PhD Defense | Cynthia Van Rompay | Ambient temperature preservation of an advanced human cardiac model for biomedical and space research: beyond cryogenic preservation strategies

Ambient temperature preservation of an advanced human cardiac model for biomedical and space research: beyond cryogenic preservation strategies

Storing living cells and complex lab-grown tissues, such as miniature heart models, so-called cardiac organoids, is usually done by freezing them at very low temperatures. Although widely used, this method has several drawbacks, including the requirement of expensive equipment, strict temperature control, and chemicals that can damage cells. These challenges are even greater in complex three-dimensional (3D) tissues, which do not freeze evenly and often suffer damage, resulting in inconsistent outcomes after thawing. In this thesis, we explored a simpler alternative, namely preserving these cardiac organoids at room temperature instead of freezing them. The aim was to determine whether cardiac organoids can be stored while remaining viable and functional upon recovery (1), and to assess how they respond to simulated space-related conditions, such as microgravity and ionizing radiation (2).

Our results show that conventional freezing performs poorly for our cardiac organoids. After thawing, organoids were smaller, had lower energy levels, and showed increased cell death, with limited recovery over time. In contrast, organoids stored at room temperature for up to seven days in a specialized medium maintained their structure and beating activity after recovery. Even after longer preservation for fourteen days, they could recover (even if more slowly), suggesting a temporary low-activity “resting” state during preservation. When exposed to space-like conditions, microgravity had little effect, whereas ionizing radiation caused clear damage. Notably, room temperature-preserved organoids were more resilient to simulated space stressors, maintaining beating and showing delayed decline compared to non-preserved organoids. Combining microgravity and ionizing radiation did not worsen the effects beyond radiation alone. Overall, this work demonstrates that room temperature-based preservation is a viable and potentially advantageous alternative to freezing. It simplifies storage and transport, reduces costs, and improves consistency, while enabling the use of ready-to-use biological models in challenging environments such as during space missions.

Promoter(s):

Prof. Xavier Casadevall i Solvas, KU Leuven

Prof. Marianne S. Carlon, KU Leuven

SCK CEN mentor(s):

Dr. Bjorn Baselet

Dr. Kevin Tabury