Researchers at the UNC School of Medicine and the Medical College of Wisconsin have found that a new kind of gene therapy led to a dramatic decline in bleeding events in dogs with naturally occurring hemophilia A.
Hemophilia A affects about 50,000 people in the United States and millions more around the world.
Before the gene treatment, the animals experienced about five serious bleeding events a year. After receiving the novel gene therapy, though, they experienced substantially fewer bleeding events over three years.
Hemophiliacs lack the coagulation factor VIII in their blood plasma. In about 35% of cases, patients develop an antibody response to factor VIII, meaning that treatment by injection of the factor no longer works.
Using a plasmapheresis machine and a blood-enrichment technique, the research team isolated specific platelet precursor cells from three dogs that had hemophilia A. The team then engineered those platelet precursor cells to incorporate a gene therapy vector that expresses factor VIII. The researchers put those engineered platelet precursors back into the dogs. As the cells proliferated and produced new platelets, more and more were found to express factor VIII.
In the 2 1/2 years since the dogs received the gene therapy, researchers found that factor VIII was still being expressed in platelets that were coursing throughout the vascular systems of all three dogs. All three experienced much less bleeding. In the dog that expressed the most factor VIII in platelets, the bleeding was limited to just one serious event each year over the course of three years. And such bleeding events were easily treatable with current standard therapies.
The researchers have published their results in the journal Nature Communications. You can read the article here.
While the goal of this research is to help human hemophiliac patients, I hope that the treatment is able to be offered more widely to dogs with the condition too!