Fig. 8

Human iCtx cells integrate into human cortical tissue and form synaptic connections. a Confocal images of a SynI-RFP⁺ iCtx cell (RFP), induced by BMF and plated on hACtx organotypic slice for 4 weeks, with Hoechst staining of surrounding nuclei. Scale bar = 30 μm. b Orthogonal views of the three-dimensional reconstruction of the SynI-RFP⁺ iCtx cell in a. Scale bar = 40 μm. c Perspective view of the three-dimensional reconstruction of the SynI-RFP⁺ iCtx cell in a. Enlarged images of the spines (green arrowheads) in the neurites of the iCtx cell. Scale bar = 3 μm. d Voltage trace illustrating AP generation during a 50pA current step lasting 500 ms. e,f Current traces of the fast inward sodium current (e, left) and sustained outward potassium current (f, left) activated by step depolarizations from a holding potential of +70 mV. * Inward current peak (e) or sustained outward current (f). Current-voltage plot of the fast inward (e, right) and the sustained outward current (f, right) (n = 10). g–k Afferent synapsis on transplanted iCtx cells from host neurons in hACtx slices. g Confocal image of hACtx organotypic slice showing an overview of hACtx cell labeling with tetO-GFP and subsequent tracing with ΔG-rabies virus (white arrowhead). h–k hACtx cells labeled with tetO-GFP (i) and retrogradely traced with ΔG-rabies virus (h) after infection of grafted iCtx cells were either mCherry /GFP (h) or mCherry /GFP (k''', white arrowhead). Nontraced hACtx cells were GFP only (k''', white arrow). j Merged image of h and i; k Magnification of the box in j to k' (RFP), k'' (GFP), k''' (merged) and k'''' (Hoechst). Scale bar= 100 μm for g; 20 μm for h–j; 10 μm for k