Тромбоцити: біологічні властивості та клінічний потенціал

Abstract

В статті представлений огляд робіт, де розглянуто морфологію, вміст та біологічні властивості тромбоцитів. Автором систематизовано дані щодо застосування тромбоцитів в різних біотехнологічних варіантах в експериментальних та клінічних дослідженнях, а також викладені результати власного досвіду роботи зі збагаченою тромбоцитами плазмою при моделюванні патологічних процесів у тварин.

В статье представлен обзор работ, где рассмотрена морфология, содержимое и биологические свойства тромбоцитов. Автором систематизированы данные о применении тромбоцитов в разных биотехнологических вариантах в экспериментальных и клинических исследованиях, а также изложены результаты собственного опыта работы с обогащенной тромбоцитами плазмой при моделировании патологических процессов у животных.

The key feature of platelets is the absence of the nucleus what makes them immunologically safe for use in the allogenic variant. However, platelets contain a large number of biologically active compounds that are involved in a wide range of hemostasis processes, activation of neoangiogenesis, stimulation of regenerative properties of tissues, support of homeostasis, and others. After aggregation, the platelets begin to realize the contents of the granules, and this process most actively lasts for the first hour, and the synthesis of cytokines continues for at least 7 days. Platelet-rich plasma (PRP) began to be manufactured for clinical purposes in the 1970s. It is a platelet concentrate in a small amount of plasma, with 5 times increase of the platelet concentration, but the clinical significance has a PRP with a platelet content of not less than 1x106 / ml. Actually, not only platelets, but also a small number of red blood cells and leukocytes, including progenitor cells of varying degrees of maturity, are present in the PRP. Some pathological conditions of an organism influence quantitative and qualitative characteristics of platelets and limit the possibility of their use in the autologous version. Our studies have revealed the ultra-microscopic features of platelets in rats with induced toxic hepatitis. Thus, there was a change in the ratio of activated and unactivated platelets to the increase of the latter, significant fluctuations of the plate aggregation index within the experimental group, a significant decrease in the density of alpha and delta granules. The release of cytokines, chemokines and growth factors from platelets stimulates the activation and proliferation of regenerative cells: fibroblasts, neutrophils, monocytes, smooth myocytes and mesenchymal stem cells. Of interest is the fact that the concentration of growth factors in PRP almost 8 times exceeds their content in the whole blood. In a series of studies we performed on rats demonstrated a significant improvement of morpho-functional state of the liver in animals with CCl4-induced chronic hepatitis after PRP administration. It was noted that the introduction of PRP leads to normalization of blood biochemical characteristics, revealed the amount of connective tissue and speed up the process of regeneration of liver tissue. We also demonstrated the application of PRP under the experimental liver cirrhosis in rats induces active regeneration, normalization of liver size, rebuilt lobular organization, the newly formed blood vessels, increase content of PAS-positive substances. The researchers found the need for direct contact of the platelets and hepatocytes to implement proliferative effect because it triggers signaling to activate the growth factors. To correct degenerative changes in the intervertebral discs of the spine we carried out experimental therapy by PRP that reduce the number of lesions fibronecrosis, the degree of desorganisation of collagen fibers, increase the height of the fibrous ring and the vertebral epiphysis. Thus, these data indicate that currently experimental studies show high clinical potential of platelets, which is not substancially involved in the clinic. The uniqueness of these cells is due, above all, the ability to use them both autologous and in heterogeneous form, the use of products with platelets and cell mixtures in various biotechnological options also availability and relatively simple preparation for clinical use.