Intraoperative Ultrasound Examination Is Useful for Monitoring Transplanted Islets

Abstract

The failure to maintain insulin independence is considered to be due to the loss of islet grafts, which can occur rapidly due to the instant blood-mediated inflammatory reaction, immune rejection, non-specific inflammation or ischemia of donor-islets. Therefore, monitoring transplanted islets is important to evaluate their state and to adopt appropriate measures to counteract graft loss. For this purpose, we performed ultrasound (US) examination using BALB/c mice, which were transplanted with syngeneic or xenogeneic (Sprague Dawley rat) islets, and assessed whether engrafted or damaged islets could be visualized in a previous study (Sakata N, et al. Islets 2011), and confirmed that syngeneic islets could be seen as hyperechoic lesion and xenogeneic islets as hypoechoic mass by US examination. We consider that US examination is useful for detecting the location of transplanted islets and condition of the islets. Recently, we encountered a patient who received total pancreatectomy with islet autotransplantation (TP with IAT) and performed intraoperative US examination for detecting islets at transplantation. A 39 years-old man, who had an episode of pancreatic bleeding due to an arteriovenous malformation, received TP with IAT in our institution. Following our islet autotransplantation protocol, 1) we cannulated a double lumen catheter (14 G. sized, 70 cm length) into the portal vein via the superior mesenteric vein for transplantation and monitoring the portal vein pressure, 2) the tip of the catheter was positioned at the bifurcation of the anterior and posterior branch of the portal vein and the islets were selectively infused into the right lobe of the liver to prevent total liver embolization. We did intraoperative US examination for detecting islets in the portal vein. 230,000 islet equivalents (IEQ) were acquired from the pancreas. The tissue volume was 600 μL. Islet autotransplantation was done before closing the abdomen under general anesthesia. Pre-transplant, the portal vein pressure was 8 mmHg and did not change during the transplantation. Intraoperative US examination revealed the transplanted islets as hyperechoic clusters in the portal vein. They emerged from the tip of the catheter located at the bifurcation between the anterior and posterior branch of the portal vein to the peripheral lesion. After transplantation, the patient had good glycemic control, requiring only small doses of insulin (approximately 10 units/day) after transplantation, and with no complications. In conclusion, the hyperechoic clusters shown in the patient were viable islets and we could confirm that these islets were successfully transplanted into the portal vein in the right lobe of the liver by intraoperative US examination. Intraoperative US examination is useful for detecting islets.