Expression of Pancreatic Endocrine Markers by Prolactin-Treated Rat Bone Marrow Mesenchymal Stem Cells

Background

Mesenchymal stem cells (MSCs) are an attractive source for generation of cells with β-cell properties. Previous studies have demonstrated the ability of prolactin to induce an increase in β-cell mass and maturation, which suggests beneficial effects of its use in MSC differentiation protocols.

Objective

To evaluate the expression of endocrine differentiation markers in rat MSCs treated in vitro with prolactin.

Methods

Mesenchymal stem cells from bone marrow of Wistar rats were isolated, expanded, and characterized. Differentiation of MSCs was induced in medium containing 23 mmol/L of glucose, and nicotinamide, 2-mercaptoethanol, and exendin-4, in the presence or absence of 500 ng/mL of rat recombinant prolactin. Expression of endocrine markers and prolactin receptor genes was evaluated using real-time polymerase chain reaction, and compared between culture stages and presence vs absence of prolactin in the culture medium. Expression of insulin, somatostatin, glucagon, and pancreatic and duodenal homeobox 1 was also evaluated at immunofluorescence microscopy.

Results

Isolated cells were mostly MSCs, as confirmed at fluorescent-activated cell sorting and cytochemistry. Pax6, Ngn-3, Isl1, NeuroD1, Nkx2.2, and Nkx6.1 exhibited varied expression during culture stages. The long form of the prolactin receptor messenger RNA was induced in prolactin-treated cultures (P < .05). The somatostatin gene was induced in early stages of differentiation (P < .05), and its expression was induced by prolactin, as confirmed using immunofluorescence.

Conclusion

Culture of rat bone marrow MSCs in differentiation medium induces expression of pancreatic endocrine-specific genes, and somatostatin and prolactin receptor expression was also induced by prolactin.