Some Mechanisms of Disturbances and Recovery of T-Lymphocyte Migratory Properties In Irradiated Mice

Abstract Migration of ⁵¹Cr-labelled T cells from irradiated mice into lymph nodes of syngeneic unirradiated recipients decreased in a dose-dependent fashion. Influx of labelled T cells between 4 and 24 hr after injection (secondary migration) is more radiosensitive than lymph-node migration of T cells in the first 4 hr (primary migration). Treatment of T cells from irradiated mice in vitro with Con A or with trypsin does not enhance radiation-induced alteration of their migratory properties, but irradiation enhances the effects of Con A and trypsin on T-cell migration. Recovery of primary migration of irradiated T cells is completed 3 months after irradiation; it is probably caused by T-cell renewal. the defect of T-cell secondary migration is more stable: it remains 6 months after irradiation in a dose of 4 Gy. Post-irradiation defects of the T-cell differentiation process as a cause of long-lasting alteration of T-cell secondary migration are discussed.     

Experimental Irradiated Arthrospore Vaccine Against Coccidioidomycosis in Mice

An experimental irradiated ((60)Co) arthrospore vaccine against coccidioidomycosis protected approximately 75% of mice from death after an intraperitoneal challenge sufficient to kill approximately 90% of the nonimmunized control mice. Although the majority of the immunized mice became infected with Coccidioides immitis, the histologic lesions were substantially less severe than those in the nonimmunized controls, particularly in the pulmonary region. Although arthrospores irradiated with 1, 2, or 3 million roentgens lost their ability to multiply in various laboratory media (probably through interference with cell division), partial conversion to the parasitic phase (spherule) was observed after animal inoculation (rounding out of arthrospores into immature spherules, but without development of endospores). Duration of viability of these structures has yet to be determined.     

Infusion of Trx-1-Overexpressing hucMSC Prolongs the Survival of Acutely Irradiated NOD/SCID Mice by Decreasing Excessive Inflammatory Injury

A protective reagent for ARI should have the ability to repair injured tissue caused by radiation and prevent continuous damage from secondary risk factors. Trx-1 was explored as a candidate therapy for ARI, as it scavenges reactive oxygen species, regulates cell growth and differentiation, participates in immune reactions, and inhibits apoptosis by acting inside and/or outside cells. Trx-1 can also decrease excessive inflammation in ARI by regulating the creation of inflamed media, by inhibiting the activation of complement, and by reducing the chemotaxis, adhesion, and migration of inflammatory cells. As effectively and stably expressing exogenous genes in the long term and regulating immune inflammation and tissue repair, MSC are a good choice for Trx-1 gene therapy. In this study, Trx-1-overexpressing hucMSC-Trx-1 were obtained by adenoviral vector-mediated infection. We first measured the redox capacity of hucMSC-Trx-1 with an antioxidant capacity (T-AOC) assay, a hydrogen peroxide (H₂O₂) content determination assay in vivo, a H₂O₂-induced oxidation hemolysis assay, and a lipid peroxidation assay in vitro. Then, we measured survival time, the protection of the hematopoietic system, and the regulation of inflammation in important organs in three treatment groups of NOD/SCID mice (treated with hucMSC-Trx-1, with hucMSC, and with saline) that were exposed to 4.5 Gy ⁶⁰Co-γ-ray radiation. The hucMSC-Trx-1 group achieved superior antioxidation results, protecting bone marrow hematopoietic stem cells (Lin⁻CD117⁺: hucMSC-Trx-1 vs. hucMSC, P<0.05; hucMSC-Trx-1 vs. NS, P<0.01), promoting the formation of red blood cells and hemoglobin (hucMSC-Trx-1 vs. hucMSC or NS, P<0.05), reducing inflammation and damage in important organs (Bone marrow and lung: hucMSC-Trx-1 vs. NS, P<0.01; hucMSC-Trx-1 vs. hucMSC, P<0.05. Liver and intestine: hucMSC-Trx-1 vs. NS, P<0.05; hucMSC-Trx-1 vs. hucMSC, P<0.05), and prolonging survival (hucMSC-Trx-1 vs. hucMSC or NS, P<0.01). Therefore, hucMSC-Trx-1 combines the merits of gene and cell therapy as a multifunctional radioprotector for ARI.     

