Background. Diabetes mellitus affects almost all body systems, but the most dramatic complications occur in the lower extremities. Diabetic foot syndrome takes the leading position in the list of complications of diabetes mellitus, leading to early disability and mortality.
 At present, a new technology - photodynamic therapy is being intensively developed worldwide. This technique can be used in many different fields of medicine, including purulent surgery.
 This study aimed to investigate the possibility of using 5-aminolevulinic acid as an photosensitizer in photodynamic therapy in the complex treatment of chronic wounds in patients with ischemic and mixed forms of diabetic foot syndrome.
 Materials and Methods. In 2021, 10 patients with type 2 diabetes mellitus and ischemic and mixed forms of diabetic foot syndrome of both sexes, aged 52 to 75 years, were observed. As a preparation for photodynamic therapy, daily dressings with hydrogel were applied (3-5 days). During this period, limb revascularization was performed, the aim of which was to restore the blood flow to the foot, preferably through the anterior or posterior tibial artery. After the restoration of the main blood flow, photodynamic therapy was performed: after sanitation of the wound surface with physiological NaCl solution, Levuderm gel (6% gel phosphate of 5-aminolaevulinic acid) was applied and covered with occlusive dressing for 2 hours, after which the gel remains were removed and irradiation with Korobov photonic matrices "Barva Flex" with 660 nm wave length was carried out. Energy applied to the wound averaged 30-40 J/cm2. The light power density was between 0.1-1.0 W/cm2, and the exposure time varied according to the wound area.
 Results. After photodynamic therapy on days 2-3, perifocal oedema decreased. By days 5-7, the quality of granulation and the degree of wound epithelialization significantly improved. The wound healing rate on days5-7 of treatment was 1,58±0,44, and on days 10-12 - 4,72±0,63 (p <0,01). The evaluation of the wound healing rate showed good and satisfactory results: By day 32, the wound in the study group was completely epithelialized in the majority of patients (88.9%).
 Conclusions. The method we have developed for treating chronic wounds using photodynamic therapy is pathogenetically feasible and highly effective compared to conventional therapies. Combined light exposure using photosensitizer stimulates the formation of reactive oxygen species, increasing the effect of phagocytic cells, which is manifested in the activation of neutrophil chemotaxis, adhesion, and endocytosis. photodynamic therapy using aminolaevulinic acid as a photosensitizer, enhances molecular mechanisms of intercellular interaction at all stages of primary immunity activation.
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