Functionalized peptide hydrogel to generate human insulin-producing cells in vitro.

Type I diabetes is a chronic disease that affects people worldwide. When insulin administration is no longer effective, transplantation of pancreatic islets represents an alternative for diabetics. However, islet grafting carries limitations, which include poor availability of donors, surgery risks, and lifelong immunosuppressive therapy. To address this, novel approaches, such as the use of soft hydrogels as vehicles of cells are being developed for tissue grafting applications. Self-assembling peptide hydrogels (SAPHs) are biocompatible and versatile materials widely used for both, three-dimensional (3D) cell culture and regenerative medicine applications. Therefore, in this study, we explored the effect of the functionalization of the SAPH FEFEFKFKK (FEK9) with extracellular matrix (ECM) motifs, RGD, GFOGER and IKVAV, to support the directed differentiation of human dental pulp stem cells (hDPSCs) into insulin-producing cells (IPCs). The resulting ECM-functionalized FEK9 hydrogel was formed under mildly acidic conditions (pH 5-6). Infrared spectroscopy confirmed that ECM-FEK9 adopts a β-sheet secondary structure and forms a dense nanofibrillar network, while rheological measurements demonstrated the formation of a soft hydrogel. hDPSC cultured in hydrogel displayed steady viability and metabolism. Moreover, under directed induction, cells in ECM-FEK9 expressed β-cell markers, such as PDX-1 and Glut-2, as well as synthetized insulin within 10 days of 3D culture in vitro, as evidenced through fluorescence confocal microscopy and spectrophotometry evaluations, respectively. Therefore, ECM-FEK9 could be a promising candidate to support the culture of hDPSCs and the generation of IPCs after refinement of directed induction under 3D cell culture conditions.