A new gene therapy has been developed which brought the level of blood clotting to the normal level in mice suffering with hemophilia. Hemophilia is a disease which renders the body unable to control the coagulation of blood. The body stops producing a protein which triggers the clotting of blood. Due to this any cut or injury becomes fatal as it may lead to heavy blood loss. The findings of the research conducted on mice were published in the Nature.
According to the US scientist ‘genome editing’, which is often described as the next step in the gene therapy, targets and repairs the DNA which have undergone mutation. This study is the first of its kind as it has been able to correct the DNA of a living being and has achieved meaningful results which are clinically useful. In humans hemophilia is of two types, hemophilia A (missing protein is clotting factor VIII) and hemophilia B (missing protein is clotting factor is clotting factor IX). The current treatment of hemophilia involves the introduction of proteins into the body, but this often results in the production of anti-bodies. This treatment is expensive too.
The leader of this research was Dr. Katherine A. High, who is a hematologist and a specialist in gene therapy, at the University of Philadelphia, in Pennsylvania. Dr. Katherine and her colleagues used AAV (adeno-associated virus) of two versions to edit the genes of mice liver cells. AAV is a virus which has been genetically engineered to be used in the gene therapy. The function of two versions of AAV was that one carried the enzymes which were required to cut DNA in the exact spot. The other version of AAV carried a replacement of the gene to be copied at the right position. Genome editing has proved to be a giant leap in the field of gene editing; it completely modifies the DNA sequence which is the cause of the disease. The research team collaborated with scientists from the University of Pennsylvania, and from Sangamo BioSciences, Inc, in Richmond, California. This team used ZFNs (zinc finger nucleases) that are engineered enzymes to modify the DNA sequence. The team wrote in the Nature paper that the recent research done on ZFNs has made it possible to carry out efficient genome editing which was earlier hard to control. When the ZFNs were injected into mice the level of blood clotting came to the normal level. The improvements shown were sustained for a period of 8 months. Also there were no toxic effects on mice or any ill-effects on the liver. Although, Dr. High is not sure about the current translation of this therapy into humans, she said that further research was required for doing the same. This study was funded by the National Institutes of Health and the Howard Hughes Medical Institute.