Texas A&M Just Figured Out
How to Freeze a Transplant Organ
Without Cracking It.
- 104,000+on the waitlistAmericans waiting for an organ transplant — HRSA · 2025
- 17die per dayU.S. patients on the transplant waitlist who die before a match arrives — HRSA
- Hourscurrent shelf lifekidneys: ~24-36 hours · hearts and lungs: 4-6 hours · the entire system runs on perishable supply
- Tuned Tgthe breakthroughPowell-Palm: tuning the glass-transition temperature of vitrification solutions stops the cracking that has historically killed cryopreserved organs
Cryopreservation of human organs is, in the abstract, exactly what the U.S. transplant system needs. 104,000 Americans are currently on the organ waitlist. 17 of them die every day, on average, before a match arrives. The reason is not that we lack matched donors — it’s that we cannot store an organ longer than its perishable hour count. A kidney is good for 24-36 hours after harvest. A heart or a lung is good for 4 to 6. After that, the cells that make the organ work begin breaking down, and the transplant becomes impossible. There is no organ “bank” in the way there is a blood bank.
Cryopreservation should solve that. In theory: drop the temperature far enough, fast enough, that water in the tissue doesn’t form ice crystals (which shred cell membranes) and instead enters a glass-like solid state — a process called vitrification. The technique works for embryos, sperm, eggs, and small tissue samples. It has not worked, reliably, for whole organs. Two reasons: ice crystals on the warming-back-up phase, and physical cracking of the vitrified tissue under the thermal stresses of the cool-down and re-warming cycle.
Dr. Matthew Powell-Palm, primary investigator at the J. Mike Walker ‘66 Department of Mechanical Engineering at Texas A&M, working with Dr. Soheil Kavian, PhD students Crystal Alvarez and Ron Sellers, undergraduate Gabriel Arismendi Sanchez, and Department Head Dr. Guillermo Aguilar, attacked the second of those two problems — the cracking. The paper appeared in Scientific Reports, volume 15(1), 2025.
The team’s insight is straightforward in retrospect, which is the highest form of compliment one engineer can pay another: the cracking happens because the cryoprotectant solution and the surrounding tissue have different glass-transition temperatures (Tg). When the system cools through Tg, those mismatches generate enough internal stress to fracture the vitrified specimen. Adjust the chemistry of the cryoprotectant cocktail to raiseTg — and align it more closely with the tissue’s own thermal response — and the cracking stops.
“Higher glass transition temperatures reduce the likelihood of cracking.”
Dr. Matthew Powell-Palm, Texas A&M University · Scientific Reports 15(1), 2025
Glass transition (Tg): the temperature at which an amorphous solid (like glass, or a vitrified tissue specimen) transitions between a rigid, brittle state and a more pliable, rubbery state. Below Tg, the material is a true solid — molecules locked in place — and is mechanically vulnerable to thermal stress.
Cryoprotectant cocktail: the chemical mixture that replaces water in the tissue before freezing, so that crystals don’t form. Standard cryoprotectants include DMSO, ethylene glycol, and various sugars. Powell-Palm’s contribution: tune that mixture to raise its Tg above the temperature range where the cracking propagation peaks.
Why this matters beyond transplants: applications in vaccine cold-chain (longer shelf life at less expense), wildlife genetic preservation (banking germline tissue from endangered species), and food preservation. The technique is not organ-specific.
The Powell-Palm paper solves oneof the two big remaining problems with whole-organ cryopreservation. The other — ice-crystal formation during re-warming, especially through the “dangerous” temperature zone between -150°C and 0°C — is being attacked by other groups (notably the University of Minnesota team using nanoparticle-mediated rewarming, and the Berkeley/Stanford collaboration on isochoric pressure systems). Solve both, and bankable organs become real on a 5-10 year horizon. Solve only this one, and you have improved tissue and small-organ preservation, plus a measurably better bench-research tool, but not yet a kidney bank.
What does become real, faster: the National Science Foundation’s Engineering Research Center for Advanced Technologies for the Preservation of Biological Systems (ATP-Bio), which funded the work, gets a meaningful win on the cracking-prevention pillar of its multi-year roadmap. Vaccine cold-chain applications get cheaper. Wildlife conservation programs get a usable banking pipeline. Food-preservation research gets new chemistry to work with. And the field of cryobiology gets, for the first time in a long time, a paper that lands a real engineering result on a sixty-year-old problem.
The organ transplant system in this country runs on a stopwatch. Powell-Palm’s paper does not stop the clock. It makes one of the two fundamental obstacles to stopping the clock — structural fracturing of vitrified tissue — tractable engineering instead of theoretical problem. The next breakthrough is rewarming. When that lands, the kidney that came out of a Houston donor on a Friday can be transplanted into a recipient in Maine on a Tuesday. The 17-a-day number falls. The waitlist falls. The math of organ donation in America changes. Texas A&M just took the first hard step.