Stem cells: Despite intensive research, no successful therapies
Research on embryonic stem cells has led to intense controversy in recent years, which continues to this day. While the advocates of stem cell research emphasize the medical possibilities, critics see an ethically unjustifiable procedure in the extraction of the stem cells. Because this requires the destruction of early human embryos. Research on so-called adult stem cells, which can be obtained from the bone marrow of patients, for example, is less controversial.
The limits in research with embryonic stem cells are set in Germany by the Stem Cell Research Act of 2002. Here, scientists are also given the opportunity to use the embryonic stem cells under certain conditions despite the ethical controversy. But what medical benefits has embryonic stem cell research brought so far? None, according to the critics.
Adult stem cells have been used for treatment for decades. Blood-forming (adult) stem cells have been used in the treatment of patients for over 40 years. They are primarily used to regenerate the organism after chemotherapy for leukemia or to compensate for cell damage caused by certain diseases. Before the treatment, cancer patients or a suitable donor take stem cells from the bone marrow, which can be re-injected after chemotherapy has been completed. Here the blood-forming stem cells help with the (re) building of the red and white blood cells. But adult stem cells have also been used for other purposes, such as the treatment of Parkinson's or paralysis due to spinal injuries. US researchers from the University of Louisville in Kentucky and Harvard Medical School in Boston also treated heart attack patients with adult stem cells last year, with regeneration of the dead, scarred heart muscle tissue being achieved by injection of the heart's stem cells. Overall, however, the possible uses of adult stem cells always remain limited, since they cannot convert into any body cells. This means that adult stem cells of the heart muscle are unable to transform into cells of other organs.
Clinical studies on embryonic stem cells in short supply
In contrast, embryonic stem cells are pluripotent. They can develop into all cells of the organism. Since its discovery 14 years ago, numerous possible uses of embryonic stem cells have been discussed and researched. Various studies have successfully transformed embryonic stem cells into a wide variety of tissues. However, the research work has so far mainly been limited to laboratory tests or studies on animals. Clinical studies on the use of embryonic stem cells in humans are in short supply - although there were numerous possible uses immediately after their discovery. The supporters saw the embryonic stem cells as a veritable magic weapon, which promised healing in countless diseases. The German research location would be badly damaged if studies in Germany with embryonic stem cells were not possible, argued the advocates when a legal regulation of stem cell research was due around ten years ago. The stem cell research law enacted in 2002 also allows research on embryonic stem cells in Germany - but only under certain conditions.
Research work in the field of embryonic stem cells Today 54 research teams in Germany work with human embryonic stem cells. According to the Stem Cell Research Act, the application for the import and use of embryonic stem cells is only granted if "the stem cells serve high-ranking scientific purposes for which animal stem cells are not sufficient as research objects". In addition, the stem cells must have been produced to effect pregnancy before May 1, 2007 (originally due on October 10, 2002) and must be made available free of charge, according to the legal text. The Robert Koch Institute (RKI) is responsible for approving appropriately justified applications. A total of 72 applications have been submitted to the RKI so far, 70 research projects have been approved and two rejected. Overall, German legislation allows research on embryonic stem cells, but in an international comparison, relatively restrictive regulations apply in this country.
Only two attempts at healing based on stem cells In retrospect, however, this has hardly harmed Germany as a research location, and it can be doubted whether the high expectations that some researchers have of embryonic stem cells will be met. So far, only two clinical studies have been carried out worldwide, in which healing should be achieved with the help of embryonic stem cells. As part of the first clinical study, researchers from the US biotech company Geron injected cells from stem cells into the spinal cord of a paraplegic patient in October 2010. A total of ten patients were to be treated with this method within the scope of the study, but the trial series was terminated, according to Geron, 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 two patients' eye diseases. The eyesight of the two women with macular degeneration improved significantly after the treatment, according to the study. However, in a study with only two participants, the informative value can be doubted.
Stem cell research falls short of expectations However, embryonic stem cells may lose their importance for research in the next few years anyway, since many scientists today also favor the use of so-called induced pluripotent stem cells (iPS) due to the ethical problem. These are usually obtained through the reprogramming of adult human body cells and can be used in a variety of ways like embryonic stem cells. Since dead fetuses do not have to be used to obtain them, the iPS are 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 severe genetic changes occurred increasingly in the embryonic and induced pluripotent stem cell lines. For example, this was associated with a significantly increased risk of cancer. In this way, the possible medical success of pluripotent stem cells could quickly be reversed. So far, stem cell research has in any case fallen far short of the expectations originally placed in it by the proponents. (fp)
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