Abstract TP142: Post-Ischemic Cortical Excitability and Gene Expression are Modulated by Transplanted Human Neural Stem Cells

Abstract

Human neural stem cell (hNSC) transplantation improves recovery in preclinical stroke models. However their effects on surviving sensorimotor circuits are not well understood. Here we performed a comprehensive electrophysiological assessment and RNA-seq analysis of the stroke-injured rat cortex after transplantation of two hNSC lines, G010 (fetal-derived) and NR1 (hES-derived). Vehicle, G010, or NR1 cells were transplanted into the ischemic cortex of Nude rats 1 wk after distal middle cerebral artery occlusion. Neurological recovery was accessed by the Whisker-paw test. Acute brain slices were prepared 1 wk post-transplantation for electrophysiological recording. A linear multichannel recording probe was placed in the peri-infarct motor cortex and local field potentials (LFPs) recorded simultaneously from all cortical layers following circuit activation in layer 2/3. For RNA-seq analysis, the transplantation area was dissected, RNA extracted and cDNA libraries prepared for RNA-seq. G010 and NR1 cells enhanced post-stroke behavioral recovery starting 1 or 3 wks post-transplantation, respectively. Current source density (CSD) analysis of evoked LFPs, a method used to more accurately localize synaptic currents, revealed that both G010 and NR1 cells restored circuit excitability in layer 2/3, through reduction in inhibitory/excitatory (I/E) balance. However, the mechanisms driving the I/E balance shift were different, with NR1 cells enhancing excitation while G010 cells reduced inhibition. RNA-seq analysis of the cortex revealed that stem cell- versus vehicle-treated animals had different gene expression patterns in all cortical layers. Moreover, NR1 and G010 cells affected different genes. Layer 2/3-specific genes significantly affected by G010 grafts include Arpp21, Enpp2, Gbe1, Mylk, Pea15, Pkig, Rcn1, Slit3, Uchl1 and Wfs1; while NR1 grafts altered expression of Hapln4, Kcnc1, Ppp1r1b, Scn1a, Slit3 and Slitrk1. GO analysis revealed that both stem cell treatments activated critical canonical pathways e.g. Actin Cytoskeleton Signaling and Synaptic Long Term Depression. Stem cell transplantation modulates host gene expression and this is associated with increased circuit excitability and motor-sensory function.