The in vivo positional identity gene expression code is not preserved in neural stem cells grown in culture

Abstract

Neural stem cell specification depends on antero-posterior (AP) and dorso-ventral (DV) information provided during development. In the present study we identified similar neural stem cell (NSC) populations along the AP axis of the mouse central nervous system: the 'early' NSCs responsive to fibroblast growth factor-2 and the 'late' NSCs responsive to epidermal growth factor (EGF). Gene expression analysis shows that AP and DV transcription factor code is not preserved in NSCs in culture. Neurospheres generated with EGF from different regions showed Emx2, En2 and Krox20 expression beyond their corresponding AP restricted areas (telencephalon, mesencephalon and rhomboencephalon, respectively). Hox genes were rarely expressed. DV markers such as Pax7 and Dbx1 were not expressed in neurosphere cells, whereas Pax6 and Nkx2.1 were highly expressed independently of the NSC source region. In general, this pattern was found under different culture conditions. We propose that signals surrounding NSCs determine their positional identity gene expression code, which may be relevant to establish their definitive fate.

Serotonin Depletion Hampers Survival and Proliferation in Neurospheres Derived from Adult Neural Stem Cells

“…This is also true for TPH1 and TPH2 gene expression as well as for functional features, such as selfrenewal and multipotency, and for functional results (eg, rescue experiments) that were always confirmed throughout subculturing passages. This indicates that, if properly applied, the NSA culture system allows the maintenance of stable functional properties of ANSC over time, excluding the possibility of artifacts because of increasing time in culture (Santa-Olalla et al, 2003).…”

Cerebellum- and forebrain-derived stem cells possess intrinsic regional character

“…Upon passaging, numerous examples suggest that to varying degrees region characteristics are lost (Gabay et al, 2003;Hack et al, 2004;Hitoshi et al, 2002;Jensen et al, 2004;Ostenfeld et al, 2002;Parmar et al, 2002;Santa-Olalla et al, 2003). In this regard, our studies only examine neural progenitors expanded in culture without passaging, and even so full differentiation to normal fates could only be achieved in vivo upon homotopic transplantation.…”

Origin of Oligodendrocytes in the Subventricular Zone of the Adult Brain

“…However, neurospheres are exposed to growth factors, which may modify the normal differentiation program of neural progenitors (Doetsch et al, 2002;Gabay et al, 2003;Santa-Olalla et al, 2003;Hack et al, 2004;Reynolds and Rietze, 2005). To determine whether SVZ progenitors could give rise to oligodendrocytes in vitro, we plated freshly dissociated adult SVZ cells onto a confluent monolayer of cortical astrocytes using a modified protocol (see Materials and Methods) used previously to study neuronal differentiation .…”