Our Faculty

David C. Mulligan, MD, is an abdominal organ transplant surgeon performing both living and deceased donor liver, kidney, and pancreas transplants.

He currently serves as Professor and Chair of Transplantation and Immunology in the Department of Surgery at Yale School of Medicine/Yale New Haven Health System.

His clinical and academic focus surrounds living donor liver transplantation, expanding donation, and working on ways to utilize ex-vivo organ perfusion systems to increase transplantation in the United States.

Dr. Mulligan and his team are testing novel strategies in immunosuppression; improved biomechanical organ preservation methods to reduce ischemia/reperfusion injury and promote regeneration; and working in the field of 3D bioprinting to collaborate in finding ways to grow new organs from stem cell precursors.

He has performed more than 250 living donor transplants and has authored more that 180 publications. He also has served on numerous editorial review boards and presented across the U.S. and internationally.

Dr. Mulligan’s leadership in solid organ transplantation across national and international platforms has grown considerably and he now serves as Immediate Past President of the United Network of Organ Sharing (UNOS)/Organ Procurement Transplant Network (OPTN), Member at-large on the Governing Board of the American Association for the Study of Liver Diseases, Past Chair of the Advisory Council on Transplantation (ACOT) to the Secretary of HHS, special government employee for FDA Medical Device Advisory Committee and chair of the Business Practice Committee of the American Society of Transplant Surgeons. He also contributes to the oversight and recommendations regarding the impacts of COVID-19 on solid organ transplantation in the U.S. for both the AASLD and the ASTS.

In these visionary roles, he has led major changes in organ allocation and distribution and will hopefully culminate in substantial increases in organ transplants. Passionate about patient-centered care and building more resilient teams, he makes time to share his enjoyment of spending time in nature, especially near the ocean, with his wife and three children.

Ramesh Batra, MD, is the surgical director of liver transplant program at Yale Transplant Center. He is also a living donor liver surgeon for the transplant center besides being a multiorgan transplant surgeon for adult and pediatric patients. Alongside his transplant roles, he also performs complex hepatobiliary operations for liver tumors and biliary tract disorders in high risk patients.

Dr. Batra's expertise is in living organ donation and also in transplanting extended spectrum aka “marginal” organs, both liver and kidneys for early transplant and reducing the time on organ transplant waiting list. With this ability, he continually seeks to find “opportunity” in organs declined by other transplant centers for his patients. Aside from maximizing utility and reducing organ discard, he is passionate about alleviating the ethical barriers in organ donation and transplantation. As a qualified and trained ethicist, he is nationally acclaimed in the field and constantly seeks to push the boundaries in organ transplant

Dr. Batra in the early foundational years underwent the British system of surgical training in NHS based hospitals in United Kingdom, and was subsequently admitted to the Membership and Fellowship of The Royal College of Surgeons. He also completed the ASTS (American Society of Transplant Surgeons) abdominal transplant fellowship at the Mayo Clinic in liver, kidney and pancreas transplants along with pediatric liver transplants at Phoenix Children's hospital. 

He is an active member of the American Society of Transplant Surgeons, American Society for Bioethics and Humanities, and also a Fellow of the American College of Surgeons. He currently serves on various national and international transplant and ethics committees along-with being on various editorial boards for medical and surgical journals to be at the forefront of transplant innovation.

Danielle is excited to have joined the surgical faculty at the Yale New Haven Transplant Center and School of Medicine.  She is originally from Colorado and completed several years of research, her undergraduate education and her medical education at Colorado State University and University of Colorado.  She moved to Arizona for her surgical training completing both General Surgery Residency and an Abdominal Transplant Surgical Fellowship at Mayo Clinic Arizona.  Her research interests include the diabetic management of surgical and transplant patients, marginal organ utilization and surgical education.  Danielle loves teaching and mentorship of future physicians and healthcare providers.  In her free time she enjoys spending time with her family, music, reading, cooking, hiking and yoga.

