Radiation-induced neurotoxicity: investigating human neuronal damage in MEA-integrated microfluidic platforms.

In this study, we utilized a novel microelectrode array (MEA)-integrated 3D tissue-on-a-chip platform, developed by our team, to retain human glutamatergic neuronal networks and assess their functional response to 2.5 Gy and 5 Gy gamma radiation exposure. This platform enables real-time electrophysiology monitoring and mimics the human brain tissue 3D microenvironment more accurately than traditional 2D cultures. Cell viability analysis using live/dead staining in both the 3D microfluidic device and conventional 2D cultures revealed significant radiation-induced reductions in neuronal survival, with evidence of delayed onset of cell death following exposure. Longitudinal electrophysiological (EPHYS) measurements over a one week post-irradiation period demonstrated progressive deterioration of neuronal network performance, reflected by reduced firing frequency and decreased action potential amplitude. Biochemical assessments showed a marked downregulation of creatine kinase (CK), indicating impaired metabolic capacity in irradiated neurons. Additionally, DNA methylation analysis revealed radiation-associated alterations in epigenetic regulation, suggesting persistent molecular changes that may influence long-term neuronal function. Together, these findings highlight the susceptibility of human neuronal systems to ionizing radiation and demonstrate the value of microfluidic tissue-on-chip platforms for modeling extraterrestrial health risks. The combined decline in electrophysiological activity, metabolic integrity, and epigenetic stability provides key mechanistic insights into radiation-induced neurodegeneration and supports development of targeted countermeasures for astronaut health during deep-space missions.