2085-LB: Alleviation of Instant Blood-Mediated Inflammatory Reaction in Human Islets with Aptamers

Introduction and Objective: The instant blood-mediated inflammatory reaction (IBMIR) is a major factor that causes damage to transplanted islets. The blockade of pro-inflammatory mediators is a promising approach to improve islet engraftment. We hypothesized that blocking of key pro-inflammatory proteins by aptamers will dampen the IBMIR response and promote islet graft survival. We evaluated the blockade of inflammatory proteins such as interleukin 1 beta (IL-1β), and tumor necrosis factor-alpha (TNFα) using surface immobilization of aptamers (IL-1βApt, and TNFαApt) with bissulfosuccinimidyl suberate (BS3). Methods: Initially toxicity studies were performed using human islets and beta cell lines. Further, human islets were exposed to cytokine cocktail (IL-1β, TNFα and IFNγ) in the presence and absence of individual and combined aptamers free and surface-immobilized aptamers. Gene expression of pro inflammatory cytokines were tested by qPCR analysis. Apoptotic genes were also measured to investigate the anti-apoptosis effect of aptamers. Results: Toxicity studies with aptamers showed that IL-1βApt and TNFαApt up to 100µM concentrations were safe for cells and showed excellent anti-inflammatory effects in vitro. Both IL-1βApt and TNFαApt reversed the upregulation of proinflammatory genes induced by IL-1β and TNFα in the human islets respectively, and this was comparable to established IL-1β and TNFα antagonists. Further, we immobilized the aptamers on the surface of the islets and noticed that surface-immobilized aptamers have potent anti-inflammatory, and anti-apoptotic properties. Our results clearly show that aptamers are functional even after immobilization on the islet's surface. Conclusion: The current study offers a new potential target to improve islet engraftment and pave the way for further studies to better determine the role of these aptamers in allogeneic settings in combination with a well-established immune-suppressive platform.