Inhibition of Na+/H+ exchanger modulates microglial activation and scar formation following microelectrode implantation

Objective. Intracortical microelectrodes are an important tool for neuroscience research and have great potential for clinical use. However, the use of microelectrode arrays to treat neurological disorders and control prosthetics is limited by biological challenges such as glial scarring, which can impair chronic recording performance. Microglia activation is an early and prominent contributor to glial scarring. After insertion of an intracortical microelectrode, nearby microglia transition into a state of activation, migrate, and encapsulate the device. Na+/H+ exchanger isoform-1 (NHE-1) is involved in various microglial functions, including their polarity and motility, and has been implicated in pro-inflammatory responses to tissue injury. HOE-642 (cariporide) is an inhibitor of NHE-1 and has been shown to depress microglial activation and inflammatory response in brain injury models. Approach. In this study, the effects of HOE-642 treatment on microglial interactions to intracortical microelectrodes was evaluated using two-photon microscopy in vivo. Main results. The rate at which microglia processes and soma migrate in response to electrode implantation was unaffected by HOE-642 administration. However, HOE-642 administration effectively reduced the radius of microglia activation at 72 h post-implantation from 222.2 mu m to 177.9 mu m. Furthermore, treatment with HOE-642 significantly reduced microglial encapsulation of implanted devices at 5 h post-insertion from 50.7 +/- 6.0% to 8.9 +/- 6.1%, which suggests an NHE-1-specific mechanism mediating microglia reactivity and gliosis during implantation injury. Significance. This study implicates NHE-1 as a potential target of interest in microglial reactivity and HOE-642 as a potential treatment to attenuate the glial response and scar formation around implanted intracortical microelectrodes.

Automated summary

The study investigated the effects of HOE-642 on microglial interactions with intracortical microelectrodes using two-photon microscopy in vivo. While HOE-642 did not affect the migration of microglia processes and soma in response to electrode implantation, it significantly reduced the radius of microglial activation and the encapsulation of implanted devices, suggesting a potential treatment to attenuate the glial response and scar formation.