|
|
Developmental Biology - Pre-Natal Lung Disease
3 Prenatal CRISPR Gene Editing Studies
Researchers use gene editing with CRISPR to treat lethal lung diseases before birth...
Using CRISPR gene editing, a team from Children's Hospital of Philadelphia (CHOP) and Penn Medicine have prevented a lethal lung disease which otherwise causes death within hours after birth. This proof-of-concept study in an animal model, appears in the journal Science Translational Medicine. As an in-utero editing procedure, it is a promising approach for eliminating known lethal genes before birth.
"The developing fetus has many innate properties that make it an attractive recipient for therapeutic gene editing. The ability to cure or mitigate a disease via gene editing in mid to late gestation — before birth and the onset of an irreversible pathology — is very exciting. This is particularly true for diseases that affect the lungs whose function becomes dramatically more important at the time of birth," says William H. Peranteau MD, CHOP's Center for Fetal Research, Pediatric and fetal surgery, CHOP's Center for Fetal Diagnosis and Treatment and study co-leader.
The congenital lung diseases the team is hoping to solve — such as surfactant protein deficiency, cystic fibrosis, and alpha-1 antitrypsin — are characterized by respiratory failure at birth and as chronic lung disease with few options for therapies.
About 22 percent of all pediatric hospital admissions are because of respiratory disorders. Congenital respiratory diseases are often lethal, despite advances in care and a deep understanding of their molecular beginnings. As the lung is a barrier organ in direct contact with the outside environment, the idea of fixing defective genes is an attractive idea for therapy.
"We wanted to know if this could work," explains study co-leader Edward E. Morrisey PhD, a professor of Cardiovascular Medicine in the Perelman School of Medicine at the University of Pennsylvania. "The trick was how to target gene-editing cells that line the airways of the lungs."
Researchers found delivery of CRISPR gene-editing reagents into the amniotic fluid of fetal mice, just four days before birth — analogous to a human's third trimester of pregnancy, produced significant change in post natal lungs.
Cells showing the highest percentage of change were alveolar epithelial cells or airway secretory cells which line lung airways. Morrisey's team identified alveolar epithelial progenitor (AEP) cells embedded within the larger population of alveolar type 2 cells in 2018.
AEP cells generate pulmonary surfactant, which reduces surface tension in lungs, keeping them from collapsing with every breath. AEPs are a stable cell type that turns over very slowly, yet replicates rapidly after injury so as to regenerate the lining of alveoli, and restore gas exchange. This work is published in the journal Science Translational Medicine.
In a second mouse experiment, researchers used prenatal gene-editing to reduce the severity of another interstitial lung disease, surfactant protein C (SFTPC) deficiency, with a common disease-causing mutation also in the human SFTPC gene.
One hundred percent of untreated mice with the surfactant protein C (SFTPC) mutation die from respiratory failure within hours of birth.
In contrast, prenatal gene editing which inactivated the mutant Sftpc gene, improved lung morphology and survival for more than 22 percent of the mice.
Future studies will be directed towards increasing efficiency in editing genes in the epithelial lining of lungs, along with evaluating different mechanisms to deliver the technology. "Different gene editing techniques are also being explored that may one day be able to correct the exact mutations observed in genetic lung diseases in [human] infants," says Morrisey.
Morrisey recently collaborated on a third study in mice led by Peranteau and Kiran Musunuru MD PhD, associate professor of Cardiovascular Medicine at Penn. This study as well demonstrated the feasibility of in utero gene editing as it rescued pre-natal mouse pups from a lethal metabolic liver disease. It was the first time an in utero CRISPR-mediated gene edit had prevented this lethal metabolic disorder in mice.
"The current research in proof-of-concept studies highlight the exciting future prospects for prenatal treatments. Including gene editing and replacement gene therapy for the treatment of [human] congenital diseases."
Edward E. Morrisey PhD, Department of Medicine; 4Penn Center for Pulmonary Biology; 5Penn Cardiovascular Institute, Perelman School of Medicine at the University of Pennsylvania Philadelphia, Philadelphia, PA, USA.
