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Certain stem cells linked to obesity

jbrehm2, May 12, 2014 | View original publication

Certain stem cells linked to obesity

A type of stem cell that morphs into fat cells may hold secrets to reducing obesity, a major public health problem. A University of Nebraska-Lincoln engineer's research to understand that process may one day lead to therapies to control obesity.

            Jung Yul Lim, assistant professor of mechanical and materials engineering, has earned a five-year, $430,554 Faculty Early Career Development Program Award from the National Science Foundation for this research. These grants, known as CAREER awards, support pre-tenure faculty who exemplify the role of teacher-scholars through outstanding research, excellent education and the integration of education and research.

            Mesenchymal stem cells (MSC) are simple, self-regenerating cells capable of turning into a variety of specialized cell types, including bone, skin, muscle and fat. Studies show that one biological process causing obesity is an increase in MSC differentiation into fat cells, a process called adipogenesis.

            "This project aims to understand how MSCs choose their fate," Lim said. "If we can inhibit in some way the MSC adipogenesis, it may be a treatment method for obesity."

            Lim's preliminary research has found that "stretching" the cells suppresses adipogenesis. By seeding cells onto an elastic membrane, Lim can apply a mechanical stretching force to the cells. Then he waits to see what they do.

            "That stretching motion is mimicking some of the actual stretching motion in our bodies, like walking, running," Lim said. "It varies depending on cell type and the position inside the body, but generally cells are exposed to a mechanical stretching motion every day."

            The CAREER award allows Lim to further explore how different stretching conditions affect MSC adipogenesis, such as the amount of stretch, or strain, applied. Other conditions include a continuous versus stretch-and-relax motion, or sinusoidal stretching, as well as the frequency of that motion. He'll also investigate stretching's effect at different stages of MSC evolution into fat cells.

            Lim also is investigating the molecular mechanisms underlying how stretching inhibits adipogenesis. Finding the proteins or genes responsible may lead to future therapies, he said.

            To do that, he will use molecular biology techniques to turn off, or silence, several genes responsible for producing proteins involved in allowing cells to stick to each other and their surroundings, a mechanism researchers suspect is involved. If the altered cells don’t exhibit the same inhibition when stretched as normal cells, then Lim can infer that the silenced protein or protein complex is involved.

            The CAREER award also allows Lim to continue developing curricula on stem cell-based bioengineering and to train graduate and undergraduate students in his lab. Additionally, Lim will continue a program he developed to help home-schooled students gain laboratory experience.

            More information is available on Lim's lab homepage,