Cryopreservation, the process of preserving biological tissue by cooling it to extremely low temperatures, often sounds like something out of science fiction. In reality, scientists have been studying and refining this technique for nearly a century. Progress remained slow for decades, but that began to change in 2023, when researchers at the University of Minnesota successfully transplanted a cryopreserved kidney into another rat. That milestone demonstrated that frozen organs could one day be used in human transplants.
Despite that progress, preserving larger organs remains a major hurdle. One of the biggest problems is cracking, which can occur when tissues are cooled too quickly. These fractures can damage the organ and make it unusable, making crack prevention a critical goal for advancing organ preservation and transplantation.
A team at Texas A&M University, led by Dr. Matthew Powell-Palm from the J. Mike Walker '66 Department of Mechanical Engineering, has introduced a new approach aimed at addressing this issue. Their research outlines a method that could reduce the likelihood of cracking during cryopreservation.
Vitrification and the Role of Glass Transition Temperature
To keep organs viable outside the body for longer periods, scientists rely on a process called vitrification. This technique involves cooling tissue in a specialized solution until it enters a glass-like state. In this condition, cells are effectively "frozen in time" without forming damaging ice crystals.
The composition of the vitrification solution plays a key role in how well the tissue survives the process. By adjusting this mixture, researchers can examine how different properties influence the risk of cracking.
"In this study, we investigated different glass transition temperatures, which we believe play a dominant role in cracking," said Powell-Palm, an assistant professor of mechanical engineering. "We learned that higher glass transition temperatures reduce the likelihood of cracking."
Designing Safer Cryopreservation Solutions
This finding gives scientists a clearer direction for improving cryopreservation methods. By developing aqueous vitrification solutions with higher glass transition temperatures, researchers may be able to better protect organs from structural damage during freezing.
"Cracking is only one part of the problem," Powell-Palm said. "The solutions need to be biocompatible with the tissue as well."
Broader Impact Beyond Organ Transplants
Advances in cryopreservation extend far beyond transplant medicine. Improved preservation techniques could support wildlife and biodiversity conservation, enhance vaccine storage, and help reduce food waste. Because the method can prolong the viability of biological materials, it has the potential to benefit many areas of life science research and application.
"This study offers a seminal contribution to our understanding of aqueous solution thermodynamics," said co-author and Mechanical Engineering Department Head Dr. Guillermo Aguilar, who serves as the James and Ada Forsyth Professor. "I look forward to more encouraging results in this direction, which will ultimately yield an increased viability of biological systems of all scales -- from single cells to whole organs."
Research Team and Support
The study also involved Dr. Soheil Kavian, Ph.D. students Crystal Alvarez and Ron Sellers, and undergraduate student Gabriel Arismendi Sanchez, all from the mechanical engineering department.
"At its core, mechanical engineering requires an understanding of how something -- anything -- works. This project integrates physical chemistry, glass physics, thermomechanics, and cryobiology," said Powell-Palm. "These students have done an amazing job applying the holistic thinking that mechanical engineering requires to this work."
Funding for the research was provided by the National Science Foundation's Engineering Research Center for Advanced Technologies for the Preservation of Biological Systems, which supports leading-edge work in cryopreservation.
