History Of Stem Cell Research

Canadian physicians and scientists, Dr. Ernest Armstrong McCulloch and Dr. James Edgar Till, made a fascinating discover in the 1963 while studying mouse hematopoiesis (blood formation). They identified cells that would give rise to individual cellular colonies on the host spleen when transplanted into irradiated mice. These colonies underwent self-renewal and differentiated into three different cell lines: erythrocytes (red blood cells), granulocytes (a type of white blood cell) and megakaryocytes (a bone marrow cell responsible for the production of platelets). These results supported the Unitarian Theory of Hematopoiesis proposed by a Russian scientist, Alexander A. Maximov in 1908.

McCulloch and Till aren’t the only researchers who took important first steps in stem cell research. Joseph Altman put forth the question, "Are new neurons formed in the brains of adult mammals?" in 1962, a year before the Canadian scientists’ publication. Altman’s data supported his hypothesis that cells adjacent to brain lesions in rats were forming neuroblasts, neurons, and glia cells. This finding contradicted the accepted dogma of the day, "no new neurons". This belief that new neurons cannot form left Altman's work largely ignored until the early 1990's, when Dr. B. A. Reynolds and S. Weiss first isolated neural progenitor and stem cells in mice.