Hydrogel nanoparticles covered by neuroligin-2-derived peptide-protected β cells under oxidative stress and increase their proliferation

Protein complexes that mediate secretion and adhesion are located on the plasma membrane of pancreatic β cells. Neuroligins and their binding partners, the neurexins, are among these complexes. β cell maturation and physiologically regulated insulin secretion, as a response to high levels of blood glucose, are dependent on their three-dimensional (3D) arrangement. Both insulin secretion and the proliferation rates of β cells dramatically increase when β cells are co-cultured with clusters of a member of the neuroligin family: NL-2. A membranal protein, such as NL-2, has very limited drugability owing to its low biostability and bioavailability. Thus, based on in silico modeling, a short NL-2 peptide (HSA-28), which was able to mimic NL-2-positive effects on β cells, was designed, as we described in previous publication. However, the peptide was active only as a cluster, created by the covering the maghemite (γ-Fe2O3)-based nanoparticles (NPs) with limited biocompatibility. In this brief communication, we will show that conjugation of HSA-28 to biocompatible hydrogel NPs exhibits an impressive protective effect on INS-1E β cells under oxidative stress and induces their proliferation rate via augmentation of PDX1 nuclear translocation. The diameter of coated by the peptide NPs was 206 ± 63 nm (DLS) and 114 ± 27 nm (cryo-TEM). This significant change in size can be explained by the very hydrophilic character of the proteinoid NPs, inducing adsorption of many water molecules on their surface, which are accounted only by the DLS. The ability of biocompatible hydrogel NPs to prevent apoptosis and increase β cell mass might be used for developing novel β cell protective therapies.