Sustainable hardware development to study biological systems under altered gravity conditions

Abstract

Crewed spaceflight induces a variety of gravity-related symptoms and health issues in astronauts. Yet, underlying mechanisms are still unexplored to a large degree. In order to investigate the physiological responses of neuronal cells to altered gravity conditions on a cellular and molecular level, experiment modules needed to be developed that provide the required environmental conditions for optimal cultivation as well as in-flight analysis capabilities. Our research aims to understand how neuronal cells change their behavior and might adapt to extreme environments, such as altered (hyper- and micro-) gravity conditions. We have developed sustainable “frequent-flyer” reusable modules for the utilization on different gravity research platforms. Namely the ZARM Drop Tower (Bremen, Germany), the DLR Short-Arm Human Centrifuge (Cologne, Germany), parabolic flights (Bordeaux, France) and sounding rockets (ESRANGE, Kiruna, Sweden), such as the DLR MAPHEUS rocket. The BIODECODER module allows in-flight electrophysiological experiments, using a multi-electrode array (MEA) system to measure the synaptic activity in single neurons as well as neuronal networks. The module provides optimal cultivation conditions including thermalization, pressure stability and electromagnetic shielding. The gravity-dependence of neuronal activity changes could be recorded during altered gravity exposure on the drop tower, human centrifuge and MAPHEUS rocket flights (M-12 10/22 und M-13 05/23 und M-14 02/24). The second module, LIFT, was designed to enable fast and reliable chemical fixation of biological samples during various acceleration phases in rockets flights. Custom-designed cultivation vessels are used to enable low-shear-stress fixation of different cell types during launch (hypergravity) as well as after the microgravity phase. The modularity and reliability of the design were proven already during two rocket launches (M-13 05/23 und M-14 02/24). The versatility of the LIFT module enabled the analysis of two different cell types per flight, including IPSC-derived neurons, motoneurons and primary murine astrocytes. Both modules are optimized to meet the requirements and constraints of the mentioned platforms, while in parallel creating ideal cultivation conditions starting from sample preparation, transport to the launch vehicle, countdown delays, flight and post-processing. In order to ensure optimal conditions for the rather sensitive cells, an analogue heating system was developed and certified, to meet safety requirements, while in parallel ensuring optimal scientific conditions. Designing the modules to be suitable for different gravity research platforms increases comparability of results and allows us to answer how altered gravity conditions influence the functionality of cellular systems and thus indicate the corresponding changes in humans on the larger scale.