Betacellulin (BTC), a
ligand of the
epidermal growth factor receptor, has been shown to promote growth and differentiation of pancreatic β-cells and to improve
glucose metabolism in experimental diabetic rodent models. Mesenchymal stem cells (MSCs) have been already proved to be multipotent. Recent work has attributed to rat and human MSCs the potential to differentiate into insulin-secreting cells. Our goal was to transfect rat MSCs with a plasmid containing BTC
cDNA to guide MSC differentiation into
insulin-producing cells. Prior to induction of cell MSC transfection, MSCs were characterized by flow cytometry and the ability to in vitro differentiate into mesoderm cell types was evaluated. After rat MSC characterization, these cells were electroporated with a plasmid containing BTC
cDNA. Transfected cells were cultivated in Dulbecco's modified Eagle medium high
glucose (H-DMEM) with 10 mM
nicotinamide. Then, the capability of MSC-BTC to produce
insulin in vitro and in vivo was evaluated. It was possible to demonstrate by radioimmunoassay analysis that 10(4) MSC-BTC cells produced up to 0.4 ng/mL of
insulin, whereas MSCs transfected with the empty vector (negative control) produced no detectable
insulin levels. Moreover, MSC-BTC were positive for
insulin in immunohistochemistry assay. In parallel, the expression of pancreatic marker genes was demonstrated by molecular analysis of MSC-BTC. Further, when MSC-BTC were transplanted to
streptozotocin diabetic rats, BTC-transfected cells ameliorated
hyperglycemia from over 500 to about 200 mg/dL at 35 days post-
cell transplantation. In this way, our results clearly demonstrate that BTC overabundance enhances
glucose-induced insulin secretion in MSCs in vitro as well as in vivo.