Background: Cell-therapy provides a promising alternative for the treatment of type 1 diabetes. Monocytes which have a reprogramming or differentiation potential and are more available than any other types of stem cells, have been recognized as candidates for such investigations. The aim of the present study was to evaluate the differentiation potential of rat peripheral blood monocytes into insulin-producing cells by the use of rat pancreatic extract (2 days after a 60% pancreatectomy).

Methods: Rat peripheral blood monocytes were isolated and cultured. Adherent monocytes were induced to differentiate into programmable cells in RPMI supplemented by 10% FCS, β-mercaptoetanol, M-CSF and IL-3 for six days. The dedifferentiated cells were analyzed by invert microscopy. Cultures of Programmable Cells of Monocytic Origin (PCMOs) were continued in RPMI, containing 10% FBS, pancreatic extract and 5 mmol/L glucose for 15 days. The medium was replaced every three days. At the end of the protocol, insulin and c-peptide excreted by the differentiated cells were tested by radioimmunoassay on days 6, 14, and 21. In order to verify insulin production in the cells, dithizone-staining, which is a method for insulin identification, was employed.

Results: The results showed that the cells cultured in rat pancreatic extract secreted insulin and c-peptide relative to the control group. Dithizone-staining was positive in the aforesaid cells (P<0/05).

Conclusion: The results of the current study showed that pancreatic extract treatment can differentiate rat peripheral blood monocytes into insulin-producing cells which can be regarded as a potential source for the treatment of diabetes.