Interspecies chimerism with human embryonic stem cells generates functional human dopamine neurons at low efficiency

<p>Interspecies chimeras offer great potential for regenerative medicine and creation of human disease models. Whether human pluripotent stem cell (hPSC) derived neurons in an interspecies chimera can differentiate into functional neurons and integrate into host neural circuity is not known. Here we show, using Engrailed 1 (En1) as a development niche that human naïve-like ES cells can incorporate into embryonic and adult mouse brains. Human-derived neurons including tyrosine hydroxylase (TH) positive neurons integrate into the mouse brain at low efficiency.  These TH-positive neurons have electrophysiologic properties consistent with their human origin. Additionally, these human-derived neurons in the mouse brain accumulate pathologic phosphorylated α-synuclein in response to α-synuclein preformed fibrils.  Optimization of human/mouse chimeras could be utilized to study human neuronal differentiation and human brain disorders.</p>