The success of the Edmonton Protocol for islet transplantation has provided new hope in the treatment of type 1 diabetes. This study reports on the assessment of 83 human islet grafts transplanted using the Edmonton Protocol since 1999. Cellular composition, as assessed by immunohistochemistry, showed a lower islet purity (ϳ40%) than has been reported in previous studies using dithizone staining to quantitate islet equivalents. Furthermore, grafts were found to contain substantial populations of exocrine and ductal tissue. Total cellular insulin transplanted was 8,097.6 ؎ 3,164.4 g/patient, and was significantly lower in bottom gradient layer grafts than top gradient layer or whole/combined grafts (P < 0.0005). A static incubation test for islet function gave a stimulation index of 3-4, although this measure did not correlate with posttransplant metabolic outcome. Furthermore, we confirmed a previously reported trend in which donor age affects islet yield and purity. It is important to note that a significant positive correlation was observed between the number of islet progenitor (ductal-epithelial) cells transplanted and long-term metabolic success as assessed an by intravenous glucose tolerance test at ϳ2 years posttransplant. In summary, careful assessment of islet graft composition is needed in a clinical transplantation program to accurately estimate islet purity and assess the contribution of other cell types present, such as islet progenitor cells.

Improvements in methods to preserve and recover ischemically damaged human pancreases before islet isolation and transplant could be extremely beneficial to the field of clinical islet transplantation. This preliminary study shows that additional short preservation by the two-layer (UW/PFC) cold-storage method can significantly improve islet recovery and increase opportunities of islet transplantation from human pancreases after prolonged cold ischemia.

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Background The efficacy of low‐voltage‐area ( LVA ) ablation has not been well determined. This study aimed to investigate the efficacy of LVA ablation in addition to pulmonary vein isolation on rhythm outcomes in patients with paroxysmal atrial fibrillation ( AF ). Methods and Results VOLCANO (Catheter Ablation Targeting Low‐Voltage Areas After Pulmonary Vein Isolation in Paroxysmal Atrial Fibrillation Patients) trial included paroxysmal AF patients undergoing initial AF ablation. Of 398 patients in whom a left atrial voltage map was obtained after pulmonary vein isolation, 336 (85%) had no LVA (group A). The remaining 62 (15%) patients with LVA s were randomly allocated to undergo LVA ablation (group B, n=30) or not (group C, n=32) in a 1:1 fashion. Primary end point was 1‐year AF ‐recurrence‐free survival rate. No adverse events related to LVA ablation occurred. Procedural (124±40 versus 95±33 minutes, P =0.003) and fluoroscopic times (29±11 versus 24±8 minutes, P =0.034) were longer in group B than group C. Patients with LVA s demonstrated lower AF ‐recurrence‐free survival rates (88%) than those without LVA (B, 57%, P <0.0001; C, 53%, P <0.0001). However, LVA ablation in addition to pulmonary vein isolation did not impact AF ‐recurrence‐free survival rate (group B versus C, P =0.67). Conclusions The presence of LVA was a strong predictor of AF recurrence after pulmonary vein isolation in patients with paroxysmal AF . However, LVA ablation had no beneficial impact on 1‐year rhythm outcomes. Registration URL: https://www.umin.ac.jp/ctr ; Unique identifier: UMIN000023403.