MOLECULAR AND CELULLAR MEDICINE ADVANCES = ETERNAL YOUTH? Part I
The fact that this problem has not been solved is one of the reasons why GT cannot be done in human fetal cells. It cannot be guaranteed that the gene is going to be inserted in its proper location or that it is not going to damage an existing normal one. In both cases, there are disastrous consequences for the fetus, since each and every one of its cells are going to be affected.
Since there are no vectors capable of delivering a gene to its proper location, researchers have had to use other vehicles that at least allow the transported gene to be expressed; hence, the third problem.
The ideal delivery vehicle should not: a.- insert itself into places in which it could activate an oncogene which, in turn, could cause cancer; or, b-. insert itself into a functional gene damaging it, which will in turn cause disease or c.- produce an acute immune reaction. Conversely, it should guarantee a controlled expression of the injected gene so that the protein it codes for is produced when needed and only in the organ in which it is needed. Finally, the vector should last long enough so that the gene does not have to be re-injected frequently.
So far, no vectors have been developed with those characteristics. Thus, the third problem has yet to be solved. In 1998 Novartis, which had invested a lot of money in GT, decided to stop all new trials until vehicles with the appropriate characteristics are found.
To further complicate things, last November an unexpected problem came up: the death of a patient that has been directly attributed to GT. Jesse Gelsinger, an 18-year-old man from Arizona who decided to collaborate in a study at the University of Pennsylvania Institute for Human Gene Therapy, died of a treatment that supposedly would benefit other people more than it would him. I do not think that his death was a direct consequence of GT, as such. For me, it was an experiment that should have never been carried out. It was the manner in which the therapy was administered. It is as if you say that a new surgery technique is unsafe because a 90 years-old patient with a very low red blood cell count, suffering from malnutrition and hypertension is operated upon and he dies.
In Mr. Gelsinger case the gene was conveyed by a
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