New Stem Cell Research Changes What We thought We Knew about Human Blood Cell Formation

Susanna Sisson's picture
Blood cell formation dick canana

Scientists can be an arrogant lot of people, so it takes proof to humble and change views, yet Dr. John Dick, Senior Scientist at the Princess Margaret Cancer Center, University Health Network (UHN) in Toronto, Canada has done just that. Dr. Dick has worked for over 25 years in stem cell research and molecular genetics. Recently, he and his team discovered that the body’s mechanism by which all blood cells develop, hematopoiesis, does not function the way previously thought. The discovery means that what every person who has studied even basic biology and has learned about blood cell formation since the 1960’s, is incorrect.


Dr. Dick is lead investigator and Professor in the Department of Molecular Genetics, University of Toronto. He holds a Canada Research Chair in Stem Cell Biology and is also Director of the Cancer Stem Cell Program at the Ontario Institute for Cancer Research. Dr. Dick and his team developed new methodology to determine how different kinds of blood cells form from the stem cell -- the most potent blood cell in the system – rather than being formed later in the developmental process. [1] The results of the study were published last week in Science Journal. [2]
“Co-authors Dr. Faiyaz Notta and Dr. Sasan Zandi from the Dick lab write that in redefining the architecture of blood development, the research team mapped the lineage potential of nearly 3,000 single cells from 33 different cell populations of stem and progenitor cells obtained from human blood samples taken at various life stages and ages.” [1]

Imagine a gumball machine as a giant stem cell compartment, but rather than one dispenser, there are several outlets which exclusively and very rapidly dispense different colored gumballs which represent different types of blood cells. This would be a very similar image of how a new blood cells are formed. Dr. Dick compared the process to a rainbow splitting off different colors to form differentiated blood cells but in rapid fire succession. [3]

"In human blood formation,” says Dr. Dick, “everything begins with the stem cell, which is the executive decision-maker quickly driving the process that replenishes blood at a daily rate that exceeds 300 billion cells." [1]

Dr. Dick's research has focused on studying the cellular processes underlying how normal blood stem cells work to regenerate human blood after transplantation. His team has also studied what mechanisms go awry in the development of specialized blood cells that lead to both anemias and leukemias, as well as what role stems cells may play. Dr. Dick’s new findings open up many new possibilities in the treatment of not only blood diseases but all disease processes. In 2011, he and his team had a breakthrough when they discovered and isolated a human blood stem cell in its purest form – as a single stem cell capable of regenerating the entire blood system. [1]


"Four years ago, when we isolated the pure stem cell,” says Dick, “we realized we had also uncovered populations of stem-cell like 'daughter' cells that we thought at the time were other types of stem cells.” Upon further investigation the team determined that these 'daughters' were actually already mature blood lineages that had broken off almost immediately from the stem cell compartment rather than having developed downstream through the slow, gradual 'textbook' process. [1]

Stem cells were first discovered by the late Dr. Earnest McColloch in the early 1960’s. Continuing research with colleague Dr. J.E. Till, McCulloch created the first quantitative, clonal method to identify stem cells. Till and McCulloch were joined by graduate student Andy Becker, and demonstrated that each nodule did indeed arise from a single cell. They published their results in Nature in 1963. In the same year, in collaboration with Lou Siminovitch, a trailblazing Canadian molecular biologist, they obtained evidence that these cells were capable of self-renewal, a crucial aspect of the functional definition of stem cells that they had formulated. [4]

Dick’s new findings are historical, and show a difference not only between the old concepts of blood formation but, differences between fetal and adult blood cell formation. “In an adult,” says Dr. Dick, “we have a two-tiered system which is different than the formation of fetal cells. The potential clinical utility will be that we will be able to understand far better a wide variety of human blood disorders. Our new high resolution monitoring ability actually will allow us to go back and redefine disease states. It means every patient could be getting their own individualized therapy.” [3]

This is the second recent medical discovery to alter what has been taught in biology classes and medical schools for decades, the other being the discovery of a connection between the brain and lymphatic system by scientists at the Center for Brain Immunology and Glia at the University of Virginia in Charlottesville, Virginia. [5] These discoveries challenge conventional beliefs and have made current medical textbooks obsolete.

3. Dr. John Dick