Transplant Faculty

Dr. Marc L. Melcher graduated from Harvard (1989) with high honors and Columbia College of Physician and Surgeon (1999) where he was inducted into Alpha Omega Alpha.  In between these degrees, he earned a Ph.D. in Molecular and Cellular Biology from the University of California, Berkeley.  He completed general surgery training at Stanford University (2004) and his abdominal transplant surgery fellowship at the University of California, San Francisco (2006).

Dr. Melcher joined the Stanford Division of Abdominal Transplantation in 2006. He has served as the Program Director of the General Surgery Residency and currently is the Program Director of the Abdominal Transplant Surgery Fellowship.

His research interests are in applying the power of algorithms to increase the number of patients who can benefit from organ transplantation. He has put together a group to apply artificial intelligence to the challenges of assessing donor organs and clinical transplant decision-making. They have trained a neural network artificial intelligence algorithm that accurately labeled and quantified fat globules on liver biopsy slides (PLoS Computational Biology, 2020).  Subsequently, they showed that the percent steatosis determined by our algorithm correlated with early allograft dysfunction after liver transplant more strongly than the percent steatosis determined by pathologists (HPB, 2021). The availability of this objective algorithm with reproducible results will enable them to understand the implications of steatosis better and to match donors and recipients more effectively. It also portends big changes in how AI will facilitate other clinical decisions.

Carlos O. Esquivel, M.D., Ph.D. is Professor of Surgery and by courtesy Professor of Pediatrics at the Stanford University School of Medicine, Associate Director of the Institute of Immunity, Transplantation and Infection, an umbrella institute that fosters interdisciplinary research between basic scientists and clinicians. Dr. Esquivel is the first recipient of the Arnold and Barbara Silverman Professorship in Transplantation. He received his M.D. degree from the University of Costa Rica School of Medicine, completed general surgery training at the University of California Davis under the tutelage of F. William Blaisdell,  and then obtained a doctoral degree from the University of Lund in Sweden under the mentorship of Prof. Sven-Erick Bergentz.  He trained in transplantation of the liver, kidney, pancreas and intestine at the University of Pittsburgh under the direction of Dr. Thomas Starzl. In 1988, he founded the adult and pediatric liver and intestinal transplant programs at California Pacific Medical Center in San Francisco. In 1995 he was recruited to Stanford to start the Abdominal Pediatric Transplant Programs at Stanford Children’s and rebuild the Adult Liver and Kidney Transplant Programs.  Under his guidance, his team has performed more than 5000 abdominal transplants during a span of almost 25 years.

Dr. Esquivel is recognized worldwide as an expert and pioneer in transplantation. He is a creative and productive investigator having contributed over 500 publications in the medical literature and given over 200 lectures throughout the United States and internationally. He oversees multiple basic science and clinical research projects and is currently PI for a 5-year, multi-center NIH grant to develop biomarkers for Epstein-Barr Virus-induced post-transplant lymphomas in children.  As a transplant leader at Stanford and in key national and international societies, he promotes team cooperation, embraces change and creates an environment for fostering discovery, and for training leaders of the future.  In recognition of his many contributions to surgical education, Dr. Esquivel received the American Society of Transplant Surgeons 2015 Francis Moore Excellence in Mentorship in the Field of Transplantation Award.  In spring of 2019, Dr. Esquivel was elected as President-Elect of the International Pediatric Transplant Association, a position held for 2 years prior to assuming presidency.

Dr. Bonham is Associate Professor of Surgery in the Division of Abdominal Transplantation, Director of the Adult & Pediatric Living Donor Programs and Director of the Intestinal Transplant Program. His general surgery training was at Cornell University Medical School. He received advanced fellowship training in transplantation from the University of Pittsburgh under the direction of Dr. Thomas Starzl. Dr. Bonham joined the Stanford Division of Abdominal Transplant in 2002. In addition to adult and pediatric liver and intestine transplantation and hepatobiliary surgery, he has expertise in combined en bloc heart/liver transplantation, a technique perfected at Stanford for patients suffering from congenital heart disease and cirrhosis. His research interests include stem cell biology, particularly as it relates to organ regeneration, and immunologic tolerance. He has directed clinical trials to establish tolerance after liver transplantation, successfully maintaining a number of patients off all immunosuppression for periods as long as 12 years.

Dr. Stephan Bonham is Professor of Surgery in the Division of Abdominal Transplantation and Director of the Adult Kidney and Pancreas Transplant Program. He completed his general surgery residency at the University of Montreal and his transplant surgery fellowship at California Pacific Medical Center. His research interest is centered on the improvement of clinical immunosuppression which involves the evaluation of new immunosuppressive drugs that are potentially more efficacious and/or less toxic. This also includes better monitoring of the effect of these drugs. The ultimate goal is to achieve tolerance, a state that would obviate the need for any drugs. Other interests include the development and study of efficacy strategies to desensitized organ transplant recipients and expending our capabilities to tailor the immunosuppression needs of specific patients through new immune-monitoring tests. Ultimately these research projects are aimed at improving the outcomes of organ transplant recipients.

Dr. Sheri M. Krams is currently Professor of Surgery, Division of Abdominal Transplantation and the School of Medicine’s Senior Associate Dean for Graduate Education and Postdoctoral Affairs.

A faculty member with the Stanford University School of Medicine since 1995, Dr. Krams has a track record of excellence as a researcher and is highly regarded as a strong advocate for trainees. In December, she was appointed Associate Dean of Graduate Education and Postdoctoral Affairs, where she has supported trainees’ academic and professional development, enhanced diversity in the biosciences, and strengthened training of graduate students and postdoctoral scholars.