Editing out a lethal lung disease
Surfactant, a lipoprotein mixture that reduces lung surface tension, is essential for normal lung function. In rare cases, infants are born with genetic surfactant deficiency, resulting in rapid death from respiratory failure. Because of the immediate perinatal fatality associated with this disease, any effective intervention would need to be applied before delivery. Alapati et al. used a mouse model of genetic surfactant deficiency to demonstrate the feasibility of in utero gene editing to delete the mutant allele. The authors showed that correction of the genetic defect before birth improved lung development and survival in the treated animals, demonstrating the feasibility of this therapeutic intervention.
Abstract
Monogenic lung diseases that are caused by mutations in surfactant genes of the pulmonary epithelium are marked by perinatal lethal respiratory failure or chronic diffuse parenchymal lung disease with few therapeutic options. Using a CRISPR fluorescent reporter system, we demonstrate that precisely timed in utero intra-amniotic delivery of CRISPR-Cas9 gene editing reagents during fetal development results in targeted and specific gene editing in fetal lungs. Pulmonary epithelial cells are predominantly targeted in this approach, with alveolar type 1, alveolar type 2, and airway secretory cells exhibiting high and persistent gene editing. We then used this in utero technique to evaluate a therapeutic approach to reduce the severity of the lethal interstitial lung disease observed in a mouse model of the human SFTPCI73T mutation. Embryonic expression of SftpcI73T alleles is characterized by severe diffuse parenchymal lung damage and rapid demise of mutant mice at birth. After in utero CRISPR-Cas9–mediated inactivation of the mutant SftpcI73T gene, fetuses and postnatal mice showed improved lung morphology and increased survival. These proof-of-concept studies demonstrate that in utero gene editing is a promising approach for treatment and rescue of monogenic lung diseases that are lethal at birth.
Authors
Deepthi Alapati, William J. Zacharias, Heather A. Hartman, Avery C. Rossidis, John D. Stratigis, Nicholas J Ahn, Barbara Coons, Su Zhou, Hiaying Li, Kshitiz Singh, Jeremy Katzen, Yaniv Tomer, Alexandra C. Chadwick, Kiran Musunuru, Michael F. Beers, Edward E. Morrisey and William H. Peranteau.
Acknowledgements
Funding for this work came from the National Institutes of Health (HL134745, HL132999, and TR001878), the UPenn Orphan Disease Center, the Pulmonary Fibrosis Foundation Fund in Cardiovascular Innovation, and gifts to Children's Hospital of Philadelphia.
About Children's Hospital of Philadelphia: Children's Hospital of Philadelphia was founded in 1855 as the nation's first pediatric hospital. Through its long-standing commitment to providing exceptional patient care, training new generations of pediatric healthcare professionals, and pioneering major research initiatives, Children's Hospital has fostered many discoveries that have benefited children worldwide. Its pediatric research program is among the largest in the country. In addition, its unique family-centered care and public service programs have brought the 564-bed hospital recognition as a leading advocate for children and adolescents. For more information, visit http://www.chop.edu
About Children's Hospital of Philadelphia: Children's Hospital of Philadelphia was founded in 1855 as the nation's first pediatric hospital. Through its long-standing commitment to providing exceptional patient care, training new generations of pediatric healthcare professionals, and pioneering major research initiatives, Children's Hospital has fostered many discoveries that have benefited children worldwide. Its pediatric research program is among the largest in the country. In addition, its unique family-centered care and public service programs have brought the 564-bed hospital recognition as a leading advocate for children and adolescents. For more information, visit http://www.chop.edu
Return to top of page
| |
|
Apr 23 2019 Fetal Timeline Maternal Timeline News
 5233.jpg) CRISPR-edited lung cells, stained green with fluorescent protein. Many, but not all, are alveolar type 2 cells. CREDIT: Penn Medicine
|
Commons License.