Director of Quality Control Laboratories: Hui-Jian Zhang, M.D.
Associate Directors of Islet Processing: Thomas Gilmore, B.S.
The Diabetes Institute for Immunology and Transplantation (DIIT) at the University of Minnesota remains one of the pioneering centers in the field of islet transplantation and beta cell replacement therapy for the treatment of diabetes. The center’s current position of leadership and innovation in the field are the result of the vision and drive of Drs. Sutherland and Hering. They have worked tirelessly to build a program positioned to move the field forward towards the goal of finding a cure for the diabetes.
The Islet Processing Team might be considered as part of the foundation of this work. The team has grown and evolved significantly over the years to become one of the most productive islet facilities in the world.
In its early years, the Islet Processing Team was led by Jeff Ansite, Tom Gilmore and Dr. Hui-Jian Zhang. Together, they assisted Dr. Sutherland in refining procedures so as to realize his vision of building the preeminent center in the world for islet autograft procedures. In an islet autograft procedure, the organ donor and recipient are the same individual. For example, a patient’s pancreas is removed, their islets are isolated from the rest of their pancreas, and then their islets are infused back into the patient. In this case, the patient does not need to be on immunosuppressive medications after the transplant procedure.
Beginning in 1996, they began to work with Dr. Hering to exhaustively evaluate the many details involved in the isolation, purification, culture and transplantation of islet allografts and xenografts*. During the ensuing decade, they redefined the islet isolation process for both human and porcine pancreata. As a result of the dedicated efforts of these three and under the direction of Dr. Hering, the University of Minnesota has become one of the few programs in the world capable of consistently producing high quality porcine islets for xenotransplantation research. In tandem with these efforts, this small core of dedicated professionals facilitated the creation of one of the most dynamic islet allotransplant centers, and a world leader in the application of single donor islet allotransplantation.
The recent history of the islet core has been characterized by a rapid growth in technical staff. This growth has been in response to the need for a highly productive islet processing laboratory. Together, the islet processing team comprises the Human Islet Isolation, Porcine Islet Isolation and Quality Control subgroups within the overarching Islet Processing Team.
With an emphasis on productivity and quality assurance, the current team will process in excess of 45 human and 60 porcine pancreata annually. Above and beyond the routine islet isolation process, this team performs a host of Quality Control and Quality Assessment evaluations of the isolated islets. These evaluations range from simple viability measures to highly technical transplantation studies and detailed cellular compositional analyses of isolated islet tissue. These efforts are designed to provide not only high quality islet tissue for allotransplantation, but also for xenotransplantation studies and research efforts to prospectively define islet quality and suitability for transplant. In this manner, the Islet Processing Team facilitates research efforts that will contribute to continued advancements in beta cell replacement therapy and to the continued leadership of the DIIT in the field.
*In an islet allograft procedure, islets are isolated from the pancreas of an organ donor. In this case, the recipient of the islets must be on immunosuppressive medications to help prevent rejection after the transplant. In a xenograft procedure, islets from one species are transplanted into the body of another species. Currently, there is a shortage of organs to be used for transplantation. Unfortunately, the result of this shortage is that some people die waiting for an organ to become available so that they can have a transplant. New technology, such as xenotransplantation and stem cell research can potentially increase the number of organs and islets available for transplant – saving the lives of countless people.
Recent progress in clinical islet transplantation has accentuated the need for the development a dependable means to characterize islet product after it is isolated from a donor pancreas and before it is infused into an islet transplant recipient. Standardization of islet counting is fundamental for the precise dosing of islets for transplantation. The Diabetes Institute for Immunology and Transplantation has developed a standardized method for objectively assessing the quantity and quality of islet products. We are in the process of optimizing techniques used to determine the quantity, purity, integrity, cellular identity, and viability of islet product by using digital imaging analysis and confocal microscopy. We have developed methods of digital imaging for visual documentation of the islet characteristics. We hope that our expertise in this area will lead to universal acceptance of objective, standardized methods of assessing islet quantity and quality in the beta cell replacement therapy world. Dr. Hui-Jian Zhang welcomes your input regarding the information below.
1. Computerized islet counting
We use exceptional technique to capture islets and non-islet tissues into images with true color that are very clearly distinguishable from each other and the background. Only this unique image can be used for multiple imaging analyses to determine islet identity, integrity, quantity and purity. The dithizone-stained islets and not-stained clusters are selected and counted by using a computer. The purity of the islet product is determined by the volume ratio of total islets to total tissues in the sample. The integrity of the islets is assessed by computing the volume ratio of dithizone-stained particles which are smaller than 50 micrometers in diameter to the total dithizone-stained tissues and islet size distributions are sorted by computer.
2. Computerized beta cell counting
We developed a new, fast technique to instantly determine beta cell identity, quantity and purity of islet product. A zinc fluorescent indicator stains insulin-containing beta cells in dissociated islets. The beta cells showing characteristic yellow or light green granules are counted. The ratio of beta cells to non beta cells is calculated by computer.
3. Confocal microscopy and image analysis for assessment of islet viability
This method can count the number of live, dead and injured cells. Note that the photo on the left shows a higher quality sample of islets than the photo on the right. The ratio of live, dead and injured cells in the islets represents the islet viability.
Back to About DIIT