Ganguly D, Johnson C D L, Gottipati M K, Rende D, Borca-Tasciuc D-A, Gilbert R J
Department of Mechanical, Aerospace, and Nuclear Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180, United States.
Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, New York 12180, United States.
ACS Biomater Sci Eng. 2018 Jan 8;4(1):128-141. doi: 10.1021/acsbiomaterials.7b00760. Epub 2017 Dec 6.
Electrodes implanted in the brain or spinal cord trigger the activation of resident astrocytes. In their reactive state, astrocytes surrounding the electrode form a glial scar, compromising the ability of the electrode to interface with the surrounding neural tissue. One approach to reduce the inhibiting scar tissue is to incorporate nanoarchitecture on the surface of the implanted materials to modify the astrocytic response. The incorporated nanoarchitecture changes both the surface characteristics and the material properties of the implant interface. We investigated the response of rat cortical astrocytes to nanoporous anodic aluminum oxide (AAO) surfaces. Astrocytes were seeded onto nonporous aluminum control surfaces and AAO surfaces with average nanopore diameters of 20 and 90 nm. The surfaces were characterized by assessing their nanomorphology, hydrophobicity, surface chemistry, mechanical properties, and surface roughness. For cell response characterization, calcein-based viability and adhesion studies were performed. Plasmid-assisted vinculin live cell imaging was done to characterize focal adhesion number and distribution. Immunocytochemistry was used to assess glial fibrillary acidic protein (GFAP) expression. We found that astrocyte adhesion was significantly higher on small pore surfaces compared to large pore surfaces. Astrocytes produced more focal adhesions (FA) and distributed these FA peripherally when cultured on small pore samples compared to the other groups. Astrocyte GFAP expression was lower when astrocytes were cultured on surfaces with small nanopores compared to the control and large pore surfaces. These results indicate that unique surface nanoporosities influence astrocyte adhesion and subsequent cellular response. The reduction in GFAP immunoreactivity exhibited by the smaller pore surfaces can improve the long-term performance of the implanted neurodevices, thus making them credible candidates as a coating material for neural implants.
植入大脑或脊髓的电极会触发驻留星形胶质细胞的激活。处于反应状态时，电极周围的星形胶质细胞会形成胶质瘢痕，损害电极与周围神经组织的界面连接能力。减少抑制性瘢痕组织的一种方法是在植入材料表面引入纳米结构，以改变星形胶质细胞的反应。引入的纳米结构会改变植入物界面的表面特性和材料性能。我们研究了大鼠皮质星形胶质细胞对纳米多孔阳极氧化铝（AAO）表面的反应。将星形胶质细胞接种到无孔铝对照表面以及平均纳米孔径为20纳米和90纳米的AAO表面上。通过评估其纳米形态、疏水性、表面化学、机械性能和表面粗糙度来表征这些表面。为了表征细胞反应，进行了基于钙黄绿素的活力和粘附研究。进行了质粒辅助的纽蛋白活细胞成像，以表征粘着斑的数量和分布。采用免疫细胞化学方法评估胶质纤维酸性蛋白（GFAP）的表达。我们发现，与大孔表面相比，星形胶质细胞在小孔表面的粘附力明显更高。与其他组相比，当在小孔样品上培养时，星形胶质细胞产生更多的粘着斑（FA），并将这些FA分布在周边。与对照和大孔表面相比，当星形胶质细胞在具有小纳米孔的表面上培养时，其GFAP表达较低。这些结果表明，独特的表面纳米孔隙率会影响星形胶质细胞的粘附和随后的细胞反应。较小孔表面显示出的GFAP免疫反应性降低可以改善植入神经装置的长期性能，从而使其成为神经植入物涂层材料的可靠候选者。
