Discovery of Stem Cells

Achievement Details
Type of Achievement: 
Sunday, January 1, 1922

The stem cell story began in 1958 with the building of the University of Toronto’s Department of Medical Biophysics, attracting hematologist, Dr. Ernest A. McCulloch and biophysicist, Dr. James E. Till.  The two met at a party hosted by head of the Department of Medical Biophysics, Arthur Ham, where, after hearing of McCulloch’s interest in doing research on total body irradiation and his need for a physicist to assist him, Till volunteered to contribute to the study.   McCulloch and Till’s efforts focused on the biological effects of radiation on cancer cells by replacing dead bone marrow cells with healthy cells. They observed that the transplanted cells developed “colony forming units,” which proved to be self-renewing precursors of new blood cells.  These new cells were later called “stem cells.”  This dynamic team revolutionized medical literature, uncovered new ways to treat many diseases, and laid the foundation for bone marrow transplantation.