Vascular permeability

{{Short description|Attribute of blood vessels}}

{{Technical|date=March 2025}}

File:Enhanced permeability and retention (EPR) effect.png]]

Vascular permeability, often in the form of capillary permeability or microvascular permeability, characterizes the permeability of a blood vessel wall–in other words, the blood vessel wall's capacity to allow for the flow of small molecules (such as drugs, nutrients, water, or ions) or even whole cells (such as lymphocytes on their way to a site of inflammation) in and out of the vessel. Blood vessel walls are lined by a single layer of endothelial cells. The gaps between endothelial cells (cell junctions) are strictly regulated depending on the type and physiological state of the tissue.{{Cite journal |last1=Azzi |first1=Sandy |last2=Hebda |first2=Jagoda K. |last3=Gavard |first3=Julie |date=2013 |title=Vascular Permeability and Drug Delivery in Cancers |journal=Frontiers in Oncology |volume=3 |page=211 |doi=10.3389/fonc.2013.00211 |issn=2234-943X |pmc=3744053 |pmid=23967403|doi-access=free }}{{Cite journal |last1=Park-Windhol |first1=Cindy |last2=D'Amore |first2=Patricia A. |date=2016-05-23 |title=Disorders of Vascular Permeability |journal=Annual Review of Pathology: Mechanisms of Disease |language=en |volume=11 |issue=1 |pages=251–281 |doi=10.1146/annurev-pathol-012615-044506 |pmid=26907525 |pmc=8462517 |issn=1553-4006}}{{Cite journal |last1=Komarova |first1=Yulia |last2=Malik |first2=Asrar B. |date=2010-03-17 |title=Regulation of Endothelial Permeability via Paracellular and Transcellular Transport Pathways |url=https://www.annualreviews.org/doi/10.1146/annurev-physiol-021909-135833 |journal=Annual Review of Physiology |language=en |volume=72 |issue=1 |pages=463–493 |doi=10.1146/annurev-physiol-021909-135833 |pmid=20148685 |issn=0066-4278|url-access=subscription }}{{Cite journal |last1=Park |first1=Ki-Sook |last2=Schecterson |first2=Leslayann |last3=Gumbiner |first3=Barry M. |date=2021-04-01 |title=Enhanced endothelial barrier function by monoclonal antibody activation of vascular endothelial cadherin |journal=American Journal of Physiology. Heart and Circulatory Physiology |volume=320 |issue=4 |pages=H1403–H1410 |doi=10.1152/ajpheart.00002.2021 |issn=0363-6135 |pmc=8260392 |pmid=33577432}}

There are several techniques to measure vascular permeability to certain molecules. For instance, the cannulation of a single microvessel with a micropipette: the microvessel is perfused with a certain pressure, occluded downstream, and then the velocity of some cells will be related to the permeability.Michel, C. C., Mason, J. C., Curry, F. E. & Tooke, J. E. Development of Landis Technique for Measuring Filtration Coefficient of Individual Capillaries in Frog Mesentery. Q J Exp Physiol Cms 59, 283-309 (1974).Bates, D. O. & Harper, S. J. Regulation of vascular permeability by vascular endothelial growth factors. Vascul Pharmacol 39, 225-237 (2002) Another technique uses multiphoton fluorescence intravital microscopy through which the flow is related to fluorescence intensity and the permeability is estimated from the Patlak transformation.Patlak, C. S., Blasberg, R. G. & Fenstermacher, J. D. Graphical evaluation of blood-to-brain transfer constants from multiple-time uptake data. J Cereb Blood Flow Metab 3, 1-7 (1983).{{Clarify|reason=Explain Patlak transformation, or wikilink to an explanation in another article|date=March 2025}}

An example of increased vascular permeability is in the initial lesion of periodontal disease, in which the gingival plexus becomes engorged and dilated, allowing large numbers of neutrophils to extravasate and appear within the junctional epithelium and underlying connective tissue.Page, RC; Schroeder, HE. "Pathogenesis of Inflammatory Periodontal Disease: A Summary of Current Work." Lab Invest 1976;34(3):235-249