PHILADELPHIA - Bioengineers at the University of Pennsylvania have created a system to control the flexibility of the substrate surfaces on which cells are grown without changing the surface properties, providing a technique for more controlled lab experiments on cellular mechanobiology, an important step in the scientific effort to understand how cells sense and respond to mechanical forces in their environment.
Researchers created a library of micromolded, hexagonally spaced elastomeric micropost arrays, one to a few microns high, on which they cultivated cells. The micropost system allowed engineers to modulate the rigidity and flexibility of the substrate surface without changing the adhesive or other material surface properties that could affect cell growth. Post height determined the degree to which a post would bend in response to a cell's horizontal traction force. The system enabled researchers to map cell traction forces to individual focal adhesions and spatially quantify sub-cellular distributions of focal-adhesion area, traction force and focal-adhesion stress.
The research, published in the current issue of the journal Nature Methods, demonstrated that the height of the posts determined the flexibility of the surface substrate, which in turn impacted the cell's morphology, leading to differences in focal adhesions, cytoskeletal contractility and stem-cell differentiation. Furthermore, early changes in cytoskeletal contractility measured by the devices predicted lineage fate decisions made days later by the stem cells.
"The library of micropost arrays spanned a more than 1,000-fold range of rigidity from 1.31 nN μm−1 up to 1,556 nN μm−1," said Chris Chen, lead author and the Skirkanich Professor of Innovation in Bioengineering in the School of Engineering and Applied Science at Penn. "Furthermore, the micropost array library will be made available to researchers in other laboratories."
|Contact: Jordan Reese|
University of Pennsylvania