Characterization of Mechanically Matched Hydrogel Coatings to Improve the Biocompatibility of Neural Implants

TitleCharacterization of Mechanically Matched Hydrogel Coatings to Improve the Biocompatibility of Neural Implants
Publication TypeJournal Article
Year of Publication2017
AuthorsSpencer, KC, Sy, JC, Ramadi, KB, Graybiel, AM, Langer, R, Cima, MJ
JournalScientific Reports
Volume7
Pagination1952
Date Published2017/05/16/
ISBN Number2045-2322
Keywordscerebral-cortex, deep brain-stimulation, diffusion-barriers, glial scar, in-vivo, induced strain, poly(ethylene glycol), rat spinal-cord, silicon microelectrode arrays, tissue interface
Abstract

Glial scar is a significant barrier to neural implant function. Micromotion between the implant and tissue is suspected to be a key driver of glial scar formation around neural implants. This study explores the ability of soft hydrogel coatings to modulate glial scar formation by reducing local strain. PEG hydrogels with controllable thickness and elastic moduli were formed on the surface of neural probes. These coatings significantly reduced the local strain resulting from micromotion around the implants. Coated implants were found to significantly reduce scarring in vivo, compared to hard implants of identical diameter. Increasing implant diameter was found to significantly increase scarring for glass implants, as well as increase local BBB permeability, increase macrophage activation, and decrease the local neural density. These results highlight the tradeoff in mechanical benefit with the size effects from increasing the overall diameter following the addition of a hydrogel coating. This study emphasizes the importance of both mechanical and geometric factors of neural implants on chronic timescales.

Short TitleSci Rep