Investigating human oligodendrogenesis and the interaction of oligodendrocytes with neurons and astrocytes would accelerate our understanding of the mechanisms underlying white matter disorders. However, this is challenging because of the limited accessibility of functional human brain tissue. Here, we developed a new differentiation method of human induced pluripotent stem cells to generate three-dimensional brain organoids that contain oligodendrocytes as well as neurons and astrocytes, called human oligodendrocyte spheroids. We found that oligodendrocyte lineage cells derived in human oligodendrocyte spheroids transitioned through developmental stages similar to primary human oligodendrocytes and that the migration of oligodendrocyte lineage cells and their susceptibility to lysolecithin exposure could be captured by live imaging. Moreover, their morphology changed as they matured over time in vitro and started myelinating neurons. We anticipate that this method can be used to study oligodendrocyte development, myelination, and interactions with other major cell types in the CNS.

/pdf/differentiation-and-maturation-of-oligodendrocytes-in-human-327cxbi9gg.pdf

Differentiation and maturation of oligodendrocytes in human three-dimensional neural cultures.

Epigenetic Regulation in Neurodegenerative Diseases.

https://academiccommons.columbia.edu/doi/10.7916/D87Q0B0K/download

Huntington’s Disease iPSC-Derived Brain Microvascular Endothelial Cells Reveal WNT-Mediated Angiogenic and Blood-Brain Barrier Deficits

Although Huntington's disease is a late-manifesting neurodegenerative disorder, both mouse studies and neuroimaging studies of presymptomatic mutation carriers suggest that Huntington's disease might affect neurodevelopment. To determine whether this is actually the case, we examined tissue from human fetuses (13 weeks gestation) that carried the Huntington's disease mutation. These tissues showed clear abnormalities in the developing cortex, including mislocalization of mutant huntingtin and junctional complex proteins, defects in neuroprogenitor cell polarity and differentiation, abnormal ciliogenesis, and changes in mitosis and cell cycle progression. We observed the same phenomena in Huntington's disease mouse embryos, where we linked these abnormalities to defects in interkinetic nuclear migration of progenitor cells. Huntington's disease thus has a neurodevelopmental component and is not solely a degenerative disease.

https://science.sciencemag.org/content/sci/early/2020/07/15/science.aax3338.full.pdf

Huntington’s disease alters human neurodevelopment

Increasing evidence suggests that early neurodevelopmental defects in Huntington’s disease (HD) patients could contribute to the later adult neurodegenerative phenotype. Here, by using HD-derived induced pluripotent stem cell lines, we report that early telencephalic induction and late neural identity are affected in cortical and striatal populations. We show that a large CAG expansion causes complete failure of the neuro-ectodermal acquisition, while cells carrying shorter CAGs repeats show gross abnormalities in neural rosette formation as well as disrupted cytoarchitecture in cortical organoids. Gene-expression analysis showed that control organoid overlapped with mature human fetal cortical areas, while HD organoids correlated with the immature ventricular zone/subventricular zone. We also report that defects in neuroectoderm and rosette formation could be rescued by molecular and pharmacological approaches leading to a recovery of striatal identity. These results show that mutant huntingtin precludes normal neuronal fate acquisition and highlights a possible connection between mutant huntingtin and abnormal neural development in HD.

https://www.pnas.org/content/pnas/115/4/E762.full.pdf

Faulty neuronal determination and cell polarization are reverted by modulating HD early phenotypes

Neural cultures derived from Huntington’s disease (HD) patient-derived induced pluripotent stem cells were used for ‘omics’ analyses to identify mechanisms underlying neurodegeneration. RNA-seq analysis identified genes in glutamate and GABA signaling, axonal guidance and calcium influx whose expression was decreased in HD cultures. One-third of gene changes were in pathways regulating neuronal development and maturation. When mapped to stages of mouse striatal development, the profiles aligned with earlier embryonic stages of neuronal differentiation. We observed a strong correlation between HD-related histone marks, gene expression and unique peak profiles associated with dysregulated genes, suggesting a coordinated epigenetic program. Treatment with isoxazole-9, which targets key dysregulated pathways, led to amelioration of expanded polyglutamine repeat-associated phenotypes in neural cells and of cognitive impairment and synaptic pathology in HD model R6/2 mice. These data suggest that mutant huntingtin impairs neurodevelopmental pathways that could disrupt synaptic homeostasis and increase vulnerability to the pathologic consequence of expanded polyglutamine repeats over time.

/pdf/developmental-alterations-in-huntington-s-disease-neural-3p4vstas5a.pdf

A Gerardo García Díaz-Barriga

Papers

Developmental alterations in Huntington's disease neural cells and pharmacological rescue in cells and mice

Developmental alterations in Huntington's disease neural cells and pharmacological rescue in cells and mice