染料木黄酮改善γ射线损伤小鼠抗氧化功能的作用

用137Csγ射线照射雄性昆明小鼠,观察饲料中补充染料木黄酮(Genistein,Gen)对抗氧化功能的保护作用,探讨其抗辐射作用的机制。结果表明,Gen可以提高辐射小鼠脾和胸腺组织总抗氧化能力(T-AOC)、降低血清、肝脏和胸腺组织丙二醛(MDA)水平;显著提高辐射小鼠抗氧化功能。     

Treatment of Irradiated Mice with High-Dose Ascorbic Acid Reduced Lethality

Ascorbic acid is an effective antioxidant and free radical scavenger. Therefore, it is expected that ascorbic acid should act as a radioprotectant. We investigated the effects of post-radiation treatment with ascorbic acid on mouse survival. Mice received whole body irradiation (WBI) followed by intraperitoneal administration of ascorbic acid. Administration of 3 g/kg of ascorbic acid immediately after exposure significantly increased mouse survival after WBI at 7 to 8 Gy. However, administration of less than 3 g/kg of ascorbic acid was ineffective, and 4 or more g/kg was harmful to the mice. Post-exposure treatment with 3 g/kg of ascorbic acid reduced radiation-induced apoptosis in bone marrow cells and restored hematopoietic function. Treatment with ascorbic acid (3 g/kg) up to 24 h (1, 6, 12, or 24 h) after WBI at 7.5 Gy effectively improved mouse survival; however, treatments beyond 36 h were ineffective. Two treatments with ascorbic acid (1.5 g/kg × 2, immediately and 24 h after radiation, 3 g/kg in total) also improved mouse survival after WBI at 7.5 Gy, accompanied with suppression of radiation-induced free radical metabolites. In conclusion, administration of high-dose ascorbic acid might reduce radiation lethality in mice even after exposure.     

Suppression of Cytochrome P450 Reductase Enhances Long-Term Hematopoietic Stem Cell Repopulation Efficiency in Mice

Background

Bone marrow microenvironment (niche) plays essential roles in the fate of hematopoietic stem cells (HSCs). Intracellular and extracellular redox metabolic microenvironment is one of the critical factors for the maintenance of the niche. Cytochrome P450 reductase (CPR) is an obligate electron donor to all microsomal cytochrome P450 enzymes (P450 or CYP), and contributes to the redox metabolic process. However, its role in maintaining HSCs is unknown.

Objective

To examine the effects of low CPR expression on HSCs function using a mouse model of globally suppressed Cpr gene expression (Cpr Low, CL mice).

Methods

Hematopoietic cell subpopulations in bone marrow (BM) and peripheral blood (PB) from WT and CL mice were examined for their repopulation and differentiation ability upon BM competitive transplantation and enriched HSC (LKS⁺) transplantation. Effects of low CPR expression on hematopoiesis were examined by transplanting normal BM cells into CL recipients. Reactive oxygen species (ROS), cell cycle, and apoptosis in CL mice were analyzed by flow cytometry for DCF-DA fluorescence intensity, Ki67 protein, and Annexin-V, respectively.

Results

The levels of ROS in BM cells, HPCs and HSCs were comparable between CL and WT mice. In comparison to WT mice, the number of LT-HSCs or ST-HSCs was lower in CL mice while CMPs, GMPs and MEPs in CL mice were higher than that in WT control. Competitive transplantation assay revealed enhanced repopulation capacity of HSCs with low CPR expression, but no difference in differentiation potential upon in vitro experiments. Furthermore, lymphoid differentiation of donor cells decreased while their myeloid differentiation increased under CL microenvironment although the overall level of donor hematopoietic repopulation was not significantly altered.

