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23 September 2009

Stem cell research: where it is at

Is stem cell research equal to abortion? Bush seems to think so. But recently embryonic stem cells were harvested without destroying embryos. We bring you the latest developments.

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In March 2009, US President Barack Obama overturned an eight-year ban imposed by former US President George W. Bush that barred the US National Institutes of Health from funding research on embryonic stem cells.

A new era for independent research into embryonic stem cells was introduced. At the same time, exciting research into pluripotent stem cells (iPS) – cells that aren't derived from embryonic cells, but rather from cells sourced from adult lab animals – was underway. In July 2009, Chinese researchers succeeded in producing dozens of healthy mouse pups using only iPS cells. (Click here to view a timeline of major stem-cell events.)

Despite the research activity abroad, however, no embryonic stem cell research is currently being done in South Africa. No formal policies exist and there's no government funding for research into this field.

But this doesn't mean that South Africans aren't affected by the progress that's being made by overseas research teams. The research done in countries like the United States and China has the potential to change medicine as we know it. Yet the issue of embryonic stem-cell research remains controversial.

Debate: where life begins
In order to understand the stem-cell controversy that's been making headlines over the past decade, it's worth taking a look at where these cells come from.

Prof Michael Pepper, Extraordinary Professor in Immunology at the University of Pretoria's Faculty of Health Sciences, explains that there are two types of stem cells: 1) embryonic stem cells; and 2) adult stem cells.

The period that stretches from the moment of fertilisation up until the eighth week of pregnancy is generally regarded as the embryonic stage, while the foetal stage lasts from the eight-week mark up until birth.

Embryonic stem cells are "harvested" during the blastocyst stage – an early stage of embryonic development that consists of a hollow ball of cells with a localised thickening (called the "inner cell mass"). This ball of cells will eventually develop into the embryo. (Click here to view our stem cell glossary.)

Research shows that embryonic stem cells are remarkably useful. These cells can develop into every type of cell in the body, and has the potential to treat a myriad of diseases.

But their use is regarded as unethical by some, and the debate seems to be centred on the definition of the point at which life begins. According to Pepper, there are generally four ways of thinking about it:

  • life begins at the moment of fertilisation;
  • life begins when the organs start to develop;
  • life begins at the moment of perceived consciousness;
  • life begins at the moment when the foetus is able to survive outside of the womb (somewhere between 22 and 24 weeks).

"I don't know which one is correct," Pepper says. "But Bush, for example, believes that life begins at the moment of fertilisation." Bush and many others who oppose embryonic stem-cell research believe that when scientists take stem cells from the embryo during the blastocyst stage, they're taking away life.

Unethical use of stem cells
Apart from the global controversy regarding the use of embryonic stem cells, both adult and embryonic cells have also been in the news for another reason: its unethical use in the treatment and prevention of disease.

In 2006, a Cape Town couple, Stephen van Rooyen and Laura Brown, was accused of exploiting desperate patients by providing them with ampoules containing cord stem-cells from a registered laboratory. It was claimed that they sold stem-cell medication that was never properly tested.

There have also been reports of stem cells from animals being used in the treatment of humans. And supplements of a blue-green algae called Aphanizomenon flos-aquae (AFA) are now being marketed as a way of releasing stem cells from the bone marrow. These supplements purportedly "supports wellness", even though there hasn't been enough scientific research to back up these claims.

According to Pepper, bone-marrow transplants are currently the only universally accepted use of stem cells. "Any other applications are either in a legitimate experimental stage or are unethical, and aren't accepted by the medical community as a routine form of therapy," he says.

Several potential uses of stem cells are currently being investigated, but are not yet a reality in a clinical sense. Some of these applications include:

  • The use of stem cells in the treatment of nervous system disorders, such as Parkinson's disease, spinal cord injury and blindness.
  • Treating diabetes by using embryonic stem cells to make insulin-producing beta cells.
  • Using stem cells in the treatment of patients with heart failure as well as in those with heart attacks.

Bone-marrow transplants
The use of stem cells for bone-marrow transplantation is used mainly in the treatment of cancer, but also in treating other diseases. This type of therapy, in which adult stem cells are used, is already popular worldwide.

Stem cells make it possible for patients to receive very high doses of chemotherapy and/or radiation therapy.

Both these treatments are aimed at dividing cancer cells. Unfortunately, healthy cells are affected too, for example the cells in the hair roots. This is why cancer patients often experience hair loss during and after treatment.

Radio- and chemotherapy also affect the cells in the bone marrow, which are responsible for producing the body's red and white blood cells, as well as the blood platelets. Without these, the body is susceptible to anaemia, infection and bleeding.

When the cells in the bone marrow are wiped out, stem cells can replace them. "After treatment, the stem cells populate the bone marrow, ensuring that these blood elements are formed again," Pepper says.

Stem cells for bone-marrow transplants can be obtained either from the patient being treated or from another individual. Sources of these stem cells include:

  • the bone marrow itself;
  • peripheral, circulating blood; and
  • blood from the umbilical cord.

Stem cells in SA
The practice of using stem cells in bone-marrow transplants has been applied in South Africa for years. What is new here is that umbilical cord stem cells can now be obtained from two private stem cell banks around the country. South Africa might also soon have a public umbilical cord blood bank.

About the fact that no research studies on embryonic stem cells are currently being conducted here, Pepper remains positive: "I believe this will change in future as embryonic stem cell research is translated into clinical reality. The potential is enormous."

(Carine Visagie, Health24, updated August 2009)

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Stem cells - hope or hype?
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