miR-216a-targeting theranostic nanoparticles promote proliferation of insulin-secreting cells in type 1 diabetes animal model

Abstract

Aberrant expression of miRNAs in pancreatic islets is closely related to the development of type 1 diabetes (T1D). The aim of this study was to identify key miRNAs dysregulated in pancreatic islets during T1D progression and to develop a theranostic approach to modify their expression using an MRI-based nanodrug consisting of iron oxide nanoparticles conjugated to miRNA-targeting oligonucleotides in a mouse model of T1D. Isolated pancreatic islets were derived from NOD mice of three distinct age groups (3, 8 and 18-week-old). Total RNA collected from cultured islets was purified and global miRNA profiling was performed with 3D-Gene global miRNA microarray mouse chips encompassing all mouse miRNAs available on the Sanger miRBase V16. Of the miRNAs that were found to be differentially expressed across three age groups, we identified one candidate (miR-216a) implicated in beta cell proliferation for subsequent validation by RT-PCR. Alterations in miR-216a expression within pancreatic beta cells were also examined using in situ hybridization on the frozen pancreatic sections. For in vitro studies, miR-216a mimics/inhibitors were conjugated to iron oxide nanoparticles and incubated with beta cell line, βTC-6. Cell proliferation marker Ki67 was evaluated. Expression of the phosphatase and tensin homolog (PTEN), which is one of the direct targets of miR-216a, was analyzed using western blot. For in vivo study, the miR-216a mimics/inhibitors conjugated to the nanoparticles were injected into 12-week-old female diabetic Balb/c mice via pancreatic duct. The delivery of the nanodrug was monitored by in vivo MRI. Blood glucose of the treated mice was monitored post injection. Ex vivo histological analysis of the pancreatic sections included staining for insulin, PTEN and Ki67. miRNA microarray demonstrated that the expression of miR-216a in the islets from NOD mice significantly changed during T1D progression. In vitro studies showed that treatment with a miR-216a inhibitor nanodrug suppressed proliferation of beta cells and increased the expression of PTEN, a miR-216a target. In contrast, introduction of a mimic nanodrug decreased PTEN expression and increased beta cell proliferation. Animals treated in vivo with a mimic nanodrug had higher insulinproducing functionality compared to controls. These observations were in line with downregulation of PTEN and increase in beta cell proliferation in that group. Our studies demonstrated that miR-216a could serve as a potential therapeutic target for the treatment of diabetes. miR-216a-targeting theranostic nanodrugs served as exploratory tools to define functionality of this miRNA in conjunction with in vivo MR imaging.

3D in vivo Magnetic Particle Imaging of Human Stem Cell-Derived Islet Organoid Transplantation Using a Machine Learning Algorithm

“…After the last round of MPI, animals were sacrificed and left kidneys were removed, fixed in 4% paraformaldehyde solution for 16 h at 4 • C, and embedded in paraffin. Paraffin sections of grafts under the left kidney capsule were incubated with anti-C-peptide primary antibody (Abcam, Cambridge, MA, United States) and anti-dextran antibody (STEMCELL Technologies, Vancouver, BC, Canada) at 4 • C for 16 h, followed by an FITC-labeled goat anti-mouse secondary IgG (Abcam, Cambridge, MA, United States) and Texas red conjugated goat anti-rabbit secondary IgG (1:100 dilution, Santa Cruz Biotechnology, Santa Cruz, CA, United States) at room temperature for 1 h. All sections were mounted with a mounting medium containing DAPI (Vectashield; Vector Laboratories) and analyzed using fluorescence microscopy (Eclipse 50i; Nikon Metrology, Brighton, MI, United States) (Pomposelli et al, 2020;Wang et al, 2020).…”

<p>Islet Transplantation Imaging in vivo</p>

“…These nanoparticles could be imagined via MRI and promoted the proliferation of β-cells by downregulating PTEN expression in a type 1 diabetes animal model. 37 Although nanoparticles can travel through biological barriers, the tendency of aggregation limits their synthesis. 38…”

<p>Knockdown of lncRNA ABHD11-AS1 Suppresses the Tumorigenesis of Pancreatic Cancer via Sponging miR-1231</p>

“…For miR-1231 transfection, pancreatic cancer cells were transfected with miR-1231 agomir, miR-1231 antagomir or NC by Lipofectamine 2000 according to the previous reference. 16 MiR-1231 agomir, miR-1231 antagomir and negative control RNAs were purchased from GenePharma (Shanghai, China).…”