Cell adhesion in blood vessel walls.

With the help of complex computer simulations, scientists at the Max Planck Institute (Potsdam, Germany) and the University of Heidelberg have discovered how the shape and distribution of some pieces of adhesion certain cells affect the adhesion of cells in blood vessels.

According to this study, the number and size of these sticky areas are not the most important factors but the most important factor is their emergence from the cell surface. Leukocytes and red blood cells affected by malaria were found to use a spherical-like structure with many sharp spines as shown in the image to carry out their sticking ' strategy '.

Blood is a common means of transport in the body through which different types of cells are transported in our bodies. The movement of blood is determined by hydrodynamics. Cells anchor them to blood vessel walls in the target tissue (target tissue) with the help of special adhesion molecules, which are also called receptors.

The image is illustrated by a computer model, simulating cell adhesion in hydrodynamic flow.It consists of a sphere with randomly distributed plaques and a substrate with the cells involved and able to complement each other.(Photo: Max Planck Academy (Potsdam, Germany))

In many cases, these receptors congregate on the surface of the cell into nanometer-sized arrays. The bonding process is based on a key lock rule: it is a cohesive molecule that only binds to certain cells. This is to ensure that cells are only transported to a place where they are forced to complete their biological function there.

These processes have great implications for medicine. For example, red blood cells affected by malaria will attach to the walls of blood vessels to ' escape ' from being destroyed in the spleen and ' patrol ' white blood cells that will bind to blood vessel walls to search for Strange objects are in the immediate adjacent tissue. These ' wandering sticky cells ' also include stem cells, cells that travel from the bone marrow to their target tissues, and also cancer cells, which cause metastasis in the body.

In order to understand these processes more clearly, it is necessary to see and monitor the process of interaction between hydrodynamics and molecular adhesives in detail. To do this, scientists at the Max Planck Institute (postdam, Germany) and the University of Heidelberg have developed a computer model that can systematically monitor how dense, clickable The size and number of receptor groups affects cell adhesion.

Receptor (Photo: sci.uidaho.edu)

In millions of computer tests, scientists have to verify the extent to which these factors affect how much time an array has to spend to find a ' friend ' on the target while blood is transporting cells according to hydrodynamic principles . These calculations are very complicated because scientists have to calculate hundreds of adhesive arrays for each cell.

And the initial simulations that study the effect of blood flow on cell adhesion have shown that the faster the blood flow rate, the faster the cells find their " friends " by Because cells can ' sweep ' over a wider area thanks to the rapid flow of blood.

The scientists then changed the density of the sticky plaques and verified that: above the threshold level are a few hundred receptors on each cell, there will be no increase in the rate of cell adhesion. again because starting from that threshold, the radius of influence of the cohesive plates will overlap due to their random thermal motion.

The result is similar for the size of the cohesive regions, although this size is of course of less importance in providing effective adhesion.

However, when changing the height, the sticky patches protruding from the cell membrane have yielded surprising results, that is: just a little higher this height makes the speed adhesion increases very quickly.

The white blood cells use this way by coating them with hundreds of protrusions called microvilli, protruding from the cell surface about 350 nanometers - nearly 4% of the diameter of the cell. The erythrocytes affected by malaria also use the tactic ' this urchin '. They have ' humps ' that are 20 nanometers tall raised from the surface of the cell.

Scientists are skeptical that their simulations have helped them discover common biological design rules, a rule that also occurs in other hydrodynamic cases - for bacteria, for example: Gather in medical devices through places where fluid flows through such as urinary catheters or dialysis devices.

In the future, software developed by scientists can allow such studies to be more carefully observed than ever before and will be a step forward on the path to biology. ' computer '.

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