Hibernation and Radioprotection: Gene Expression in the Liver and Testicle of Rats Irradiated under Synthetic Torpor.

Hibernation has been proposed as a tool for human space travel. In recent years, a procedure to induce a metabolic state known as "synthetic torpor" in non-hibernating mammals was successfully developed. Synthetic torpor may not only be an efficient method to spare resources and reduce psychological problems in long-term exploratory-class missions, but may also represent a countermeasure against cosmic rays. Here we show the preliminary results from an experiment in rats exposed to ionizing radiation in normothermic conditions or synthetic torpor. Animals were irradiated with 3 Gy X-rays and organs were collected 4 h after exposure. Histological analysis of liver and testicle showed a reduced toxicity in animals irradiated in torpor compared to controls irradiated at normal temperature and metabolic activity. The expression of ataxia telangiectasia mutated (ATM) in the liver was significantly downregulated in the group of animal in synthetic torpor. In the testicle, more genes involved in the DNA damage signaling were downregulated during synthetic torpor. These data show for the first time that synthetic torpor is a radioprotector in non-hibernators, similarly to natural torpor in hibernating animals. Synthetic torpor can be an effective strategy to protect humans during long term space exploration of the solar system.

Modelling a new approach for radio-ablation after resection of breast ductal carcinoma in-situ based on the BAT-90 medical device.

The majority of local recurrences, after conservative surgery of breast cancer, occurs in the same anatomical area where the tumour was originally located. For the treatment of ductal carcinoma in situ (DCIS), a new medical device, named BAT-90, (BetaGlue Technologies SpA) has been proposed. BAT-90 is based on the administration of 90Y ß-emitting microspheres, embedded in a bio-compatible matrix. In this work, the Geant4 simulation toolkit is used to simulate BAT-90 as a homogenous cylindrical 90Y layer placed in the middle of a bulk material. The activity needed to deliver a 20 Gy isodose at a given distance z from the BAT-90 layer is calculated for different device thicknesses, tumour bed sizes and for water and adipose bulk materials. A radiobiological analysis has been performed using both the Poisson and logistic Tumour Control Probability (TCP) models. A range of radiobiological parameters (α and ß), target sizes, and densities of tumour cells were considered. Increasing α values, TCP increases too, while, for a fixed α value, TCP decreases as a function of clonogenic cell density. The models predict very solid results in case of limited tumour burden while the activity/dose ratio could be further optimized in case of larger tumour beds.

Hibernation for space travel: Impact on radioprotection.

Hibernation is a state of reduced metabolic activity used by some animals to survive in harsh environmental conditions. The idea of exploiting hibernation for space exploration has been proposed many years ago, but in recent years it is becoming more realistic, thanks to the introduction of specific methods to induce hibernation-like conditions (synthetic torpor) in non-hibernating animals. In addition to the expected advantages in long-term exploratory-class missions in terms of resource consumptions, aging, and psychology, hibernation may provide protection from cosmic radiation damage to the crew. Data from over half century ago in animal models suggest indeed that radiation effects are reduced during hibernation. We will review the mechanisms of increased radioprotection in hibernation, and discuss possible impact on human space exploration.