Microvascular Structure and Blood Brain Barrier Function are Compromised in Developing Cortices Following Prenatal Alcohol Exposure
Poster presented at the Brain & Behavioral Health Research Day 2023
Fetal Alcohol Spectrum Disorders (FASD) occur due to in utero alcohol exposure. FASD presents as a wide range of neurocognitive deficits that may be caused by abnormal vascular development in the brain and expression of factors that regulate vessel formation. We and others have shown that miR-150-5p alters pathways important for vascular development, including angiogenesis and integrity of the blood-brain barrier (BBB). In an established mouse model of moderate prenatal alcohol exposure (PAE), we found that brain microvascular endothelial cells (BMVECs) isolated from cortices of EtOH-exposed pups at embryonic day 18 (E18) contained significantly higher levels of miR-150-5p compared to saccharin (SAC)-exposed controls. To assess the structure of the developing microvasculature, we used CLARITY, an imaging technique that renders tissue optically transparent. After tissue clearing and staining of the vasculature, 3D images were taken with the Leica TCS SP8 confocal microscope, fitted with a long working distance objective designed for imaging thick tissue sections. Imaris cell imaging software was used for image visualization and quantification. We found that PAE E18 cortices displayed significant reductions in vessel area, volume, and mean vessel diameter. Further, intracerebroventricular (ICV) injection of miR-150-5p inhibitors could reverse some of the vascular deficits. To assess BBB function, TRITC-labeled dextran tracers were injected into embryonic livers. This was followed by immunohistochemistry and confocal microscopy of the embryonic cortices. A permeability index was calculated from the dextran signal found outside the blood vessels compared to the total dextran signal for each cortex. We found that PAE cortices had an increased permeability index compared to controls, indicating compromised BBB function. Our work suggests that PAE-mediated elevation of miR-150-5p within BMVECs alters molecular pathways affecting angiogenesis and BBB permeability during development and may contribute to neurodevelopmental deficits seen in patients with FASD.