Platelets are the second largest component of blood after erythrocytes. Their primary function is to stop bleeding when the blood vessel walls are damaged. Contact with foreign substances, those that are usually absent from the bloodstream, leads to activation of the platelets. When activated, the platelets stick to the damaged surface and to each other, forming a mechanical "plug". Activation is a very fast and complex process that includes a sharp change in the cell’s shape. The transformation of the cell from disk form to spherical occurs in a few seconds. This morphological change can be vital to prevent blood loss. However, the understanding of its significance is incomplete. This may be because there is no quantitative description of the platelet form before activation.
Alexander Moskalensky, Head of the NSU Laboratory of Optics and Dynamics of Biological Systems talked about their work,
We were interested in considering these cells from the biophysics point of view, how they participate in the blood folding process. The change in the platelet form upon activation has been described in the literature for a long time, but no one can explain why and how it occurs. In recent years, detailed studies of this process began to appear. For example, in thrombocytes there is a ring of microtubules, which in a relaxed state stretches the cell and makes it a disc-shaped pancake. When activated, this ring of microtubules passes into a three-dimensional folded structure that allows the cell to assume a spherical shape. We began to study this phenomenon and saw that the curved structure of the microtubule ring had a constant curvature. The next step was our hypothesis that the surface of the platelet, the cell membrane plus the cortex, encircles the microtubule framework both in a relaxed state and in a folded state. Based on these assumptions, we mathematically derived the form of the platelet and developed an easy program so that anyone can model it.
In their article, the researchers described a change in shape based on a physical examination of the platelet cytoskeleton. Then, they proposed a mathematically rigorous formulation of the problem whose solution is a wide class of discoid and activated cell forms. The biophysicists hope this tool will lead to a better understanding of the behavior mechanisms of these cells and be able to influence them. For example, with excessive activity, platelets participate in the formation of blood clots inside the vessels, and this needs to be corrected. In such cases, antiplatelet therapy is used: patients are given drugs that block the platelets activity. The focus now is finding new types of therapy because traditional drugs are not always effective and are addictive. Researching the effect on the shape of the cell appears promising but currently medications related to this do not exist. This is probably because there is not a sufficient understanding of how the form of a thrombocyte is connected to its functions.
The work of the NSU biophysicists will continue thanks to the support of the Russian Science Foundation. The laboratory received a grant for research in the field of biophotonics. Their goal is to find out how platelets are involved in the formation of vascular complications in diabetic patients and to suggest new treatment methods. The project will be implemented in cooperation with the Scientific Research Institute for Clinical and Experimental Lymphology (a branch of the Institute of Cytology and Genetics of SB RAS) and Aston University (UK).
