Islet assessment for transplantation

Abstract

Purpose of review-There is a critical need for meaningful viability and potency assays that characterize islet preparations for release prior to clinical islet cell transplantation (ICT). Development, testing, and validation of such assays have been the subject of intense investigation for the past decade. These efforts are reviewed, highlighting the most recent results while focusing on the most promising assays.Recent Findings-Assays based on membrane integrity do not reflect true viability when applied to either intact islets or dispersed islet cells. Assays requiring disaggregation of intact islets into individual cells for assessment introduce additional problems of cell damage and loss. Assays evaluating mitochondrial function, specifically mitochondrial membrane potential, bioenergetic status, and cellular oxygen consumption rate (OCR), especially when conducted with intact islets, appear most promising in evaluating their quality prior to ICT. Prospective, quantitative assays based on measurements of OCR with intact islets have been developed, validated and their results correlated with transplant outcomes in the diabetic nude mouse bioassay.Conclusion-More sensitive and reliable islet viability and potency tests have been recently developed and tested. Those evaluating mitochondrial function are most promising, correlate with transplant outcomes in mice, and are currently being evaluated in the clinical setting.

Surface-Enhanced Raman Spectroscopy-Based Label-Free Insulin Detection at Physiological Concentrations for Analysis of Islet Performance

“…Before transplantation these islets are screened for their viability and functional response to changing glucose concentration in order to reduce the chances of transplant failure. [7][8][9] Sensors capable of detecting secretion of insulin from beta cells in a costeffective, label-free manner with minimal stress to the cells can serve vital roles in clinical quality assessment of islets. External monitoring of insulin concentration can also help in disease diagnosis and management as well as prevent potentially fatal insulin overdoses or hypoglycemia in diabetic patients.…”

Correlation of Released HMGB1 Levels with the Degree of Islet Damage in Mice and Humans and with the Outcomes of Islet Transplantation in Mice

“…Islet transplantation is a promising therapy for type 1 diabetes mellitus (26) and is preferred by patients over Currently, the in vivo islet transplantation assay using diabetic mice is thought to most reliably correlate with insulin injection therapy (6). However, major issues still prevent the use of islet transplantation as a standard therclinical islet transplantation (20). However, results from this assay can be obtained only after several days and apy (10,27), including limitations of the current potency assays (20).…”

“…completed within hours) (20). Development of such an assay has been mandated by the US Food and Drug Administration (34).…”

“…It should also be able to work with relatively small yet representative islet numbers without potency assay using a transplantation model. Currently, the cell membrane integrity test (2), ATP assay (4,8,29), requiring islet handpicking (which may bias the results) and should be able to provide real-time results (i.e., glucose-stimulated insulin secretion (GSIS) test ( Mouse and human isolated islets were cultured in DMEM (Sigma-Aldrich, St. Louis, MO) and CMRL1066 and the results of the in vivo transplantation assay (20). Recently, tests for cellular composition and β-cell via-(Mediatech, Inc., Manassas, VA), respectively, at 37°C in 95% air and 5% CO 2 for 24 h after islet isolation.…”

Filtration is a time-efficient option to Histopaque, providing good-quality islets in mouse islet isolation

“…However, although GSIS is an important predictor of islet function it does not have a correlation with clinical transplantation outcomes (Ricordi et al 2001;Street et al 2004). Therefore, islets obtained by filtration (with the lowest GSIS and the highest viability) may recover once transplanted and improve their functionality in vivo (Papas et al 2009). …”