Gene Therapy Halts Progression of Pulmonary Hypertension in a Large Animal Pre-Clinical Study
Scientists have used a novel gene therapy to halt the progression of pulmonary hypertension, a form of high blood pressure in the lung blood vessels that is linked to heart failure, according to a study led by Roger J. Hajjar, MD, Professor of Medicine and Director of the Cardiovascular Research Center at the Icahn School of Medicine at Mount Sinai. The study was published online this week, and will appear in the May 3 issue of the Journal of the American College of Cardiology (JACC).
Pulmonary arterial hypertension (PAH) is a rare, rapidly progressing disease that occurs when blood pressure is too high in vessels leading from the heart to the lungs. There is currently no cure for PAH, and about 50 percent of people who are diagnosed will die from the disease within five years. The high pressure is caused by abnormal remodeling of the lung blood vessels that sometimes leads to failure of the right ventricle and premature death. Thickening and narrowing of pulmonary vessels is seen with all types of pulmonary hypertension and is triggered by abnormal calcium levels within the vascular cells. The sarcoplasmic reticulum calcium ATPase pump (SERCA2a) regulates intracellular calcium in vascular cells and prevents them from proliferating in the vessel wall.
“There is considerable need for new treatments that improve functional capacity, symptoms, and survival,” said Dr. Hajjar. “This treatment with gene therapy offers a novel method of treating a deadly disease that disproportionately affects young adults and women,” he said. Female patients make up about 72 percent of the total population of patients with PAH.
“The therapeutic potential of using gene therapy to treat pulmonary hypertension by delivery of aerosolized adeno-associated virus carrying SERCA2a to directly target vascular remodeling through the overexpression of the SERCA2a protein is very significant,” said co-senior study author Jane A. Leopold, MD, of Brigham and Women’s Hospital, Harvard Medical School. “In addition, as other novel targets are identified by deep phenotyping of patients with pulmonary hypertension in the National Institutes of Health/National, Heart, Lung, & Blood Institute-funded Pulmonary Vascular Disease Phenomics (PVDOMICS) study, they may be viable candidates for aerosolized gene transfer using adeno-associated viral vectors.”
There were two primary objectives for this study, which was conducted by Mount Sinai and research teams from Brigham & Women’s Hospital in Boston, MA, and Centro Nacional de Investigaciones Cardiovasculares Carlos III in Madrid, Spain. First, scientists wanted to learn if it is feasible to deliver a therapeutic gene called SERCA2a in aerosol form to damaged blood vessels of the lung using an engineered adeno-associated virus as a “vector.” Second, they wanted to see if there was a sustained beneficial impact, and if the transferred genes effectively slowed or stopped the vascular changes in the airways that are the hallmark of PAH and other forms of pulmonary hypertension.
Previously, the novel aerosol inhalation technique used to deliver the SERCA2a gene in this study had proven effective in a rodent model. However, the current study is the first to explore this approach in a large animal—specifically, a Yorkshire swine model that closely resembles PH in humans.
In the study, 20 pigs were divided into two groups, half of which received the aerosolized viral vector carrying the SERCA2a gene and half a saline spray. Two months after the gene delivery, scientists performed tests to see if the new therapeutic genes were present and functioning in the vessels of the animals’ lungs, and whether the transfer was producing the desired effects. When they examined the animals, they found that that heart and lung function had improved and abnormal cellular changes causing PH were reduced.
“I’m excited that there is a potential new treatment for patients with this deadly disease,” Dr. Hajjar said. “By tailoring the gene therapy, it looks like we can halt the proliferation of smooth muscle cells in the blood vessels. This should help restore function and improve survival in human patients.”
Dr. Hajjar said that additional animal studies focusing on long-term efficacy and safety are warranted before advancing this approach, known as airway gene delivery, to human clinical trials. That’s because the current study involved a small number of animals, and they were assessed just eight weeks after gene delivery. Nevertheless, he said, airway gene delivery appears to modify fundamental pathophysiology, and therefore might offer therapeutic benefit to humans with a variety of pulmonary vascular diseases.
About the Mount Sinai Health System
The Mount Sinai Health System is New York City's largest integrated delivery system, encompassing eight hospitals, a leading medical school, and a vast network of ambulatory practices throughout the greater New York region. Mount Sinai's vision is to produce the safest care, the highest quality, the highest satisfaction, the best access and the best value of any health system in the nation. The Health System includes approximately 7,480 primary and specialty care physicians; 11 joint-venture ambulatory surgery centers; more than 410 ambulatory practices throughout the five boroughs of New York City, Westchester, Long Island, and Florida; and 31 affiliated community health centers. The Icahn School of Medicine is one of three medical schools that have earned distinction by multiple indicators: ranked in the top 20 by U.S. News & World Report's "Best Medical Schools", aligned with a U.S. News & World Report's "Honor Roll" Hospital, No. 12 in the nation for National Institutes of Health funding, and among the top 10 most innovative research institutions as ranked by the journal Nature in its Nature Innovation Index. This reflects a special level of excellence in education, clinical practice, and research. The Mount Sinai Hospital is ranked No. 18 on U.S. News & World Report's "Honor Roll" of top U.S. hospitals; it is one of the nation's top 20 hospitals in Cardiology/Heart Surgery, Gastroenterology/GI Surgery, Geriatrics, Nephrology, and Neurology/Neurosurgery, and in the top 50 in six other specialties in the 2018-2019 "Best Hospitals" issue. Mount Sinai's Kravis Children's Hospital also is ranked nationally in five out of ten pediatric specialties by U.S. News & World Report. The New York Eye and Ear Infirmary of Mount Sinai is ranked 11th nationally for Ophthalmology and 44th for Ear, Nose, and Throat. Mount Sinai Beth Israel, Mount Sinai St. Luke's, Mount Sinai West, and South Nassau Communities Hospital are ranked regionally.