Xenotransplanted human cortical neurons reveal species-specific development and functional integration into mouse visual circuits
SummaryHow neural circuits develop in the human brain has remained almost impossible to study at the neuronal level. Here we investigate human cortical neuron development, plasticity and function, using a mouse/human chimera model in which xenotransplanted human cortical pyramidal neurons integrate as single cells into the mouse cortex. Combined neuronal tracing, electrophysiology, andin vivostructural and functional imaging revealed that the human neurons develop morphologically and functionally following a prolonged developmental timeline, revealing the cell-intrinsic retention of juvenile properties of cortical neurons as an important mechanism underlying human brain neoteny. Following maturation, human neurons transplanted in the visual cortex display tuned responses to visual stimuli that are similar to those of mouse neurons, indicating capacity for physiological synaptic integration of human neurons in mouse cortical circuits. These findings provide new insights into human neuronal development, and open novel experimental avenues for the study of human neuronal function and diseases.Highlights:Coordinated morphological and functional maturation of ESC-derived human cortical neurons transplanted in the mouse cortex.Transplanted neurons display prolonged juvenile features indicative of intrinsic species-specific neoteny.Transplanted neurons develop elaborate dendritic arbors, stable spine patterns and long-term synaptic plasticity.In the visual cortex transplanted neurons display tuned visual responses that resemble those of the host cortical neurons.