Protective Effect of Carrageenan against Murine Cytomegalovirus Infection in Mice

The protective effect of iota-carrageenan (CAR) was evaluated against murine cytomegalovirus (MCMV) infection in mice. Female ICR mice were challenged intraperitoneally (i.p.) with 3 LD50 of salivary gland-passaged MCMV. More than 0.5 mg of CAR showed a protective effect on mice only when CAR was administered i.p. and then MCMV was inoculated i.p. The protective effect of CAR was evidenced by an increase in plaque-forming unit per LD50 and a decrease in the titre of infectious viruses in the target organs. Neither a virucidal nor a virustatic effect on MCMV was evidenced for CAR. The protective effect of CAR seemed to be host-mediated.

Pretreatment of mice with CAR augmented natural killer (NK) activity of the spleen cells without elevating the serum interferon level. However, administration of anti-asialo GM1 antibody did not nullify the inhibitory effect of CAR on virus replication in the target organs. MCMV infection induced leukopenia including neutropenia and lymphopenia in saline-treated mice. Pretreatment with CAR protected mice from those signs, except for slight lymphopenia. Administration of cyclophosphamide induced severe leukopenia including neutropenia and lymphopenia even in CAR-treated mice. Under such conditions, the protective effect of CAR against MCMV infection was abrogated by cyclophosphamide. Thus, the protective effect of CAR seems to be non-NK-mediated.

Hematopoietic Stem and Immune Cells in Chronic HIV Infection

Hematopoietic stem cell (HSC) belongs to multipotent adult somatic stem cells. A single HSC can reconstitute the entire blood system via self-renewal, differentiation into all lineages of blood cells, and replenishment of cells lost due to attrition or disease in a person's lifetime. Although all blood and immune cells derive from HSC, immune cells, specifically immune memory cells, have the properties of HSC on self-renewal and differentiation into lineage effector cells responding to the invading pathogens. Moreover, the interplay between immune memory cell and viral pathogen determines the course of a viral infection. Here, we state our point of view on the role of blood stem and progenitor cell in chronic HIV infection, with a focus on memory CD4 T-cell in the context of HIV/AIDS eradication and cure.

Haemotoxicity of busulphan, doxorubicin, cisplatin and cyclophosphamide in the female BALB/c mouse using a brief regimen of drug administration

Many anticancer drugs are myelotoxic and cause bone marrow depression; however, generally, the marrow/blood returns to normal after treatment. Nevertheless, after the administration of some anti-neoplastic agents (e.g. busulphan, BU) under conditions as yet undefined, the marrow may begin a return towards normal, but normality may not be achieved, and late-stage/residual marrow injury may be evident. The present studies were conducted to develop a short-term mouse model (a 'screen') to identify late-stage/residual marrow injury using a brief regimen of drug administration. Female BALB/c mice were treated with BU, doxorubicin (DOX), cisplatin (CISPLAT) or cyclophosphamide (CYCLOPHOS) on days 1, 3 and 5. In 'preliminary studies', a maximum tolerated dose (MTD) for each drug was determined for use in 'main studies'. In main studies, mice were treated with vehicle (control), low and high (the MTD) dose levels of each agent. Necropsies were performed, and blood parameters and femoral/humeral nucleated marrow cell counts (FNCC/HNCC) were assessed on six occasions (from days 1 to 60/61 post-dosing). Late-stage/residual changes were apparent in BU-treated mice at day 61 post-dosing: RBC, Hb and haematocrit were reduced, mean cell volume/mean cell haemoglobin were increased and platelet and FNCC counts were decreased. Mice given DOX, CISPLAT and CYCLOPHOS, in general, showed no clear late-stage/residual effects (day 60/61). It was concluded that a brief regimen of drug administration, at an MTD, with assessment at day 60/61 post-dosing was a suitable short-term method/screen in the mouse for detecting late-stage/residual marrow injury for BU, a drug shown to exhibit these effects in man.

