Timothy D. O'Brien

Timothy D. O'Brien is a Professor and Division Head of Comparative Pathology in the Department of Veterinary Population Medicine at the University of Minnesota College of Veterinary Medicine. He holds multiple affiliations including the Stem Cell Institute, Masonic Cancer Center, and Institute for Engineering in Medicine. Dr. O'Brien also serves as faculty for the Masters Program in Stem Cell Biology.

Dr. O'Brien earned his BS, DVM, and PhD degrees from the University of Minnesota in 1976, 1978, and 1985 respectively. He is a Diplomate of the American College of Veterinary Pathologists (Anatomic Pathology, 1984).

His research spans veterinary pathology, transplantation biology, stem cell research, and cancer biology with a focus on comparative pathology models. He has made significant contributions to understanding interspecies organogenesis, islet xenotransplantation, and animal models for human diseases. His work bridges veterinary and human medicine, exploring translational applications of findings from animal models to human conditions. Recent publications highlight innovative approaches to transplantation without long-term immunosuppression and studies on hemangiosarcoma biology.

Dr. O'Brien's publication record demonstrates expertise across multiple disciplines including diabetes research using feline models, lung cancer heterogeneity, and innovative transplantation techniques. His work frequently involves interdisciplinary collaborations across veterinary medicine, engineering, and human medical specialties, reflecting the integrative nature of modern biomedical research.

His research program involves extensive collaborations across the University of Minnesota and beyond, working on projects related to stem cell biology, cancer research, and transplantation medicine. As Division Head of Comparative Pathology, he oversees diagnostic pathology services while maintaining an active research program that contributes to advancing our understanding of disease mechanisms through comparative approaches.