Improved Islet Yields From Macaca Nemestrina and Marginal Human Pancreata After Two-Layer Method Preservation and Endogenous Trypsin Inhibition

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We tested whether two-layer method (TLM) pancreas preservation and trypsin inhibition (Pefabloc) during processing allows longer preservation while retaining or improving viable islet recovery. Non-marginal primate (Macaca nemestrina) and marginal human (ischemic or preservation-injured) pancreata were processed with a research-oriented pan technique (Seattle method). Organs were processed upon arrival (± Pefabloc), or after TLM or University of Wisconsin solution (UW) preservation (+ Pefabloc). Islet yield, viability, and function were assessed.

Pefabloc increased M. nemestrina islet yields from 9696 ± 1749 IE/g to 15 822 ± 1332 IE/g (p < 0.01). Two-layer method preservation (< 6 h) further increased yields, to 23 769 ± 2773 IE/g (vs. + Pefabloc; p < 0.01). Similarly, Pefabloc increased marginal human islet yields from 2473 ± 472 IE/g to 4723 ± 1006 IE/g (p < 0.04). This increase was maintained after lengthy TLM preservation (> 30 h; 4801 ± 1066 IE/g).

We also tested the applicability of TLM preservation (23.5 ± 3.2 h) to the processing of marginal human pancreata by the Edmonton/Immune Tolerance Network clinical protocol. Islet yield and function approached published results of pancreata processed 4.8 ± 0.8 h after organ recovery (p = 0.06).

Pefabloc, and TLM vs. UW preservation, prolonged the tolerable interval between organ recovery and islet isolation. Islet yield, viability, and functionality improved from both marginal and nonmarginal pancreata.