"Previous attempts at systemic gene therapy for muscle have not been very effective because blood vessel capillaries act much like a mosquito net, blocking the gene drugs from reaching the muscle cells. Fortunately, we found a virus that is just small and sneaky enough to get through this net and deliver the therapeutic gene to both skeletal and cardiac muscle cells," said lead author, Xiao Xiao, Ph.D., associate professor of orthopaedic surgery at the University of Pittsburgh School of Medicine.
The virus used by Dr. Xiao and his colleagues for delivering the corrective gene is known as adeno-associated virus, or AAV, a class of relatively small viruses that do not cause any known disease. In earlier studies, Dr. Xiao's team found that direct intramuscular injection of AAV was effective in transferring a gene into muscle cells in a fairly wide area around the injection site. However, for gene therapy treatments to be successful, particularly for muscular dystrophies where many organs and tissues are affected throughout the body, intramuscular injection is not practical for delivering a corrective gene to the body's more than 600 muscle groups.
Recently, Dr. Xiao's team demonstrated that a type of AAV, known as AAV-8, is particularly efficient at penetrating the capillary barrier, making it a good candidate for whole-body gene delivery. In this study, they tested AAV-8 in an animal model of human muscular dystrophy called limb girdle muscular dystrophy, or LGMD. In human LGMD, defects in a muscle cell membrane protein known as delta-sarcoglyc
Source:University of Pittsburgh Medical Center