How To Track Blood Flow In Tiny Vessels

Scientists have designed gold nanoparticles, no bigger than 100 nanometres, which can be coated and used to track blood flow in the smallest blood vessels in the body. By improving our understanding of blood flow in vivo the nanoprobes represent an opportunity to help in the early diagnosis of diseaseLight microscopy is a rapidly evolving field for understanding in vivo systems where high resolution is required. It is particularly crucial for cardiovascular research, where clinical studies are based on ultrasound technologies which inherently have lower resolution and provide limited information.

The ability to monitor blood flow in the sophisticated vascular tree (notably in the smallest elements of the microvasculaturecapillaries) can provide invaluable information to understand disease processes such as thrombosis and vascular inflammation. There are further applications for the improved delivery of therapeutics, such as targeting tumours.

Currently, blood flow in the microvasculature is poorly understood. Nanoscience is uniquely placed to help understand the processes happening in the micron-dimensioned vessels. Designing probes to monitor blood flow is challenging because of the environment; the high protein levels in plasma and the high red blood cell concentrations are detrimental to optical imaging. Conventional techniques rely on staining red blood cells, using organic dyes with short-lived usage due to photobleaching, as the tracking motif. The relatively large size of the red blood cells (7-8 micrometres), which are effectively the probes, limits the resolution in imaging and analysis of flow dynamics of the smallest vessels which are of a similar width. Therefore, to have more detailed resolution and information about the blood flow in the microvasculature, even smaller probes are required.

The key to these iridium-coated nanoparticles lies in both their small size, and in the characteristic luminescent properties. The iridium gives a luminescent signal in the visible spectrum, providing an optical window which can be detected in blood. It is also long-lived compared to organic fluorophores, while the tiny gold particles are shown to be ideal for tracking flow and detect clearly in tissues“, explains Professor Zoe Pikramenou, from the School of Chemistry at  the University of Birmingham.

The findings have been published in the journal Nanomedicine.


Artificial Blood Vessels Resistant To Thrombosis

Scientists from ITMO University (Russia) developed artificial blood vessels that are not susceptible to blood clot formation. The achievement was made possible by a new generation of drug-containing coating applied to the inner surface of the vesselSurgery, associated with cardiovascular diseases, such as ischemia, often require the implantation of vascular graftsartificial blood vessels, aimed at restoring the blood flow in a problematic part of the circulatory system. A serious disadvantage of vascular grafts is their tendency to get blocked due to clot formation, which results in compulsory and lifelong intake of anticoagulants among patients and sometimes may even require an additional surgical intervention.

In the study, a research team led by Vladimir Vinogradov, head of the International Laboratory of Solution Chemistry of Advanced Materials and Technologies at ITMO University proposed a solution to the problem. The team managed to synthesize a thin film made of densely packed aluminum oxide nanorods blended with molecules of a thrombolytic enzyme (urokinase-type plasminogen activator). Adhered to the inner surface of a vascular graft, the film causes the parietal area of the graft to get filled with a stable concentration of a substance, called plasmin, which is capable of dissolving the appearing clots. Yulia Chapurina, laboratory researcher and first author of the paper, set up several in vitro experiments that helped demonstrate just how effective the film is.


artificial blood vessel

In order to test how our improved vascular graft worked, we grew an artificial clot made of blood plasma mixed with thrombin and placed it inside the graft. The results of the experiment amazed us”, she explains. “Very soon the clot started to dissolve and leak through the graft. In reality, our coating would destroy clots at the stage of formation, constantly ensuring an unobstructed blood flow in the graft.

The results of the study were published in the Journal of Medicinal Chemistry.


NanoDrones Destroy Fat In Arteries

Nanometer-sized “drones” will deliver a special type of healing molecule to fat deposits in arteries. This is new approach to prevent heart attacks caused by atherosclerosis, according to a study in pre-clinical models by scientists at Brigham and Women’s Hospital (BWH) and Columbia University Medical Center.

Although current treatments have reduced the number of deaths from atherosclerosis-related disease, atherosclerosis remains a dangerous health problem: Atherosclerosis of the coronary arteries is the #1 killer of women and men in the U.S., resulting in one out of every four deaths. In the study, targeted biodegradable nanodrones’ that delivered a special type of drug that promotes healing (‘resolution‘) successfully restructured atherosclerotic plaques in mice to make them more stable. This remodeling of the plaque environment would be predicted in humans to block plaque rupture and thrombosis and thereby prevent heart attacks and strokes.
nanodronesNanometer-sized ‘drones’ that deliver a special type of healing molecule to fat deposits in arteries could become a new way to prevent heart attacks caused by atherosclerosis
This is the first example of a targeted nanoparticle technology that reduces atherosclerosis in an animal model,” said co-senior author Omid Farokhzad, MD, associate professor and director of the Laboratory of Nanomedicine and Biomaterials at BWH and Harvard Medical School (HMS). “Years of research and collaboration have culminated in our ability to use nanotechnology to resolve inflammation, remodel and stabilize plaques in a model of advanced atherosclerosis.”

These findings are published in the February 18th online issue of Science Translational Medicine.