (4.3 vs. 6.0, p = 0.031). In conclusion, Baculo-BMP-7-BMDMSC can slow down the progression of disc degeneration, but could not provide evidence of regeneration. Early treatment might obtain more distinct results.     

基于修正Kelvin模型的活检针预穿刺模型建立与分析

针对预穿刺过程中活检针的受力变化难以分析的现状,提出了一种修正Kelvin模型,对预穿刺过程中活检针的受力特点进行建模分析.与原有理论模型Kelvin-Voigt模型相比,修正Kelvin模型在考虑组织黏弹性的同时,研究了预穿刺力随穿刺时间和穿刺速度的变化情况.最后利用穿刺实验进行验证,通过对比分析Kelvin-Voigt模型和修正Kelvin模型的相对误差,发现修正Kelvin模型能够与实验数据实现更好的吻合.研究表明,修正Kelvin模型对预穿刺力进行建模分析更具合理性.     

基于矫正力的前列腺粒子植入穿刺控制策略研究

以前列腺粒子植入机器人精准穿刺为目标,针对机器人辅助前列腺粒子植入手术的现存不足和发展趋势,开展针挠曲形变预测模型和穿刺控制策略等方面的研究。研究了针挠曲形变预测模型的参数获取问题,提出基于矫正力的术中组织杨氏模量识别方法,解决术中组织杨氏模量获取困难的问题。随后,建立基于矫正力的穿刺控制策略,分为两个阶段,即术前针尖轨迹规划阶段和术中穿刺策略调整阶段。在术前针尖轨迹规划阶段,基于针挠曲形变预测模型构建成本函数获取最佳针尖轨迹与穿刺参数。在术中穿刺策略调整阶段,构建了反向针挠曲形变预测模型,对矫正力的数值进行术中补偿,并采用基于强化学习(RL)的自适应PID方法设计控制器控制矫正力的施加,实现精准穿刺。自主搭建了粒子植入机器人实验平台以验证所提穿刺控制策略的有效性,粒子植入的平均误差为1.96 mm,标准误差为0.56 mm,实验结果表明,基于矫正力的穿刺控制策略能够有效降低针尖挠曲值,可以提高粒子植入精度。     

芳纶短纤维在泥地轮胎胎面胶中的应用

研究芳纶短纤维在泥地轮胎胎面胶中的应用。结果表明:与未添加芳纶短纤维的胶料相比,添加芳纶短纤维的胶料焦烧时间和正硫化时间略有延长,硫化返原时间呈缩短趋势;硫化胶的抗切割和抗刺扎性能明显提高,损耗因子减小,剪切温升明显降低;当芳纶短纤维用量为3份时性能最佳;成品轮胎的耐久性能随着芳纶短纤维用量增大而提高。