Seymour John P, Kipke Daryl R
Department of Biomedical Engineering, University of Michigan, 2212 Lurie Biomedical Engineering Building, 1101 Beal Avenue, Ann Arbor, MI 48109-2099, USA.
Biomaterials. 2007 Sep;28(25):3594-607. doi: 10.1016/j.biomaterials.2007.03.024. Epub 2007 Apr 5.
This study investigated relationships between a microscale neural probe's size and shape and its chronic reactive tissue response. Parylene-based probes were microfabricated with a thick shank (48 microm by 68 microm) and an integrated thin lateral platform (5 microm by 100 microm, either solid or one of three lattice sizes). Devices were implanted in rat cerebral cortex for 4 weeks before immunostaining for neurons, astrocytes, microglia, fibronectin, laminin, and neurofilament. While nonneuronal density (NND) generally increased and neuronal density decreased within 75 microm of a probe interface compared to unimplanted control regions, there were significant differential tissue responses within 25 microm of the platform's lateral edge compared to the shank. The NND in this region of the lateral edge was less than one-third of the corresponding region of the shank (129% and 425% increase, respectively). Moreover, neuronal density around the platform lateral edge was about one-third higher than at the shank (0.70 and 0.52 relative to control, respectively). Also, microglia reactivity and extracellular protein deposition was reduced at the lateral edge. There were no significant differences among platform designs. These results suggest that neural probe geometry is an important parameter for reducing chronic tissue encapsulation.
本研究调查了一种微尺度神经探针的尺寸和形状与其慢性反应性组织反应之间的关系。基于聚对二甲苯的探针通过微加工制成，具有较粗的柄部（48微米×68微米）和集成的薄横向平台（5微米×100微米，实心或三种晶格尺寸之一）。将这些装置植入大鼠大脑皮层4周，然后对神经元、星形胶质细胞、小胶质细胞、纤连蛋白、层粘连蛋白和神经丝进行免疫染色。与未植入的对照区域相比，在探针界面75微米范围内，非神经元密度（NND）通常增加而神经元密度降低，但与柄部相比，在平台侧边缘25微米范围内存在明显的组织反应差异。侧边缘该区域的NND不到柄部相应区域的三分之一（分别增加129%和425%）。此外，平台侧边缘周围的神经元密度比柄部高约三分之一（相对于对照分别为0.70和0.52）。而且，小胶质细胞反应性和细胞外蛋白沉积在侧边缘处减少。不同平台设计之间没有显著差异。这些结果表明，神经探针的几何形状是减少慢性组织包裹的一个重要参数。