Conclusions

Our studies demonstrate that suppressing CPR expression enhances the repopulation efficiency of HSCs and a low CPR expression microenvironment favors the differentiation of myeloid over lymphoid lineage cells.     

Survival of Listeria monocytogenes in Experimentally Infected Mice

Physiological saline was found to be very detrimental to the viability of Listeria monocytogenes. The LD(50) value was substantially reduced when peptone was used as the suspending fluid rather than saline. Normal splenic tissue was not inhibitory to the survival of Listeria. In experimentally infected mice, L. monocytogenes survived for 8 days in the peritoneal cavity and for at least 11 days in the spleen.     

Differentiation of Pluripotent Embryonic Stem Cells in the Peritoneal Cavity of Irradiated Mice

We studied the behavior and differentiation of pluripotent embryonic stem cells of R1 mice in vivo. Undifferentiated embryonic stem cells and differentiating embryoid bodies implanted in the abdominal cavity of irradiated mice were shown to form tumors containing the derivatives of all germ layers. Cells of the embryoid bodies form tumors two weeks after implantation, while undifferentiated embryonic stem cells form tumors only by week three.     

Dysmyelination of Shiverer Mutant Mice In Vivo and In Vitro

Demyelination in the CNS of shiverer mutant mice was studied in vivo and in vitro. By immunohistochemical reaction with glial fibrillary acidic protein antibody, hypertrophy of the fibrous astrocytes was observed in the white matter of shiverer cerebella. The cerebella of shiverer mice in primary culture from the day of birth showed very poor myelination under optical microscopy. Axons of Purkinje cells are thought to be the main myelinated axons in the primary culture of the cerebellum. Purkinje cells from shiverer appeared normal with regard to Bodian silver impregnation, hematoxylin and eosin staining, and P400 protein characterization of Purkinje cells. Addition of the conditioned culture medium of shiverer to the control culture did not interfere with myelination. We concluded that the demyelination in the CNS of shiverer could be caused by an intrinsic defect of the oligodendrocyte rather than by hypertrophy of the astrocytes or by diffusible factors.     

Thrombomodulin Contributes to Gamma Tocotrienol-Mediated Lethality Protection and Hematopoietic Cell Recovery in Irradiated Mice

Systemic administration of recombinant thrombomodulin (TM) confers radiation protection partly by accelerating hematopoietic recovery. The uniquely potent radioprotector gamma tocotrienol (GT3), in addition to being a strong antioxidant, inhibits the enzyme hydroxy-methyl-glutaryl-coenzyme A reductase (HMGCR) and thereby likely modulates the expression of TM. We hypothesized that the mechanism underlying the exceptional radioprotective properties of GT3 partly depends on the presence of endothelial TM. In vitro studies confirmed that ionizing radiation suppresses endothelial TM (about 40% at 4 hr after 5 Gy γ-irradiation) and that GT3 induces TM expression (about 2 fold at the mRNA level after 5 μM GT3 treatment for 4 hr). In vivo survival studies showed that GT3 was significantly more effective as a radioprotector in TM wild type (TM^+/+) mice than in mice with low TM function (TM^Pro/-). After exposure to 9 Gy TBI, GT3 pre-treatment conferred 85% survival in TM^+/+ mice compared to only 50% in TM^Pro/-. Thus, GT3-mediated radiation lethality protection is partly dependent on endothelial TM. Significant post-TBI recovery of hematopoietic cells, particularly leukocytes, was observed in TM^+/+ mice (p = 0.003), but not in TM^Pro/- mice, despite the fact that GT3 induced higher levels of granulocyte colony stimulating factor (G-CSF) in TM^Pro/- mice (p = 0.0001). These data demonstrate a critical, G-CSF-independent, role for endothelial TM in GT3-mediated lethality protection and hematopoietic recovery after exposure to TBI and may point to new strategies to enhance the efficacy of current medical countermeasures in radiological/nuclear emergencies.     

