Protection against radiation-induced hematopoietic damage in bone marrow by hepatocyte growth factor gene transfer

Protection of the hematopoietic system against radiation-induced damage: drugs, mechanisms, and developments

Sometimes, people can be exposed to moderate or high doses of radiation accidentally or through the environment. Radiation can cause great harm to several systems within organisms, especially the hematopoietic system. Several types of drugs protect the hematopoietic system against radiation damage in different ways. They can be classified as "synthetic drugs" and "natural compounds." Their cellular mechanisms to protect organisms from radiation damage include free radical-scavenging, anti-oxidation, reducing genotoxicity and apoptosis, and alleviating suppression of the bone marrow. These topics have been reviewed to provide new ideas for the development and research of drugs alleviating radiation-induced damage to the hematopoietic system.

Growth Factor Gene-Modified Mesenchymal Stem Cells in Tissue Regeneration

There have been marked changes in the field of stem cell therapeutics in recent years, with many clinical trials having been conducted to date in an effort to treat myriad diseases. Mesenchymal stem cells (MSCs) are the cell type most frequently utilized in stem cell therapeutic and tissue regenerative strategies, and have been used with excellent safety to date. Unfortunately, these MSCs have limited ability to engraft and survive, reducing their clinical utility. MSCs are able to secrete growth factors that can support the regeneration of tissues, and engineering MSCs to express such growth factors can improve their survival, proliferation, differentiation, and tissue reconstructing abilities. As such, it is likely that such genetically modified MSCs may represent the next stage of regenerative therapy. Indeed, increasing volumes of preclinical research suggests that such modified MSCs expressing growth factors can effectively treat many forms of tissue damage. In the present review, we survey recent approaches to producing and utilizing growth factor gene-modified MSCs in the context of tissue repair and discuss its prospects for clinical application.

Amentoflavone protects the hematopoietic system of mice against γ-irradiation

Some flavonoids have been shown to exhibit good antioxidant activity and protect mice from damage induced by radiation. Amentoflavone (AMF), a biflavonoid derived from the traditional herb-Selaginella tamariscina, has been reported to have antioxidant properties. The protective effects and mechanism of action of AMF against radiation injury remain unknown. In this study, male C57BL/6 mice were subjected to total-body ⁶⁰Co γ-irradiation at 7.5 or 3.0 Gy. The survival rate and mean survival time were evaluated to determine the radioprotective effect of AMF. Number of peripheral blood cells, frequency of colony forming unit-granulocytes, monocytes and micronuclei were measured to assess the protective effects of AMF on the hematopoietic system. Levels of superoxide dismutase and glutathione, and pathological changes in the bone marrow were determined. Additionally, next-generation sequencing technology was used to explore potential targets of AMF. We observed that AMF markedly extends average survival time, reduces injury to the hematopoietic system and promotes its recovery. Furthermore, treatment with AMF significantly attenuated radiation-induced oxidative stress. In addition, AMF had a significant effect on gene tumor necrosis factor alpha-induced protein 2. Together, the results of this study suggest that AMF is a potential protective agent against radiation injury.

Gene therapy and cell therapy for the management of radiation damages to healthy tissues: Rationale and early results

Nowadays, ionizing radiations have numerous applications, especially in medicine for diagnosis and therapy. Pharmacological radioprotection aims at increasing detoxification of free radicals. Radiomitigation aims at improving survival and proliferation of damaged cells. Both strategies are essential research area, as non-contained radiation can lead to harmful effects. Some advances allowing the comprehension of normal tissue injury mechanisms, and the discovery of related predictive biomarkers, have led to developing several highly promising radioprotector or radiomitigator drugs. Next to these drugs, a growing interest does exist for biotherapy in this field, including gene therapy and cell therapy through mesenchymal stem cells. In this review article, we provide an overview of the management of radiation damages to healthy tissues via gene or cell therapy in the context of radiotherapy. The early management aims at preventing the occurrence of these damages before exposure or just after exposure. The late management offers promises in the reversion of constituted late damages following irradiation.

