The effect of folate binding protein on the colony-forming activity of GM-CFC cells in vitro.

A modified method for the preparation of specific folate binding protein was described. The GM-CFC stimulating activity of this SFBP preparation was investigated on tissue cultures of human bone marrow cells. It has been found that in the presence of HPCM the cell proliferation was markedly increased by the SFBP. In the absence of HPCM, however, the cell proliferation has been influenced either positively or negatively presumably in dependence on the expression of folate receptors on the GM-CFC bone marrow cells.

The effect of fibrinogen-methotrexate derivatives on HeLa cell growth.

Proteolytic cleavage of bovine fibrinogen with covalently bound methotrexate (MTX) was studied using four different proteolytic enzymes--trypsin, chymotrypsin, pepsin, and cathepsin D and the interaction of the modified fibrinogen (or fibrin) with HeLa cells was investigated. The presence of fibrin-MTX derivative did not induce any significant morphological alternations of cells. The fibrin-MTX derivative in the gel form was solubilized easily by the action of all proteinases investigated, hydrolysis of highly crosslinked denatured fibrin-MTX in suspension proceeded slower. The solubilized fibrin-MTX degradation products had a strong inhibiting effect on the growth of HeLa cells cultured in monolayer indicating the liberation of chemotherapeutically active MTX from its fibrin derivative.

Inhibition of phagocytosis of polymorphonuclear leucocytes by adenosine and HoCl3 in vitro.

Phagocytosis of polymorphonuclear leucocytes treated with NaF, HoCl3 and adenosine were studied. The highest concentration used was 25 mM of NaF, 25 mM of adenosine and 5 mM of HoCl3. It was ascertained that these substances, inhibitors of erythrocyte contractile protein, inhibit both phagocytosis and ability of polymorphonuclear leucocytes to change their shape. These unfavourable effects may be induced by the chemicals interfering with polymorphonuclear leucocytes contractile protein. NaF, HoCl3 and adenosine are also responsible for morphological changes in the cell nucleus.

Bone marrow transplantation. Separation of stem cells.

Attempts were made to separate haemopoeitic stem cells of murine and human bone marrow by fractionating the native bone marrow on Verografin gradient, density 1.077. The in vivo and in vitro methods demonstrated that the numbers of stem cells present following fractionation on the gradient layer were significantly increased as compared to the controls. The stem cells form haemopoietic CFU-S colonies in murine spleens, as well as CFU-C during culture in agar medium. The simple, easily reproducible and routine techniques are believed to be a valuable help in practice.

Human placental conditioned medium (from different phase of pregnancy) as a source of colony-stimulating activity for cultures of human and mouse. granulocyte-macrophage colony-forming cells in semisolid agar.

We have investigated the effect of conditioned medium derived from cultures of human placental tissue from different phases of pregnancy on in vitro growth of human and mouse granulocyte-macrophage colony forming cells in semisolid agar. We have confirmed that the colony-stimulating activity of human placental conditioned (normal delivery) medium was equivalent to the activity of peripheral blood leucocyte underlayers when medium was added at a 5%-20% concentration to the semisolid agar. Placentas from the 12th amd 10th week of gestation were found not convenient for preparation of medium with high CSA; the activity of media prepared from their cultures was not significantly higher than the autostimulating activity of bone marrow alone. Human placental conditioned medium proved inconvenient for cultures of mouse GM-CFC in semisolid agar containing foetal calf serum.

Cultivation and differentiation of haemopoietic CFU-C cells in semisolid medium.

The possibilities of cultivating murine bone marrow in semisolid agar and in methyl cellulose were investigated. The proliferative capacity of the haemopoietic CFU-C stem cells were demonstrated. The growth of CFU-C in fresh murine bone marrow and murine marrow short-term preserved at -75 degrees C was compared. The content of cells capable of proliferation was lower and the onset of colony formation was delayed in preserved bone marrow. Procedures appropriate for routine work were employed for evaluating haemopoietic colonies.

Cultivation of frozen mouse bone marrow cells in agar.

The authors attempted to cultivate frozen mouse bone marrow cells in a semisolid medium. They demonstrated that the stem haematopoietic cells of frozen mouse bone marrow were capable of proliferation and of colony formation on agar. The much smaller number of colonies from frozen mouse bone marrow (about 80% fewer) compared with fresh marrow is evidence that part of the stem haematopoietic cell population retains proliferative capacity even after freezing.

Cultivation of fresh and frozen mouse bone marrow. - Application of methyl cellulose.

The culture of cells of both fresh and frozen mouse bone marrow on methyl cellulose (MC) was approached. We used 1.5%-concentration of MC and proved the stem cells of fresh and frozen mouse bone marrow to proliferate and form haemopoietic colonies on MC. We established that the freezing process did not significantly decrease the proliferative capacity of CFU-C stem cells.

[Transplantation of bone marrow cells into lethally irradiated mice. Morphology of megakaryocytes]. / Uber die Transplantation von Knochenmarkzellen auf letal bestrahlte Mäuse Morphologie der Megakaryozyten.

We described morphological changes of megakaryocytes in the bone marrow and spleen of lethally irradiated mice, dependent on the time lapse following bone marrow transplantation. The functional active megakaryocytes of various morphological types were found to predominate in the tissues on about day 20 to 25.