β1 Integrin Maintains Integrity of the Embryonic Neocortical Stem Cell Niche

IInteractions between laminins and integrin receptors hold neural stem cells in place at the ventricular surface of embryonic brain. Transient disruption leads to abnormal stem cell divisions and permanent cortical malformation

The Protective Effect of Glibenclamide in a Model of Hemorrhagic Encephalopathy of Prematurity

brain science

Cerebral microbleeds in a neonatal rat model.

BACKGROUND:In adult humans, cerebral microbleeds play important roles in neurodegenerative diseases but in neonates, the consequences of cerebral microbleeds are unknown. In rats, a single pro-angiogenic stimulus in utero predisposes to cerebral microbleeds after birth at term, a time when late oligodendrocyte progenitors (pre-oligodendrocytes) dominate in the rat brain. We hypothesized that two independent pro-angiogenic stimuli in utero would be associated with a high likelihood of perinatal microbleeds that would be severely damaging to white matter. METHODS:Pregnant Wistar rats were subjected to intrauterine ischemia (IUI) and low-dose maternal lipopolysaccharide (mLPS) at embryonic day (E) 19. Pups were born vaginally or abdominally at E21-22. Brains were evaluated for angiogenic markers, microhemorrhages, myelination and axonal development. Neurological function was assessed out to 6 weeks. RESULTS:mRNA (Vegf, Cd31, Mmp2, Mmp9, Timp1, Timp2) and protein (CD31, MMP2, MMP9) for angiogenic markers, in situ proteolytic activity, and collagen IV immunoreactivity were altered, consistent with an angiogenic response. Vaginally delivered pups exposed to prenatal IUI+mLPS had spontaneous cerebral microbleeds, abnormal neurological function, and dysmorphic, hypomyelinated white matter and axonopathy. Pups exposed to the same pro-angiogenic stimuli in utero but delivered abdominally had minimal cerebral microbleeds, preserved myelination and axonal development, and neurological function similar to naïve controls. CONCLUSIONS:In rats, pro-angiogenic stimuli in utero can predispose to vascular fragility and lead to cerebral microbleeds. The study of microbleeds in the neonatal rat brain at full gestation may give insights into the consequences of microbleeds in human preterm infants during critical periods of white matter development

Correction: Cerebral microbleeds in a neonatal rat model.

[This corrects the article DOI: 10.1371/journal.pone.0171163.]

Cerebral microbleeds are linked to pro-angiogenic stimuli <i>in utero</i> followed by vaginal delivery.

<p><b>A,B</b>: H&E-stained sections of P0 brains showing representative microbleeds (<i>arrows</i>) in pup following prenatal pro-angiogenic stimuli with vaginal delivery (PS-VD) (A, <i>left panel</i>; B, <i>all panels</i>) but not following prenatal pro-angiogenic stimuli with abdominal delivery (PS-AD) (A, <i>right panel</i>); scale bars, 1 and 0.25 mm in (A) and (B), respectively. <b>C</b>: Maps showing the locations and sizes of microbleeds identified in the coronal section 2.5 mm from the rostral extent of the lateral ventricle, on P0 in PS-VD pups (<i>left panel</i>) and in PS-AD pups (<i>right panel</i>); data from the right and left hemispheres of 10 pups are superimposed; scale bar, 1 mm. <b>D</b>: Averages of the total area occupied by hemorrhages in 9 coronal sections (see <i>inset</i>) in CTR-VD pups, PS-VD pups, and in PS-AD pups; 10 pups per group; **, <i>p</i><0.01 comparing CTR-VD and PS-VD; §§, <i>p</i><0.01 comparing PS-VD and PS-AD. <b>E</b>: Histogram showing the frequency distribution of microbleeds by size in the 3 groups; same coronal plane as in (C); inset shows the data plotted with an extended abscissa and the ordinate in log scale.</p

The effect of cerebral microbleeds on neurological function.

<p><b>A</b>: Performance on the righting reflex and on the negative geotaxis test on P3–14 in naïve pups with vaginal delivery (CTR-VD), pups following prenatal pro-angiogenic stimuli with vaginal delivery (PS-VD), and pups following prenatal pro-angiogenic stimuli with abdominal delivery (PS-AD). <b>B</b>: Performance on the open field test at P24, the elevated plus maze at P31, and on thigmotaxis at P35, in CTR-VD pups, PS-VD pups, and PS-AD pups. <b>C</b>: Spontaneous rearing at P31, performance on the beam balance test at P31, and grip strength at P31 in CTR-VD pups, PS-VD pups, and PS-AD pups. <b>D</b>: Incremental spatial learning on P35–39, performance on the memory probe at P40, and on the rapid learning test at P42 in CTR-VD pups, PS-VD pups, and PS-AD pups. For all panels, 19–25 pups/group; * and **, <i>p</i><0.05 and 0.01, respectively, comparing CTR-VD and PS-VD; §§, <i>p</i>< 0.01comparing PS-VD and PS-AD.</p

IUI+mLPS increases proteolytic activity and decreases collagen IV immunoreactivity.

<p><b>A–C</b>: <i>In situ</i> zymography (A,B), with quantification (C), of coronal sections from naïve control (CTR) and 24 hours after dual prenatal pro-angiogenic stimuli (PS) of IUI+mLPS, shown at low (A) and at high (B) magnification; the subventricular zone is shown in (B); nuclei stained with DAPI (blue); scale bars, 1 mm (A), 25 μm (B); 3 pups per group; *, <i>p</i><0.05; **, <i>p</i><0.01. <b>D,E</b>: Images of vessels identified by immunolabeling for RECA (red), that show proteolytic activity on <i>in situ</i> zymography (green); merged images are shown on the right; nuclei stained with DAPI (blue); scale bars, 50 μm. <b>F</b>: Immunolabeling for collagen IV (<i>left</i>), with quantification (<i>right</i>), on P0 in naïve controls (CTR), after IUI alone, after mLPS alone, and after the dual pro-angiogenic stimuli of IUI+mLPS (PS), in all cases after vaginal delivery, in coronal brain sections; 5 pups per group; tissues from the IUI alone group were from a previous study [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0171163#pone.0171163.ref020" target="_blank">20</a>].</p