Human Islets Exhibit Electrical Activity on Microelectrode Arrays (MEA)

This study demonstrates for the first time that the microelectrode array (MEA) technique allows analysis of electrical activity of islets isolated from human biopsies. We have shown before that this method, i.e., measuring beta cell electrical activity with extracellular electrodes, is a powerful tool to assess glucose responsiveness of isolated murine islets. In the present study, human islets were shown to exhibit glucose-dependent oscillatory electrical activity. The glucose responsiveness could be furthermore demonstrated by an increase of insulin secretion in response to glucose. Electrical activity was increased by tolbutamide and inhibited by diazoxide. In human islets bursts of electrical activity were markedly blunted by the Na+ channel inhibitor tetrodotoxin which does not affect electrical activity in mouse islets. Thus, the MEA technique emerges as a powerful tool to decipher online the unique features of human islets. Additionally, this technique will enable research with human islets even if only a few islets are available and it will allow a fast and easy test of metabolic integrity of islets destined for transplantation.