Scientists have a future vision, when people can regrow organs and
obtain immortality. Particularly, they aim to cure a number of
diseases - cancer, Alzheimer's, Parkinson's, diabetes, and other,
using stem cells. The only question is how to direct stem cells to
become the proper tissue type.
There are a rich variety of cells -- endothelial cells, muscle cells,
blood cells, osteoblasts (bone), and nerve cells in the human body.
These cell lines were created by a biochemical signal which
instructing stem cells to become the particular cell type. Scientists
at Cambridge University and Rice bioengineers, Oleg Igoshin and Jatin
Narula, have examined one of such critical biochemical signals. Based
on a computer model (developed at Rice and experiments at Cambridge),
researches are sure about a trio of regulatory proteins (known more as
the "Scl-Gata2-Fli1 triad") controlling the differentiation of
hematopoietic stem cells (HSCs), the self-renewing cells the body uses
to make new blood cells.
To the fact, every day HSCs are responsible for the creation of 100
billion new white and red blood cells in the human body. The
hematopoietic stem cells are also capable of "self-renewing".
The Rice research delved into looking at the three regulatory proteins
and developing an mathematical model for how they interacted with
hematopoietic stem cells. In a new model of the scientists, the
proteins act as a bistable switch. During the process they have two
states: "replenish HSC" and "differentiate". The system throws the
switch only when a signal persists, ignoring extraneous signals.
In examining the results from the model, the researches found the
triad did have the characteristics of a master regulator. The first
time it's switched on, all the cells stay on. It also handled
deactivation in a controlled manner, so that some cells differentiated
and got deactivated. They had the ability to discern whether or not
the level of signal is present only for a short burst or for a
significantly long time. There is a hope that the regulatory triad
motif reappears in other types of stem cells, possibly leading to more
The study is published in the journal PLoS Computational Biology.