Dimethyl sulfoxide, a potent oral radioprotective agent, confers radioprotection of hematopoietic stem and progenitor cells independent of apoptosis

Biomaterials-mediated radiation-induced diseases treatment and radiation protection

In recent years, the intersection of the academic and medical domains has increasingly spotlighted the utilization of biomaterials in radioactive disease treatment and radiation protection. Biomaterials, distinguished from conventional molecular pharmaceuticals, offer a suite of advantages in addressing radiological conditions. These include their superior biological activity, chemical stability, exceptional histocompatibility, and targeted delivery capabilities. This review comprehensively delineates the therapeutic mechanisms employed by various biomaterials in treating radiological afflictions impacting the skin, lungs, gastrointestinal tract, and hematopoietic systems. Significantly, these nanomaterials function not only as efficient drug delivery vehicles but also as protective agents against radiation, mitigating its detrimental effects on the human body. Notably, the strategic amalgamation of specific biomaterials with particular pharmacological agents can lead to a synergistic therapeutic outcome, opening new avenues in the treatment of radiation- induced diseases. However, despite their broad potential applications, the biosafety and clinical efficacy of these biomaterials still require in-depth research and investigation. Ultimately, this review aims to not only bridge the current knowledge gaps in the application of biomaterials for radiation-induced diseases but also to inspire future innovations and research directions in this rapidly evolving field.

Sequential administration of delta-tocotrienol ameliorates radiation-induced myelosuppression in mice and non-human primates through inducing G-CSF production

To date only four recombinant growth factors, including Filgrastim (rhG-CSF), have been approved by FDA as radiomitigators to ameliorate hematopoietic acute radiation syndrome (H-ARS). These approved agents are not stable under room-temperature, needing to be stored at 2-8 °C, and would not be feasible in a mass casualty scenario where rapid and cost-effective intervention is crucial. Delta-tocotrienol (δ-T3H), the most potent G-CSF-inducing agent among vitamin E isoforms, exhibited efficiency and selectivity on G-CSF production in comparison with TLR and STING agonists in mice. Five-dose δ-T3H was utilized as the optimal therapeutic regimen due to long-term G-CSF production and the best peripheral blood (PB) recovery of irradiated mice. Comparable with rhG-CSF, sequential administration of δ-T3H post-irradiation improved hematologic recovery and accelerated the regeneration of hematopoietic stem cells (HSCs) and hematopoietic progenitor cells (HPCs) in the bone marrow (BM) and spleen of 6.5Gy irradiated mice; and consistently enhanced repopulation of BM-HSCs. In 4.0Gy irradiated nonhuman primates, δ-T3H exhibited comparable efficacy as rhG-CSF to promote PB recovery and colony-formation of BM-HPCs. Altogether, we demonstrated that sequential administration of delta-tocotrienol ameliorates radiation-induced myelosuppression in mice and non-human primates through inducing G-CSF production, indicated δ-T3H as a promising radiomitigator for the management of H-ARS, particularly in a mass casualty scenario.

Radioprotective effectiveness of a novel delta-tocotrienol prodrug on mouse hematopoietic system against 60Co gamma-ray irradiation through inducing granulocyte-colony stimulating factor production

Considering the increasing risk of nuclear attacks worldwide, the development of develop potent and safe radioprotective agents for nuclear emergencies is urgently needed. γ-tocotrienol (GT3) and δ-tocotrienol (DT3) have demonstrated a potent radioprotective effect by inducing the production of granulocyte-colony stimulating factor (G-CSF) in vivo. However, their application is limited because of their low bioavailability. The utilization of ester prodrugs can be an effective strategy for modifying the pharmacokinetic properties of drug molecules. In this study, we initially confirmed that DT3 exhibited the most significant potential for inducing G-CSF effects among eight natural vitamin E homologs. Consequently, we designed and synthesized a series of DT3 ester and ether derivatives, leading to improved radioprotective effects. The metabolic study conducted in vitro and in vivo has identified DT3 succinate 5b as a prodrug of DT3 with an approximately seven-fold higher bioavailability compared to DT3 alone. And DT3 ether derivative 8a were relatively stable and approximately 4 times more bioavailable than DT3 prototype. Furthermore, 5b exhibited superior ability to mitigate radiation-induced pancytopenia, enhance the recovery of bone marrow hematopoietic stem and progenitor cells, and promote splenic extramedullary hematopoiesis in sublethal irradiated mice. Similarly, 8a shown potential radiation protection, but its radiation protection is less than DT3. Based on these findings, we identified 5b as a DT3 prodrug, and providing an attractive candidate for further drug development.

