MYOCARDIAL PATHOMORPHOLOGY IN DISTANT BONE TISSUE DAMAGE AND APPLICATION OF EXOSOMES OF MULTIPOTENT STROMAL CELLS
The structural reactions of the rabbit myocardium with distant damage of the bone tissue in proximal tibial condyle (PTC) and the use of exosomes of multipotent stromal cells (EMSCs) as a potential regenerative component were studied. Under aseptic and antiseptic conditions, one animal was injected with warm saline solution in phosphate buffer into the defect of the PTC on the right and left limbs, while others were injected into the defect on both limbs with 39 μg of EMSCs per animal (or 19.5 μg per one limb) in the same buffer. Morphological and stereological analysis of the myocardium of the right and left ventricles of the heart was performed after 3, 7 and 10 days. It was found that damage of the PTC in rabbits is accompanied by the development of dystrophic (lytic) changes in cardiomyocytes, myocardial edema, plethora, leukocyte infiltration with a predominance of lymphocytes. The use of EMSCs is accompanied by a more pronounced dilatation of blood vessels with the formation of extensive hemorrhages (especially in the initial stages of the experiment), the formation of blood clots in the cavities of the heart and its vessels, prolongation of edema, but a decrease in the severity of lytic changes in cardiomyocytes. The most pronounced changes in the structural organization of the myocardium of the right and left ventricles of the heart of rabbits after damage of bone tissue, including with the introduction of EMSCs, were revealed after 7 days of the experiment, namely, a decrease in the volume density of cardiomyocytes by 20-22%, an increase in the volume density of blood vessels (more pronounced in the right ventricle - up to 8.9 times without the use of EMSCs and up to 9.8 times with their introduction) and the volume density of connective tissue 5-7 times. The data obtained indicate that the use of EMSCs can help reduce lytic changes in cardiomyocytes while maintaining/increasing hemodynamic disturbances in the myocardium as responses to distant damage of bone tissue.