Gene therapy breakthrough offers hope to patients with inherited high cholesterol levels

New research published in BMC Molecular Biology explains how a new technique for introducing genes into mammalian cells using the virus responsible for warts could be a major step forward in developing gene therapy treatments for people with familial hypercholesterolemia (FH), a genetic disease that affects around 12 million people worldwide.

People with FH have a genetic defect that prevents their liver cells from absorbing chlolesterol in the form of low density lipoprotein (LDL). This leads to high levels of cholesterol in the bloodstream increasing the risk of heart disease. It is estimated that about half of men and a third of women with FH suffer a heart attack by the age of 60.

FH occurs as a result of a single defective gene that codes for a LDL receptor in the liver. Many single gene defects like the one that causes FH are candidates for gene therapy, a medical treatment used to repair or replace faulty genes (this is because it is much easier to repair one gene that causes a disease than it is to tackle other genetic diseases that involves several faulty genes).

Since the first successful attempts at gene therapy in 1990 there has been an intense research effort to develop ways of curing genetic diseases. By 1996 over 3000 patients had been treated using gene therapy, but most of these cases were unsuccessful. There are major obstacles to overcome to increase the success of gene therapy trials. Firstly, ways of getting multiple copies of healthy genes into enough cells to reverse the underlying disease need to be established. Secondly, it is important that the expression of healthy genes is sustained and finally any virus used to repair or replace faulty genes must not be attacked by the immune system of the patient receiving gene therapy.

The research published in BMC Molecular Biology showed that the virus responsible for warts (bovine papilloma virus) could be used to restore the function of cells with defective LDL receptors. Furthermore, it showed that the cells continued to function normally throughout the 32 week observation period.

The next step in this exciting research is to test the ability of the virus to repair faulty genes in animals with defective LDL receptor genes to establish whether an animal`s immune system will react to the papilloma virus. The researchers remain optimistic that this technique will save lives given that preliminary studies have shown that the human form of the virus is unlikely to attacked by the immune system.