engleski

“ Early microglial colonisation of the developing human telencephalon and its involvement in white matter damage in the preterm infant “

Microglial cells penetrate into and scatter throughout the human telencephalic white and grey matter according to a specific spatiotemporal pattern during the 2 first trimesters of gestation. Starting at 4.5 gestational weeks (gw) ameboid microglial cells characterized in single and double labelings by different antibodies as Iba1+, CD68+, CD45+ and MCHII penetrated the telencephalon mainly through the choroid plexus, the meninges and the ventricular lumen. Within the cerebral wall, migration was mainly radial and tangential toward the immature white matter, subplate and cortical plate, whereas pial cells populated the prospective layer 1. Ameboid microglia accumulated and proliferated -as detected by MIB and Ki67 markers-along the limit of the subplate-cortical plate around 13gw. The intraparenchymal vascular route of entry was detectable from this stage on. In the developing diencephalon-telencephalon, microglial clusters were located in areas of crossroads in the white matter. Interestingly, from 19 to 30 gw, intermediate microglia accumulated at the level of the semi-ovale center rostrally (crossroad C2). In premature babies, this area is a target for white matter injury evolving in focal cystic or diffuse lesions (periventricular white matter injury - PWMI). Very preterm infants (<30 gw) have more risks to develop neurological disabilities, behavioural and cognitive dysfunctions. In very preterm brains, necrosis is detected in C1 (junction internal-external capsule) and spongiosis in C2 (semi-ovale center). Microglia-macrophage activation is the main glial feature observed in very preterm PWMI with different subpopulations expressing Iba1, CD68 and CD45. The deep subplate near the lesion displayed intermediate-macrophage microglia as observed in the lesion whereas the superficial subplate showed a ramified phenotype as detected in the cortical plate. The spatiotemporal organization of microglia-macrophage in the immature white and grey matter suggests that these cells may play active roles in developmental processes and in injury of preterm brain.

microglia; preterm

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