Nutraceutical augmentation of circulating endothelial progenitor cells and hematopoietic stem cells in human subjects

The medical significance of circulating endothelial or hematopoietic progenitors is becoming increasing recognized. While therapeutic augmentation of circulating progenitor cells using G-CSF has resulted in promising preclinical and early clinical data for several degenerative conditions, this approach is limited by cost and inability to perform chronic administration. Stem-Kine is a food supplement that was previously reported to augment circulating EPC in a pilot study. Here we report a trial in 18 healthy volunteers administered Stem-Kine twice daily for a 2 week period. Significant increases in circulating CD133 and CD34 cells were observed at days 1, 2, 7, and 14 subsequent to initiation of administration, which correlated with increased hematopoietic progenitors as detected by the HALO assay. Augmentation of EPC numbers in circulation was detected by KDR-1/CD34 staining and colony forming assays. These data suggest Stem-Kine supplementation may be useful as a stimulator of reparative processes associated with mobilization of hematopoietic and endothelial progenitors.

Residual hematopoietic effect in mice exposed to ochratoxin A prior to irradiation

Ochratoxin A (OCT A) has the potential to cause myelotoxicity in addition to the well-known toxic effects on the liver and kidney. Whereas in previous studies the bone marrow parameters were examined shortly after injection, experiments reported here were designed to determine whether mice would recover from the myelotoxic effects induced to OCT A injection and secondly whether mice previously injected to OCT A would be more sensitive to radiation-induced myelotoxicity than vehicle controls. Six-week old female B6C3F1 mice were injected intraperitoneally on alternate days over a week with a total dose of 20 or 40 mg/kg of OCT A and bone marrow parameters monitored for up to 16 weeks. Controls received vehicle alone. There was a suppression of marrow granulocyte macrophage progenitors (CFU-C) in OCT A-treated animals which returned to normal values by 2 weeks (20 mg/kg group) or by 5 weeks (40 mg/kg group) following the last treatment. Some of the OCT A-treated mice were additionally irradiated with 200 rads of whole body irradiation (WBI) at 10 and 52 days following OCT A injections. Irradiation caused a significant reduction in CFU-Cs in all mice but the effects were more pronounced in the mice that had received OCT A previously. The bone marrow parameters of 40 mg/kg OCT A-treated mice returned to normal by 6 weeks after first WBI. A second WBI produced similar depression in CFU-Cs with again a delayed 8 weeks recovery as compared to controls in both dose groups of OCT A-treated mice. The delayed recovery in bone marrow progenitors was also reflected in lower peripheral white blood counts after the second irradiation in 40 mg/kg OCT A-treated mice as compared to the untreated irradiated controls. This indicated that residual bone marrow effect of OCT A makes the mice more sensitive to subsequent irradiation induced injury.

Effects of hypoxia on megakaryocytopoiesis and granulopoiesis

Previous studies have reported that exposure of mice to hypoxic conditions results in a decrease in blood platelets. To further explore the effect of hypoxia on megakaryocytopoiesis, megakaryocytes and their progenitor cells (CFU-M) were studied in hypoxic mice. Mice were exposed to hypoxia by enclosure in cages covered with dimethyl-silicone rubber membranes for up to 10 d. At various times during the hypoxic and ex-hypoxic periods the total megakaryocytes and CFU-M were determined in the humerus and spleen. CFU-M were assayed in the soft gel colony forming assay using pokeweed mitogen-stimulated spleen cell conditioned medium (PWCM) as a source of colony stimulating activity. After 10 d of hypoxia, packed red cell volume (PRCV) increased to 148% of control levels and blood platelets decreased to 40% of controls. Total megakaryocytes and CFU-M per humerus decreased to 18% and 50% of controls respectively. 4 d into the ex-hypoxic phase, PRCV was still increased at 128% of controls while marrow megakaryocytes and CFU-M increased to normal levels. Platelet recovery was somewhat slower, returning to normal by d 6. In contrast to the findings in the marrow, total spleen megakaryocytes and CFU-M increased to about 3- and 5-fold of control levels respectively by 6 d of hypoxia. During the exhypoxic phase, CFU-M decreased to normal on d 4, followed by a rebound of 3-fold control values on d 8. Spleen megakaryocytes decreased more slowly, returning to normal by d 10. A marked granulocytosis was observed during the hypoxic phase.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of cyclophosphamide on murine bone marrow and splenic megakaryocyte-CFC, granulocyte-macrophage-CFC, and peripheral blood cell levels