Linking In Vitro and In Vivo Survival of Clinical Leishmania donovani Strains

Background

Leishmania donovani is an intracellular protozoan parasite that causes a lethal systemic disease, visceral leishmaniasis (VL), and is transmitted between mammalian hosts by phlebotomine sandflies. Leishmania expertly survives in these ‘hostile’ environments with a unique redox system protecting against oxidative damage, and host manipulation skills suppressing oxidative outbursts of the mammalian host. Treating patients imposes an additional stress on the parasite and sodium stibogluconate (SSG) was used for over 70 years in the Indian subcontinent.

Methodology/Principal Findings

We evaluated whether the survival capacity of clinical L. donovani isolates varies significantly at different stages of their life cycle by comparing proliferation, oxidative stress tolerance and infection capacity of 3 Nepalese L. donovani strains in several in vitro and in vivo models. In general, the two strains that were resistant to SSG, a stress encountered in patients, attained stationary phase at a higher parasite density, contained a higher amount of metacyclic parasites and had a greater capacity to cause in vivo infection in mice compared to the SSG-sensitive strain.

Conclusions/Significance

The 2 SSG-resistant strains had superior survival skills as promastigotes and as amastigotes compared to the SSG-sensitive strain. These results could indicate that Leishmania parasites adapting successfully to antimonial drug pressure acquire an overall increased fitness, which stands in contrast to what is found for other organisms, where drug resistance is usually linked to a fitness cost. Further validation experiments are under way to verify this hypothesis.     

FAK Inhibition Decreases Hepatoblastoma Survival Both In Vitro and In Vivo

Hepatoblastoma is the most frequently diagnosed liver tumor of childhood, and children with advanced, metastatic or relapsed disease have a disease-free survival rate under 50%. Focal adhesion kinase (FAK) is a nonreceptor tyrosine kinase that is important in many facets of tumor development and progression. FAK has been found in other pediatric solid tumors and in adult hepatocellular carcinoma, leading us to hypothesize that FAK would be present in hepatoblastoma and would impact its cellular survival. In the current study, we showed that FAK was present and phosphorylated in human hepatoblastoma tumor specimens. We also examined the effects of FAK inhibition upon hepatoblastoma cells using a number of parallel approaches to block FAK including RNAi and small molecule FAK inhibitors. FAK inhibition resulted in decreased cellular survival, invasion, and migration and increased apoptosis. Further, small molecule inhibition of FAK led to decreased tumor growth in a nude mouse xenograft model of hepatoblastoma. The findings from this study will help to further our understanding of the regulation of hepatoblastoma tumorigenesis and may provide desperately needed novel therapeutic strategies and targets for aggressive, recurrent, or metastatic hepatoblastomas.     

Kinetics of Micronucleus Expression In Synchronized Irradiated Chinese Hamster Ovary Cells

The kinetics of expression of radiation-induced micronuclei (MN) in synchronized Chinese hamster cells (CHO) was examined. the purpose of the study was to determine if the cell cycle distribution of a population significantly influences the levels of radiation induced MN, thereby obscuring the exact quantification of the radiation effect. Cells were synchronized by centrifugal elutriation, irradiated, and then different phases of the cell cycle were examined for: cell cycle progression, division probability, and temporal expression of MN. the results demonstrate that the time interval for maximal MN expression is long enough that the position of cells in the cell cycle and radiation induced division delays do not prevent the majority of cells from completing their first post-irradiation mitosis, therefore, expressing MN. By following the progression of synchronized cell populations by flow cytometry and also examining the time of division of individual cells for 24 hr after irradiation, we observed that the maximum number of cells from all phases of the cell cycle are in their first post-irradiation interphase at that time, thus explaining the MN results.     

