Research Article Nicotinamide induces differentiation of embryonic stem cells into insulin-secreting cells Pilar Vaca a , Genoveva Berná b , Raquel Araujo b , Everardo M. Carneiro c , Francisco J. Bedoya b , Bernat Soria b , Franz Martín b, ⁎ a Institute of Bioengineering, University Miguel Hernandez, Alicante 03550, Spain b Andalusian Center of Molecular Biology and Regenerative Medicine, CIBERDEM, Seville 41092, Spain c Institute of Biology, University of Campinas, Campinas 13.083-907, Brazil ARTICLE INFORMATION ABSTRACT Article Chronology: Received 17 July 2007 Revised version received 21 November 2007 Accepted 22 November 2007 The poly(ADP-ribose) polymerase (PARP) inhibitor, nicotinamide, induces differentiation and maturation of fetal pancreatic cells. In addition, we have previously reported evidence that nicotinamide increases the insulin content of cells differentiated from embryonic stem (ES) cells, but the possibility of nicotinamide acting as a differentiating agent on its own has never been completely explored. Islet cell differentiation was studied by: (i) X-gal staining after neomycin selection; (ii) BrdU studies; (iii) single and double immunohistochemistry for insulin, C-peptide and Glut-2; (iv) insulin and C-peptide content and secretion assays; and (v) transplantation of differentiated cells, under the kidney capsule, into streptozotocin (STZ)-diabetic mice. Here we show that undifferentiated mouse ES cells treated with nicotinamide: (i) showed an 80% decrease in cell proliferation; (ii) co-expressed insulin, C-peptide and Glut-2; (iii) had values of insulin and C-peptide corresponding to 10% of normal mouse islets; (iv) released insulin and C-peptide in response to stimulatory glucose concentrations; and (v) after transplantation into diabetic mice, normalized blood glucose levels over 7 weeks. Our data indicate that nicotinamide decreases ES cell proliferation and induces differentiation into insulin-secreting cells. Both aspects are very important when thinking about cell therapy for the treatment of diabetes based on ES cells. © 2007 Elsevier Inc. All rights reserved. Keywords: Diabetes Islet of Langerhans Insulin Nicotinamide Embryonic stem cells Cell therapy Introduction Nicotinamide, the amide derivative of nicotinic acid, has been used over the last few decades for a variety of therapeutic applications. High doses of nicotinamide have protective effects on β-cell survival and function in animal and in vitro studies [1]. In this regard, nicotinamide prevents the develop- ment of diabetes in experimental animals following adminis- tration of a range of β-cell toxins [2] and in mouse models of diabetes [3]. Nicotinamide has also been reported to affect insulin production and cell proliferation in adult mouse islets in culture and following transplantation [4,5]. Further studies have demonstrated that nicotinamide enhances the forma- tion of β-cells in fetal porcine islet-like cell clusters grafted into diabetic nude mice [6]. Moreover, increases in insulin production and content of cultured fetal pig islet-like cell clusters were seen as a consequence of β-cell neoformation through differentiation [7]. Finally, nicotinamide stimulates EXPERIMENTAL CELL RESEARCH XX (2008) XXX – XXX ⁎ Corresponding author. Andalusian Center of Molecular Biology and Regenerative Medicine, Avda. Americo Vespucio s/n, E-41092 Seville, Spain. Fax: +34 954 34 98 13. E-mail address: fmarber@upo.es (F. Martín). YEXCR-07682; No. of pages: 6; 4C: 3 0014-4827/$ – see front matter © 2007 Elsevier Inc. All rights reserved. doi:10.1016/j.yexcr.2007.11.019 available at www.sciencedirect.com www.elsevier.com/locate/yexcr ARTICLE IN PRESS Please cite this article as: P. Vaca, et al., Nicotinamide induces differentiation of embryonic stem cells into insulin-secreting cells, Exp. Cell Res. (2008), doi:10.1016/j.yexcr.2007.11.019