Effect of thymocytes on the quantity of polypotent hematopoietic mast cells in the spleen of sublethally irradiated mice]

With the aid of Till and McCulloch's method, 5 times 10(-6) thymic cells were found to cause an increase in the number of hemopoietic endogenous spleen colonies in syngeneic donor-recipient combination. Thymic cells of C57BL mice had no effect on the number of endogenous colonies in the spleen. 40 times 10(-6) thymic cells administered 24 hr after sublethal irradiation caused an increase in the number of colony forming units in the spleen within 14 days. Possible ways of the thymus effect on hemopoiesis are discussed.     

Effects of polysaccharide from Thuja occidentale L. on stromal precursor cells of hematopoietic microenvironment in mice]

The effect of high molecular polysaccharide subfraction from Thuja occidentale L. (TPS) on stromal precursor cells of hematopoietic microenvironment under the "steady-state" conditions and after sublethal irradiation was investigated. The stromal precursor cells of different stages of differentiation were detected by the implantation of mouse bone marrow under the renal capsule of syngeneic intact recipients and chimeras. It was shown that TPS did not occur the toxic influence on the stromal precursor cells and provided the defense effect on them under the strong (6 Gy) radiation damages.     

Role of MAdCAM-1 and its ligand on the homing of transplanted hematopoietic cells in irradiated mice

We examined the expression of VCAM-1 and MAdCAM-1 after bone marrow transplantation (BMT). We also examined the influence of alpha(4)beta(7) integrin blockade on the homing of cells to the bone marrow and spleen. The expression of VCAM-1 and MAdCAM-1 by endothelial cells in the spleen and bone marrow was examined by immunoelectron microscopy using colloidal gold and was analyzed semiquantitatively. To examine the role of alpha(4)beta(7) integrin in donor cells, a homing assay was conducted following alpha(4)beta(7) integrin blockade in bone marrow-derived hematopoietic cells or spleen colony cells. Immediately after BMT, the expression of VCAM-1 and MAdCAM1 markedly decreased, but expression recovered significantly between 12 and 24 h after BMT. VCAM-1 recovered more acutely than MAdCAM-1 from 12 h onward. In the group transplanted with anti-alpha(4)beta(7) integrin antibody-treated bone marrow cells, the numbers of homing cells in the spleen and bone marrow were significantly decreased in an antibody dose-dependent manner. However, the number of homing cells was not different in either the spleen or bone marrow between anti-alpha(4)beta(7) integrin antibody treated and untreated spleen colony cells. It has been reported that alpha(4)beta(1) integrin and its receptor VCAM-1 play major roles in the homing of hematopoietic cells to bone marrow. Our study indicates the importance of MAdCAM-1 and its ligand, alpha(4)beta(7) integrin, in the homing of bone marrow-derived hematopoietic cells, but not spleen colony-derived cells, to both the spleen and bone marrow.     

Effect of erythrocyte degradation products on the migration of hematopoietic stem cells in lethally irradiated mice

In experiments on CBA mice it was shown that erythrocytes administered at the stage of prehemolysis or the stromal fraction of erythrolysate caused an additional increase in the haemopoietic stem cell migration which had been intensified by hemorrhage or hypoxic hypoxia.     

Development of osteogenic tissue in diffusion chambers from early precursor cells in bone marrow of adult rats

Diffusion chambers containing bone marrow cells from adult rats were implanted intraperitoneally into rat hosts and cultured in vivo for up to 64 days. Biochemical and histological analyses of the contents of the chambers demonstrate that a connective tissue consisting of bone, cartilage and fibrous tissues is formed by precursor cells present in marrow stroma. The amounts of osteogenic tissue and DNA are directly correlated with time of implantation and with number of cells inoculated. In the chambers there is initial formation of fibrous tissue which is strongly reactive to collagen type III, laminin and fibronectin. In areas of osteogenesis which appear later within this fibrous anlage, expression of collagen type III, laminin and fibronectin decrease and collagen types I and II increase in association with bone and cartilage respectively. Where osteogenesis does not develop, fibrous tissue continues to express collagen type III. The sequential expression of the different extracellular matrix components is similar to that previously observed during osteogenic differentiation in embryonic and adult developmental systems. It is concluded that the formation of fibrous and osteogenic tissues in diffusion chambers by precursor cells present in adult marrow, resembles the normal developmental process.     

Cloning stem cells in the bone marrow of irradiated mice]

Different amount of intact or irradiated bone marrow from syngenous donors was administered to mice irradiated with a lethal dose. There was revealed a linear dependence of the number of the 8-9-day colonies grown in the bone marrow of the femur on the amount of the administered cells, and an exponential dependence on the irradiation dose. Regularity of the stem cell cloning in the bone marrow was analogous to such in the spleen. Radiosensitivity of the colony-forming units (CFU) differed depending on the site (the spleen, the bone marrow) of their colony formation. The CFU settling in the marrow proved to be more radioresistant (D(0) equalled 160-200 P) in comparison with the CFU settling in the spleen (D(0) constituted 80-100 P). It is supposed that a different radiosensitivity of the CFU was caused by the presence of heterogenic population of the stem cells and also by specific peculiarities of the organ (the spleen, the bone marrow) in which the colonies formed.     

The cyclic nucleotide content of the blood plasma in mice irradiated at different doses]

Cyclic nucleotide content of plasma was shown to increase after irradiation of mice within a wide range of doses. Compared was the dynamics of changes in the cyclic nucleotide content 24 hr following irradiation with supralethal doses.     

Myelopeptide correction of the differentiation of hematopoietic precursor cells in mice with experimental T-immunodeficiency

The influence of myelopeptides on differentiation of bone marrow haemopoietic precursors cells in thymectomized and normal mice has been studied in vivo. The introduction of myelopeptides decreased the number of erythroid (E) colonies and increased that of granulocytic ones (G). This results in the decrease of initially raised E/G ratio in thymectomized mice (from 4.3) down to 1.3). Myelopeptides exerted no influence on haemopoietic precursors in normal mice (E/G-2.0).     

3-dimensional growth (spheroid formation) of tumor cells in diffusion chambers]

The three-dimension growth -- spheroidoformation of tumor cells of the primary MX-induced sarcoma in mice BALB/c, C57BL, and C3H/Sn, was studied. The tumor cells were cultured on millipore filters of the diffusion chambers implanted into the peritoneal cavity of normal syngeneic mice.     

The effect of cystamine on the outcome of dominant lethal mutations and reciprocal translocations in sex cells of mice subjected to gamma-irradiation in different doses]

Protective effect of cystamine (150 mg/kg) against genetic damages induced by gamma-irradiation in germ cells of male mice of CBA strain (at doses of 100, 300, 600 r) was studied. The application of cystamine decreased the frequency of dominant lethal mutations induced by radiation in sperms, spermatids and spermatocytes. The degree of the protective effect of cystamine depended on a radiation dose. The protective effect of cystamine was the highest at the radiation dose of 300 r. It was negligible at the radiation dose of 100 r and was completely absent at the dose of 600 r. Cystamine did not affect the rate of induced reciprocal translocations in the spermatogonia at all the radiation doses used.