Now the vessels of the brain can be seen with the accuracy of a cell Person

Now the vessels of the brain can be seen with the accuracy of a cell

To better understand how the blood supply to the brain works, researchers are mapping networks of blood vessels. To do this, various imaging methods are used, including a high-precision method based on the registration of infrared radiation with the introduction of fluorescent dyes into the bloodstream. Unfortunately, the dyes are toxic and, in addition, can cause changes in the vessels, which makes the images less reliable. Alternatively, genetically modified animals can be used, in which the inner lining of the blood vessels is modified in such a way that it emits light by itself. However, both of these methods are extremely expensive.

Skoltech and SSU researchers have developed a new, inexpensive imaging method that allows you to distinguish even the smallest capillaries of the brain. The method is based on a combination of optical microscopy and image processing and does not require the use of dyes. Thanks to its high accuracy, it allows you to detect every single red blood cell moving through the blood vessels. This is its main advantage over other methods, including those that do not use dyes, because there are not so many red blood cells in the capillaries and each of them counts when visualizing. The results of the study are published in The European Physical Journal Plus.

In our method, frame-by-frame filtering is used to process brain images obtained using a standard optical microscope. The method makes it possible to distinguish individual moving red blood cells and obtain detailed images of the network of blood vessels of the brain down to the smallest capillaries, which in turn provides an accurate assessment of the blood flow rate by digital tracer flow visualization, — says the lead author of the study, researcher at Skoltech Maxim Kurochkin.

To demonstrate the efficiency of the method, scientists used two biological models: a mouse brain and a chicken embryo. First, the team showed, using the example of the blood networks of a chicken embryo, the possibility of mapping the smallest capillaries in which the movement of red blood cells may be unstable. Then the method was tested on a more complex model — rat brain vessels. It turned out that even in systems with more inaccessible vessels, where the movement of individual red blood cells is not visible, but only color patterns that can be associated with groups of vessels are visible, it is nevertheless possible to map blood networks.

Why is it so important to have a detailed blood flow model?

The method proposed by scientists allows us to directly obtain two important characteristics of the circulatory system — the speed of blood flow and the diameter of the vessel. Having received these data, we can try to extract additional information, for example, data on vascular elasticity, membrane stiffness, blood pressure and viscosity," explains Kurochkin. — These parameters can be used by physiologists to build models of blood circulation, the operation of which can be checked, for example, on measurement data obtained from pressure and viscosity sensors.

In the future, the results obtained will allow us to better understand the physiology of endothelial cells lining the inner surface of blood vessels. And the state of the endothelium is the physiological basis of all cardiovascular diseases (which occupy the first place in terms of mortality in the world). Through the state of the endothelium, the physical nature of a particular pathology can be determined both in the brain and in other parts of the body.

For example, the main cause of hemorrhagic stroke is thinning and rupture of the walls of blood vessels of the brain. With excessive thinning or stretching, a bulging of the vessel wall is formed, known as an aneurysm. An accurate model of the vascular network can show the critical level of thinning of the vessel wall, at which its rupture occurs," adds Kurochkin.

The formation of plaques on the inner surface of the arteries leads to narrowing of the vessel lumen and eventually to the development of coronary heart disease, and the detachment of the plaque leads to blockage of the vessel and stopping blood flow, which is the cause of heart attacks and strokes. With the help of the vascular network model, it is possible to predict the redistribution of blood flow due to the expansion, narrowing or blockage of blood vessels, — the scientist notes.

The condition of blood vessels is also relevant for the study of diseases of a different nature. In particular, with the help of a new imaging method, it is possible to study tumors that absorb abnormally many nutrients and therefore become overgrown with blood vessels. Malaria has an infectious nature, but is accompanied by an increase in blood viscosity, which is due to the potential of vascular mapping in the study of this disease. Finally, the new imaging method can be used to study the process of regeneration of blood vessels in tissue at the site of mechanical damage, such as a medical puncture.

Understanding the behavior of objects that have entered the bloodstream is important not only in relation to detached atherosclerotic plaques, but also to other objects, including artificial ones. For example, microcapsules are used for targeted drug delivery, which are injected into the bloodstream, and models of blood networks are indispensable for understanding what will happen to these microcapsules and how they will behave," Kurochkin notes in conclusion.

The material is provided by the press service of Skoltech