Saving normal tissues - a goal for the ages

Almost since the earliest utilization of ionizing radiation, many within the radiation community have worked toward either preventing (i.e. protecting) normal tissues from unwanted radiation injury or rescuing them from the downstream consequences of exposure. However, despite over a century of such investigations, only incremental gains have been made toward this goal and, with certainty, no outright panacea having been found. In celebration of the 60th anniversary of the International Journal of Radiation Biology and to chronicle the efforts that have been made to date, we undertook a non-rigorous survey of the articles published by normal tissue researchers in this area, using those that have appeared in the aforementioned journal as a road map. Three 'snapshots' of publications on normal tissue countermeasures were taken: the earliest (1959-1963) and most recent (2013-2018) 5-year of issues, as well as a 5-year intermediate span (1987-1991). Limiting the survey solely to articles appearing within International Journal of Radiation Biology likely reduced the number of translational studies interrogated given the basic science tenor of this particular publication. In addition, by taking 'snapshots' rather than considering the entire breadth of the journal's history in this field, important papers that were published during the interim periods were omitted, for which we apologize. Nonetheless, since the journal's inception, we observed that, during the chosen periods, the majority of studies undertaken in the field of normal tissue countermeasures, whether investigating radiation protectants, mitigators or treatments, have focused on agents that interfere with the physical, chemical and/or biological effects known to occur during the acute period following whole body/high single dose exposures. This relatively narrow approach to the reduction of normal tissue effects, especially those that can take months, if not years, to develop, seems to contradict our growing understanding of the progressive complexities of the microenvironmental disruption that follows the initial radiation injury. Given the analytical tools now at our disposal and the enormous benefits that may be reaped in terms of improving patient outcomes, as well as the potential for offering countermeasures to those affected by accidental or mass casualty exposures, it appears time to broaden our approaches to developing normal tissue countermeasures. We have no doubt that the contributors and readership of the International Journal of Radiation Biology will continue to contribute to this effort for the foreseeable future.

Long-term health effects of persistent exposure to low-dose lr192 gamma-rays

The aim of the present study was to investigate the effect of persistent low-dose iridium-192 (Ir192) exposure on immunological function, chromosome aberration and the telomerase activity of bone marrow mononuclear cells (BMNCs), in order to increase clinical knowledge of the late effects of persistent low-dose Ir192 gamma-ray exposure. Patients (n=54) accidentally exposed to persistent low-dose Ir192 were included in this 10-year follow-up study. Clinical symptoms, peripheral blood, bone marrow, cellular and humoral immune status, chromosome aberrations and the telomerase activity of BMNCs were analyzed in this study. Exposure to low-dose Ir192 resulted in different degrees of clinical symptoms and significantly lowered complement C3 and C4 levels, CD3⁺, CD4⁺ and CD8⁺ T cell levels, the lymphocyte transformation rate and the percentage of natural killer (NK) cells. It also led to increases in peripheral blood and bone marrow abnormality rates, chromosome aberration rate and BMNC telomerase activity. Exposure to persistent low-dose Ir192 radiation resulted in different degrees of immune dysfunction, and abnormalities of blood cells and bone marrow, which recovered within 1-3 years. Chromosome aberrations were observed to take 5-10 years to recover. However, it would take >10 years for the telomerase activity of BMNCs to be reduced to normal levels. A prolonged follow-up time is required in order to monitor clonal proliferative diseases such as leukemia.

Adipose-Derived Mesenchymal Stem Cells (ADSCs) With the Potential to Ameliorate Platelet Recovery, Enhance Megakaryopoiesis, and Inhibit Apoptosis of Bone Marrow Cells in a Mouse Model of Radiation-Induced Thrombocytopenia

Substantial damage to the bone marrow can be caused by exposure to radiation, which can then develop into severe thrombocytopenia. In this study, we investigated the in vivo impact of adipose-derived mesenchymal stem cells (ADSCs) on megakaryopoiesis and platelet recovery in irradiated mice. Radiation markedly reduced peripheral blood counts. Recovery of both platelets and WBCs was better in the ADSC-treated group compared with the saline group and the fibroblast group 21 days after irradiation. A significant increase in the total CFU and MK-CFU after irradiation was observed in the ADSC group compared with the saline group and the fibroblast group. Further, the proportion of CD41(+) cells in the ADSC group was significantly higher than that in the saline group and the fibroblast group. ADSC treatment significantly improved the cellularity and decreased the apoptotic cells in the bone marrow while normal fibroblasts did not. Administration of ADSCs upregulated protein expression of phosphorylated Akt and Bcl-xL, whereas the expression of Bax, a protein related to apoptosis, was significantly lower in the ADSC group. In conclusion, this study suggests that ADSCs were capable of promoting platelet recovery, improving megakaryopoiesis, and inhibiting apoptosis of bone marrow cells in irradiated mice. The antiapoptotic effect of ADSCs is likely to be mediated via the PI3K/Akt pathway. These findings may provide a scientific basis for using ADSCs as a new therapy after irradiation.

