Genetically engineered
blood-clotting factor

Factor VIII

Excessive, uncontrolled bleeding can be fatal. Hemophilia is the most common chronic condition that involves uncontrolled bleeding. Hemophiliacs lack a protein called factor VIII, which is required for blood to clot normally. Although purified factor VIII extracted from human blood became available around 1960, it has been very expensive. In addition, impurities in the human factor VIII placed many hemophiliac patients at risk of contracting serious diseases, including hepatitis and, later, AIDS.

Artificially Created Factor VIII

In the early 1980s, scientists at Genentech, Incorporated, and Chiron Corporation in California and at the Massachusetts-based Genetics Institute began developing genetic engineering techniques to obtain pure, inexpensive factor VIII artificially. Genetic engineering refers to methods of rearranging genes —removing or adding them or transferring them from one organism to another.

At Genentech, Richard Lawn, Gordon Vehar, and their coworkers succeeded in isolating the normal gene for factor VIII in healthy people and inserting it into hamster cells, where it joined with the genetic material of the hamsters. The hamster cells then used the new genetic instructions to make pure human factor VIII.

A major problem with this promising method of treating hemophilia inexpensively and safely is that it is difficult to control the amount of factor VIII that the cells produce, and too much factor VIII causes the blood to stop circulating properly. The researchers are continuing their tests to develop a proper dosage of Factor VIII for hemophiliacs, thus making their treatment safer and much more reasonable in cost.