Kissler HJ, Niland JC, Olack B, Ricordi C, Hering B J, Naji A, Kandeel F, Oberholzer J, Fernandez L, Contreras J, Stiller T, Sowinski J, Kaufman DB. Validation of methodologies for quantifying isolated human islets: an islet cell resources study.
Clin Transplant 2009 DOI: 10.1111/j.1399‐0012.2009.01052.x.
© 2009 John Wiley & Sons A/S. :  Background:  Quantification of islet mass is a crucial criterion for defining the quality of the islet product ensuring a potent islet transplant when used as a therapeutic intervention for select patients with type I diabetes. Methods:  This multi‐center study involved all eight member institutions of the National Institutes of Health‐supported Islet Cell Resources Consortium. The study was designed to validate the standard counting procedure for quantifying isolated, dithizone‐stained human islets as a reliable methodology by ascertaining the accuracy, repeatability (intra‐observer variability), and intermediate precision (inter‐observer variability). The secondary aim of the study was to evaluate a new software‐assisted digital image analysis method as a supplement for islet quantification. Results:  The study demonstrated the accuracy, repeatability and intermediate precision of the standard counting procedure for isolated human islets. This study also demonstrated that software‐assisted digital image analysis as a supplemental method for islet quantification was more accurate and consistent than the standard manual counting method. Conclusions:  Standard counting procedures for enumerating isolated stained human islets is a valid methodology, but computer‐assisted digital image analysis assessment of islet mass has the added benefit of providing a permanent record of the isolated islet product being evaluated that improves quality assurance operations of current good manufacturing practice.