RG cells have been generated from a

RG cells have been generated from a variety of different sources of embryonic and adult brains, and embryonic stem cells (Conti et al., 2005; Liour and Yu, 2003; Bibel et al., 2004; Malatesta et al., 2000). In addition to isolating RG cells from human fetal tissue (Mo et al., 2007), it has recently been shown that RG cells can be generated from hESC (Nat et al., 2007). We have used the abbreviation hESC-RG to refer to radial glial cells generated in this manner. Originally, RG cells were demonstrated to be important in guiding radial migration of neurons (Bentivoglio and Mazzarello, 1999; Rakic, 2003). However, it has been well-documented recently that RG cells are also multipotent progenitor/stem cells, and that they account for the majority of neurogenesis in the developing and postnatal rodent jak inhibitor (Malatesta et al., 2000; Noctor et al., 2001; Miyata et al., 2001; Götz and Huttner, 2005). In the human brain RG cells express GFAP in early stages of the emerging cerebral cortex (Zecevic, 2004; Howard et al., 2006, 2008), in contrast to rodents where this happens much later in corticogenesis. Human RG cells serve as multipotent neural progenitors generating both neurons and glial cells (Mo et al., 2007; Mo and Zecevic, 2008, 2009; Hansen et al., 2010). Transcription factor Pax6 (Pair Box 6) plays a significant role in neurogenetic capabilities of human fetal radial glial cells (Mo and Zecevic, 2008). The objective of the present investigation was to compare RG cells in the human fetal forebrain (Mo et al., 2007; Mo and Zecevic, 2008) with hESC-RG cells with the idea that these cells can become an unlimited source of neurons available for research.
Material and methods
Results
Discussion RG cells can be isolated and expanded from mouse and human-derived ES cells or fetal brain and adult subventricular zone (SVZ) (Gregg and Weiss, 2003; Conti et al., 2005; Glaser and Brustle, 2005; Pollard et al., 2006; Pollard and Conti, 2007). However, RG cells from different species can display different properties (Conti et al., 2005; Hansen et al., 2010). For example, whereas, GFAP is expressed early in the human RG-like cells, it is undetectable in mouse-derived RG-like cells in vitro. Thus, it is necessary to characterize RG cells derived from hESC. In our earlier work (Mo et al., 2007) the surface marker LeX has been used to enrich human fetal RG cells in vitro. In the present study, we found that the same marker can be successfully used to isolate hESC-RG cells. Moreover, these cells are similar to the fetal cortical RG cells in their antigen characteristics, as well as their proliferation and differentiation potentials. Although not all hESC-RG express the LeX antigen, all LeX+ cells were found to express the RG markers (Fig. 1). This is consistent with the heterogeneity of the antigenic characteristics of RG in rodents (Hartfuss et al., 2001; Malatesta et al., 2003) and human fetal brain (Howard et al., 2006). Their differentiation into Foxg1+ forebrain cells was similar to previous reports that in the absence of known morphogens, hESC differentiate into cells with dorsal telencephalic characteristics (Li et al., 2009). LeX+-RG cells generated from hESC are mitotically active progenitors, with astroglial and stem cell/progenitor characteristics. They are also multipotent cells that can differentiate into all three neural lineages: astrocytes, neurons and oligodendrocytes. In these aspects, hESC-RG cells are similar to what has been reported for RG cells in the mouse (Abramova et al., 2005; Capela and Temple, 2006; Liour et al., 2006) and in the human fetal brain (Mo et al., 2007; Mo and Zecevic, 2008, 2009). Several lines of evidence suggest that Pax6 transcription factor promotes the neurogenic fate of RG cells in rodents (Götz et al., 1998). Most of the pyramidal neurons in the developing telencephalon are derived from Pax6 positive RG cells (Malatesta et al., 2003). Forced expression of Pax6 in rodent astrocytes is sufficient to drive neurogenesis in these cells (Heins et al., 2002). Moreover, Pax6 is necessary and sufficient for neuroepithelial differentiation from hESC (Zhang et al., 2010). We now demonstrate that transcription factor Pax6 influences proliferation and the number of neurons generated from hESC-RG cells.