Even if cells are officially genetically identical and belong to the same clone, individual members of that population are quite different at any given time, says Huang. This heterogeneity has usually been seen as random measurement noise, and, more recently, as gene expression noise. But it turns out to be very important, and is the basis for stem cells multipotency their ability to differentiate into multiple lineages.
Nature has created an incredibly elegant and simple way of creating variability, and maintaining it at a steady level, enabling cells to respond to changes in their environment in a systematic, controlled way, adds Chang, first author on the paper.
Practically speaking, the work suggests that stem cell biologists may need to change their approach to differentiating stem cells in the laboratory for therapeutic applications.
So far the process has been highly inefficient only 10 to 50 percent of cells respond to the hormone or whatever is given to make them differentiate, Huang says. That is because of the cells inherent heterogeneity. People have been finding more and more sophisticated stimulator cocktails, but we could make the process more efficient by harnessing the heterogeneity and identifying cells that are already highly poised to differentiate.
Chang has already done follow-up experiments showing that stem cell differentiation can be made dramatically more efficient by choosing the right subpopulation of stem cells and stimulating them promptly, while they are most apt to differentiate. Im not doing anything complicated just using what nature already has, she says.
But the findings also challenge biologists to change how they think about biological processes. The work supports the idea of biological systems moving toward a stable attractor state, a concept borrowed from physics. In this case, blood stem cells tend to remain blood stem cells, yet they
|Contact: Bess Andrews|
Children's Hospital Boston