Chimeric human-mouse brain models demonstrate that NRXN-NLGN3, SPP1, and PTN-MK pathways mediate human neuron-glia communication

Chimeric brain models generated by transplanting human pluripotent stem cell (hPSC)-derived neural cells are valuable for studying the development and function of human neural cells in vivo. To explore glial-neuronal and glial-glial interactions, we co-engraft hPSC-derived primitive neural progenitor cells and primitive macrophage progenitors into neonatal mouse brains, generating chimeric brains containing human microglia, macroglia, and neurons. Using super-resolution imaging and 3D reconstruction, we observe human microglia pruning synapses and engulfing neurons. Single-cell RNA sequencing reveals human glial progenitor populations and dynamic stages of astroglial development resembling those in the human brain. Cell-cell communication analysis identifies strong human neural interactions, including NRXN-NLGN3 signaling between neurons and astrocytes and SPP1- and PTN-MK-mediated communication between microglia and astroglia. This co-transplantation model provides a powerful approach to study complex human glial-neuronal interactions and mechanisms underlying neurological diseases.