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Taking it to heart: Researchers use engineering tools to unlock secrets of the body's natural defenses

Surgeons may be able to use the body's own natural defenses to speed recovery for heart surgery patients, thanks to recent discoveries by researchers in The University of Texas at Austin's Department of Biomedical Engineering.

Ken Diller and grad student Sihong Wang.
Photo: Marsha Miller
Ken Diller, with graduate student Sihong Wang, in his biomedical engineering lab working on HSPs, i.e. heat shock proteins that protect living cells against extreme physical and environmental stresses -- including the stress of surgery.
The engineers are studying a category of molecules called heat shock proteins (HSP) that protect living cells against extreme physical and environmental stresses, including the stress of surgery.

Naturally present in the body, HSPs — also known as molecular chaperones — multiply under conditions of elevated temperature. They function both to protect cells from harm caused by excessive heat, mechanical stress or chemical exposure, and to repair damaged cell proteins and restore cells to normal conditions of growth.

Dr. Kenneth Diller, the Joe J. King Professor in Engineering and chair of the Department of Biomedical Engineering, leads the effort to maximize HSP production in laboratory tissue cultures.

"Researchers across the world have observed the production of heat shock proteins, but there has not previously been a quantitative engineering analysis of what it takes, optimally, to produce them," Diller said.

While his work concentrates on determining the best temperatures and specific heating and cooling times, Diller speculates that tissues could one day be heated using ultrasound or other available non-invasive methods to stimulate production of the helpful proteins before surgery. Diller and doctoral students Sihong Wang and Nicole Rylander, in collaboration with Dr. Massoud Motamedi of The University of Texas Medical Branch at Galveston, are concentrating on one specific protein — HSP70 — known to be the major molecular chaperone in the heart, brain, eye and many other vital body organs.

Ken Diller
Photo: Marsha Miller
Ken Diller is the Joe J. King Professor in Engineering and chair of the Department of Biomedical Engineering.
The team’s latest laboratory results have identified an optimal combination of temperature, heating time and post-heating recovery time needed to stimulate production of HSP70 in cultures of bovine heart tissue.

The window of opportunity is crucial, Diller said. One of the strict limitations of traditional heart surgery is a four-hour "safe" period. This refers to the requirement that blood flow to the immediate region around the heart not be drastically reduced for more than four hours. After that period, necrosis (tissue death) sets in. It’s been previously shown that the more HSPs that are present, the less tissue dies.

"We’re bringing the tools of engineering to bear on understanding this problem to design clinical techniques that can be used to pre-condition tissues prior to surgery," he said. "Once we understand in a rigorous engineering way the time/temperature relationship by which cells produce these molecules, and how long the window of time we have to take advantage of their presence, we’ll be able to do that. We can design protocols that could be used to stimulate the heart prior to surgery to produce a better subsequent recovery."

By Rae Nadler-Olenick

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  Updated 2014 October 13
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