Dead bodies can provide organs for transplants, now
they might become a source of stem cells too. Huge numbers of stem cells
can still be mined from bone marrow five days after death to be
potentially used in a variety of life-saving treatments.
Human bone marrow contains mesenchymal
stem cells, which can develop into bone, cartilage, fat and other cell
types. MSCs can be transplanted and the type of cell they form depends
on where they are injected. Cells injected into the heart, for example,
can form healthy new tissue, a useful therapy for people with chronic heart conditions.
Unlike other tissue transplants, MSCs
taken from one person tend not to be rejected by another's immune
system. In fact, MSCs appear to pacify immune cells. It is this feature
which has made MSC treatments invaluable for children with graft-versus-host disease, in which transplants aimed at treating diseases such as leukaemia attack the child instead.
Stem cell therapies require a huge
numbers of cells though, and it can be difficult to obtain a sufficient
amount from a living donor. Could cadavers be the answer? After death,
most cells in the body die within a couple of days. But since MSCs live
in an environment that is very low in oxygen, Gianluca D'Ippolito and
his colleagues at the University of Miami, Florida, wondered whether
they might survive longer than the others.
To investigate, D'Ippolito's team kept
the finger bones of two cadavers for five days. The group then
extracted MSCs from the bone marrow of each bone and let them grow in a
dish. After five weeks D'Ippolito was able to transform the stem cells
into cartilage, cells that form bone, and fat cells. He presented the
results at the World Stem Cell Summit in West Palm Beach, Florida,
earlier this month. The team are now trying to get the cells to become
nerve and intestinal cells, too.
While only limited amounts of bone
marrow can be taken from a living donor, a cadaver represents a
plentiful source of cells, says D'Ippolito. "From one donor, you could
take the whole spine, for example. You are going to end up with billions
of cells."
Paolo Macchiarini, who researches
regenerative medicine at the Karolinska Institute in Stockholm, Sweden,
describes the work as an excellent advance but says that the cells may
not be as healthy as they seem. Their DNA may be affected by the death
of surrounding tissue and exposure to cold temperatures. "We need to
make sure the cells are safe," he says.
Corneal stem cells taken from the eyes
of fresh cadavers have already been used to treat blindness in people
with eye conditions that result from injury and scarring, but Chris Mason
at University College London sees a potential hurdle in using such MSCs
in therapy. "The work is novel and intriguing... but it would be better
to use a living donor," he says. That's partly because medical
regulators oppose treating individuals with stem cells from more than
one source. "You can always go back and get more stem cells from a
living donor if you need them, but if you use a cadaver, you'll
eventually run out."
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