Rational derivation of midbrain dopamine neuron progenitors from hPSCs using a selective FZD5 antibody agonist [scRNA-Seq]

Current ventral midbrain dopaminergic progenitor differentiation protocols utilize small molecule inhibitors targeting Glycogen synthase kinase-3 (GSK3) to activate Wnt signaling, a step required for the anterior-posterior patterning of the nervous system and acquisition of the midbrain fate. However, GSK3a and GSK3ß are pleiotropic kinases involved in multiple signaling pathways and their inhibition is a known trigger of neurogenesis. We predicted that direct activation of specific Wnt receptors naturally involved during neural patterning would allow for a more precise spatiotemporal control of Wnt/ß-catenin signaling and mimic endogenous cell-cell communication mechanisms to improve hPSC differentiation. Here, we characterized the expression of FZD receptors at the surface of neural progenitor cells with different regional identity. Our data shows that FZD5 expression is uniquely upregulated in anterior neural progenitors and is rapidly downregulated as cells adopt a posterior fate. This spatial regulation of Frizzled cell surface expression constitutes a novel regulatory mechanism adjusting the levels of ß-catenin signaling along the anterior-posterior axis and possibly contribute to midbrain-hindbrain boundary formation. Using a tetravalent antibody that selectively triggers FZD5 and LRP6 clustering to activate Wnt/ß-catenin signaling, we show that the resulting midbrain-patterned neural progenitors exhibit a gene expression program more closely aligned with the anatomical origin of dopaminergic neurons and could hence represent a more efficient source for cell transplant therapies. Overall design: Differentiated VM progenitors with CHIR or F5L6.13 from hPSC were subjected to single cell RNA sequencing using 10X CellPlex at day 11 and at day 30.