Fig. 5

Heterogeneity in microvasculature diameter determines the outcome of filtration steps for BBB enrichment. a The CNS vascular tree from arteries to veins. An indicative range of vessel diameter for each vascular section is provided, along with other cell types that may be co-isolated. Arteries and veins have a diameter > 100 μm, arterioles and venules from 100 μm to 50 μm. The brain microvasculature has a diameter smaller than 50 μm and consists of pre-capillary arterioles, capillaries and post-capillary venules. Capillaries are generally considered those with a diameter < 10 μm and often show diameters of about 5 μm. APC: Antigen-presenting cell. b Enzymatic digestion and mechanical disruption during CNS vascular isolation protocols alter the physical properties of the microvasculature fragments, influencing the downstream steps of the isolation protocol, particularly size dependent filtration across nylon membranes. Small vascular fragments obtained by mechanical disruption can allow for undesired vessels to pass through the filter. Enzymatic digestion leads to swelling of the blood vessels, prohibiting their elution through the filter