A team of researchers from the Massachusetts General Hospital Center for Engineering in Medicine (MGH-CEM) has found the first evidence of cell-to-cell communication by amino acids, the building blocks of proteins, rather than by known protein signaling agents such as growth factors or cytokines. Their report will appear in an upcoming issue of The FASEB Journal and has been released online.

"We were taken by complete surprise," says Rohit Jindal, PhD, a postdoctoral fellow at MGH-CEM and the paper's lead author. "Past reports have implicated various growth factors and the extracellular matrix proteins secreted by other cell types in regulating hepatocyte behavior, but to the best of our knowledge, this is the first evidence that cells can communicate by changing local amino acid concentrations."

The authors describe the development of a three-dimensional model of liver tissue in which hepatocytes (liver cells) are embedded in a layer of collagen and covered with a layer of endothelial cells - the cells that line blood vessels, which permeate the liver…