In vitro differentiation into insulin-producing β-cells of stem cells isolated from human amniotic fluid and dental pulp.

AIM To investigate the ability of human amniotic fluid stem cells and human dental pulp stem cells to differentiate into insulin-producing cells. METHODS Human amniotic fluid stem cells and human dental pulp stem cells were induced to differentiate into pancreatic β-cells by a multistep protocol. Islet-like structures were assessed in differentiated human amniotic fluid stem cells and human dental pulp stem cells after 21 days of culture by dithizone staining. Pancreatic and duodenal homebox-1, insulin and Glut-2 expression were detected by immunofluorescence and confocal microscopy. Insulin secreted from differentiated cells was tested with SELDI-TOF MS and by enzyme-linked immunosorbent assay. RESULTS Human amniotic fluid stem cells and human dental pulp stem cells, after 7 days of differentiation started to form islet-like structures that became evident after 14 days of induction. SELDI-TOF MS analysis, revealed the presence of insulin in the media of differentiated cells at day 14, further confirmed by enzyme-linked immunosorbent assay after 7, 14 and 21 days. Both stem cell types expressed, after differentiation, pancreatic and duodenal homebox-1, insulin and Glut-2 and were positively stained by dithizone. Either the cytosol to nucleus translocation of pancreatic and duodenal homebox-1, either the expression of insulin, are regulated by glucose concentration changes. Day 21 islet-like structures derived from both human amniotic fluid stem cells and human dental pulp stem cell release insulin in a glucose-dependent manner. CONCLUSION The present study demonstrates the ability of human amniotic fluid stem cells and human dental pulp stem cell to differentiate into insulin-producing cells, offering a non-pancreatic, low-invasive source of cells for islet regeneration.