PHILADELPHIA - A certain type of adult stem cell can turn into bone, muscle, neurons or other types of tissue depending on the "feel" of its physical environment, according to researchers at the University of Pennsylvania.

The researchers discovered that mesenchymal stem cells, which regularly reside in the bone marrow as part of the body's natural regenerative mechanism, depend on physical clues from their local environment in order to transform into different types of tissue. The researchers were even able to manipulate stem cells by changing the firmness of the gel on which they were grown.

The researchers believe that their findings, which appear in the Aug. 25 issue of the journal Cell, could change the way in which people work with stem cells.

"Basically, mesenchymal stem cells feel where they're at and become what they feel," said Dennis Discher, a professor in Penn's School of Engineering and Applied Science. "The results begin to establish a physical basis for both stem-cell use against diseases and for stem-cell behavior in embryonic development,"

Much of the work in stem-cell science has involved the study of the chemical microenvironment, the soup of chemical messenger signals that are generally thought to guide stem cells through the process of differentiation, where relatively "blank" stem cells turn into specific cell types. For the first time, the Penn researchers have proven that the physical microenvironment is also crucial for guiding the cells through differentiation. According to Adam Engler, the first author on the study and a graduate student in the School of Engineering and Applied Science, soft microenvironments, that mimic the brain, guide the cells toward becoming neurons, stiffer microenvironments, that mimic muscle, guide the cells toward becoming muscle cells and comparatively rigid microenvironments guide the cells toward becoming bone.

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Contact: Greg Lester
glester@pobox.upenn.edu
215-573-6604
University of Pennsylvania
24-Aug-2006