Cold blast: UT-Arlington researcher looks for best way to freeze human tissue

Food that has been frozen, thawed and then cooked is never quite the same as fresh food. And if freezer burn is involved? Well, may as well throw it away.

While human tissue is far different from foods, researchers are trying to determine the best way to freeze and preserve delicate tissues, like skin and organs. Just as a thawed food has a different texture when it’s thawed, human tissue often changes when it’s frozen and its functionality may be lost when it’s brought to a normal temperature again, said Bumsoo Han.

Cryopreservation — preserving something through freezing — is a field that incorporates several different specialties, from engineering to physics to computer programming and biology. That’s why it’s not unusual that an engineer, like Han, could work with cells and attempt to define protocols to preserve tissue without damaging it.

“Right now, this biological field isn’t just for biologists anymore,” said Han, an assistant professor in the department of mechanical and aerospace engineering at UT-Arlington.

Han recently received a four-year, $1.26 million grant from the National Institutes of Health to study the long-term storage of engineered human tissue, and his work at UT-Arlington will include work with skin-like cells and breast cancer cells. Work with the fibroblasts, a type of cell that provides a structural framework for many tissues, will include preserving them better with freezing, and the work with breast cancer will look at how to kill the cells with cold.

Cryopreservation already is used in some parts of science; blood banks and sperm banks, for example, make good use of lowering the temperature on human cells and then using them later. However, Han said, freezing cells is not the same as freezing tissue, which has a structure and includes thousands or millions of cells, all of which have an effect on the larger whole.

“A cell is not just sitting,” Han said.

Instead, a cell is sometimes physically changed when temperatures drop below freezing. Water is one of the few liquids that will expand as it freezes — that’s why ice cubes take up so much more space than liquid water. A cell is basically a plasma membrane filled with a saline solution, Han said, and as the cell freezes, the liquid in it can expand so much that it changes the cell’s structure or can rupture the membrane.

By studying fibroblasts under different conditions and gathering as much information about how to preserve a tissue’s functionality, Han is hoping to contribute toward a growing field that should someday have life-changing impacts. If researchers can master preserving small swathes of tissue millimeters thick, then they can apply the knowledge toward preserving more complicated structures, like organs, which currently can only be preserved for a few days at best.

Cryopreservation is a field that also is battling against some sci-fi stereotypes of frozen people being brought back from the dead. Han said this sort of re-animation is not remotely tied to the reality of science. Cryonics is the preservation of humans and animals until future resuscitation, but it’s strongly rejected by professional organizations like the Society for Cryobiology.

Just as lowering the temperature can successfully preserve tissue, it can also effectively destroy it — as evidenced by the need for further research in the field. This is also why Han is working on killing breast cancer cells by freezing them. Cryosurgery combined with other treatments, like chemotherapy, may prove to be less invasive and more effective at killing cancer cells than other treatment regimens, he said. His research will focus on determining what temperatures can kill cells the best, because some can survive temperatures as low as negative 20 degrees Celsius, and how to make the cells more susceptible to death by freezing.

Cryobiology doesn’t have applications just in medicine; Society for Cryobiology President John Critser said other life sciences, like agriculture and the pursuit of crops more resistant to harsh temperatures, can also draw on the knowledge gained about better cryopreservation.

“Almost all life sciences use cryopreservation — they may not think about it as cryobiology, but many, many labs use frozen cells or refrigerated tissue,” he said.

In addition to individual members, the society also has commercial members who provide products or services that have to do with cryopreservation, Critser said. As more research is done and techniques are refined, the commercial aspects of cryobiology also would be expected to grow, he said.

The society also is making an effort to educate the public and researchers about the realities of cryobiology and the future potential of the field, and as other fields of science gain new technology and information, the knowledge could be applied to cryobiology, he said.

“It is a challenge to get word out that how fascinating the field is, how many people are doing related things but may not know about it,” he said.

Contact Bassett at ebassett@bizpress.net