Biologists tend to look at cells in bulk, observing them as a group and taking the average behavior as the norm the assumption is that genetically identical cells all behave the same way. In a paper to be published in the online Early Edition of Proceedings of the National Academy of Sciences the week of March 7, 2011, Sam Sia, assistant professor of biomedical engineering at Columbia Engineering, presents the results of his four-year tissue-engineering study that show a surprising range of variation in how individual cells behave during formation of a blood vessel. Sia and his team used a new method to painstakingly observe and track individual behaviors, characterizing, for the first time, what happens when human endothelial cells move from an initial dispersed state to the formation of capillary-like structures.
"We were really surprised by this behavior," says Sia, who was named one of the world's top young innovators for 2010 by MIT's Technology Review for his work in biotechnology and medicine. "In contrast to the population-averaged behavior that most studies report, most individual cells followed distinct patterns of cell-shape changes that were not reflected in the bulk average."
This is one of the first explicit studies to look at the variations between cells during tissue formation, and overturns the assumption that genetically identical cells behave in generally similar ways. Using a systematic approach to quantifying the changes in cell shape and movement for every single endothelial cell over time, the Columbia Engineering team found unexpected hidden patterns in behavior. In addition to discovering that most cells behave differently from the average, the team also observed that groups of cells behaved in similar fashions, and that some of these clusters of behavior resulted in distinct structural roles in the final blood-vessel network.
The origins of the variations in behavior are not known right now. Sia note
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