Enhancing pseudoislet biofunctionality using gelatin bead technology

Abstract

Central necrosis hampers the formation of highly biofunctional Pseudoislets (PIs), which consist of aggregates of insulin-secreting pancreatic β-cells. Necrosis arises because of a shortage of nutrient and oxygen diffusion to the core of the PIs during culture, especially when PIs exceed >200 µm. This study aimed to generate ‘vents’ by incorporating gelatin beads (GBs) into the center of PIs and to examine if this promotes nutrient and oxygen diffusion by blocking the center for cell residence. In addition, we examined the impact of delivering GBs loaded with anti-necrosis or anti-apoptosis drugs to the center of PIs. The BRIN-BD11 rat pancreatic β-cell line was used to generate PIs by suspension culture. PIs were generated at a seeding density of 32,000 cells/PI and cultured for up to 7 days. GBs of 40 µm diameter were produced from Gelatin A and crosslinked with 5% glutaraldehyde for 6 h. The neat GBs or GBs loaded with 100 ng/mL IL-10, or 5 µg/mL anti-IL-1β were incorporated into PIs. The cell viability of the PIs was assessed using cell counting kit-8 (CCK8) and lactate dehydrogenase (LDH) assays. Glucose-stimulated insulin release (GSIS) from PIs was evaluated after stimulation with 16.7 mM glucose for 20 min. Incorporating IL-10, or anti-IL-1β -loaded GBs to PIs synergistically enhanced cell proliferation and reduced cell death. Importantly, PIs cultured for 1 week following incorporation of cytokine-loaded GBs displayed enhanced biofunctionality in terms of higher GSIS.