Dynamic and Cell-Specific DACH1 Expression in Human Neocortical and Striatal Development.

DACH1 is the human homolog of the Drosophila dachshund gene, which is involved in the development of the eye, nervous system, and limbs in the fly. Here, we systematically investigate DACH1 expression patterns during human neurodevelopment, from 5 to 21 postconceptional weeks. By immunodetection analysis, we found that DACH1 is highly expressed in the proliferating neuroprogenitors of the developing cortical ventricular and subventricular regions, while it is absent in the more differentiated cortical plate.

Neural progenitor cells orchestrate microglia migration and positioning into the developing cortex.

Microglia are observed in the early developing forebrain and contribute to the regulation of neurogenesis through still unravelled mechanisms. In the developing cerebral cortex, microglia cluster in the ventricular/subventricular zone (VZ/SVZ), a region containing Cxcl12-expressing basal progenitors (BPs). Here we show that the ablation of BP as well as genetic loss of Cxcl12 affect microglia recruitment into the SVZ.

Molecular and functional definition of the developing human striatum.

The complexity of the human brain derives from the intricate interplay of molecular instructions during development. Here we systematically investigated gene expression changes in the prenatal human striatum and cerebral cortex during development from post-conception weeks 2 to 20. We identified tissue-specific gene coexpression networks, differentially expressed genes and a minimal set of bimodal genes, including those encoding transcription factors, that distinguished striatal from neocortical identities.

Human pluripotent stem cell differentiation into authentic striatal projection neurons.

Here we present the principles and steps of a protocol that we have recently developed for the differentiation of hES/iPS cells into the authentic human striatal projection medium spiny neurons (MSNs) that die in Huntington's Disease (HD). Authenticity is judged by the convergence of multiple features within individual cells. Our procedure lasts 80 days and couples neural induction via BMP/TGF-β inhibition with exposure to the developmental factors sonic hedgehog (SHH) and dickkopf1 (DKK-1) to drive ventral telencephalic specification, followed by terminal differentiation [1].

EZ spheres: a stable and expandable culture system for the generation of pre-rosette multipotent stem cells from human ESCs and iPSCs.

We have developed a simple method to generate and expand multipotent, self-renewing pre-rosette neural stem cells from both human embryonic stem cells (hESCs) and human induced pluripotent stem cells (iPSCs) without utilizing embryoid body formation, manual selection techniques, or complex combinations of small molecules. Human ESC and iPSC colonies were lifted and placed in a neural stem cell medium containing high concentrations of EGF and FGF-2. Cell aggregates (termed EZ spheres) could be expanded for long periods using a chopping method that maintained cell-cell contact.

Developmentally coordinated extrinsic signals drive human pluripotent stem cell differentiation toward authentic DARPP-32+ medium-sized spiny neurons.

Medium-sized spiny neurons (MSNs) are the only neostriatum projection neurons, and their degeneration underlies some of the clinical features of Huntington's disease. Using knowledge of human developmental biology and exposure to key neurodevelopmental molecules, human pluripotent stem (hPS) cells were induced to differentiate into MSNs. In a feeder-free adherent culture, ventral telencephalic specification is induced by BMP/TGFβ inhibition and subsequent SHH/DKK1 treatment.

The first reported generation of several induced pluripotent stem cell lines from homozygous and heterozygous Huntington's disease patients demonstrates mutation related enhanced lysosomal activity.

Neuronal disorders, like Huntington's disease (HD), are difficult to study, due to limited cell accessibility, late onset manifestations, and low availability of material. The establishment of an in vitro model that recapitulates features of the disease may help understanding the cellular and molecular events that trigger disease manifestations. Here, we describe the generation and characterization of a series of induced pluripotent stem (iPS) cells derived from patients with HD, including two rare homozygous genotypes and one heterozygous genotype.

Induced pluripotent stem cell lines from Huntington's disease mice undergo neuronal differentiation while showing alterations in the lysosomal pathway.

Huntington's disease (HD) is an autosomal dominant neurodegenerative disorder caused by an excessive expansion of a CAG trinucleotide repeat in the gene encoding the protein huntingtin, resulting in an elongated stretch of glutamines near the N-terminus of the protein. Here we report the derivation of a collection of 11 induced pluripotent stem (iPS) cell lines generated through somatic reprogramming of fibroblasts obtained from the R6/2 transgenic HD mouse line. We show that CAG expansion has no effect on reprogramming efficiency, cell proliferation rate, brain-derived neurotrophic factor level, or neurogenic potential.