"Modeled microgravity" affects cell response to ionizing radiation and increases genomic damage.

Area of Science:

• Cell biology
• Radiation biology
• Space biology

Background:

• Understanding cellular responses to ionizing radiation is crucial, especially in environments like space where microgravity may alter these responses.
• Ionizing radiation poses risks to astronauts, and factors influencing cellular radiosensitivity require thorough investigation.

Purpose of the Study:

• To investigate the impact of modeled microgravity on the cellular response of lymphoblastoid TK6 cells to gamma irradiation.
• To determine if modeled microgravity affects cell survival, apoptosis, cell cycle, and genomic damage following radiation exposure.

Main Methods:

• Lymphoblastoid TK6 cells were exposed to various doses of gamma rays.
• Cells were subsequently incubated in a modeled microgravity environment using a Rotating Wall Vessel bioreactor or under standard 1g conditions.
• Assessed endpoints included cell survival, apoptosis, cell cycle progression, HPRT mutant frequency, and micronucleus formation.

Main Results:

• Modeled microgravity significantly reduced the number of apoptotic cells post-irradiation compared to 1g conditions.
• Irradiated cells in modeled microgravity showed fewer cells in the G2 phase and more cells in the G1 phase.
• Genomic damage, measured by HPRT mutant frequency and micronucleus assay, was higher in cells incubated in modeled microgravity after irradiation.

Conclusions:

• Modeled microgravity alters cellular responses to ionizing radiation by reducing radiation-induced apoptosis.
• The reduced apoptosis in microgravity leads to an increased frequency of surviving cells with radiation-induced genomic damage.
• These findings suggest that microgravity may enhance the risks associated with radiation exposure by promoting the survival of damaged cells.