If he wasn't a Canadian household name - like Frederick Banting, Charles Best, or Norman Bethune - he should have been. And though he wasn't a Nobel Prize winner, the leaders in his field believe he deserved to be.
Ernest (Bun) McCulloch, the Canadian scientist who with colleague James Till first proved the existence of human stem cells 50 years ago, died on Thursday in Toronto, where he was born 85 years ago.
A graduate of Upper Canada College and the University of Toronto, the married father of five children spent his life and remarkable medical career in the city of his birth.
In a cruel twist of timing, McCulloch's death comes less than two weeks before the 50th anniversary celebration of the seminal stem-cell research paper that he and Till published in 1961. That paper laid the groundwork for the modern era of stem-cell work, one of the most promising areas of medicine.
Scientists had long suspected there must be a powerful precursor cell in the human body that gives rise to various tissue types. But not until the Canadian duo set their minds to finding out did anyone prove it.
Working at a Sherbourne Street lab in the early 1960s, McCulloch, a hematologist interested in leukemia, and Till, a biophysicist, ran a series of experiments transplanting bone marrow cells in mice. The results proved that a single seed cell could indeed grow into all the different cells that make up a blood supply. They went on to describe the key traits of stem cells and how they could be studied. The work led to the first bone-marrow transplant and changed the face of cell biology.
On Feb. 1, their landmark paper is to be reprinted in the journal Radiation Research, 50 years to the day after it first appeared. A commemoration was to take place that day at Princess Margaret Hospital, but with McCulloch's unexpected death it is unclear if it will go ahead.
"I talked to him last week," said Christopher Paige, a senior scientist in the stem cell division at the Ontario Cancer Institute. "He was excited and delighted that we would do this.
"This is a sad event; a giant has passed."
A full obituary is forthcoming.