Biocompatibility of a Neurotransmitter Based Retinal and Cortical Visual Prosthesis

Abstract

Abstract: : Purpose: To assess the biocompatibility of a phototriggerable, caged molecule that could be used in a neurotransmitter-based retinal visual prosthetic device. Methods: Visual cortical neurons were cultured from 19-day old embryonic Sprague-Dawley rat pups and plated onto poly-d-lysine coated glass coverslips. Cultures were incubated for 8 days before exposure to either L-glutamate [20, 35 or 50 uM] or p-Hydroxyphenacyl (HPA) glutamate [20, 35 or 50 uM]. Cellular viability and DNA fragmentation were assessed both 6 and 24 hours after the initial exposure using trypan blue dye exclusion assay and TUNEL staining. Results: While L-glutamate demonstrates excitotoxicity to our cultures in a dose-dependent manner, the HPA glutamate treated cells demonstrated a lower rate of DNA fragmentation and a higher rate of cellular viability (see table - data represents mean and standard deviation). Conclusions: De-activation of L-glutamate with the phototriggerable HPA cage greatly attenuates dose-dependent, excitotoxic effects to our cultures. This improved biocompatibility may render HPA glutamate an important component in a neurotransmitter based visual prosthesis.  

Keywords: 490 neurotransmitters/neurotransmitter systems • 390 drug toxicity/drug effects • 402 excitatory neurotransmitters