What are stem cells?

Stem cells are incredibly
special because they
have the potential to
become any kind of cell
in the body, from red blood cells to
brain cells. They are essential to life
and growth, as they repair tissues
and replace dead cells. Skin, for
example, is constantly replenished
by skin stem cells.
Stem cells begin their life cycle as
generic, featureless cells that don’t
contain tissue-specifi c structures,
such as the ability to carry oxygen.
Stem cells become specialised
through a process called
differentiation. This is triggered by
signals inside and outside the cell.
Internal signals come from strands
of DNA that carry information for all
cellular structures, while external
signals include chemicals from
nearby cells. Stem cells can
replicate many times – known as
proliferation – while others such as
nerve cells don’t divide at all.
There are two stem cell types, as
Professor Paul Fairchild, co-director
of the Oxford Stem Cell Institute at
Oxford Martin School explains:
“Adult stem cells are multipotent,
which means they are able to
produce numerous cells that are
loosely related, such as stem cells in
the bone marrow can generate cells
that make up the blood,” he says. “In
contrast, pluripotent stem cells,
found within developing embryos,
are able to make any one of the
estimated 210 cell types that make
up the human body.”
This fascinating ability to
transform and divide has made
stem cells a rich source for medical
research. Once their true potential
has been harnessed, they could be
used to treat a huge range of
diseases and disabilities.