Biology subjects

Coelho-Santos, V.

Publications and source records attributed to Coelho-Santos, V..

8 recordsLinked to original sources

bioRxiv2026

Fetal sex influences molecular regulation of human placental vascular development across gestation

Males experience elevated mortality and morbidity during the perinatal period and infancy; however, the biological origins of this vulnerability remain unclear. Emerging evidence suggests that sex-dependent placental development may contribute to differences in fetal growth and outcomes. Vascular networks are central to placental function, established early in the first trimester to support growth and mitigate harmful exposures, and maturing by term to sustain late fetal development. Although these processes are tightly regulated by gene-expression programmes, the role of sex-specific vascular signalling in placental development remains poorly understood. To address this, we analysed raw, publicly available RNA-sequencing transcriptomics data from first trimester and term placental samples. We conducted parallel differential gene expression and functional enrichment analyses across the datasets to ensure direct comparability and to disentangle the specific contribution of sex chromosomes. We identified multiple differentially expressed genes and enriched pathways between male and female placentas. In the first trimester, male placentas exhibited significant enrichment of vascular signalling pathways, particularly Notch signalling, cell adhesion, and migration, consistent with heightened proliferative and remodelling activity. At the end of gestation, sex differences remained detectable; however differentially expressed genes was clearly sex-chromosome driven, with autosomal single-gene sex differences and autosomal-sex-specific pathways markedly reduced. This reflected a mature placental vascular system with minimal sex-based differences outside of the sex chromosome genes. These results reveal gestational stage-dependent sex differences in placental vascular development, with early male fetuses exhibiting increased angiogenic activity and immature vascular signalling, potentially contributing to accelerated growth and increased vulnerability in male neonates.

developmental biology↗

bioRxiv2024

Physiological and injury-induced microglial dynamics across the lifespan

Microglia are brains resident immune cells known for their dynamic responses to tissue and vascular injury. Little is known about how microglial activity differs across the life-stages of early development, adulthood, and aging. Using two-photon live imaging, we show that microglia in the adult cerebral cortex exhibit highly ramified processes and relatively immobile somata under basal conditions. Their responses to injury occur over minutes and are highly coordinated neighboring microglia. In neonates, microglia are denser and more mobile but less morphologically complex. Their responses to focal laser-induced injuries of capillaries or parenchymal tissue are uncoordinated, delayed and persistent over days. In the aged brain, microglia somata remain immobile under basal conditions but their processes become less ramified. Their responses to focal injuries remain coordinated but are slower and less sensitive. These studies confirm that microglia undergo significant changes in their morphology, distribution, dynamics and response to injury across the lifespan. HIGHLIGHTSO_LIMicroglia undergo significant morphological and dynamic changes between life-stages. C_LIO_LINeonatal microglia are highly dynamic, less morphologically complex and mount delayed responses to focal injury compared to adult microglia. C_LIO_LIAged microglia are slightly less ramified and their responses to focal injury are slow and less sensitive than adult microglial. C_LIO_LIMaturation of microglial morphology in the developing cortex is disrupted by focal laser injury. C_LI O_FIG O_LINKSMALLFIG WIDTH=163 HEIGHT=200 SRC="FIGDIR/small/615212v1_ufig1.gif" ALT="Figure 1"> View larger version (47K): org.highwire.dtl.DTLVardef@1ba9011org.highwire.dtl.DTLVardef@1485428org.highwire.dtl.DTLVardef@18d1f2aorg.highwire.dtl.DTLVardef@1f9086d_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗

bioRxiv2024

Stress in utero: effects on gliovascular integrity in female infant offspring

From early in life, experiences like prenatal stress profoundly affect long-term health and behavior. Maternal stress increases fetal exposure to glucocorticoids (GC), disrupting neurodevelopment and raising susceptibility to psychiatric disorders. Previous studies on synthetic GCs, such as dexamethasone (DEX), revealed impairments in neurogenesis and dendritic spine development. However, the influence of prenatal stress on the gliovascular interface remains unclear. This interface, involving the relationship between astrocytes and blood vessels, is essential for healthy brain development. Our study demonstrates that prenatal stress alters the expression and localization of astrocytic proteins crucial for maintaining vascular homeostasis, such as aquaporin-4, in female offspring exposed to DEX. While overall vascular density remains unaffected, it triggers morphological changes. Particularly, the hippocampus and prefrontal cortex exhibit heightened vulnerability to these effects. This study reveals prenatal stress as a potent disruptor of gliovascular development, urging deeper inquiry into its implications.

neuroscience↗

bioRxiv2024

Activity-dependent regulation of vascular cholesterol metabolism acts as a negative feedback mechanism for neurovascular coupling

Brain function is dependent on a continuous supply of bloodborne oxygen and nutrients. Because neurons require a greater supply of oxygen and nutrients when active, there is increased local blood flow following neuronal activity. The underlying mechanisms of this hyperemia are termed neurovascular coupling (NVC). Many complex processes contribute to NVC, and there is still much unknown about how vascular physiology adapts to changes in neuronal activity and blood flow. Here we show that neuronal activity increases brain endothelial expression of genes related to cholesterol synthesis and uptake in vivo, and that shear stress is sufficient for upregulation of these genes in vitro. We previously found that treatment with PLX5622 induces upregulation of the same cassette of cholesterol-related genes in brain endothelial cells. In the present study, we find that increasing brain endothelial cholesterol synthesis and/or uptake, either with PLX5622 or targeted AAV-mediated expression of LDLR, inhibits brain arteriole dilation in response to capillary K+ stimulation, and this deficit is rescued by cholesterol depletion. Together, these data suggest that neuronal activity regulates brain endothelial cholesterol, which in turn blocks endothelial retrograde signaling and vasodilation, thus acting as a negative feedback mechanism for NVC.

