RESUMO
PURPOSE: Type 1 diabetes is an autoimmune disease caused by the destruction of ß-cells in the pancreas. Bone marrow mesenchymal stem cells are multipotent and easy accessible adult stem cells that may provide options in the treatment of type 1 diabetes. Injured pancreatic extract can promote the differentiation of rat bone marrow mesenchymal stem cells into ß-cells. We aimed to observe the effect of quercetin in differentiation and insulin secretion in ß-cells. METHODS: Bone marrow mesenchymal stem cells were obtained from the tibiae of rats. Cell surface markers were analyzed by flow cytometry. The cells were treated with rat injured pancreatic extract and quercetin for 2 weeks. Insulin secretion was measured by ELISA. Insulin expression and some islet factors were evaluated by RT-PCR. PDX1, a marker for ß-cell function and differentiation, was evaluated by both immunocytochemistry and Western blot. ß-cell count was determined by stereology and cell count assay. RESULTS: ELISA showed significant differences in insulin secretion in the cells treated with RIPE + 20 µM quercetin (0.55 ± 0.01 µg/L) compared with the cells treated with RIPE alone (0.48 ± 0.01 µg/L) (P = 0.026). RT-PCR results confirmed insulin expression in both groups. PDX1 protein was detected in both groups by Western blot and immunocytochemistry. Stereology results showed a significant increase in ß-cell number in the RIPE + quercetin-treated cells (47 ± 2.0) when compared with RIPE treatment alone (44 ± 2.5) (P = 0.015). CONCLUSIONS: Quercetin has a strengthening effect on the differentiation of rat bone marrow mesenchymal stem cells into ß-cells and increases insulin secretion from the differentiated ß-cells in vitro.