In Vitro Platform for Studying Human Insulin Release Dynamics of Single Pancreatic Islet Microtissues at High Resolution

Abstract

Insulin is released from pancreatic islets in a biphasic and pulsatile manner in response to elevated glucose levels. This highly dynamic insulin release can be studied in vitro with islet perifusion assays. Herein, a novel platform to perform glucose‐stimulated insulin secretion (GSIS) assays with single islets is presented for studying the dynamics of insulin release at high temporal resolution. A standardized human islet model is developed and a microfluidic hanging‐drop‐based perifusion system is engineered, which facilitates rapid glucose switching, minimal sample dilution, low analyte dispersion, and short sampling intervals. Human islet microtissues feature robust and long‐term glucose responsiveness and demonstrate reproducible dynamic GSIS with a prominent first phase and a sustained, pulsatile second phase. Perifusion of single islet microtissues produces a higher peak secretion rate, higher secretion during the first and second phases of insulin release, as well as more defined pulsations during the second phase in comparison to perifusion of pooled islets. The developed platform enables to study compound effects on both phases of insulin secretion as shown with two classes of insulin secretagogs. It provides a new tool for studying physiologically relevant dynamic insulin secretion at comparably low sample‐to‐sample variation and high temporal resolution.

Human Islet Microtissues as an In Vitro and an In Vivo Model System for Diabetes

“…Moreover, FFAs alone also led to an increase in chronic insulin release. [11][12]. (e) Intracellular ATP content of islet microtissues after 14 days of incubation (n = 9-12).…”

“…However, their experimental use is hindered by heterogeneity in islet size and cellular composition, variable degrees of exocrine tissue contamination (low purity), batch-to-batch differences in functionality [9], and short ex vivo lifespan due in part to necrosis in the core of large islets [10]. Previously, we have described how these challenges can be overcome with the use of standardized human islet microtissues, produced by enzymatic dissociation and controlled scaffold-free hanging-drop-based reaggregation of primary islet cells [11]. Islet microtissues are uniform in size and cellular composition, and display long-term and stable functionality and viability during in vitro culture, thus could enable disease-modeling under T2D-relevant conditions.…”

A Parallel Perifusion Slide From Glass for the Functional and Morphological Analysis of Pancreatic Islets

“…Taken together these data show that the insulin concentration pattern in the fractionated efflux, although somewhat deformed, represents the secretory activity sufficiently well. Clearly, the temporal resolution is inferior to systems specifically designed to achieve high resolution ( Misun et al, 2020 ), but data such as presented in Figure 11 can be used to reconstruct the actual secretion profile for a given perifusion condition and thus to enable a meaningful correlation between the kinetics of the imaging data and that of the secretion data.…”

Engineering-inspired approaches to study β-cell function and diabetes

“…This approach offers a uniquely precise and uninterrupted measurement rarely seen in perfusion platforms. Insulin secretion from a single pseudoislet was able to be quantified (off chip) using a hanging drop perifusion system 77 . In single islet scenarios, higher resolution aspects of insulin secretion physiology can be observed such as oscillations during second phase insulin secretion which has previously only been shown with live Ca 2+ imaging 78,79 .…”