(J-370) Spatiotemporal expression of proteins associated with microglial activation around implanted silicon electrodes

Introduction:: Neural prostheses are devices capable of restoring lost functions from neurological disorders through interactions with neurons in the central nervous system. However, the long-term efficacy of these implantable devices is restricted by a progressive loss of neuronal signals. The cortical tissue response to implanted devices is believed to play a role in this observed loss of neuronal signals . Microglia play a crucial role in the initiation of the tissue response by migrating to the device injury, proliferating, and secreting pro-inflammatory cytokines . Recent RNA-sequencing datasets have identified that Polypyrimidine tract binding protein-1 (PTBP1) and Transferrin (TF) are spatiotemporally expressed around implanted devices at the RNA level. However, the cell type specificity and protein-level expression of these genes at the electrode interface is not yet fully understood. Increased expression of PTBP1 and TF within microglia is associated with activation following injury or disease .

Materials and Methods:: Here, we seek to identify the spatial dynamics and relative expression of PTBP1 and TF within reactive microglia at the device interface. To accomplish this, we have utilized a custom MATLAB code to quantify microglial densities and relative protein immunofluorescence of PTBP1 and TF from microglial populations around silicon electrodes implanted in the motor cortex of Sprague-Dawley rats.

Results, Conclusions, and Discussions:: Our results show that PTBP1 and TF are spatiotemporally expressed and upregulated within activated microglia 24-hours, 1-week, and 6-weeks post-implantation. The results of this study also provide evidence that PTBP1 and TF are associated with activated microglia at the device interface. These proteins may also serve as useful biomarkers for future studies of microglia around implanted devices.

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