This idea quickly evolved into an elegant tool designed expressly for biologists.
The device involves two separate comb-shaped pieces coated with living cells. These two pieces can click into place at two settings: One allows cells on the edges of the combs to touch, the other maintains a gap of 80 micrometers, or about four cell widths. The assembly is geared so that switching between these two settings involves a movement of two millimeters, an amount controllable by the human hand. Hui selected 80 micrometers as the gap setting because at shorter distances, cells sometimes migrate across the gap and end up touching. And at wider distances, some soluble signals drop off.
Bhatia and Hui have used the new device to study liver cells. The two found that to get liver cells to express specific liver functions, they needed to touch supporting stromal cells for 18 hours. For the liver cells to survive and continue to act as liver cells, they don't have to keep touching these stromal cells, but they do need to stay close.
The finding will allow Bhatia and Hui to examine more deeply which surface molecules trigger liver cell differentiation and which soluble molecules maintain it.
Such information will help the team devise different approaches to engineering liver therapeutics by helping them understand exactly which signals are needed to support specific liver cell functions. Instead of building an entire liver from scratch, Bhatia wants to isolate the key cell type, "the business end of the organ," and get it to work without replicating the entire cellular environment that supports it. "If you can get away with it, you want to get rid of the supporting cells," she says.
This simple device
Source:Massachusetts Institute of Technology