MODERATION OF QUANTITATIVE CHANGES OF REGENERATING ERYTHROPOIETIC CELLS BY EXTRACELLULAR UBIQUITIN

Hematological disorders caused by radiation remain the most challenging problem of the last decades. Environmental radiation, as well as medical application of radiation causes serious problems especially from the point of view of blood formation and passage of blood functional cells. Bone marrow emptying followed by the rise of immature cells in the bloodstream is the main pathology that must be eliminated. The importance of the issue is well recognized by all investigators. Opening of agents for regulation of spontaneous regeneration of hematopoietic cell lines is of prime importance in cancer treatment. Ubiquitin is a globular protein of eukaryotic cells. It is involved in regulation of cell cycle. Recently we studied the influence of extracellular ubiquitin on regeneration of leukopoiesis. Interestingly what is its effect on erythropoietic cell lines? Erythrocytes are more resistant to irradiation, than nucleic cells. Their depletion-elevation picks during blood regeneration clearly reveal low sharpness. Nevertheless, depletion of erythropoietic cells if not treated, may cause short- and long-term side effects. We studied the influence of intraperitoneally injected ubiquitin on the process of spontaneous regeneration of erythropoietic cell lines of bone marrow (BM) and peripheral blood (PB) after irradiation in mice. The source of radiation was 137Cs with dose rate 1Gy/min., the duration of exposure 3 min and 5 min. Nonlinear white mice of 22±2 gr. were used for experiment. Animals were divided into five groups (6 animals in each group): the first control group of intact mice; the second test group of mice irradiated by the sublethal dose of 3Gy; the third test group of mice irradiated by 3Gy intraperitoneally injected by ubiquitin by the dose of 100µg/ml at the 72 hour point after irradiation; the fourth test group of mice irradiated by the dose of LD50 5Gy; the fifth test group of mice irradiated by 5Gy intraperitoneally injected by ubiquitin at the 72 hour point after irradiation. PB and BM samples from the control group and the test groups of mice have been taken every 24 hours after irradiation during 7 days. Microscopy and statistical methods have been implicated for calculation of cell count of PB and BM. Analyzing the results we concluded that Ubiquitin prevents depletion-elevation picks of erythrocytes and erythroblasts regardless of the severity of damage caused by different doses of radiation indicating normalization of the regeneration process after irradiation. The study is important for opening new therapeutic agents for normalization of regeneration hematopoiesis after irradiation.