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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