Functional analysis and single cell characterization of human fetal ventral midbrain in 2D and 3D cultures

Parkinson disease (PD) is characterized by a loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc). The selective loss of this cell population makes PD a good candidate for cell-based therapies. Clinical trials using cells derived from human fetal ventral midbrain (hVM) have shown that dopamine release could be restored to normal levels and in some PD patients produced substantial long-term clinical improvement. The ethical issues related to the use of human fetal material as well as the low number of hVM tissue available have limited the spread of this approach and have lead researchers to find new sources of cells such as human embryonic stem cells (hESCs) and pluripotent stem cells (IPCs). This study was designed to provide a detailed molecular and functional of the fetal VM tissue in order to give a deeper understanding of its composition and characteristics. The characterization is based on the comparison of standard culture conditions (2D) versus organoids of hVM (3D). We used unbiased single cell RNA sequencing to transcriptionally compare fetal VM tissue in 2D and 3D conditions together with a functional analysis performed using whole cell patch clamp technique. Our analysis determined the molecular and functional properties of the tissue that originates dopaminergic neurons and also confirmed important differences between the culture conditions as well as it . The data can be used for quality assessment of new cell sources and provide new molecular targets for improved subtype specificity during stem cell differentiation.