Comparison of Long‐Term Survival of Pigmented Epidermal Reconstructs Cultured In Vitro vs. Xenografted on Nude Mice

Epidermal reconstructs incorporating pigment cells have been used in vitro over the last decade to study the physiology of the epidermal melanin unit. However, the major limitation of this technology is the duration of the assays, which need to be completed within 2–3 weeks to obviate the problem of epidermal senescence and excessive terminal differentiation. This becomes a major problem for studying long‐term biological phenomena in photoprotection and epidermal skin cancers. We report here a simplified surgical technique in immunotolerant mice allowing long‐term studies. The creation of a vascularized mouse skin flap is the key point of the surgical procedure. Long‐term pigmentation of the xenografts seemed macroscopically successful, but surprisingly microscopy at 11 and 16 weeks postgrafting showed mostly dermal pigment aggregates and rare Melan‐A positive dermal and epidermal pigment cells. In the same reconstructs maintained in vitro, dermal pigment and dermal pigment cells were never noted. It could be speculated that in our model, the colonization of the xenografted dead human dermis by murine cells influences melanocyte survival.     

Urothelial Proliferation In Growing Mice

Abstract. Developing murine urothelium undergoes pronounced proliferation until at least 10 days after birth. Thereafter, both mitotic and [³H]TdR-labelling indices fall sharply with age. the ratio of labelling to mitotic indices also alters dramatically during development, which is probably due to both endoreduplication and changes in the relative durations of the DNA synthesis and mitotic phases. This ratio reaches stability at 5 weeks of age. the adult labelling and mitotic indices were 0.11 and 0.019% respectively, indicating a very slow turnover.     

Reprogrammed Peripheral Blood Mononuclear Cells are Able to Survive Longer in Irradiated Female Mice

Induced multipotent stem (iMS) cells are originated from somatic cells and become multipotent by genetic and/or epigenetic modifications. Previous studies have shown that the fish oocytes extracts (FOE) can induce skin fibroblast cells into iMS cells. In this study, we aim to determine whether FOE can similarly induce mouse peripheral blood mononuclear cells (PBMCs) into the iMS state and if so, whether they can survive longer when they are transplanted into the irradiation female mice. PBMCs of GFP-transgenic male mice were cultured and transiently reprogrammed by FOE. They were deemed reaching the iMS state after detection of expression of stem cell markers. The iMS-like PBMCs were transplanted into female C57BL mice by tail vein injection. The spleen wet weights as well as numbers of colonies of the recipient mice were examined. The results showed the spleen wet weights and numbers of spleen colonies of FOE-induced group were all significantly higher than those of the non-induced group and negative control group. On day 90 after transplantation, FISH analysis detected the presence of Y chromosome in the induced group, but not of the other groups. The current findings demonstrate that FOE-induced PBMCs are able to survive longer in irradiated female mice.     

Influence of Amino Acids Shiff Bases on Irradiated DNA Stability In Vivo

To reveal protective role of the new Mn(II) complexes with Nicotinyl-l-Tyrosinate and Nicotinyl-l-Tryptophanate Schiff Bases against ionizing radiation. The DNA of the rats liver was isolated on 7, 14, and 30 days after X-ray irradiation. The differences between the DNA of irradiated rats and rats pre-treated with Mn(II) complexes were studied using the melting, microcalorimetry, and electrophoresis methods. The melting parameters and the melting enthalpy of rats livers DNA were changed after the X-ray irradiation: melting temperature and melting enthalpy were decreased and melting interval was increased. These results can be explained by destruction of DNA molecules. It was shown that pre-treatment of rats with Mn(II) complexes approximates the melting parameters to norm. Agarose gel electrophoresis data confirmed the results of melting studies. The separate DNA fragments were revealed in DNA samples isolated from irradiated animals. The DNA isolated from animals pre-treated with the Mn(II) chelates had better electrophoretic characteristics, which correspond to healthy DNA. Pre-treatment of the irradiated rats with Mn(II)(Nicotinil-l-Tyrosinate) and Mn(II)(Nicotinil-l-Tryptophanate)₂ improves the DNA characteristics.