From in vitro to in vivo: New Frontiers for Studying Muscle Degeneration

Jeong-Su Kim, an assistant professor in FSU's College of Human Sciences, studies sarcopenia, the atrophying of skeletal muscle generally brought on by aging. For his studies, Kim uses older rats and mice whose muscles have begun to experience the metabolic and microstructural changes that occur as animals age.

Kim (facing camera) and his postdocs perform surgery on an animal.

Kim is collaborating with MagLab engineer Sam Grant to develop new techniques for researching this condition, which until now has been studied almost exclusively in vitro, i.e., removing tissue from human or animal patients, in order to analyze the samples at the cellular level. In this way scientists do crossover studies that compare a group of younger animals to a group of older animals.

But in vitro crossover studies have their limits. They're not practical for studying the progression of muscle deterioration over months or years.

"Pretty much all the cell-level sarcopenia study is done by in vitro tissue," said Kim. "We want to do in vivo muscle fiber size determination using magnetic resonance, especially in the 900 MHz magnet. The 900 is sensitive enough to actually estimate change in muscle cell size without sacrificing the animal, so we can do longitudinal studies with the same animal over the years – maybe from when it's born to when it dies – seeing what's happening in the cell size."

MRI image of the skeletal muscles of a rat's hind leg.

In sarcopenia, the skeletal muscle cells shrink, causing loss of muscle mass, strength and functionality. Diet and exercise can slow this process and improve quality of life for seniors; Kim is studying proteins and genes involved in skeletal muscle regeneration to see how exercise can reduce the rate of sarcopenia.

Kim doesn't have any answers yet; they are still developing and testing techniques for exploiting this very powerful magnet. But in vivo experiments promise to provide new insights into sarcopenia and open up entire new areas of research.

"I was so excited at the beginning when I heard what's possible [with the 900]," said Kim. "It's going to be a slow process, but I think it's doable."

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