The work of the Human Genome Project and genetic research throughout the world have revealed much new and valuable information on the genetic basis of many diseases and facets of disease. The work that relates to heart disease has particular value, as heart disease remains one of the most common and costly (both in dollars and human suffering) illnesses in the world. In a heart attack, the blood supply to a portion of the heart's muscle is cut off and that muscle can die. One of the contributing factors is the presence of reactive oxygen species, sometimes called free radicals, in the damaged muscle. Genomic work has already revealed some of the genes and proteins involved in reducing free radical-induced damage.

When the blood supply is cut off to a portion of heart muscle, levels of the protein angiotensin-converting enzyme (ACE) rise, and high levels of this enzyme lead to worsening of the damage caused by that lack of blood supply. Researchers at the University of Arkansas reported in the May, 2001, issue of Gene Therapy, that they have created a strand of DNA that they call an anti-sense sequence, rather than the ACE enzyme. This anti-sense sequence can specifically bind to the mRNA that codes for the ACE protein, and this binding results in the mRNA's destruction, which in turn leads to a decrease in ACE protein levels. The researchers theorized that rats with the anti-sense DNA in their heart muscle would produce less ACE and thus experience less heart damage in a heart attack. Dividing the animals into three groups, the researchers injected some with the anti-sense DNA strands and others with a similar piece of DNA that did not affect ACE levels. The scientists induced heart attacks and then excised the animals' hearts and compared them. Those who had received the anti-ACE anti-sense DNA injections had significantly lower ACE protein levels, much less heart damage from their heart attacks than control animals, and better levels of heart muscle function than the animals who received the DNA that did not reduce ACE production. This work is clearly preliminary, but it is encouraging that it suggests that one day human heart attacks could be treated with gene therapy.

One concern about the use of gene therapy is whether genes inserted into the host's DNA actually get to the tissue they are intended to benefit. Researchers at Duke University Medical Center have been looking at methods of delivering genes directly to heart tissue. In the July, 2001 issue of the journal Circulation, surgeons at Duke performed open-heart surgery on pigs, putting them on "bypass," the procedure that stops the heart and permits surgery to be done. Using the tubes inserted into the heart during bypass for the administration of medications directly to heart muscle, the surgeons injected solutions containing specific genes they hoped would incorporate into the animals heart cells' DNA. A week later, the animals were sacrificed and autopsied. Analysis of various tissues revealed that the genes were found in high levels in heart tissue, but not in lung or liver. The researchers concluded that injection of solutions containing genes intended for the heart could be successfully delivered during bypass and that those genes would take up residence in heart muscle, as intended, rather than in tissues where they were not needed or used.