Indole-3-carboxaldehyde ameliorates ionizing radiation-induced hematopoietic injury by enhancing hematopoietic stem and progenitor cell quiescence

Indole-3-carboxaldehyde (I3A), one of tryptophan metabolites derived from gut microbiota, extends the lifespan of mice after high-dose ionizing radiation exposure. Persistent myelosuppression is the most common and fatal complication for victims of nuclear accidents and patients undergoing radiotherapy, with few therapeutic options available. However, whether and how I3A protects ionizing radiation-induced hematopoietic toxicity remain unknown. In this study, we demonstrated that I3A treatment effectively ameliorated radiation-induced hematopoietic injury through accelerating peripheral blood cells recovery, promoting bone marrow cellularity restoration and enhancing functional HSPC regeneration. Additionally, I3A also suppressed intracellular reactive oxygen species production and inhibited apoptosis in irradiated HSPCs. Mechanistically, I3A treatment significantly increased HSPC quiescence, thus conferring HSPCs with resistance against radiation injury. Finally, I3A treatment could improve survival of lethally irradiated mice. Taken together, our data suggest that I3A acts as a gut microbiota-derived paracrine factor that regulates HSPC regeneration and may serve as a promising therapeutic agent for ionizing radiation-induced myelosuppression.

Radioprotection of deinococcal exopolysaccharide BRD125 by regenerating hematopoietic stem cells

There is a substantial need for the development of biomaterials for protecting hematopoietic stem cells and enhancing hematopoiesis after radiation damage. Bacterial exopolysaccharide (EPS) has been shown to be very attractive to researchers as a radioprotectant owing to its high antioxidant, anti-cancer, and limited adverse effects. In the present study, we isolated EPS from a novel strain, Deinococcus radiodurans BRD125, which produces EPS in high abundance, and investigated its applicability as a radioprotective biomaterial. We found that EPS isolated from EPS-rich D. radiodurans BRD125 (DeinoPol-BRD125) had an excellent free-radical scavenging effect and reduced irradiation-induced apoptosis. In addition, bone-marrow and spleen-cell apoptosis in irradiated mice were significantly reduced by DeinoPol-BRD125 administration. DeinoPol-BRD125 enhanced the expression of hematopoiesis-related cytokines such as GM-CSF, G-GSF, M-CSF, and SCF, thereby enhancing hematopoietic stem cells protection and regeneration. Taken together, our findings are the first to report the immunological mechanism of a novel radioprotectant, DeinoPol-BRD125, which might constitute an ideal radioprotective and radiation mitigating agent as a supplement drug during radiotherapy.

Dimethyl Sulfoxide Attenuates Radiation-Induced Testicular Injury through Facilitating DNA Double-Strand Break Repair

The testis is susceptible to ionizing radiation, and male infertility and sexual dysfunction are prevalent problems after whole-body or local radiation exposure. Currently, there is no approved agent for the prevention or treatment of radiation-induced testicular injury. Herein, we investigated the radioprotective effect of dimethyl sulfoxide (DMSO), an organosulfur compound that acts as a free radical scavenger, on testicular injury. Treatment of mice with a single dose of DMSO prior to 5 Gy irradiation restored sex hormones and attenuated the reduction in testis weight. Histological analyses revealed that DMSO alleviated the distorted architecture of seminiferous tubules and promoted seminiferous epithelium regeneration following irradiation. Moreover, DMSO provided quantitative and qualitative protection for sperm and preserved spermatogenesis and fertility in male mice. Mechanistically, DMSO treatment enhanced GFRα-1⁺ spermatogonial stem cell and c-Kit⁺ spermatogonial survival and regeneration after radiation. DMSO also alleviated radiation-induced oxidative stress and suppressed radiation-induced germ cell apoptosis in vivo and in vitro. Additionally, DMSO efficiently reduced DNA damage accumulation and induced the expression of phosph-BRCA1, BRCA1, and RAD51 proteins, indicating that DMSO facilitates DNA damage repair with a bias toward homologous recombination. In summary, our findings demonstrate the radioprotective efficacy of DMSO on the male reproductive system, which warrants further studies for future application in the preservation of male fertility during conventional radiotherapy and nuclear accidents.

An Active Fraction of Trillium tschonoskii Promotes the Regeneration of Intestinal Epithelial Cells After Irradiation

Despite significant scientific advances toward the development of safe and effective radiation countermeasures, no drug has been approved for use in the clinic for prevention or treatment of radiation-induced acute gastrointestinal syndrome (AGS). Thus, there is an urgent need to develop potential drugs to accelerate the repair of injured intestinal tissue. In this study, we investigated that whether some fractions of Traditional Chinese Medicine (TCM) have the ability to regulate intestinal crypt cell proliferation and promotes crypt regeneration after radiation. By screening the different supplements from a TCM library, we found that an active fraction of the rhizomes of Trillium tschonoskii Maxim (TT), TT-2, strongly increased the colony-forming ability of irradiated rat intestinal epithelial cell line 6 (IEC-6) cells. TT-2 significantly promoted the proliferation and inhibited the apoptosis of irradiated IEC-6 cells. Furthermore, in a small intestinal organoid radiation model, TT-2 promoted irradiated intestinal organoid growth and increased Lgr5⁺ intestinal stem cell (ICS) numbers. More importantly, the oral administration of TT-2 remarkably enhanced intestinal crypt cell proliferation and promoted the repair of the intestinal epithelium of mice after abdominal irradiation (ABI). Mechanistically, TT-2 remarkably activated the expression of ICS-associated and proliferation-promoting genes and inhibited apoptosis-related gene expression. Our data indicate that active fraction of TT can be developed into a potential oral drug for improving the regeneration and repair of intestinal epithelia that have intestinal radiation damage.

