Clonogenic CD15 immunoreactive radial glial cells from the developing human lateral ganglionic eminence

Radial glial cells represent a subpopulation of secondary neural precursor cells that differentiate from neuroepithelial progenitors and are transiently found in the developing CNS of mammals. There is ample evidence for a temporal and spatial arrangement of increasingly committed radial glial cells that is of critical importance for the organisation and specification of different brain regions. For the human ganglionic eminence, recent findings have shown an early molecular specification of this cell type by the CD15 carbohydrate epitope, beginning already at the end of the first trimester. Here we further characterise the CD15+ radial glia cells as bFGF/EGF responsive progenitors allowing its propagation in vitro. By magnet activated cell sorting, its trilineage differentiation potential can be shown by differentiation into (PSA-NCAM ß3 tubulin immunoreactive) neurones, GFAP expressing cells of astrocytic morphology, and O4 positive oligodendrocytes. Subcloning experiments under proliferation conditions reveal ongoing CD15 expression by dividing cells. Although the relative number of CD15+ progenitor cells is found to decrease in favour of CD15- precursor cells during continuous passaging, cell sorting experiments allow the repetitive purification of high numbers of positively selected precursor cells for up to 12 weeks. In conclusion, expression of the cell adhesion molecule CD15 by a subpopulation of proliferative cells from the lateral ganglionic eminence allows easy and reproducible purification of progenitor cells by cell sorting, enabling the generation of a compartment-specific cell pool as a prerequisite for a safe and standardised therapy of neurodegenerative basal forebrain diseases.