The effect of cyclophosphamide (CY) on megakaryocytopoiesis in mice was examined with assays of megakaryocyte colony-forming cells (Meg-CFC) in bone marrow and spleen and simultaneous determinations of peripheral blood counts, after a single intraperitoneal dose (200 mg/kg) of CY. Significant rebound thrombocytosis (170% of normal) occurred at day 11 after injection with CY, although only modest preceding thrombocytopenia (70% of normal) was observed. After an initial 3-5 day period of suppression, total megakaryocyte colony-forming cells (Meg-CFC) in both bone marrow and spleen of CY-treated mice demonstrated rebound increases at 5 and 7 days, respectively, after administration of the drug. Granulocyte-macrophage colony-forming cells (GM-CFC) exhibited alterations which were similar to those of Meg-CFC, suggesting similar sensitivities of Meg-CFC and GM-CFC to CY. The increase in Meg-CFC in both bone marrow and spleen preceded development of thrombocytosis by 4-6 days. This suggests that increased platelet counts in CY-treated mice are attributable, at least in part, to alterations in feedback mechanisms which control megakaryocytopoiesis, with resultant stimulation of the megakaryocyte progenitor compartment.

Misonidazole enhances cyclophosphamide toxicity to bone marrow

Normal bone marrow function was surveyed in animals that received cyclophosphamide after treatment with small, multiple doses of misonidazole. Peripheral blood white cell counts, cell differentials, hematocrits, bone marrow white cell counts and committed granulocyte-macrophage precursors (CFUc) were monitored for several days following treatment with misonidazole and cyclophosphamide. When results obtained from animals treated with physiological saline or misonidazole in advance of cyclophosphamide were compared, no significant differences were noted in routine assays of white blood cell count, cell morphology or hematocrit. Pre-treatment with misonidazole, however, caused a significant reduction in survival and delay in recovery of bone marrow CFUc (p less than .01). The combined use of misonidazole and cyclophosphamide also reduced animal survival (DMF = 1.2), with the majority of deaths being attributable to failure of normal hematopoietic function. These results suggest that misonidazole enhances the myelotoxicity associated with cyclophosphamide use. This additional damage is not detectable using routine hematological assays, but is demonstrable in assays of bone marrow stem cells and animal survival studies.

The effects of chronic administration of cyclophosphamide on haemopoietic stem cells

The effects of cyclophosphamide given for 18 weeks in small daily doses on CFU-S, CFU-C, and CFU-E content in mice bone marrow and spleen were studied. In the bone marrow, after an initial drop, the stem cell content rises above the normal values and remains there throughout a long period. In the spleen the stem cell content shows an initial several fold increase followed by a steady decline. It seems possible that this behaviour reflects a compensative effect to the toxic action of the drug at more differentiated levels of the haemopoietic cells.

Effects of nitrogen mustard and splenectomy on mouse bone marrow colony formation in vitro

Improved tolerance of splenectomized patients with Hodgkin's disease (HD) to radiotherapy and chemotherapy has been reported. The present study was undertaken to determine the effects of splenectomy and nitrogen mustard (NM) on colony-forming cells (CFC's) of bone marrow cells obtained from CF1 male mice by in bitro agar-gel technique. Splenectomized mice were given NM intraperitoneally on day 11. On day 15, they were sacrificed and the bone marrow was cultured with a source of colony-stimulating factor (CSF). Spleen extract was prepared by grinding spleens from CF1 mice. On the eighth day of incubation, significantly higher numbers of CFC's were found in splenectomized animals at 1% confidence level (F Test) compared with the nonsplenectomized animals. Both splenectomized and non-splenectomized mice had a greater colony response after NM (at 5% confidence level) than saline-treated controls. Maximum numbers of colonies were obtained in the nustard-treated asplenic animals. Splenic extract, as well as extracts from other organs, when added to the culture plates resulted in inhibition of colony formation. The significance of in vitro inhibition after addition of organ extract is uncertain.

Experimental Study of the Relationships between Activation of Erythropoiesis and Hematotoxicity of Some Antitumoral Agents

The changes in the blood toxicity of some antitumoral chemotherapeutic agents in the presence of erythropoiesis activation by bleeding are evaluated. The general toxicity seems to be unaffected but the damage to erythropoiesis proved, in absolute terms, to be more severe in the bled animals. The recovery of hematopoiesis was slower after some drugs than others. These results are discussed in the light of present knowledge of hematopoietic kinetics and of the relationships between antiblastic drugs and stamina] hematopoietic compartments.