Modeling the Impact of Alcohol on Cortical Development in a Dish: Strategies from Mapping Neural Stem Cell Fate

Abstract

SummaryDuring the second trimester period, neuroepithelial stem cells give birth to millions of new neuroblasts, which migrate away from their germinal zones to populate the developing brain and terminally differentiate into neurons. During this period, large numbers of cells are also eliminated by programmed cell death. Therefore, the second trimester constitutes an important critical period for neuronal proliferation, migration, differentiation and apoptosis. Substantial evidence indicates that teratogens like ethanol can interfere with neuronal maturation. However, there is a paucity of good model systems to study early, second trimester events. In vivo models are inherently interpretatively complex because cell proliferation, migration, differentiation, and death mechanisms occur concurrently in regions like the cerebral cortex. This temporal overlap of multiple developmental critical periods makes it difficult to evaluate the relative vulnerability of any individual critical period. Our laboratory has elected to utilize fetal rodent cerebral corticalderived neurosphere cultures as an experimental model of the second-trimester ventricular neuroepithelium. This model has enabled us to use flow cytometric approaches to identify neuroepithelial stem cell and progenitor sub-populations and to show that ethanol accelerates the maturation of neural stem cells. We have also developed a simplified mitogen-withdrawal/matrixadhesion paradigm to model the exit of neuroepithelial cells from the ventricular zone towards the subventricular zone and cortical plate, and their maturation into multipolar neurons. We can treat neurosphere cultures with ethanol to mimic exposure during the period of neuroepithelial proliferation and by using the step-wise maturation model, ask questions about the impact of prior ethanol exposure on the subsequent maturation of neurons as they migrate and undergo terminal differentiation. The combination of neurosphere culture and stepwise maturation models will enable us to dissect out the contributions of specific developmental critical periods to the overall teratology of a drug of abuse like ethanol.

Combined transcriptome analysis of fetal human and mouse cerebral cortex exposed to alcohol

“…S4). This agrees with previous reports showing the effect of alcohol to maintain the self-renewal state of NSCs and increase gliogenesis concomitant with the decrease of neurogenesis (10,31,32,45,46), as all these effects are controlled by Wnt and/or Notch signaling activation (31,32,47). Reduced expression of TBR2, a marker for intermediate neuronal progenitors, by mFAE (Fig.…”

Variations in brain defects result from cellular mosaicism in the activation of heat shock signalling

“…The human in vitro model used the same range of EtOH concentration (50 mM (230 mg dl −1 )), by which several aspects of FASD phenotypes have been shown to be induced in the mouse cerebral cortex in vitro 60. Alcohol concentration was stable for 24 h in culture61. Consecutive brain slices were used for control and alcohol conditions to minimize regional differences between samples.…”

Prenatal alcohol exposure alters expression of neurogenesis-related genes in an ex vivo cell culture model

“…Further, in vitro alcohol exposures do not fully model what occurs in vivo during gestation, as the importance of the maternal environment, including the placenta, in the protection of the fetus from alcohol is ignored. However, it should be noted that studies using an in vitro application of ethanol have laid the foundation for this area of research, demonstrating that alcohol alters epigenetic programs (Veazey, Carnahan, Muller, Miranda, & Golding, 2013; Zhou et al, 2011), cell cycle dynamics (Hicks, Middleton, & Miller), cell fate (Kim et al, 2010; Miranda, Santillano, Camarillo, & Dohrman, 2008), Wnt signaling and differentiation (Vangipuram & Lyman, 2012), and transcription factors (Ogony, Malahias, Vadigepalli, & Anni, 2013) during development. Currently, in vivo exposures with subsequent cell culture characterization to derive transcriptome analysis typically deliver high doses of alcohol via intubation or intra-peritoneal injection for an acute period (Downing et al, 2012; Hashimoto-Torii, Kawasawa, Kuhn, & Rakic, 2011).…”