Dr. Kulkarni is a multi-organ transplant surgeon and the Director of the Kidney Transplant Program at Yale University and Yale-New Haven Hospital. The clinical program has been one of the largest programs in New England since 2008, in terms of new patients listed, the number of living donor transplants, and the total number of kidney transplants performed. Clinical highlights of the program include an accelerated work-up and listing process (AJKD 2012;60(2):288, Healthgrades Award for overall program performance 2010, and implementation of a total laparoscopic kidney donation procedure. Watch a video with Dr. Sanjay Kulkarni >>

Dr. Kulkarni is medical director of the newly established, Center for Living Organ Donors, which is founded on the free life-long welfare and clinical monitoring of living donors that have donated at Yale. This unique program provides donor-centered outreach throughout CT and engages donors long-term to assure health. It also serves as a platform to donor community development and long-term engagement with our donors to foster the sharing of health through living donation.

Dr. Kulkarni is the principal investigator on numerous clinical research trials and projects. His research has focused on the use of anti-complement therapies to improve kidney graft survival and novel approaches to improving living donor outcomes through surgical innovations, including low-pressure laparoscopy. Ongoing research initiatives include the ethics and implementation of patient-centered care in the care of living donors through shared-decision making, identifying reasons why individuals opt-out of donation, and fostering the development of local donor communities using a social capital framework.

Appointed to the role of Physician Executive Director, Clinical Continuity & Integration for Yale-New Haven Hospital, Dr. Kulkarni aims to improve the patient experience by identifying areas of fractured care within the health system and implement novel interventions to improve care coordination within the domain networks.

Dr. Gregory Tietjen earned his PhD in Biophysics at the University of Chicago before completing Postdoctoral training in the Department of Biomedical Engineering at Yale University. At all levels of his training, Dr. Tietjen’s emphasis has been on integrating multiple diverse disciplines to forge new scientific pathways. Dr. Tietjen now applies his expertise in molecular biophysics and biomedical engineering within a clinical context as an Assistant Professor in the Yale School of Medicine Department of Surgery, Section of Transplantation and Immunology. The focus of Dr. Tietjen’s current research is on utilizing non-transplanted human organs to understand mechanisms of human pathophysiology in order to guide the rational design of new precision therapies. 

Dr. Yoo is a board-certified surgeon who specializes in abdominal organ transplantation in children and adults. He is appointed as Associate Professor in the Department of Surgery, serves as the Program Director of the Yale Surgical Residency, and directs the Yale Surgical Education Research Laboratory.  

A native of New York, Dr. Yoo was an undergraduate at Dartmouth College and earned his medical degree at SUNY Stony Brook School of Medicine. He was an intern, resident, and administrative chief resident in the Department of Surgery at Yale. During residency, he completed a post-doctoral research fellowship examining mediators of angiogenesis in hepatic malignancy and obtained support from the National Institutes of Health for his work. After residency, Dr. Yoo was a fellow in organ transplantation at the Hospital of the University of Pennsylvania and the Children's Hospital of Philadelphia. Dr. Yoo directed Yale's programs in Pediatric Kidney Transplantation and the Paired Organ Exchange Program, which notably performed an 18-patient kidney exchange in 2017.  He recently became an Associate of the American College of Surgeons Academy of Master Surgeon Educators.

Dr. Yoo's research has focused on understanding and improving the clinical learning environment for surgical residents.  His groundbreaking work includes the first major study of attitudes toward pregnancy and parenthood during surgical residency (J Am Coll Surg, 2016), the first national study of sexual harassment in surgical training (Ann Surg, 2020), and numerous manuscripts regarding wellbeing/burnout, the balance between fatigue and safety, and engagement of surgical residents in society.  He was recently appointed to chair the Knowledge Assessment Committee of the Transplant Accreditation and Certification Council and is a key leader in the effort to establish tools for specialty certification in Organ Transplantation.  He speaks nationally on these topics and serves many national associations and societies in surgery, transplantation, and surgical education.