The Effect of Nano-Roughness of Neural Implants on Cell Growth, Proliferation and Adhesion of Human Neurons and Glia

Abstract

Adhesion of neurons and glia to the surfaces of brain devices governs stimulation and recording efficacy and implant life. Nanotopography allows cells to interact with implants on a physical scale similar to that of its proteins and lipids leading to improvement in cell/substrate adhesion. For neural interfaces, a strong neuronal adhesion to the recording or stimulating sites on implanted devices provides close proximity of the neurons to the device and, therefore, yields a improved electronic signal transduction. The cell/substrate interaction involves several cellular mechanisms including biomechanical and biochemical changes in the cell. The emergence of new biomaterials and advances in nanofabrication techniques has enabled fine control over substate topography. In this work, we investigate the impact of Nanotopography on biochemical and biomechanical aspects of neural and glial cellular adhesion. We used polyimide as a substrate for adhesion, a common material for brain devices, and we developed a process that allows us to control its surface roughness on the nanoscale. We used SH-SY5Y Cells (Neuroblastomas) and human astrocytes (glia) cell line in our adhesion assays. Our results showed that SH-SY5Y and glia cell growth, proliferation and adhesion was best achieved at surface nano-roughness values around 8 and 4 nm, respectively. We also observed a relationship between adhesion force and surface roughness measured via a unique single cell force spectroscopy technique. The results sheds light on the impact of on cell adhesion and provides a guide for the ideal range surface roughness for implanted devices for both glia and neurons.