Negative conclusion after 10 years of stem cell research

Stem cells: Despite intensive research no successful therapies

26.04.2012

Research on embryonic stem cells has led to heated controversy in recent years, and continues to this day. While proponents of stem cell research emphasize the medical possibilities, critics see ethically unacceptable approaches to stem cell production. Because this requires the destruction of early human embryos. Less controversial, however, is the research on so-called adult stem cells, which can be obtained, for example, from the bone marrow of patients.

The limits of embryonic stem cell research in Germany are laid down in the German Stem Cell Research Act of 2002. Here scientists are also given the opportunity, despite the ethical controversy, to resort to embryonic stem cells under certain conditions. But what medical benefits has embryonic stem cell research brought so far? Not, according to the critics.

Adult stem cells have been used for decades for treatment
Hematopoietic (adult) stem cells have been used in the treatment of patients for over 40 years. They primarily serve to regenerate the organism after chemotherapy for leukemia or to compensate for cell damage caused by certain diseases. The cancer patients or a suitable donor are removed from the bone marrow before treatment, which can be re-injected after completion of chemotherapy. Here, the hematopoietic stem cells help in the (re) construction of the red and white blood cells. However, adult stem cells have also been used for other purposes, such as the treatment of Parkinson's or spinal cord injury. US researchers at the University of Louisville in Kentucky and Harvard Medical School in Boston also treated heart attack patients with adult stem cells last year, with the ability to regenerate dead, scarred myocardial tissue by injecting their own stem cells. Overall, however, the possible uses of adult stem cells are always limited because they can not be converted into any body cells. That is, adult heart muscle stem cells are unable to transform into cells of other organs.

Clinical studies on embryonic stem cells are in short supply
Embryonic stem cells, however, are pluripotent. It could develop into all cells of the organism. Since its discovery 14 years ago, numerous uses of embryonic stem cells have been discussed and researched. Various studies have succeeded in transforming embryonic stem cells into a wide variety of tissue types. However, the research has so far been limited mainly to laboratory or animal studies. Clinical studies on the use of embryonic stem cells in humans are in short supply - although immediately after the discovery of numerous applications has been fabulated. The advocates saw in the embryonic stem cells a veritable miracle weapon that promised healing in countless diseases. The German research location would be badly damaged, if in this country no studies with embryonic stem cells are possible, argued the proponents as about ten years ago, a legal regulation of stem cell research decency. For example, the stem cell research law passed in 2002 also permits research on embryonic stem cells in this country - albeit only under certain conditions.

Research in the field of embryonic stem cells
Today 54 research teams work with human embryonic stem cells in Germany. According to the Stem Cell Research Act, the application for import and use of embryonic stem cells is only granted if „the stem cells serve high-level scientific purposes, for which animal stem cells are not sufficient as research objects“. In addition, the stem cells must before the first of May 2007 (original deadline October 10, 2002) „be produced to effect a pregnancy and be made available free of charge“, so the law text. Approval of justified motions is the responsibility of the Robert Koch Institute (RKI). A total of 72 applications have been submitted to the RKI so far, 70 research projects have been approved, and two have been rejected. All in all, German legislation allows research on embryonic stem cells, but in international comparison, relatively restrictive regulations apply in this country.

Only two healing attempts based on stem cells
In retrospect, however, this has scarcely harmed Germany as a research location, and it is doubtful whether the high expectations which some researchers set for embryonic stem cells will even be fulfilled. So far only two clinical studies took place world-wide, with which with the help of the embryonic stem cells a healing should be accomplished. In the first clinical trial, researchers from the US biotech company Geron injected cells into the spinal cord of a paraplegic stem cell patient in October 2010. In total, ten patients were to be treated with this method, but according to Geron, the trial was discontinued for financial reasons. This procedure also raised doubts about the chances of success of the treatment approach. In 2011, US researchers also tested the use of stem cells in the treatment of eye disease in two patients. The vision of both women with macular degeneration has improved significantly after treatment, according to the study. But in a study with only two participants, the validity may well be doubted.

Stem cell research falls short of expectations
However, embryonic stem cells may lose their relevance for research anyway in the next few years, since many scientists today also favor the use of so-called induced pluripotent stem cells (iPS) because of the ethical problem. These are usually obtained by the reprogramming of adult human body cells and can be used as varied as the embryonic stem cells. Since recovery does not require the use of dead fetuses, iPS is generally considered less controversial. However, researchers from the University of California at San Diego and the Scripps Research Institute at La Jolla, California, have recently shown in extensive studies that more severe genetic alterations have occurred in the embryonic and induced pluripotent stem cell lines. For example, this was associated with a significantly increased risk of cancer. Thus, the possible medical achievements of pluripotent stem cells could be reversed quickly. So far, stem cell research has in any case fallen far short of the expectations originally set by its proponents. (Fp)

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Picture credits: Martin Gapa