Gene therapy for radioprotection

Radiation therapy is a critical component of cancer treatment with over half of patients receiving radiation during their treatment. Despite advances in image-guided therapy and dose fractionation, patients receiving radiation therapy are still at risk for side effects due to off-target radiation damage of normal tissues. To reduce normal tissue damage, researchers have sought radioprotectors, which are agents capable of protecting tissue against radiation by preventing radiation damage from occurring or by decreasing cell death in the presence of radiation damage. Although much early research focused on small-molecule radioprotectors, there has been a growing interest in gene therapy for radioprotection. The amenability of gene therapy vectors to targeting, as well as the flexibility of gene therapy to accomplish ablation or augmentation of biologically relevant genes, makes gene therapy an excellent strategy for radioprotection. Future improvements to vector targeting and delivery should greatly enhance radioprotection through gene therapy.

Erythrocyte stiffness during morphological remodeling induced by carbon ion radiation

The adverse effect induced by carbon ion radiation (CIR) is still an unavoidable hazard to the treatment object. Thus, evaluation of its adverse effects on the body is a critical problem with respect to radiation therapy. We aimed to investigate the change between the configuration and mechanical properties of erythrocytes induced by radiation and found differences in both the configuration and the mechanical properties with involving in morphological remodeling process. Syrian hamsters were subjected to whole-body irradiation with carbon ion beams (1, 2, 4, and 6 Gy) or X-rays (2, 4, 6, and 12 Gy) for 3, 14 and 28 days. Erythrocytes in peripheral blood and bone marrow were collected for cytomorphological analysis. The mechanical properties of the erythrocytes were determined using atomic force microscopy, and the expression of the cytoskeletal protein spectrin-α1 was analyzed via western blotting. The results showed that dynamic changes were evident in erythrocytes exposed to different doses of carbon ion beams compared with X-rays and the control (0 Gy). The magnitude of impairment of the cell number and cellular morphology manifested the subtle variation according to the irradiation dose. In particular, the differences in the size, shape and mechanical properties of the erythrocytes were well exhibited. Furthermore, immunoblot data showed that the expression of the cytoskeletal protein spectrin-α1 was changed after irradiation, and there was a common pattern among its substantive characteristics in the irradiated group. Based on these findings, the present study concluded that CIR could induce a change in mechanical properties during morphological remodeling of erythrocytes. According to the unique characteristics of the biomechanical categories, we deduce that changes in cytomorphology and mechanical properties can be measured to evaluate the adverse effects generated by tumor radiotherapy. Additionally, for the first time, the current study provides a new strategy for enhancing the assessment of the curative effects and safety of clinical radiotherapy, as well as reducing adverse effects.

Immunomodulatory effects of high-protein diet with resveratrol supplementation on radiation-induced acute-phase inflammation in rats

We hypothesized that a high-protein diet and/or resveratrol supplementation will improve acute inflammatory responses in rats after receiving experimental abdominal radiation treatment (ART). Based on our previous study, the period of 10 days after ART was used as an acute inflammation model. Rats were exposed to a radiation dose of 17.5 Gy and were supplied with a control (C), 30% high-protein diet (HP), resveratrol supplementation (RES), or HP with RES diet ([HP+RES]). At day 10 after ART, we measured profiles of lipids, proteins, and immune cells in blood. The levels of clusters of differentiating 4(+) (CD4(+)) cells and regulatory T cells, serum proinflammatory cytokines, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) in urine were also measured. ART caused significant disturbances of lipid profiles by increasing triglyceride (TG) and low-density lipoprotein cholesterol (LDL-C), and decreasing high-density lipoprotein cholesterol. The proinflammatroy cytokine levels were also increased by ART. All the experimental diets (HP, RES, and [HP+RES]) significantly decreased levels of TG, monocytes, proinflammatory cytokines, and 8-OHdG, whereas the platelet counts were increased. In addition, the HP and [HP+RES] diets decreased the concentrations of plasma LDL-C and total cholesterol. Also, the HP and RES diets decreased regulatory T cells compared with those of the control diet in ART group. Further, the HP diet led to a significant recovery of white blood cell counts, as well as increased percentages of lymphocyte and decreased percentages of neutrophils. In summary, RES appeared to be significantly effective in minimizing radiation-induced damage to lipid metabolism and immune responses. Our study also demonstrated the importance of dietary protein intake in recovering from acute inflammation by radiation.