Evidence for the presence of stem cell-like progenitor cells in human adult pancreas.

The origin of cells replacing ageing beta-cells in adult life is unknown. This study assessed the expression of classic stem cell markers: Oct4, Sox2 and CD34 in islet-enriched fractions versus exocrine cell-enriched fractions from 25 adult human pancreases following human islet isolation. Expression of Oct4, Sox2 and CD34 mRNAs was found in all cell samples, with no significant differences between endocrine and exocrine cell fractions. Immunohistochemical staining for Oct4, Sox2, CD133, CD34, CK19, insulin and nestin on human pancreas sections showed that the majority of Oct4(+ve) cells were found in the walls of small ducts. Similar localisations were observed for Sox2(+ve) cells. The majority of Sox2(+ve) cells were found to co-express Oct4 proteins, but not vice versa. Cells positive for Oct4 and Sox2 appeared to be a unique cell population in the adult human pancreases without co-expression for CK19, CD34, CD133, insulin and nestin proteins. The numbers of Oct4(+ve) and Sox2(+ve) cells varied among donors and were approximately 1-200 and 1-30 per 100 000 pancreatic cells respectively.