WASHINGTON (AFP) – Ernest McCulloch, a Canadian researcher who was part of a team that first proved the existence of stem cells more than five decades ago died this week at the age of 84, his colleagues said Friday.

McCulloch and his research partner James Till together created the first method for identifying stem cells in mice, and their work is credited with revolutionizing the field of cell biology and the treatment of chronic disease.

Many had speculated they could have won the Nobel Prize for their groundbreaking work. The pair was nominated in 2009 but did not win. The prize cannot be awarded posthumously.

"Scientists around the world can trace their 'lineage' to Dr McCulloch, and as their work progresses, so too does his influence," said a statement by the Canadian Stem Cell Foundation.

McCulloch died on Wednesday, just days away from the 50th anniversary of his discovery, the foundation said. No cause of death was given.

"I feel a strong sense of loss," Till told AFP in an email. "Dr McCulloch was a trusted and creative colleague, and a supportive and steadfast friend."

The man who went by the nickname "Bun" was considered a pioneer in the field.

"In addition to providing detailed information about blood cell development, they (McCulloch and Till) established the concept of stem cells and set the framework in which stem cells are studied today," said the Canadian Medical Hall of Fame, into which McCulloch was inducted in 2004.

"Their work gains a new freshness with the current interest in harnessing the developmental program of stem cells for therapeutic purposes."

In 2005, the pair received the Albert Lasker Award for Basic Medical Research, seen by many as a likely predictor of a Nobel Prize.

McCulloch was born in Toronto on April 26, 1926. He was also a lead researcher at the Ontario Cancer Institute and the Institute of Medical Science at the University of Toronto.

He previously served as president of the Academy of Science of the Royal Society of Canada, and was a fellow of the Royal Society of London.