Professor, Department of Medical Imaging
Faculty, Biomedical Engineering Graduate Interdisciplinary Program
Faculty, Department of Radiology Graduate Interdisciplinary Program
Faculty, Physiology Graduate Interdisciplinary Program
Dr. Papas has worked on the development and validation of equipment and assays (especially ones based on mitochondrial function such as oxygen consumption rate, OCR) for the real-time, objective assessment of islet (and other cell and tissue) quality prior to transplantation. The OCR assay has been validated based on its ability to predict diabetes reversal in rodents and clinical human islet allo transplants in patients with Type 1 Diabetes as well as islet auto transplants in patients with chronic pancreatitis. He utilized these assays along with engineering principles to optimize critical steps in the islet transplantation process. These steps include pancreas procurement, pancreas preservation, islet isolation and purification, islet culture and shipment and islet transplantation and engraftment in the recipient. He is also involved through NIH funding in research seeking improvement in organ preservation technology to extend the time window from procurement to transplantation and the use of organs from expanded-criteria donors without compromising clinical outcomes.
A major focus of his current research, which is sponsored by the JDRF Encapsulation Consortium and the NIH NIDDK, is the successful clinical transplantation of islets or stem-cell derived β-cells to reverse diabetes without the need for immunosuppression. His work focuses on the optimization of β-cell viability and function post-transplantation by improving oxygenation. He utilizes novel methods for in situ oxygen delivery [via a miniaturized wearable and ultimately fully implantable (size of a few pennies), electrochemical oxygen generators] to retrievable vascularization inducing macro-encapsulation immunoisolation devices. Enhanced oxygenation to such immunoisolation devices in vivo can: 1) dramatically reduce the necessary size from that of a 40” flat-screen TV to that of a postage stamp); 2) enhance beta cell functionality (in terms of glucose-stimulated secretion within them); and 3) reduce the dose of cells required to reverse diabetes. If successfully translated to the clinic, his work in this area (conducted in collaboration with Giner Inc. and Theracyte has the potential to have a profound impact on reducing overall costs, increasing availability, and improving short-and long-term outcomes of β-cell therapies for the treatment of diabetes while eliminating the need for immunosuppression.
Stephan Gruessner (MSRP 2013): "Quantification of Hypoxia in Human ?-TC6 Islet Cells"
Casey Charlton (MSRP 2017): "Imaging and Analysis of Mass and Function of Insulin Replacement Devices"
Daline Do (2015) Cell Transplantation for Type 1 Diabetes
Ariana Ceballos, 2017, "ORGAN preservation methods Comparison between Static Cold Storage and Persufflation"
Juan Contreras, 2017, "ORGAN preservation methods Comparison between Static Cold Storage and Persufflation"