Although many signaling pathways have been shown to promote beta-cell growth, surprisingly little is known about the normal life cycle of preexisting beta-cells or the signaling pathways required for beta-cell survival.
Adult beta-cells have been speculated to have a finite life span, with ongoing adult beta-cell replication throughout life to replace lost cells.
However, little solid evidence supports this idea.
To more accurately measure adult beta-cell turnover, scientists performed continuous long-term labeling of proliferating cells with the DNA precursor analog 5-bromo-2-deoxyuridine (BrdU) in 1-year-old mice.
They show that beta-cells of aged adult mice have extremely low rates of replication, with minimal evidence of turnover.
Although some pancreatic components acquired BrdU label in a linear fashion, only 1 in approximately 1,400 adult beta-cells were found to undergo replication per day.
Scientists conclude that adult beta-cells are very long lived.