Improvement of Pancreatic Islet Cell Isolation for Transplantation

Abstract

Pancreatic islet transplantation is a promising treatment for diabetes but still faces several challenges. Poor islet isolation efficiency and poor long-term insulin independence are currently two major issues, although donor shortage and the need for immunosuppressants also need to be addressed. We established the Kyoto islet isolation method (KIIM), which has enabled us to isolate and transplant islets even from non-heart-beating donors. KIIM involves 1) cooling the donor pancreas in situ, 2) preserving the ducts with modified Kyoto solution, 3) using a modified two-layer pancreas preservation method, and 4) adjusting the density of the density gradient centrifugation and using an iodixanol-based solution for purification. KIIM has enabled us to transplant 17 islet preparations out of 21 isolations (an 81% success rate). All transplanted islets functioned, and all transplanted patients had improved glycemic control without hypoglycemic unawareness. Recently, we used KIIM for islet isolation from a brain-dead donor at Baylor, which resulted in a very high islet yield (789,984 IE) with high viability (100% by fluorescein diacetate/propidium iodide staining and a stimulation index of 4.7). This preliminary evidence suggests that KIIM may also be promising for islet isolation from brain-dead donors. In addition, to assess engrafted islet mass, we developed a secretory unit of islet transplant objects (SUITO) index: fasting C-peptide (ng/dL) / [fasting blood glucose (mg/dL) - 63] x 1500. This simple index has enabled us to monitor the engrafted islet mass. This index should be useful when deciding whether to perform additional islet transplantations to maintain insulin independence. Poor islet isolation efficacy and poor long-term results could be resolved with ongoing research.

THERAPY OF ENDOCRINE DISEASE: Islet transplantation for type 1 diabetes: so close and yet so far away

“…The islet isolation success rate is affected by factors such as donor characteristics, pancreas preservation, enzyme solutions, and density gradients for purification. Donor characteristics such as weight and BMI (O30) significantly affect islet yield (76,77). Andres et al (78) have claimed that a major pancreas injury which involves the main pancreatic duct during procurement is significantly associated with lower islet yield.…”

“…In addition, the pancreas preservation method has undergone improvement in the past few years with the use of perfluorocarbon (PFC), which slowly releases oxygen. PFC in combination with University of Wisconsin (UW) solution is a two-layer method for pancreatic preservation during the cold ischemia time, which leads to a higher islet yield (77). In terms of enzyme solution effects in pancreas digestion and islet separation from acinar tissues (79,80), although liberase HI has been determined to be very effective in pancreas digestion, its use in clinical islet isolation was discontinued due to the potential risk of bovine spongiform encephalopathy transmission (79,80).…”

Brittle Diabetes: A Contemporary Review of the Myth and Its Realization

“…In addition, approximately 70% of transplanted patients with type 1 diabetes have achieved insulin independence (Matsumoto et al, 2005). Isolated islet transplantation, which restores glucose sensing, should be considered in cases of hypoglycemic unawareness and/or lability especially if the body mass index is <25kg/m 2 , but with current immunosuppressive protocols patients must have normal renal function and preferably no plans for pregnancy (Matsumoto et al, 2007). The main limiting factor of beta-cell function replacement by transplantation is so far represented by the potentially severe side effects of the immunosuppressant therapy necessary to avoid graft rejection and recurrence of autoimmunity.…”

Why Do Japan's Advanced Medical Treatments Never Get Ahead?

“…Islet transplantation is consisted of four following processes; 1) retrieval of the pancreas, 2) preservation of the pancreas, 3) isolation of the pancreatic islets, and 4) purification of the pancreatic islets. 6 Many researchers are examining the pancreatic islet isolation process. However, the Kyoto University group added modifications to these processes.…”