From PhysOrg:
Stem-cell scientists led by Dr. John Dick have discovered a completely new view of how human blood is made, upending conventional dogma from the 1960s. The findings, published online today in the journal Science, prove “that the whole classic 'textbook' view we thought we knew doesn't actually even exist,” says principal investigator John Dick, Senior Scientist at Princess Margaret Cancer Centre, University Health Network (UHN), and Professor in the Department of Molecular Genetics, University of Toronto. “Instead, through a series of experiments we have been able to finally resolve how different kinds of blood cells form quickly from the stem cell – the most potent blood cell in the system – and not further downstream as has been traditionally thought,” says Dr. Dick, who 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.
…”Four years ago, when we isolated the pure stem cell, 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,” says Dr. Dick. “When we burrowed further to study these 'daughters', we discovered they were actually already mature blood lineages. In other words, lineages that had broken off almost immediately from the stem cell compartment and had not developed downstream through the slow, gradual 'textbook' process. “So in human blood formation, 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.”
More here.
