Effect of synthetic polyribonucleotides on the immunological and colony-forming activity of irradiated bone marrow cells

The experimental data are presented concerning the effect of polyribonucleotides on the immunologic and colony forming ability of bone marrow or irradiated mice. All the compounds under study exhibited a pronounced, but to a different degree, colony-forming and immunostimulating action. The comparative study of the influence of polyribonucleotides on the number of endogenous colonies and antibody-forming cells showed an inverse relationship between these parameters: The preparations exerting the most pronounced immunostimulating effect had an insignificant colony-forming action and vice versa. This is evidently indicative of the capacity of these preparations to turn the differentiation of haemopoietic stem cells towards the immunopoiesis.     

Reaction of bone marrow colony-forming cells in irradiated mice to phlogogenic factors]

The experiments on irradiated mice (600 and 800 r) demonstrated that under the influence of flogogenic factors the quantity of colonies in the spleen increases and their morphological structures change. It is suggested that under the action of the damaging agent the "hypothetic factor" which causes the pointed changes, is formed in the skin.     

The possible pathways of IL-2 stimulation of colony formation by bone marrow cells irradiated in vitro

The authors have made an attempt to find out the reasons of IL-2 stimulation of spleen colony growth by in vitro (1 Gy) irradiated bone marrow cells. It was shown that the effect of IL on haemopoiesis manifests itself with merely small radiation doses implying that the influence of the preparation makes the process of haemopoietic organ repopulation start at a higher level of cell survival, which is presumably related to a more active repair of radiation-induced CFUs damages: this leads, with other things being equal (e.g. proliferation rate and f factor), to a higher yield of colonies than it is observed with the recipients protected with the exposed bone marrow only.     

Opiate activity of a bone marrow humoral factor which stimulates antibody production

The radioceptor method was used to demonstrate that humoral factor of the bone marrow, a stimulant of antibody production (SAP), contains substances that competitively remove 3H-morphine and 3H-met-enkephalin from opiate receptors of the rat brain, and 3H-met-enkephalin from specific binding sites on human lymphocytes. Comparison of the magnitudes EC50 SAP obtained during the removal of labeled opiates allows a suggestion to be made that opiates contained by the preparation under study have a greater capability to interact with delta-type opiate receptors rather than with those of the mu-type.     

Proliferative and differentiation potentials of skeletogenic bone marrow colony-forming cells

The clonal nature of bone marrow fibroblast colonies derived from clonogenic bone marrow osteogenic cells (CFUf) was proved by the chromosome analysis. During subsequent passages of multi-colony derived bone marrow fibroblast strains there occurs a pronounced increase in the cell number and in the number of osteogenic units (tested by transplantation in diffusion chambers). Single colony-derived strains are capable of forming bone and cartilage simultaneously. It follows that CFUf or part of them are clonogenic cells with high proliferative potentials and are common precursors for bone and cartilage tissue. Thus, CFUf may be regarded as osteogenic stem cells.     

Rubidium transport in irradiated vitamin-E-deficient bone marrow cells

We showed previously that the Rb⁺ transport rate in bone marrow cells (BMC) of vitamin-E-deficient mice is significantly lower than that in BMC of euvitaminotic mice. It is now evident that 4 h after whole-body, low-dose (0.01–1.0 Gy) gamma-irradiation of avitaminotic mice, there is an increase in the rate of Rb⁺ transport. This increase is quite pronounced, exceeding at all dose levels the rate of Rb⁺ transport in euvitaminotic mice exposed to the same radiation dose.On leave from the University of Rochester, School of Medicine and Dentistry, Department of Biophysics, Rochester, New York, USA     

Radiosensitivity of colony-forming units of dog bone marrow in agar cultures]

Radiosensitivity of the bone-marrow colony-forming cells was determined by a modified method of hemopoietic cells cloning in vivo in semihard agar gel in diffusion chambers. Do for the commited precursor cells of granulopoiesis (CFUc) was 144 +/- 14.8 rad (n = 0.8), and Do for the precursor cells forming "stellate" colonies of fibroblast-like cells (PFUf) was 468 +/- 35.8 rad (n == 0.9). A conclusion was drawn that PFUf were referred to the class of stromal precursors of the hemopoietic organs. This system can be applied for a simultaneous study of the hemopoietic and stromal precursor cells in dogs.     

Response of murine bone marrow granulocyte-macrophage colony-forming units to hyperthermia in situ

A detailed understanding of how bone marrow stem cell progenitors are affected by heat is prerequisite to predicting how whole-body or regional hyperthermia protocols may affect bone marrow function. This investigation reports the reproductive integrity of murine tibial bone marrow granulocyte-macrophage colony-forming units (CFU-GM) after in situ hyperthermia. Heat was applied by water bath immersion of the leg of male BALB/c mice anesthetized with 90 mg/kg pentobarbital given subcutaneously. Tibial and rectal temperatures were monitored in representative animals by microthermocouples (tip diameter approximately 100 microns). By approximately 3 min after immersion of the limb, marrow temperature was within 0.3 degree C of water bath temperature (O'Hara et al., Int. J. Hyperthermia 5, 589-601, 1989) and was within 0.1 degree C by 5 min after immersion. The CFU-GM were cultured in "lung-conditioned" McCoy's 5A medium supplemented with 15% fetal calf serum and 0.3% Bacto agar. In situ heating of tibial marrow to exposure temperatures of 42, 42.5, 43, 44, and 45 degrees C gave D0's (+/- 95% CI) of 91 +/- 44, 44 +/- 27, 27 +/- 2.2, 16 +/- 6, and 7 +/- 4 min, respectively. Heating to 41.5 degrees C for up to 180 min did not result in cytotoxicity. Development of thermotolerance after approximately 100 min of heating was apparent by the presence of a "resistant tail" of the 42 degrees C survival curve. A plot of D0 vs water bath temperature was bimodal with an inflection point at approximately 42.5 degrees C. The inactivation enthalpy for temperatures above 42.5 degrees C was 586 kJ/mol (140 kcal/mol) and for temperatures below 42.5 degrees C was estimated to be 1205 kJ/mol (288 kcal/mol). These results show that CFU-GM can be heated predictably in situ, can be inactivated with thermal exposures as low as 42 degrees C, and are capable of developing thermotolerance. These findings underscore the necessity to understand stem cell inactivation by hyperthermia in situ prior to widespread implementation of clinical hyperthermia protocols where bone marrow may be included in the treatment field.     

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.