Placenta extracts obtained by various methods have been already widely used in practical medicine. At the same time experimental and clinical studies of the therapeutic efficacy of placenta extracts in relation to various pathologies, including inflammatory diseases, osteoarthritis, chronic pain, ischemic brain damage, liver damage, etc. are still in progress. Cryogenic technologies could be used for widening the perspectives of placenta extracts clinical application. However, the low temperature effect on extracts properties of their therapeutic efficacy is not studied well. The purpose of the research was to investigate the effect of freeze-thawing of placenta on the ability of its aqueous-saline extracts to increase the thermal stability of erythrocytes, which is an indicator of anti-inflammatory activity. Material and methods. Human placentas obtained from healthy parturients with their informed consent, stored for no more than 24 hours at 4°C, were used in the research. Aqueous-saline extracts were obtained from fresh, frozen down to -20°C and -196°C and thawed human placentas by tissue homogenization and further exposing to PBS (pH 7.4). Individual fractions were received using gel chromatography. The level of human erythrocytes thermal hemolysis (20 min., 55°C) was determined by the hemoglobin content in supernatant at 540 nm. Thermodependent dynamic state of cytosol and a membrane barrier function of erythrocytes were studied at hyperthermia using the method of EPR spin probe. Results and discussion. The freezing of placentas down to -20°C and -196°C did not result in the loss of ability of their extracts and individual fractions to reduce the erythrocyte thermal hemolysis. The most effective enhancement of erythrocyte thermal resistance was found after incubation with fractions of < 4 kDa and 12-20 kDa. Placenta extracts modified both the state of erythrocyte cytosol, its microviscosity, at temperatures +(40-50)°C, and their thermal stability, reducing the speed of disturbance of membrane barrier properties at 55°C. The freezing of placentas down to -20°C and -196°C did not affect the ability of the whole extract to modify the state of cytosol and the membrane barrier function at hyperthermia. Conclusions. The obtained results proved the possibility of freezing placentas down to -20°C and -196°C without losing of biological activity of their extracts, in particular, their ability to improve the thermal stability of erythrocytes, which is an indicator of anti-inflammatory properties.
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