Thursday, November 3, 2011

Bleeding disorder can be treated using gene therapy

Patients suffering from a rare bleeding disorder that prevent proper clotting of the blood during injury may very well be treated with a combination of stem cells with gene therapy in the near future. Experiments on sheep show that administering stem cells that posses a copy of a gene coding for a missing protein in haemophilia, ameliorate the disease. The injected stem cells produce a clotting factor, and are able to migrate to a site of inflammation, which is a sign for injury, and consequently bleeding. Although the therapy has not yet been tested on humans, it is a fine example of how controversial therapies such as stem cells and gene therapy can help us.

Factor VIII.
In haemophilia A, the clotting factor VIII is missing, which results in prolonged bleeding after injury. There are many factors involved in the process of blood clotting, and a missing factor VIII is the most common cause of haemophilia. Because the blood does not clot, patients can easily bleed out, highlighting the need for a proper therapy for this currently untreatable disease. While the scientists could not cure haemophilia in sheep, their novel therapy was able to decrease the severity of the symptoms, which is possibly enough to save a  patient's life in the case of bleeding.

For their experiments, scientists genetically modified mesenchymal stem cells. These are adult stem cells, committed to a cellular lineage that is supposed to form connective tissue, to stitch cells together. However, researchers have found that these stem cells can relatively easy be persuaded to develop into other cells, which may come in handy for regenerative medicine. In this case, the mesenchymal population was likely chosen for their ability to migrate: because injury can happen everywhere in the body, the repair cells need to be mobilized and ready to travel when the body is in need of clotting factors.

The main problem of injecting sheep with modified stem cells is that the immune system develops a response against clotting factor VIII, because it is recognized as a foreign molecule. For the therapy to remain effective, scientists need to find a way around the immune system. Else, the therapy will likely not be working anymore after the first treatment.

One of the most famous cases of haemophilia is the one of Alexei Nikolaevich, son of the Russian tsar. Born in 1904, he was diagnosed with haemophilia B, which differs slightly from haemophilia A in terms of missing clotting factors. According to historic tales, he was once saved from haemophiliac complications by the famous Rasputin, who served as an advisor of the tsar. In the end, it did not help him, as the whole family was murdered in 1918, in the bolshevik revolution that started the Soviet Union.

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