Research Magazine 2006

Freezing human tissue

Bumsoo Han

Isaac Asimov novels and Woody Allen and Mel Gibson movies all have explored preserving human bodies through freezing. Rumors even exist that Walt Disney had his body frozen after death so he could be brought back to life if a cure is found for the disease that killed him.

But the question remains whether the science of cryonics is possible or even effective in the long-term preservation of the human body. It’s also the question that mechanical engineering Assistant Professor Bumsoo Han explores through a $400,000 CAREER program award. Granted in January 2008, the award funds high-quality imaging systems, graduate student research assistants and a program for summer scholars.

Bumsoo Han

Dr. Han has conducted research at UT Arlington for four years as part of the aerospace engineering program. His work looks at freezing human tissues, such as skin, to determine the physical effects of the process and the long-term potential for cryopreservation.

Cryopreservation is a process where cells or whole tissues are preserved by cooling to subzero temperatures. This stops biological activity, including the biochemical reactions that lead to cell death.

“Right now we can use freezing to preserve individual cells,” Han says. “But we have very limited ability in tissues because they are complex, three-dimensional architectures of heterogeneous cells.”

Small clumps of individual cells, such as semen, blood cells and human eggs and embryos, can be preserved with cryoprotectants that act like antifreeze to protect biological tissue by decreasing ice crystal formation.

“We are looking at how we can preserve tissue in the long term and how tissues respond to freezing without losing functionality.”

However, tissue cryopreservation needs to maintain three-dimensional cellular architectures as well as individual cell viability. These three-dimensional architectures are critical to tissue functionality.

“We are looking at how tissues respond to freezing and how we can preserve tissue in the long term without losing functionality,” Han says.

To determine this, he and his graduate student researchers use a fluorescence microscope that lets them visualize the physical changes that take place in the microstructure of the cells and tissue during the freezing process.

He wants to understand the physics of the process as a prelude to determining ways to minimize the damage. He’s working with artificial tissues engineered to mimic biological functions. One of the most promising is artificial skin for burn victims. He hopes to discover how to freeze the artificial tissues and then duplicate the results in the lab using human tissue.

Han knows one thing for sure: Science has a long way to go before it catches up with the imagination of novelists and movie directors. But he’s doing everything he can to get there—one frozen cell at a time.

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- Becky Purvis