Ichii H et al. (2005) A novel method for the assessment of cellular composition and beta-cell viability in human islet preparations. Am J Transplant 5: 1635–1645

Failure of some experimental islet transplantations to reverse type 1 diabetes mellitus could be due to the inability of current tests that use DNA-binding dyes to reliably assess the quality of islet preparations. Ichii et al. evaluated the utility of laser scanning cytometry (LSC) coupled with fluorescence-activated cell sorter analysis as a new islet screening method.

Analysis with LSC was able to determine the cellular composition of 62 human islet preparations. The proportion of β cells was much lower than expected for samples assessed as being ≥90% pure by dithizone staining. Despite this fact, no differences in β-cell content between live islet cell samples and preparations of 78% dead islet cells were revealed using LSC analysis, indicating that LSC cannot detect β-cell viability. An accurate estimate of proportions of dead cells, however, was obtained using TMRE staining and fluorescence-activated cell sorter analysis. This method was used to correctly predict that cells treated with 6 h of hypoxia/starvation would produce an unfavorable outcome when transplanted into diabetic immunodeficient rats. It was also capable of identifying islet cell damage caused by a variety of noxious conditions.

The investigators conclude that this new analytical method may be used on its own, or in conjunction with other potential predictive tests, such as electron microscopy or analysis of ATP contents, to isolate islets that have a suitable β-cell mass and viability for them to be used for transplantation.