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The paper describes some biological features of the radioprotective effect of double-stranded RNA preparation. It was found that yeast RNA preparation has a prolonged radioprotective effect after irradiation by a lethal dose of 9.4 Gy. 100 % of animals survive on the 70th day of observation when irradiated 1 hour or 4 days after 7 mg RNA preparation injection, 60 % animals survive when irradiated on day 8 or 12. Time parameters of repair of double-stranded breaks induced by gamma rays were estimated. It was found that the injection of the RNA preparation at the time of maximum number of double-stranded breaks, 1 hour after irradiation, reduces the efficacy of radioprotective action compared with the injection 1 hour before irradiation and 4 hours after irradiation. A comparison of the radioprotective effect of the standard radioprotector B-190 and the RNA preparation was made in one experiment. It has been established that the total RNA preparation is more efficacious than B-190. Survival on the 40th day after irradiation was 78 % for the group of mice treated with the RNA preparation and 67 % for those treated with B-190. In the course of analytical studies of the total yeast RNA preparation, it was found that the preparation is a mixture of single-stranded and double-stranded RNA. It was shown that only double-stranded RNA has radioprotective properties. Injection of 160 μg double-stranded RNA protects 100 % of the experimental animals from an absolutely lethal dose of gamma radiation, 9.4 Gy. It was established that the radioprotective effect of double-stranded RNA does not depend on sequence, but depends on its double-stranded form and the presence of “open” ends of the molecule. It is supposed that the radioprotective effect of double-stranded RNA is associated with the participation of RNA molecules in the correct repair of radiation-damaged chromatin in blood stem cells. The hematopoietic pluripotent cells that have survived migrate to the periphery, reach the spleen and actively proliferate. The newly formed cell population restores the hematopoietic and immune systems, which determines the survival of lethally irradiated animals.

The article presents data on the cultivation and characteristics of mesenchymal stem cells (MSC) isolated from the bone marrow of patients with dysplastic coxarthrosis. Several morphological phenotypes were found in the fraction of adhesive MSC: spindle-shaped elongated cells, large flattened cells, and thin stellate cells in both samples of bone marrow. Immunophenotypic analysis showed that cells express surface antigens (CD90, CD73, CD105, CD45 and CD34), which are characteristic for typical stem cells. It was shown that the use of a new growth medium containing no components of animal origin for the cultivation of human MSC allowed to achieve confluence of the cell culture on the 16th-8th day of incubation without delaying the proliferative activity of the cells and without loss of ability to differentiate into chondro- and osteogenic types of tissues. Multipotency of MSC was confirmed by osteogenic and chondrogenic differentiation of cells, during prolonged cultivation of MSCs in induction media in vitro . The differentiation of MSC into osteoblasts was confirmed by immunocytochemical staining for alkaline phosphatase and alizarin red S. Specific differentiation of MSC in chondrogenic type was revealed by staining of cartilage deposits with alcian blue. For the first time, such characteristics of human MSC as: mitotic index, trajectory of cells migration and average speed of migration on culture plastics were determined. The mitotic index of actively proliferating MSC was from 2.7 to 3.4 % of the total cell number. The moving activity (speed of cell migration) was 38-42 μm/h. Thus, bone marrow aspirate from patients with orthopedic pathology is the source of stem cells that meet all the criteria for MSC as determined by the International Society of Cellular Therapy and can be used in regenerative therapy of bone and cartilage.

Injections ofexogenous DNAin combination witha cytostatic agent cyclophosphamide (CP) cause illness anddeathofexperimental mice. This phenomenon is referredto this as delayeddeath. It has been foundthat upon intraperitoneal injections fragments ofexogenous DNAreachthe bone marrowniche andenter the nuclei ofbone marrowcells (BMCs). Also, fragments ofexogenous DNAare capturedfrom culture medium byBMCs generatedex vivo. Upon suchtreatment, the fragments are incorporatedinto cells in a non-degradedform. We estimate that under suchconditions upto 1800 kb ofexogenous DNAcan be present in BMCs as fragments. After ex vivo incubation withBMCs, fragments ofexogenous DNAinternalizedin cells ofbothintact andCP pre-treatedmice become circularized. It has been shown that fragments ofexogenous DNAcan form high-molecular weight structures in vivo. Moreover, fragments localizedin BMCnuclei are suggestedto integrate into chromosome(s) ofrecipient mouse genomes when treatedwithCP andexogenous DNA.