Features of apoptotic and proliferative processes in experimental infected radiation-induced skin ulcer under conditions of photodynamic therapy and the use of platelet-rich plasma

Abstract

Aim: The purpose of the study was to identify the features of apoptotic and proliferative processes in experimental Staphylococcus aureus-infected radiation skin ulcer under conditions of photodynamic therapy and the use of platelet-rich plasma. Materials and Methods: An experimental study was conducted on 95 six-month-old male rats of the WAG population, which were divided into three groups. Group 1 included 25 animals that were simulated a radiation ulcer of the skin in the thigh area with subsequent application to its surface on the 7th day after irradiation with 0.2 ml of a suspension of the Staphylococcus aureus (ATCC 25923) reference strain (0.5 million microbial cells/cm2 ). Group 2 included 25 animals with Staphylococcus aureus-infected radiation skin ulcer, which were subjected to photodynamic therapy a day after infection. Group 3 included 45 animals with Staphylococcus aureus-infected radiation skin ulcers, which, 1 day after infection, received photodynamic therapy in the first half of the day, and in the second half of the day the periphery of the wound defect was injected with platelet-rich plasma. The material for the study was skin with underlying soft tissues from the area of radiation exposure. Histological, immunohistochemical, morphometric and statistical methods were used. Results: In cases of simultaneous use of photodynamic therapy and platelet-rich plasma, compared with photodynamic therapy alone, the processes of apoptosis and proliferation were more balanced, active, with a shift in the proliferative-apoptotic ratio towards proliferation processes and met the needs of the regenerative process. From the 10th to the 22nd day of the experiment these processes increased, which indicated active healing processes, that, during survey microscopy on the 22nd day, were manifested by the complete filling of the wound cavity with granulation and connective tissues with the presence of an epithelial layer on the surface of the regenerate. From the 22nd to the 45th day of the experiment, a decrease in the rate of regeneration was recorded, as evidenced by a decrease in the intensity of apoptotic and proliferative processes. The intensity of the latter was sufficient, which led to the healing of Staphylococcus aureus-infected radiation skin ulcer on the 45th day with complete restoration of the original structure of the skin. Conclusions: Photodynamic therapy in combination with the use of platelet-rich plasma balancedly activates apoptotic and proliferative processes with a predominance of the latter in granulation and connective tissues filling the lumen of Staphylococcus aureus-infected radiation skin ulcer, which on the 45th day of the experiment leads to wound healing with complete restoration of the original structure of the skin.