A simple, minimally invasive new tool for observing differences in the nasal airways of cystic fibrosis patients in vivo at a cellular level has recently been described in a paper published in Science Translational Medicine.
The new method offers high-resolution images of the hair-like structures called cilia that are found throughout nasal airways as well as complete features of the clearance of mucus, which is weakened in people with CF, causing major morbidity.
The imaging catheter, which is roughly 2-mm in diameter, uses optical coherence tomography having a resolution of about 1 micrometer—a 50th the size of a human hair—allowing scientists to probe the nasal passages of patients without even having to anesthetize them.
"We've done a lot of benchtop imaging with micro-OCT but this is the first time we've been able to use it in people," said co-principal investigator Guillermo Tearney, MD, PhD, a pathologist and investigator for the Department of Pathology and Wellman Center for Photomedicine at Massachusetts General Hospital (MGH), the Remondi Family MGH Research Institute Chair, and professor of pathology at Harvard Medical School (HMS). "It's unprecedented to see this pathophysiology dynamically in living patients. It will allow us to begin to understand things we never even knew were there."
Among the scientists' learning was that in CF patients, the mucus had more inflammatory cells than in control subjects and it was dehydrated, moving gradually and impacting cilia speed. The scientists were astonished that they could measure the mucus's reflective quality, which they established was an indicator of viscosity, and that patches of CF patients' epithelium and cilia were ablated.
We thought they were there but just not functioning well, but in places, they were completely gone.
Guillermo Tearney, MD, PhD, Co-Principal Investigator, Department of Pathology and Wellman Center for Photomedicine, MGH
In the US, approximately 30,000 patients deal with cystic fibrosis and have an average life expectancy of about 45 years. The new method will enable early diagnosis of diseases that impact the airways, and allow clinicians to monitor them and enhance drug therapies for individual patients.
Visualizing abnormal mucus will be a powerful tool. Now we'll be able to see how various treatments affect the airway—not only agents intended to fix abnormal mucus, which is applicable to many diseases, but also treatments that repair the basic CF defect itself.
Steven M. Rowe, MD, MSPH, Director of Gregory Fleming James Cystic Fibrosis Research Center, and professor of medicine, University of Alabama at Birmingham
Rowe is also a co-principal investigator of the study.
The scientists anticipate micro-OCT will have a number of applications other than cystic fibrosis—from diagnosing and treating respiratory illnesses like chronic sinus disease, primary ciliary dyskinesia, and chronic obstructive pulmonary disease (COPD) to screening the GI tract for diseases and imaging coronary artery cells. "The goal is to figure out who else it can be used to help," said Rowe, "and make it more broadly accessible as a device."