[The effect of low frequency electrical stimulation on bone tissue regeneration].

The study was performed on 30 male rats of Wistar line (weight 330-360 g, age 3.5 months).In an experimental model of damage to the femur bone in the hip joint studied the effect of low frequency electrical stimulation of the damaged area on the rate of regeneration of bone.

[Heterogeneity and possible structure of mesenchymal stromal cell population].

Mesenchymal stromal cells (MSC) represent a heterogeneous population of cells that differ in morphology, phenotype, ability to grow and differentiate, and other properties. Differences between MSC are related in part to the influence of their microenvironment. However, the heterogeneity of these cells also is due to their parent-progeny relationship.

[Cellular composition and regulatory function of fetal liver stroma].

Hematopoietic differentiation and formation of hepatic tissue both take place in mammalian liver during its prenatal development. Hematopoietic and hepatic stem cells self-renew, proliferate and differentiate within specific microenvironment that is organized by stromal elements. Stroma of developing liver consists of different cell populations such as mesenchymal stromal cells, Ito cells, portal fibroblasts and myofibroblasts, vascular endothelial and smooth muscle cells, cells undergoing epithelial-to-mesenchymal transition.

[The sensitivity of mesenchymal stromal cell subpopulations with different times of adhesion property manifestation and derived from hemopoietic organs to growth factors EGF, bFGF, and PDGF].

The action of three growth factors (EGF, bFGF, and PDGF) on mesenchymal stromal cell (MSC) subpopulations from mature bone marrow (BM) and rat embryo liver (EL) was investigated. These cells are plastic-adhesive and have different rates of adhesion (AC1-AC4 subpopulations). The efficiency of colony-formation, the size of colonies, and the number of early osteogenic progenitors with alkaline phosphatase activity in colonies and induced osteogenesis were analyzed.

[Mesenchymal stem cells: sources, phenotype, and differentiation potential].

Mesenchymal stem cells present in the bone marrow and some other organs are primitive pluripotent precursors of osseous, cartilaginous, adipose, and other mesenchymal tissues. The recently revealed capacity of these cells for differentiation into nonmesenchymal derivatives is of considerable theoretical and practical interest. However, many aspects of the biology of these cells remain obscure despite active research.

[Alkylating damage by dipin of hematopoietic and stromal cells of the bone marrow].

Effect of alkylating agent dipin was studied on hematopoietic (CFU-S) and stromal (CFU-F) progenitor cells. Single administration of dipin (0.06 mg/g) to adult (CBAxC57Bl/6) F1 hybrid mice induced a long-term (2 years) oscillations in the numbers of day 7 CFU-S and day 11 CFU-S in the bone marrow and spleen.

[Embryonic sources of definitive hemopoietic stem cells].

A review of one of the key problems of experimental hematology: the origin of hemopoietic stem cells in the development of vertebrates (amphibians, birds, and mammals). The appearance and functioning of two independent sources of hemopoietic stem cells (extra- and intraembryonic) were considered in amphibians, birds, and mammals. The contribution of each source to the formation of definitive hemopoietic tissue was analyzed.

[Comparative investigation of mesenchymal stem cells isolated from the bone marrow and embryonic liver of mouse and rat].

We studied the properties of cells forming fibroblast colonies from the bone marrow and embryonic liver of mouse and rat. Bone marrow and embryonic liver cells formed colonies in vitro including fibroblasts as well as a considerable proportion of macrophages. The colonies formed from bone marrow and hepatic cells of rat differed from the murine ones by a higher proportion of fibroblasts.

[Effects of 10-day long exposure to gamma irradiation at low doses on bone marrow cells in mice].

Effects of ten day long exposure to gamma-irradiation at low doses (mean dose rate of 1.5-2.0 m Gy/day, total dose of 15 m Gy) on hemopoietic (CFU-S) and stromal (CFU-F) progenitor cells from murine bone marrow were examined.

[Effect of continuous gamma-radiation at low doses on clonogenic hemopoietic (CFU-S) and stromal (CFU-F) bone marrow cells ].

We studied the effects of low doses of continuous gamma-irradiation (Co60, 10 days, mean daily dose power 1.5-2.0 mGy, total dose 15 mGy) on hemopoietic and stromal progenitor cells of murine bone marrow.

[Chondro- and osteogenesis in ectopic transplants of embryonic mouse liver].

It was shown for the first time that when the liver of 14 day-old mouse fetuses was transplanted under the renal capsule or in the subcutaneous connective tissue of adult recipients, successive de novo formation of hyaline cartilage, bone, and hemopoietic foci took place. We propose that the liver mesenchyme, which preserves wider differentiation potencies in fetuses, is the cellular source of different types of mechanocytes: cartilaginous, bone, and reticular cells.

[Clonogenic hematopoietic cells (CFU-S) of mouse embryonic liver during short-term in-vivo cultivation].

The stem cell compartment of hemopoietic clonogenic cells (CFU-S) of mouse embryos in a closed system was studied, when the hemopoietic tissue was devoid of supply of the hemopoietic cells and grafted into adult recipients with diverse regulatory influences. The content of hemopoietic clonogenic cells (CFU-S-7, CFU-S-11, and CFU-S-el) was determined in the transplants of the 14-day embryonic liver placed under the renal capsule of preirradiated syngeneic adult recipients. Relatively younger clonogenic cells (CFU-S-11) were practically absent from the transplant in the end of cultivation, while the more advanced stages (CFU-S-7) became more abundant.

