1448-P: Partial Pancreatectomy Increased α-Cell Volume Density, but Not Compensated ß-Cell Volume in Japanese Subjects

In type 2 diabetes, deficit of insulin secretion is often ascribed to the reduction of β-cell volume, implying that regeneration of β-cells could be one of its radical treatments. Hitherto, several models are known to elicit β-cell compensation in rodents. Among them, application of partial pancreatectomy can induce replenishment of β-cell volume in young mice, while it is unclear whether this occurs in humans. In the present study, islet pathology was evaluated using the pancreatic specimens from the patients with pancreatic cancer who underwent repeated (i.e., partial followed by total) pancreatectomy because of its local recurrence after the initial surgery. Ten subjects (5 males and 5 females) at Hirosaki University Hospital or Chiba University Hospital were evaluated. Morphometric analysis was performed on formalin fixed pancreatic sections, in which the quadruple immunostaining for each hormone and the fluorescent immunostaining for ALDH1A3 was conducted. The mean age at the first and second operations was 66.2±and 71.6±5.8 years old, respectively. The mean duration until recurrence was 3.2±2.0 years. There were no significant differences in HbA1c and BMI between first and second preoperation. In morphometrical analysis, α-cell volume in the second surgery was significantly increased compared to the first surgery (p<0.04) , while β-cell volume was comparable. There was a positive correlation between the frequency of conduit glucagon positive cells and islet α-cell volume (r=0.66, p<0.05) . The frequency of ALDH1A3 positive cells were positively correlated with the α-cell/ β-cell ratio in the second surgical specimen (r=0.81, p<0.01) . Taken together, unlike rodents, our results indicate that partial pancreatectomy did not induce replenishment of β-cell volume, but increased α-cell volume in human subjects. As its mechanism, the neogenesis of ductal endocrine cells and/or the transdifferentiation of β-cells to α-cells in the islets may be involved. Disclosure Y.Takeuchi: None. H.Mizukami: None. S.Osonoi: None. K.Kudoh: None. T.Sasaki: None. S.Yagihashi: None.