In the second reporting period of the project, we have further defined the operating principles of the PULSE device. We have refined a mathematical and numerical model of the system, which provides insights on the required process parameters to perform magneto-acoustic levitation. The refined model provides a better understanding of how cellular spheroids would be first brought together by magnetic levitation and then shaped into the final tissue construct by acoustic levitation. Accordingly, the first prototype capable of both magnetic and acoustic levitation within a closed bioassembly chamber was designed, manufactured and assembled for ground experiments. The first prototype of the PULSE magneto-acoustic levitation device has gone through a number of iterations to provide a system that could work on ground (Earth), yet being qualified also for operating on the ISS. The design is currently being finalized to enter into testing and validation phase for space mission in 2026. In parallel, we have generated an adapted design to be launched for a parabolic flight in October 2025. The parabolic flight serves as an intermediate experimental testbed for the device under conditions that simulate the closest possible the launch to ISS in 2027. Currently, the ground experiments include polystyrene beads for the validation of the levitation process as well as cell spheroids and organoids for optimizing process parameters of the PULSE device.
Hydrogel selection has been completed, identifying hydrogels specific compositions as best candidates for all cells. In particular, the selected hydrogels showed to support the culture of the cardiovascular cells and cardioids, supporting vascularization.
We have further characterized endothelial cells, cardiomyocytes, cardiofibroblasts, and cardioids in culture conditions emulating some of the challenging microenvironment conditions that cells will experience during transport and launching to the ISS. Results showed that cells are robust to maintain viability and functionality in refrigerated conditions with specific culture media conditions.
We have developed a complete framework as preparatory work on primary and commercial human cardiovascular cell lines to identify a suitable platform and model for testing under simulated microgravity conditions and to elucidate possible effects on target cells. We validated the space condition simulator platform and obtained preliminary results of the effect of radiotherapy radiation and microgravity on heart organoids.
We have further refined the requirements for launching of the PULSE device to the ISS. We have established the initial system engineering framework for the qualification and performance verification of the PULSE bioprinter. The document defines model philosophy, verification subjects, verification approach, verification strategy, and verification tools. The verification campaign will include several types of tests. Qualification and environmental tests, including random vibration, EMC, DC magnetic field, micro-g disturbances, audible noise, leak test, and proof pressure tests. Interface tests will be conducted using the PULSE device and the ground model of the ICE Cubes Facility, ensuring mechanical and electrical fit, as well as compatibility with communication, software, and thermal interfaces. Functional tests will be conducted to verify functional and performance requirements. The functional test campaign will be complemented by extensive breadboard testing for each subsystem.
Finally, we are building the PULSE stakeholder network, engaging a wide range of partners to build confidence on PULSE technology. To do so, we have set up an advisory board with key representatives from several sectors close to the PULSE innovation, and we started to contact ESA groups involved in the follow-up of the technology in space. We are also reaching out to a vast network of students and young generation scientists connected to space medicine and tissue engineering via the organization of a summer school. Next steps will involve building relationships with pharma companies interested in cardiac organoids, ESA, and the ISS National Laboratory.
