Cadaver stem cells offer new hope

Fuente: http://www.newscientist.com/article/dn23034-cadaver-stem-cells-offer-new-hope-of-life-after-death.html

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. 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."