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Dr. Weissman, MD, is a professor of pathology and developmental biology and,  by courtesy, of Neurosurgery and Biology at Stanford University. He is the Founding Director of the Stanford Institute of Stem Cell Biology and Regenerative Medicine, Director of the Ludwig Center for Cancer Stem Cell Research at Stanford, and the former Director of the Stanford Cancer Center.

Born and raised in Montana, Weissman at age 16 started research on the development of immune system with Dr Ernst Eichwald, a Jewish refugee from Germany, who after faculty stints at Harvard and Utah, moved to Great Falls, Montana. Weissman was supported by the Montana division of the American Cancer Society in Great Falls, received his pre-med B.S. from Montana State University in 1961,  graduated from Stanford Medical School in 1965 and has been at Stanford ever since. He is a world-renowned scientist widely respected for his innovation and leadership, and has received extensive recognition for his work. He has published more than 900 papers, received multiple patents, and co-founded a number of biotechnology companies were established to develop new therapies based on scientific discoveries from his lab including Systemix, Stem Cells Inc, Cellerant, and recently Forty Seven Sciences.

As the first scientist to ever define and isolate mammalian stem cells, the blood-forming stem cells in mice (1988) and then humans (1992), Irv Weissman is known as the ‘father’ of stem cell biology. He pioneered the biological definition, prospective isolation and transplantation of stem cells and his methodology is considered the gold standard in this field of research. Following the isolation of blood-forming stem cells, his group has successfully defined the stages of development that occur between those stems cells and mature blood cells, and then went on to the isolation of stem cells of other tissues including brain stem cells, muscle stem cells, and skeletal stem cells that give rise to bone, cartilage and bone marrow cells that support the blood-forming stem cells. His research on blood formation and cancer has led to several discoveries and the development of new therapies. These include the isolation and transplantation of pure hematopoietic stem cells (HSCs), the demonstration that the accumulation of mutations associated with the stepwise preleukemic progression occurs in hematopoietic stem cells with the last mutation giving rise to leukemic stem cells and the comparison of cancer to normal stem cells that led to the discovery of CD47 as a ‘don’t eat me’ signal used by all human cancers to evade innate immunity. Binding of CD47 to SIRPa, its receptor on macrophages, inhibits phagocytosis, and blocking this interaction with anti CD47 antibodies unleashes phagocytosis of cancer cells by macrophages. Weissman then led the clinical development of CD47 blockade as a new cancer immunotherapy, the first that’s based on mavcrophage checkpoint inhibition, in clinical trials conducted by Forty Seven Inc. In phase-I clinical trials significant therapeutic anti-cancer effects were achieved, remarkably complete remissions were observed with a combination therapy of anti CD47 and Rituximab in lymphoma patients who failed all other therapies.


Professor Weissman is a member of the National Academy of Sciences, the Institute of Medicine at the National Academy, and the American Association of Arts and Sciences. He has received many awards, including the Kaiser Award for Excellence in Preclinical Teaching, the Pasarow Award in Cancer Research, the California Scientist of the Year, the De Villiers International Achievement Award of the Leukemia Society of America, the Robert Koch Award, the Rosenstiel Award, The max Delbruck Medal, the Jessie Stevenson Kovalenko Award of the National Academy of Sciences and the Albany Prize. He is also the 2004 New York Academy of Medicine Award for distinguished contributions to biomedical research, and has several honorary doctorates.


In addition to his scientific contribution, Weissman has been central to promoting and regulating stem cell research and public policy, and was the main force behind proposition 71 which was approved in 2004 and  established the California Institute of Regenerative Medicine, followed by proposition 14 that was approved in 2020 to fund research not funded by the federal government, and to bring discoveries to and through early phase clinical trials.

Caring deeply about education he’s been working to increase public knowledge of the field, and remains committed to teaching and training the next generation of scientists.