Supramolecular Biomaterials as a Biomimetic Platform for Investigating Immunopathological Processes of Human Type 1 Diabetes

Abstract

A major goal of type 1 diabetes (T1D) research is development of state-of-the-art devices that recreate the human islet microenvironment to help elucidate the molecular and cellular mechanisms of beta cell loss due to autoimmunity. We recently reported a novel synthetic biomaterial technology to form hydrogels from a pair of oppositely-charged peptides that co-assemble into a network of interpenetrating β-sheet nanofibers. Here, we explored the potential of this biomaterial, referred to as “CATCH” for Co-Assembly Tags based on Charge complementarity, to serve as a 3D microenvironment for studies of the islet—immune cell interface within the context of human T1D. Supramolecular CATCH hydrogels offer a number of key advantages for engineering islet biomimetic microenvironments: 1) they are fabricated via self-assembly at neutral pH and 37°C; 2) require no chemical reaction to form; and 3) are intrinsically capable of installing folded proteins or peptides via covalent fusion to one of the synthetic peptides sequences. In initial experiments, we established that CATCH hydrogels are cyto-compatible with human beta cells via encapsulation of BetaLox5 cells (βL5), an immortalized human beta cell line, by demonstrating strong viability (Calcein-AM/Ethidium homodimer-1 stain) of encapsulated βL5 at 3 and 24 hours after gelation similar to βL5 seeded on 2D surfaces. CATCH gels also showed promise as a viable platform for interrogating the engagement of autoreactive immune cells with human beta cells. Engineered CD8+ human T cell avatars expressing human T cell receptors for the islet antigen pre-proinsulin co-embedded into CATCH hydrogels with βL5 cells show strong beta cell killing in 3D by T cells over an 18-hour period (assessed via loss of TMRM staining of mitochondrial membrane potential). These initial successes are guiding our development of CATCH hydrogels for further detailed 3D studies of islet—immune cell interactions relevant to human T1D. Disclosure M. Becker: None. D. Seroski: None. S. Stimpson: None. C.E. Mathews: None. G. Hudalla: None. E.A. Phelps: None.