Two-layer challenge test as an assessment to predict islet graft function.

Background/Aims: To investigate graft viability assessment before transplantation using P-31-Nuclear Magnetic Resonance (NMR) spectroscopy combining a two-layer old storage method (TLM). Methodology: Rat pancreases were divided into three groups and respectively subjected to 0 (group1); and 30 minutes (group 2) of warm ischemia (WI) before procurement. Pancreases were digested and pancreatic digest tissues were preserved for 3 h using TLM. P-31-NMR spectroscopy was used to measure ATP levels of digest tissue. After TLM, the ratio of beta-adenosine triphosphate to phosphate monoester (beta ATP/PME) obtained by P-31-NMR spectroscopy was evaluated. Isolated islets were assessed for yield and in vivo function separately using nude mice. Results: The beta ATP/PME ratios were 0.11 +/- 0.04, and 0.03 +/- 0,01 in groups 1 and 2, respectively (P<0.05). Islet yields (IEQ/pancreas) were significantly less in group 3 (P<0.05) and the cure rate after transplantation of 200 islets to athymic nude mice were 100% (7/7), and 0% (0/7) in groups 1 and 2, respectively. We regard groups 1 as viable group and group 2 as non-viable group. The viable groups and the non-viable group were clearly distinguished by beta ATP/PME ratios. Conclusion: P-31-NMR spectroscopy combining TLM provided an objective and rapid means to assess severity of islet graft damage prior to transplantation in the rat model.