title: The late response of rat subependymal zone stem and progenitor cells to stroke is restricted to directly affected areas of their niche.
abstract: Ischaemia leads to increased proliferation of progenitors in the subependymal zone (SEZ) neurogenic niche of the adult brain and to generation and migration of newborn neurons. Here we investigated the spatiotemporal characteristics of the mitotic activity of adult neural stem and progenitor cells in the SEZ during the sub-acute and chronic post-ischaemic phases. Ischaemia was induced by performing a 1h unilateral middle cerebral artery occlusion (MCAO) and tissue was collected 4/5 weeks and 1 year after the insult. Neural stem cells (NSCs) responded differently from their downstream progenitors to MCAO, with NSCs being activated only transiently whilst progenitors remain activated even at 1 year post-injury. Importantly, mitotic activation was observed only in the affected areas of the niche and specifically in the dorsal half of the SEZ. Analysis of the topography of mitoses, in relation to the anatomy of the lesion and to the position of ependymal cells and blood vessels, suggested an interplay between lesion-derived recruiting signals and the local signals that normally control proliferation in the chronic post-ischaemic phase.
authors.affiliation: MRC Cambridge Centre for Stem Cell Biology and Regenerative Medicine and Department of Veterinary Medicine, University of Cambridge, Cambridge, UK. Electronic address: ik255@cam.ac.uk.
authors.forename: Ilias
authors.initials: I
authors.lastname: Kazanis
authors.forename: Natalia
authors.initials: N
authors.lastname: Gorenkova
authors.forename: Jing-Wei
authors.initials: JW
authors.lastname: Zhao
authors.forename: Robin J M
authors.initials: RJ
authors.lastname: Franklin
authors.forename: Michel
authors.initials: M
authors.lastname: Modo
authors.forename: Charles
authors.initials: C
authors.lastname: Ffrench-Constant
mesh_terms: D000818:Animals; D001921:Brain / Q000473:pathology; D049109:Cell Proliferation; D002552:Cerebral Ventricles / Q000473:pathology*; D008297:Male; D008938:Mitosis / Q000502:physiology; D055495:Neurogenesis / Q000502:physiology*; D009474:Neurons / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D055153:Stem Cell Niche / Q000502:physiology*; D020521:Stroke / Q000473:pathology*
keywords: Ischaemia; Neural stem cells; Neurogenesis; Progenitors; Proliferation; Stroke; Subependymal zone/subventricular zone