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Microvascular hyperpermeability and thrombosis induced by light/dye treatment
Qin Liu1, Min Zeng, Bingmei M Fu
1Department of Biomedical Engineering, The City College of the City University of New York, 140th Street & Convent Ave., New York, NY 10031, USA.
Biomechanics and Modeling in Mechanobiology
|June 10, 2010
Summary
Photodynamic therapy increases microvascular permeability and thrombosis by damaging the endothelial glycocalyx layer. This leads to faster thrombus formation and vessel occlusion in rat mesenteries.
Area of Science:
- Physiology
- Biomedical Engineering
- Pharmacology
Background:
- Photodynamic therapy (PDT) and light/dye treatments are used in various medical applications.
- Understanding the mechanisms of microvascular damage induced by these treatments is crucial for optimizing their use and minimizing side effects.
Purpose of the Study:
- To investigate the microvascular hyperpermeability and thrombosis induced by photodynamic therapy or light/dye treatment.
- To quantify the temporal dynamics of thrombus formation, growth, and microvessel occlusion.
- To measure changes in microvessel hydraulic conductivity (Lp) and solute permeability (P) and correlate them with structural changes.
Main Methods:
- Experiments were conducted on post-capillary venules in rat mesenteries.
- Thrombus initiation time, growth rate, and occlusion time were quantified under specific light/dye treatment conditions.
- Microvessel hydraulic conductivity (Lp) and solute permeability (P) to TRITC-BSA were measured.
- Data were compared with mathematical models of inter-endothelial clefts.
Main Results:
- Under 0.37 mW/mm(2) irradiation, thrombus initiation occurred in 3.8 ± 0.4 min, with a growth rate of 3.9 ± 0.3%/min, leading to complete occlusion in 29.3 ± 2.2 min.
- Microvessel hydraulic conductivity (Lp) and solute permeability (P) increased significantly, reaching a plateau within 3-5 min.
- At the plateau, Lp increased 2.2-fold and P increased 4.1-fold, with no further increase upon prolonged exposure.
Conclusions:
- Light/dye treatments significantly increase microvascular permeability and induce thrombosis.
- The observed changes in Lp and P suggest a structural alteration at the endothelial surface.
- Depletion of the endothelial glycocalyx layer is proposed as a primary mechanism for light/dye-induced microvascular hyperpermeability and thrombosis.