Throughout her career, Dr. Krams has proven to be a dedicated and motivational teacher. She also has received numerous awards for her mentorship, including the Stanford School of Medicine Office of Graduate Education Award for Excellence in Diversity and Inclusion (2019), Stanford School of Medicine’s Excellence in Teaching Award (2014), and The Transplantation Society’s International Basic Science Mentor Award (2010).  Among many other roles, Dr. Krams has served as chair of pre-doctoral admissions in the Immunology Graduate Program since 2012 and on Stanford University’s Committee of Graduate Admissions and Policy since 2010.

As a researcher in the Division of Abdominal Transplantation, Dr. Krams has made numerous discoveries that have helped improve outcomes for recipients of organ transplants. Her work has focused on defining the role of NK cells in response to viral and allo-antigen and led to a paradigm shift by demonstrating that NK cells directly influence the immune response after solid organ transplantation and contribute to both acute and chronic allograft rejection. Recent studies, using both experimental models and human immunology, define how exosomes and microRNAs regulate immune responses after transplantation. Dr. Krams was elected as an American Society of Transplantation fellow in 2015, two years after receiving the organization’s Basic Science Investigator Award.

Dr. Olivia M. Martinez is currently Professor of Surgery, Division of Abdominal Transplantation, and Vice Chair of Basic & Translational Research in the Department of Surgery.  She is also the Director of Stanford Immunology and Director of the PhD Program in Immunology at the Stanford University School of Medicine.

Dr. Martinez received her Ph.D. in Immunology from the University of California, Berkeley.  She is the recipient of a number of awards and honors including the Fujisawa Basic Science Award, the Office of Graduate Education Faculty Award for Student Service, the Stanford Biosciences Faculty Award for Excellence in Mentoring, and a Fellow of the American Society of Transplantation. Her distinguished career and outstanding contributions as a researcher, teacher, and leader were recently recognized by the AAI where she was named a Distinguished Fellow.

Dr. Martinez has established a leading research program on viral immunity and regulation of the immune response to cellular and solid organ grafts.  She is also a widely recognized expert on the development of post-transplant malignancies including virally-induced B cell lymphomas and this work has led to improved diagnosis and management of transplant recipients.

Dr. Martinez is author of over 130 original research publications, review articles, book chapters and conference proceedings.  Her laboratory has been funded by the NIH for over 25 years and has also been supported by the Roche Organ Transplant Research Foundation, the American Heart Association, and the Department of Defense

Dr. Pham completed his medical degree at the University Of Cincinnati College Of Medicine in 2007.  He then completed his general surgery residency at The Ohio State University Medical Center in 2014.  Dr. Pham received The National Kidney Foundation, Folkert Belzer MD Research Award from American Society of Transplant Surgeons in 2010 to support him during his post-doctoral research where he studied the alloantibody response following hepatocellular transplantation.  During that time he also obtained a Masters in Medical Science in 2011 from The Ohio State University School of Medicine.  He then completed his Abdominal Transplant Surgery Fellowship at the Stanford School of Medicine in 2016.  He is board certified in general surgery.

Dr. Pham joined Stanford Abdominal Transplant Surgery in 2018.  He is currently a Clinical Assistant Professor of Surgery in the Division of Abdominal Transplantation.  Dr. Pham also serves as the Associate Program Director of the Stanford Abdominal Transplant Surgery Fellowship.  He maintains a practice at Stanford Health Care and Lucille Packard Children’s Hospital.

His research interests include tolerance induction following kidney transplantation, outcomes research in single and multi-organ transplant recipients and implications paired kidney exchange in highly sensitized individuals.  

Dr. Kazunari Sasaki received his medical degree in 2004 from Shiga University of Medical Science in Japan and completed his general surgical training at Toranomon Hospital in Tokyo. He moved to the US in 2015 and completed a clinical fellowship in transplantation at Cleveland Clinic, where he was subsequently appointed to the surgical faculty. He specializes in liver transplantation and minimally invasive hepatobiliary surgeries

Dr. Sasaki joined Stanford Abdominal Transplant Surgery in 2021.  He is currently a Clinical Associate Professor in the Division of Abdominal Transplantation.  

Dr. Varvara Kirchner completed her medical school, surgical residency and multi-organ transplant fellowship in adult and pediatric liver, pancreas, kidney transplantation and total pancreatectomy with islet auto-transplantation at the University of Minnesota. She underwent further training in living donor liver transplantation and hepatobiliary surgery at the Asan Medical Center, Seoul, South Korea. Her clinical practice involves living and deceased donor liver and kidney transplantation in adult and pediatric patients as well as total pancreatectomy with islet auto-transplantation for patients with chronic and acute recurrent pancreatitis. She currently serves as Surgical Director of the Islet Cell Auto-Transplant at Stanford Children’s and Associate Director of the Living Donor Liver Transplant Program at the Division of Abdominal Transplantation.

Dr. Kirchner joined Stanford Abdominal Transplant Surgery in 2022.  She is currently an Associate Professor in the Division of Abdominal Transplantation.  

Her research focuses on the biology of aging, cellular and solid organ transplantation. Her specific interests are in auto-islet transplantation, iPSC-derived hepatocyte therapies and liver regeneration. Dr. Kirchner's research on the impact of donor age on generation of iPSC-derived hepatocyte-like cells is supported by the NIA K08 Faculty Development Award. She is an active member of the American Society of Transplant Surgeons and the International Liver Transplantation Society.