The occurrence of fractures in the development of cancer in the body is due to changes in bone metabolism in the form of osteoporosis and metastatic bone damage. Their appearance leads to the postponement or cessation of treatment of cancer, which affects the life expectancy of such patients and the chances of recovery. Antitumor chemotherapy, as one of the main methods of cancer treatment, is prescribed for long-term courses and affects the healing of fractures. However, according to the literature, the effect of antitumor chemotherapeutics on reparative regeneration is poorly understood today. The purpose of the work is to study the morphological features of reparative osteogenesis under the influence of antitumor chemotherapy. Materials and methods. The study was performed on 96 white laboratory male rats 7 months of age weighing 230±10 g. All animals had a perforated defect with a diameter of 2 mm spherical cutter to the bone marrow canal in the middle third of the femoral shaft. Animals were divided into control (n = 24, without chemotherapy) and three experimental groups (I, II, III, n = 72), which after injury and every 21 days of the study were administered intraperitoneal anticancer chemotherapeutics: I (n = 24) – doxorubicin (60 mg / m²), II (n = 24) – 5-fluorouracil (600 mg / m²), III (n = 24) – methotrexate (40 mg / m²). On the 15th, 30th, 45th, 60th days after injury, the animals were removed from the experiment, followed by removal of the injured long tubular bones. Histological preparations stained with hematoxylin-eosin, followed by their morphometry, scanning electron microscopy with the method of X-ray energy dispersion spectroscopy, immunohistochemical examination were performed. Results and discussion. Antitumor chemotherapeutics causes delayed callus formation, which is manifested by an increase in the area of connective and reticulofibrous bone tissue in the regenerate, along with the slow formation of lamellar bone tissue. Chemotherapy leads to disorders of phosphorus-calcium metabolism both in the regenerate and in the maternal bone in the form of reducing the intensity of mineralization of the newly formed bone matrix and slowing down the remodeling activity of the maternal bone. Chemotherapy is accompanied by an increase in the expression of the bone resorption marker cathepsin K and a decrease in the expression of the osteopontin bone marker, which indicates a delay in the formation of regenerate in the area of injury and a decrease in the rate of reparative regeneration. Conclusion. The most pronounced delay in the processes of remodeling of bone regenerate was found with the use of doxorubicin and methotrexate, while 5-fluorouracil showed less inhibitory effect on these processes
Keywords: bone regenerate, antitumor chemotherapeutics, morphometry, scanning microscopy, spectral analysis, immunohistochemistry
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