[The similar capacity for self-maintenance of clonogenic hemopoietic cells (CFU-S-11) from the liver and peripheral blood of sexually mature mice].

The capacity of CFU-S-11, which formed colonies in the spleen on day 11 after transplantation to an irradiated recipient for self-maintenance, was studied. The indices for self-renewal of individual CFU-S from the spleen, bone marrow, and peripheral blood were compared in the same sexually mature donor mice by retransplanting the colonies isolated from the spleen parenchyma to secondary recipients. The number of secondary CFU-S-11 per primary CFU-S-11 originating from the liver hardly differed from that originating from the peripheral blood, but is almost twice less than for the bone marrow CFU-S-11.

[The 5-fluorouracil sensitivity of the hematopoietic stroma of the bone marrow and spleen].

We studied the effect of a single injection of 5-fluorouracil (5-FU) (150 mg/kg) on the numbers of stromal precursor cells (CFU-F) in the bone marrow and spleen and their capacity for formation of hemopoietic foci after ectopic transplantation under the renal capsule. 5-FU decreased the number of CFU-F in the bone marrow and spleen of mice and rats to 30 - 50% of the control values. The size of transplants, as estimated according to the number of hemopoietic clonogenic (CFU-S) and nucleated cells, diminished within the first two months after transplantation.

[The effect of 5-fluorouracil on the clonogenic hematopoietic cells (CFU-S) of embryonic and sexually mature mice].

We studied sensitivity of various types of clonogenic hemopoietic cells (CFU-S-7, CFU-S-11, and CFU-ep) on the liver of 14-days embryos and from the bone marrow and spleen of adult mice to the cytotoxic agent 5-fluorouracil (5-FU) in vitro and in vivo. We discovered that different types of CFU-S of the embryos and adult mice has similar sensitivity to 5-FU in vitro. At the same time in vivo the bone marrow CFU-S-7 display a higher sensitivity to 5-FU than CFU-S-11, thus agreeing with the published data (Hodgson and Bradley, 1979).

[The effect of space flight factors on the peripheral blood in the newt Pleurodeles waltlii].

The effects of space flight factors (SFF) on the peripheral blood in Pleurodeles waltlii were assessed after 12-day flight on board of the biosatellite "Kosmos-2229". These animals were also used to study regeneration of the limb, tail and lens. The corresponding control groups of animals allowed to distinguish between the effects of the operation, non-specific and specific SFFs: (1) basal control-operated animals; (2) synchronous control-operated animals kept on the Earth under the same conditions as the flight group, and (3) intact animals.

[Clonogenic hemopoietic cells (CFU-S) in mouse pre- and postnatal ontogeny].

Content of three classes of clonogenic haemopoietic cells (CFU-S-7, CFU-S-11 and CFU-S-ep) was determined in haemopoietic organs of mouse during embryogenesis (10, 14 and 18 day) and postnatal ontogenesis (2, 3 and 7 day, 1, 2, 3 and 18 month). CFU-S-7 and CFU-S-11 that from big splenic colonies on 7th and 11th days of transplantation are present in liver, spleen and bone marrow at all developmental stages. However their concentration and CFU-S-7 CFU-S-11 ratio change in haemopoietic organs.

[Histological study of splenic colonies at different times following the transplantation of hematopoietic cells from embryonic liver].

Histological analysis was carried out on the hemopoietic spleen colonies within 7 and 11 days after transplantation of the embryonic liver cells. Large superficial colonies were always present and were, predominantly, erythroid and mixed. Small superficial colonies consisted of undifferentiated cells and, unlike large colonies, appeared on the 11th day only.

[Existence of pre-CFU-S in the liver of mouse embryos].

Two types of CFU-s different in the size of their colonies have been found in the liver of 14 day old mice embryo. Statistic processing of the data allowed to prove that large spleen colonies are formed directly by CFU-s, whereas small colonies are formed by pre-CFU-s which undergo preliminary proliferation and only the stochastically differentiate into CFU-s. Approximate concentration of pre-CFU-s constitutes 2.

[Sensitivity of the hematopoietic stem cells of anemic animals to actinomycin D].

It was shown on the model of anemic animals by the method of spleen colonies that non-proliferating CFU-S were resistant against the cytotoxic effect of actinomycin D in concentrations 0.04 to 0.4 micrograms/ml.

[Effect of actinomycin D on hematopoietic stem cells].

The effect of actinomycin D on stem hemopoietic cells in the bone marrow of adult mice has been studied by means of spleen colonies. The antibiotic at a dose of 0.4 mu g/ml (g) inhibited the colony formation when applied in vitro and stimulated this process in vivo.

[RNA synthesis in bone marrow hematopoietic stem cells].

The effect of inhibitors of DNA-dependent RNA synthesis (sibiromycin and actinomycin D) and radio toxic doses of 3H-uridine on the bone marrow stem hemopoietic cells in adult mice was studied by means of spleen colonies. The short-term in vitro preincubation of the bone marrow cell suspension with the antibiotics and 3H-uridine resulted in the practically complete inhibition of colony formation. The bone marrow stem hemopoietic cells incorporated 3H-uridine intensively.

[Changes in the number of stem cells during mouse bone marrow cultivation on a sublayer of fibroblast-like cells].

A determination was made of the number of colonies in the spleen of irradiated mice after administration to them of a culture of mouse bone marrow cells. Colony-forming units proved to persist in the culture only for a short time. Use of preliminarily grown underlayer of fibroblasts of bone marrow origin had no effect on the perservation and dynamics of the changes in the number oc colony-forming units.