For ingenious experiments that first identified a stem cell — the blood-forming stem cell — which set the stage for all current research on adult and embryonic stem cells.
The 2005 Albert Lasker Award for Basic Medical Research honors two scientists who first identified a stem cell, which set the stage for all current research on adult and embryonic stem cells. By the turn of the 20th century, scientists were postulating the existence of self-renewing cells that could specialize for a wide variety of purposes. In a series of ingenious and elegant experiments 60 years later, Ernest McCulloch and James Till demonstrated that such a type of cell in the blood-forming — or hematopoietic — system existed. They established the properties of stem cells, which still hold true today. Furthermore, they lay the foundation for the isolation of stem cells and for the detection of proteins that help these precursor cells develop and mature. Till and McCulloch's discoveries explained the basis of bone marrow transplantation, which prolongs the lives of patients with leukemia and other cancers of the blood. Moreover, the team set a new standard of rigor for the field of hematology, transforming it from an observational science to a quantitative experimental discipline.
In the late 1950s, McCulloch and Till, newly appointed scientists at the Ontario Cancer Institute in Toronto, began to explore how ionizing radiation affects mammalian cells. This enterprise held great importance for several reasons. Scientists were trying to understand why and under what circumstances radiation therapy defeated cancer. Furthermore, the Cold War was in full swing, so people wanted to devise strategies to save military personnel who might sustain whole-body irradiation from nuclear weapons. Finally, the technique of bone marrow transplantation was in its infancy; investigators knew that this treatment replenished the essential cells of the blood system and were eager to define the source of these cells.
Award presentation by Thomas Stossel
To begin to explain what today's Basic Science Lasker Award winners, Ernest McCullough and James Till, accomplished, let me point out that the reason we are all enjoying this luncheon is that we have blood cells — red blood cells that carry oxygen around, white blood cells that protect us from germs and platelets that keep us from bleeding. We constantly produce these cells, and we make trillions of them every day.
Since the late 19th century we could recognize these different blood cells but we had no understanding as to how they were produced. To be sure, we knew that they came from inside of the bones — in the bone marrow — and we could identify immature forms of them. But how they really were made was a mystery.