Transplanted Functional Islet Mass: Donor, Islet Preparation, and Recipient Factors Influence Early Graft Function in Islet-After-Kidney Patients

Background. The ability to predict clinical function of a specific islet batch released for clinical transplantation using standardized variables remains an elusive goal. Methods. Analysis of 10 donor, 7 islet isolation, 3 quality control, and 6 recipient variables was undertaken in 110 islet-after-kidney transplants and correlated to the pre- to 28-day posttransplant change in C-peptide to glucose and creatinine ratio (Delta CP/GCr). Results. Univariate analysis yielded islet volume transplanted (Spearman r = 0.360, P < 0.001) and increment of insulin secretion (r = 0.377, P < 0.001) as variables positively associated to Delta CP/GCr. A negative association to Delta CP/GCr was cold ischemia time (r = -0.330, P < 0.001). A linear, backward-selection multiple regression was used to obtain a model for the transplanted functional islet mass (TFIM). The TFIM model, composed of islet volume transplanted, increment of insulin secretion, cold ischemia time, and exocrine tissue volume transplanted, accounted for 43% of the variance of the clinical outcome in the islet-after-kidney data set. Conclusion. The TFIM provides a straightforward and potent tool to guide the decision to use a specific islet preparation for clinical transplantation.