Intermittent Low-Magnitude Pressure Applied Across Macroencapsulation Devices Enables Physiological Insulin Delivery Dynamics

Abstract

Cadaveric islet and stem cell-derived transplantation hold promise as treatments for type 1 diabetes (T1D). To tackle the issue of immunocompatibility, numerous cellular macroencapsulation techniques that utilize diffusion to transport insulin across an immunoisolating barrier have been developed. However, despite several devices progressing to human clinical trials, none have successfully attained physiologic glucose control or insulin independence. Based on empirical evidence, macroencapsulation methods with multilayered, high islet surface density are incompatible with on-demand insulin delivery and physiologic glucose regulation, when solely reliant on diffusion. An additional driving force is essential to overcome the distance limit of diffusion. In this study, we present both theoretical evidence and experimental validation that applying pressure, at levels comparable to physiological diastolic blood pressure, significantly enhances insulin flux across immunoisolation membranes—increasing it by nearly three orders of magnitude. This significant enhancement in transport rate allows for precise, sub-minute regulation of both bolus and basal insulin delivery. By incorporating this technique with a pumpbased extravascular system, we demonstrate the ability to rapidly reduce glucose levels in diabetic rodent models, replicating the timescale and therapeutic effect of subcutaneous insulin injection or infusion. This advance provides a potential path towards achieving insulin independence with islet macroencapsulation.