Silk fibroin preserves beta cell function under inflammatory stress while stimulating islet cell surface GLUT2 expression

Abstract

Silk fibroin is a novel biomaterial for enhancing transplanted islet cell function and survival. This study investigated whether silk fibroin may have unique properties that improve islet function in the face of inflammatory-mediated stress during transplantation. Murine islet function was tested in vitro with either silk fibroin or alginate and challenged with inflammatory cytokines. The glucose-stimulated insulin secretion index for all conditions decreased with inflammatory cytokines, but was better preserved for islets exposed to silk compared to those exposed to alginate or medium. GLUT2 transporter expression on the cell surface of islets exposed to silk was increased compared to alginate or medium alone. Upon cytokine stress, a greater percentage of islet cells exposed to silk expressed GLUT2 on their surface. We conclude that preconditioning islets with silk fibroin stimulates islet cell surface GLUT2 expression, an increase, which persists under inflammatory stress, and may improve islet engraftment and function after transplantation.

The innate immune response of self-assembling silk fibroin hydrogels

“…For example, silk fibroin hydrogels are particularly promising because these materials can serve both as an extracellular matrix mimetic 5 or as a release reservoir for therapeutic payloads 6,7 . Proposed applications include, but are not limited to, anticancer drug delivery 6,8 , pancreatic islet transplantation 9,10 , soft 11,12 and hard tissue 13 engineering and tissue fillers (Silk Medical Aesthetics, Inc. Medford, MA, USA; ClinicalTrials.gov Identifier NCT04085822). The Food and Drug Administration (USA) recently approved the first silk fibroin hydrogel product (Silk Voice, Sofregen Inc, Medford, MA, USA) for use in humans in the treatment of vocal fold medialisation and vocal fold insufficiency.…”

Decorating Bacteria with a Therapeutic Nanocoating for Synergistically Enhanced Biotherapy

“…Intestinal mucositis is an inflammatory disease associated with the cytotoxicity of chemotherapy and radiotherapy, in which the use of anti‐metabolite agents is an important cause. [ 50–52 ] Taking advantage of the anti‐inflammatory activity and inflammatory targeting ability of silk fibroin as well as the clinical therapeutic merits of EcN in treating inflammatory bowel diseases, [ 53–16 ] we speculated that a synergistically enhanced therapeutic effect of SEcN 4 could be achieved for treating intestinal mucositis. In addition, the increment in oral availability of EcN by the combination with silk fibroin might further strengthen the treatment efficacy.…”

Exocrine pancreas proteases regulate β-cell proliferation in zebrafish ciliopathy models and in murine systems

“…Islets were isolated from 10-week-old C57BL/6 male mice (kindly gifted from the Bromberg group through the University of Maryland Animal Resources) following established protocols (Ashari et al, 2018;Szot et al, 2007), picked, and plated in supplemented RPMI medium 1640 [10% fetal bovine serum (FBS; Gemini), 1% penicillin-streptomycin (P/S) (Invitrogen)]. Following Ficoll separation from the islets, the exocrine tissue was washed twice in PBS (Corning) containing 2.5 mM EDTA (Corning), plated in supplemented RPMI+1% P/S, and cultured for 24 h at 37°C before harvest of the media supernatant.…”

“…Islets were dissociated (Cell Dissociation Buffer, enzyme-free, Hanks' Balanced Salt Solution; Gibco) at 37°C for 10 min and washed in PBS containing 2.5 mM EDTA (Corning). Flow cytometry was performed as previously described (Ashari et al, 2018) using isotype-and fluorophorematched FACS antibody staining with Alexa Fluor 647 IgG1 mouse antiinsulin (BD Pharmingen), Pacific Blue IgG2a mouse anti-glucagon pacific Blue (R&D Systems) and PE Cy7 IgG2a rat anti-Ki67 (BioLegend). The positive gates for each parameter were established using single-stained isotype controls, Alexa Fluor 647 mouse IgG1 (BioLegend) and PE Cy7 rat IgG2a (eBioscience) with respective positive thresholds for insulin, glucagon, and Ki67 including 1% of the cells in the corresponding isotype-stained sample.…”