The principle of gene therapy

First the principle of gene therapy shall be described in general. Nearly all human diseases, like cancer, alzheimer, arthritis, cardiovascular diseases and of course hairloss, have genetic causes. In the 1980s animal studies prove, that the disease-causing genes can be cured by therapeutic genes. This is called gene therapy. A gene therapy cures the real cause of the disease (the disease-causing gene). Current drugs often only treat the symptoms of the illness and have serious side-effects, as they are not specific enough. The first human gene therapy was done in 1990. Up to now more than 5000 people were treated by gene therapy in clinical studies, mostly against cancer and AIDS. The principle is always similar. The therapeutic gene is delivered to the desired body cells (e.g. the cancer cells or the liver cells) by a "gene taxi" - the so-called gene vector. The biggest problem of all gene therapies is the delivery problem of the therapeutic gene. That means, how can the new genes be transported most effectively without side-effects? Current studies often use disabled viruses (like the virus of the common cold) or liposomes (fat droplets). Thousands of researchers are working hard to find the perfect gene vector, e.g. they try to combine viruses and liposomes, try to deliver naked DNA without a gene vector and so on. And indeed there are first groundbreaking results in human clinical trials. In May 2000 the French researcher Dr. Alain Fischer (Neckar Hospital Paris) published, that he was able to cure a severe immune disease named SCID in several children without side-effects. Children with this disease usually die within 2 or 3 years after birth without treatment. US researchers were able to grow new blood vessels to the heart by using a growth factor gene ( ). Also a gene therapy against haemophilia A showed good results ( ) and there are several genetherapeutic studies against various forms of cancer, that improve current therapeutic options ( . In 1999 researchers were able to repair a genetic defect permanently in an animal model ( Human trials will start in late 2001 or early 2002. Obviously gene therapy starts to fullfil ist promisses. It should be added, that the new genes donīt influence the germline or the sperms.