Pancreatic cell size linked to mammalian lifespan, finds zoo animal analysis

June 18, 2018, Cell Press

More than two thousand years ago, Greek philosopher Aristotle observed that larger animals tend to live longer than smaller ones. On June 18 in the journal Developmental Cell, scientists report that it's cell size, not body size, that intrinsically correlates with and perhaps affects lifespan. By examining the pancreases of 24 mammalian species—including shrews, humans, and tigers—researchers in Israel, Canada, and Germany found that animals with larger pancreatic cells tend to age faster, while smaller cells seem to go hand in hand with longer lifespans.

"That there was a correlation between two things that are so remote was shockingly beautiful and unexpected," says senior author Yuval Dor, who studies developmental biology at the Institute for Medical Research Israel-Canada and The Hebrew University-Hadassah Medical School in Jerusalem.

"This study has exposed a trend that seems to transcend all animal life," says co-author Ran Kafri, a computational biologist at the University of Toronto and the Hospital for Sick Children in Canada. "It demonstrates that there's a property that can be measured on a single cell that predicts the lifespan of a whole animal."

Scientists had thought that after birth, most mammals' organs, including the pancreas, grow by cell proliferation. However, Dor, Kafri, and colleagues made a serendipitous observation; they needed a higher magnification to look at pancreatic cells of new-born mice through a microscope than they did to look at those of adults, suggesting that each cell's volume was substantially increasing from infant to adult life.

Repeated measurements showed that the growth of individual exocrine pancreatic cells, known as acinar cells, is responsible for much of the overall organ growth after birth. "This was surprising because the assumption was that postnatally, the pancreas grows by increasing the number of cells just like most organs that we think about," says Dor.

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