neuroscience↗

bioRxiv2023

Endothelial structure contributes to heterogeneity in brain capillary diameter

The high metabolic demand of brain tissue is supported by a constant supply of blood through dense microvascular networks. Capillaries are the smallest class of vessels and vary in diameter between [~]2 to 5 m in the brain. This diameter range plays a significant role in the optimization of blood flow resistance, blood cell distribution, and oxygen extraction. The control of capillary diameter has largely been ascribed to pericyte contractility, but it remains unclear if endothelial wall architecture also contributes to capillary diameter heterogeneity. Here, we use public, large-scale volume electron microscopy data from mouse cortex (MICrONS Explorer, Cortical MM^3) to examine how endothelial cell number, endothelial cell thickness, and pericyte coverage relates to microvascular lumen size. We find that transitional vessels near the penetrating arteriole and ascending venule are composed of 2 to 5 interlocked endothelial cells, while the numerous capillary segments intervening these zones are composed of either 1 or 2 endothelial cells, with roughly equal proportions. The luminal area and diameter is on average slightly larger with capillary segments composed of 2 interlocked endothelial cells versus 1 endothelial cell. However, this difference is insufficient to explain the full range of capillary diameters seen in vivo. This suggests that both endothelial structure and other influences, such as pericyte tone, contribute to the basal diameter and optimized perfusion of brain capillaries.

neuroscience↗

bioRxiv2023

Meningeal origins and dynamics of perivascular fibroblast development on the mouse cerebral vasculature

Perivascular fibroblasts (PVFs) are a fibroblast-like cell type that reside on large-diameter blood vessels in the adult meninges and central nervous system (CNS). PVFs drive fibrosis following injury but their homeostatic functions are not well detailed. In mice, PVFs were previously shown to be absent from most brain regions at birth and are only detected postnatally within the cerebral cortex. However, the origin, timing, and cellular mechanisms of PVF development are not known. We used Col1a1-GFP and Col1a2-CreERT transgenic mice to track PVF developmental timing and progression in postnatal mice. Using a combination of lineage tracing and in vivo imaging we show that brain PVFs originate from the meninges and are first seen on parenchymal cerebrovasculature at postnatal day (P)5. After P5, PVF coverage of the cerebrovasculature rapidly expands via mechanisms of local cell proliferation and migration from the meninges, reaching adult levels at P14. Finally, we show that PVFs and perivascular macrophages (PVMs) develop concurrently along postnatal cerebral blood vessels, where the location and depth of PVMs and PVFs highly correlate. These findings provide the first complete timeline for PVF development in the brain, enabling future work into how PVF development is coordinated with cell types and structures in and around the perivascular spaces to support normal CNS vascular function. SummaryBrain perivascular fibroblasts migrate from their origin in the meninges and proliferate locally to fully cover penetrating vessels during postnatal mouse development.

developmental biology↗

bioRxiv2022

Public volume electron microscopy data: An essential resource to study the brain microvasculature

Electron microscopy is the primary approach to study ultrastructural features of the cerebrovasculature. However, 2D snapshots of a vascular bed capture only a small fraction of its complexity. Recent efforts to synaptically map neuronal circuitry using volume electron microscopy have also sampled the brain microvasculature in 3D. Here, we perform a meta-analysis of 6 data sets spanning different species and brain regions, including 2 data sets from the MICrONS consortium that have made efforts to segment vasculature in addition to all parenchymal cell types in mouse visual cortex. Exploration of these data have revealed rich information for detailed investigation of the cerebrovasculature. Neurovascular unit cell types (including, but not limited to, endothelial cells, mural cells, perivascular fibroblasts, microglia, and astrocytes) could be discerned across broad microvascular zones. Image contrast was sufficient to identify subcellular details, including endothelial junctions, caveolae, peg-and-socket interactions, mitochondria, Golgi cisternae, microvilli and other cellular protrusions of potential significance to vascular signaling. Additionally, noncellular structures including the basement membrane and perivascular spaces were visible and could be traced between arterio-venous zones along the vascular wall. These explorations revealed structural features that may be important for vascular functions, such as blood-brain barrier integrity, blood flow control, brain clearance, and bioenergetics. They also identified limitations where accuracy and consistency of segmentation could be further honed by future efforts. The purpose of this article is to introduce these valuable community resources within the framework of cerebrovascular research by providing an assessment of their vascular contents, identifying features of significance for further study, and discussing next step ideas for refining vascular segmentation and analysis.

neuroscience↗

bioRxiv2017

Genetic ablation of RhoA in adult microglia causes synapse and neuronal loss

Nervous tissue homeostasis requires regulation of microglia activity. Using conditional gene targeting in mice, we demonstrate that genetic ablation of the small GTPase Rhoa in adult microglia is sufficient to trigger spontaneous microglia activation producing a neurological phenotype (including synapse and neuron loss, impairment of LTP, formation of {beta}-amyloid plaques and memory deficits). Mechanistically, loss of Rhoa in microglia triggers Src activation and Src-mediated Tnf production, leading to excitotoxic glutamate secretion. Inhibiting Src in microglia Rhoa-deficient mice attenuates microglia dysregulation and the ensuing neurological phenotype. We also found that the Rhoa/Src signaling pathway was disrupted in microglia of the APP/PS1 mouse model of Alzheimers disease and that low doses of A{beta} oligomers triggered microglia neurotoxic polarization through the disruption of Rhoa-to-Src signaling. Overall, our results indicate that disturbing RhoGTPase signaling in microglia can directly cause neurodegeneration.

neuroscience↗