Investigation of the "foreign body response" and its pharmacological regulation in chronic intracerebral cannula implantation in rats

Abstract

Chronic brain implants cause a tissue response, also referred to as "foreign body response", which involves the formation of a glial scar as well as progressive neurodegeneration. Both contribute to inconsistent performance of electrodes in the field of brain-computer-interfaces (BCIs). In order to improve the biocompatibility of chronic brain implants and to promote neuronal survival in the vicinity of the implant, the excitotoxic and inflammatory cascades after device implantation were aimed to be suppressed at a very early stage. For this purpose, the uncompetitive NMDA receptor antagonist memantine, the ATP/ADP-hydrolysing enzyme apyrase, and the antibiotic minocycline were locally applied during cannula implantation in the caudal forelimb area (CFA) of the motor cortex (M1) in Lister Hooded rats. The rats' behavioural performance was assessed before and once weekly after cannula implantation in a skilled reaching and a ladder rung walking task as well as in the open field and, moreover, the neuronal and glial distribution in the vicinity of the implant were examined after two and six weeks.