Radioprotective effect of radiation-induced Lactococcus lactis cell-free extract against 60Coγ injury in mice

Ionizing radiation (IR) is widely used in the diagnosis and treatment of various cancers. However, IR can cause damage to human health by producing reactive oxygen species. Lactococcus lactis is a type of microorganism that is beneficial to human health and has a strong antioxidant capacity. In this study, the protective effect of normal and IR-induced L. lactis IL1403 cell-free extracts (CFE and IR-CFE, respectively) against oxidative damage in vitro and the radioprotective effect of IR-CFE in vivo was evaluated using ⁶⁰Coγ-induced oxidative damage model in mice. Results showed that IR-CFE exhibited a stronger oxidative damage-protective effect than CFE for L. lactis IL1403 under H₂O₂ in vitro. Moreover, IR-CFE also showed strong radioprotective effect on hepatocyte cells (AML-12) under radiation condition, and the effect was better than that of CFE. Animal experiment indicated that IR-CFE could reduce the IR-induced damage to the hematopoietic system by increasing the number of white blood cells and red blood cells in peripheral blood of irradiated mice. It was also observed that IR-CFE could markedly alleviate the ⁶⁰Coγ-induced oxidative stress via increasing the activities of superoxide dismutase and glutathione peroxidase, enhancing the levels of glutathione, and decreasing the contents of malondialdehyde in serum, liver, and spleen. In addition, IR-CFE also could reduce the activities of alanine transaminase and aspartate aminotransferase in serum, thereby reducing radiation damage to the liver. These results suggested that IR-CFE could be considered as potential candidates for natural radioprotective agents. This study provides a theoretical basis for improving the application of lactic acid bacteria.

Chemical and biological basis for development of novel radioprotective drugs for cancer therapy

Ionizing radiation (IR) causes chemical changes in biological systems through direct interaction with the macromolecules or by causing radiolysis of water. This property of IR is harnessed in the clinic for radiotherapy in almost 50% of cancers patients. Despite the advent of stereotactic radiotherapy instruments and other advancements in shielding techniques, the inadvertent deposition of radiation dose in the surrounding normal tissue can cause late effects of radiation injury in normal tissues. Radioprotectors, which are chemical or biological agents, can reduce or mitigate these toxic side-effects of radiotherapy in cancer patients and also during radiation accidents. The desired characteristics of an ideal radioprotector include low chemical toxicity, high risk to benefit ratio and specific protection of normal cells against the harmful effects of radiation without compromising the cytotoxic effects of IR on cancer cells. Since reactive oxygen species (ROS) are the major contributors of IR mediated toxicity, plethora of studies have highlighted the potential role of antioxidants to protect against IR induced damage. However, owing to the lack of any clinically approved radioprotector against whole body radiation, researchers have shifted the focus toward finding alternate targets that could be exploited for the development of novel agents. The present review provides a comprehensive insight in to the different strategies, encompassing prime molecular targets, which have been employed to develop radiation protectors/countermeasures. It is anticipated that understanding such factors will lead to the development of novel strategies for increasing the outcome of radiotherapy by minimizing normal tissue toxicity.

Radicals in 'biologically relevant' concentrations behave differently: Uncovering new radical reactions following the reaction of hydroxyl radicals with DMSO

Methyl radicals play key roles in various chemical and biological processes. Mechanistic studies of methyl radicals with their precursor, Dimethyl Sulfoxide (DMSO), were extensively studied. Though the involved mechanisms seemed to be clarified, essentially none of the studies have been performed at conditions relevant to both biological and catalytic systems, i.e. low steady state radical concentrations. A chain-like reaction, as an inverse function of the radicals concentrations ([^•CH₃]_ss), increases the methyl radical yields. The nature of the additional products obtained differs from those commonly observed. Furthermore it is shown that methyl radicals abstract a methyl group from DMSO to yield ethane. Herein we report a novel mechanism relevant mainly at low steady state radical concentrations, which may change the understanding of certain reaction routes present in both biological systems and catalytic chemical systems. Thus the results point out that mechanistic studies have to be carried out at dose rates forming radicals at analogous concentrations to those present in the process of interest.

5-Nitro-2,4-Dichloropyrimidine as an Universal Model for Low-Energy Electron Processes Relevant for Radiosensitization

We report experimental results of low-energy electron interactions with.