Interactions between glial progenitors and blood vessels during early postnatal corticogenesis: Blood vessel contact represents an early stage of astrocyte differentiation

Abstract

The post-neurogenic period in the mammalian neocortex is characterized by the growth of astrocyte and oligodendrocyte populations and their incorporation into the network of the developing central nervous system (CNS). Many of these glial cells originate as progenitors in the subventricular zone (SVZ) and then migrate into white and gray matter before differentiating. What determines the specific cellular fate of progenitors in vivo is not known, however. In examining the early stages of gliogenesis from progenitors in the SVZ, we noted that interactions with cortical blood vessels took place at what appeared to be an early stage of glial differentiation. We have examined in more detail the interactions of progenitors with blood vessels in the early postnatal rat neocortex after labeling progenitors in vivo with a LacZ-encoding retrovirus. These early interactions are accompanied by an increase in intermediate filament expression, consistent with astrocytic differentiation. Because astrocytes interact with blood vessels and pia, we suggest that such contact represents an early stage in astrocytic differentiation. Furthermore, since angiogenesis and astrogenesis occur over a similar period, the growth of blood vessels may even play a role in the selection of astrocytic fate by a progenitor. As vessel growth slows, fewer progenitors may be directed toward an astrocyte fate, allowing more to differentiate into oligodendrocytes, perhaps explaining the shift from astrocyte genesis to oligodendrocyte genesis during early postnatal cortical development.

NG2 cells generate both oligodendrocytes and gray matter astrocytes

“…These faintly NG2+ astrocyte-like cells had broadened web-like end-feet on blood vessels, a feature that is rarely seen in postnatal NG2 glia. These vascular contacts of the intermediate cells resembled those described for immature astrocytes by Zerlin and Goldman (Zerlin and Goldman, 1997). EGFP+ astrocytes increased in number in NG2creBAC:Z/EG double tg mice between E18 and P14 and persisted through P60.…”

Selective ablation of αv integrins in the central nervous system leads to cerebral hemorrhage, seizures, axonal degeneration and premature death

“…Besides carrying essential oxygen and nutrients to cells of the CNS, blood vessels also provide growth, guidance and survival cues that regulate various aspects of CNS development and maintenance (Louissaint et al, 2002;Mi et al, 2001;Palmer et al, 2000;Song et al, 2002;Zerlin and Goldman, 1997). In turn, cells of the CNS microenvironment provide factors that influence blood vessel growth and survival (Haigh et al, 2003).…”

Neural Transmembrane Protease and Endothelial Gs Protein Activation in Cell Contact-dependent Signaling between Neural Stem/Progenitor Cells and Brain Endothelial Cells

“…In the developing CNS, nervous and vascular systems are both derived from the neural tube (1). Endothelial cells and neural stem cells appear at the same stages during development and are co-localized in the neural geminal zones (2). Invasion of spouts from the perineural vascular plexus into the ventral region of the neural tube are associated with the proliferation of neuroepithelium.…”