Gene therapy could lower blood pressure

A virus that introduces a blood pressure-lowering gene into cells promises to help people maintain healthy blood pressure for four months.

According to news release from Baylor College of Medicine :

The gene in question -- atrial natriuretic peptide or ANP -- promises to control blood pressure through a variety of effects on key areas involved in the problem of hypertension, including the relaxation of smooth muscle cells in blood vessels, increasing the vessels' diameters, and reducing the manner in which the vessels react to agents that can constrict those vessels. ANP also improves the manner in which the kidney eliminates sodium or salt from the body and inhibits other systems, such as the sympathetic nervous system, believed linked to development of high blood pressure.

"This makes ANP an attractive agent for use in treating blood pressure," said [Bert] O'Malley. "However, its use is limited by the fact that it has such short-lived activity in the blood system."

Its activity is halved 30 seconds after it enters the blood stream.

Gene therapy can make cells generate more ANP. In previous studies, however, this kind of gene reduced blood pressure to dangerously low levels, said O'Malley. Obviously, a method of controlling the gene and the amount of ANP a cell makes was needed.

The special viral vector developed by O'Malley and his colleagues combines a special kind of adenovirus altered so it does not produce disease connected to a gene regulatory system turned on by the drug mifepristone.

Using the vector, O'Malley and colleagues introduced the ANP gene into the cells of mice. Tiny doses of drug then turned on the regulatory system, which controlled the amount of ANP made so that blood pressure remained at healthy levels for 125 days—74 days longer than in any previous gene therapy study.

One important question for human use, however, is whether the body will accept repeated injections of the viral vector or if the immune system would eventually react against it, says O'Malley.

The research is reported in the Proceedings of the National Academy of Sciences .