超声激励神经干细胞修复脊髓损伤的方法研究

Spinal cord injury can lead to loss of kinetic and perceived ability. So far there is no treatment to restore the patient to live independently. Spinal cord injury is one of the earliest diseases proposed by stem cell transplantation. Clinical results indicate that neural stem cell transplantation is effective in recovering from spinal cord injury but the effect is still insufficient. In this project, we will carry out the work of using ultrasound to stimulate the proliferation and differentiation efficiency of neural stem cells: establishing the model of ultrasound exciting stem cells, through the simulation to understand the dynamical, thermal and piezoelectric effects of ultrasound on the cell proliferation, differentiation mechanisms. The effect of acoustic radiation, acoustic streaming and strain gradient on cell will also be studied. Scanning probe microscopy is used to measure the elasticity and piezoelectricity of the neural stem cell to identify whether the cell is in resting or mobilization state. The elasticity and piezoelectricity of neurons and glial cells will also be studied. The ultrasonic parameters to get the highest efficiency of differentiation of neural stem cells to neuronal cells will be determined experimentally. The method and mechanism of ultrasonic stimulation of neural stem cell proliferation and differentiation were obtained by the above study, which provided the theoretical and experimental basis for the treatment of spinal cord injury by ultrasound.

脊髓损伤可导致生物体行动和感知能力的丢失。至今没有治疗方法能一定程度上使患者恢复到能独立生活。脊髓损伤是最早提出用干细胞移植治疗的疾病之一，临床结果表明神经干细胞移植对脊髓损伤恢复有效但效果仍不够。本项目拟开展用超声激励神经干细胞增加其增殖和分化效率的相关工作：建立超声对干细胞激励模型，通过计算结果探讨超声激励干细胞增殖、分化的力学、热学和压电效应，以及声辐射力、声流和应变梯度对细胞的作用；利用扫描探针显微术测量细胞弹性和压电性，得到神经干细胞在静息、动员状态下的物理量差异及神经元和胶质细胞的弹性和压电性差异；研究并确定使神经干细胞向神经元细胞分化效率最高的超声参数。通过以上研究得到超声激励神经干细胞增殖和分化的方法和机理，为超声治疗脊髓损伤提供理论和实验依据。

本项目主要研究超声辐照对神经干细胞增殖分化的影响，并进一步为脊髓损伤修复提供有效手段。为完成这一目标，我们在项目执行期内实现了超声辐照声压的定标，得到了电压与声压之间的对应关系。并且通过研究发现了超声辐射力具有让神经干细胞向神经元细胞分化的趋势。并发现利用超声辐照可增加神经干细胞成球效率，通过对超声连续波和脉冲波的重复周期、辐照时间、占空比以及持续时间等的改变，研究了超声参数对神经干细胞增殖和分化的影响，并且找到了脉冲超声辐照对神经干细胞激励的优化参数。并进一步研究了低强度脉冲超声对神经兴奋性、神经元兴奋性、对神经元胞内钙浓度、神经元钙通道电流以及超声刺激在转录水平对神经元兴奋性的影响。分别研制了适合于细胞和小动物在体辐照的超声换能器，建立了小鼠脊髓损伤模型，开展了在体实验。通过实验验证了超声辐照对生物体脊髓损伤修复的有效性。并通过扫描探针显微镜研究了神经干细胞的形貌和弹性。完成了神经干细胞对超声辐照响应的建模，通过生化方法明确了超声对神经干细胞增殖分化的物理因素影响机理。为利用超声激励神经干细胞治疗脊髓损伤提供方法。在项目执行期间内培养硕士2名，参加国内外学术交流10次，其中特邀和大会报告5次。相关研究成果发表SCI刊物10余篇。