So-called low-intensity blood stem cell transplants, which use milder conditioning agents than standard stem cell transplants, do not appear to damage the lungs and may help improve lung function in some patients with sickle cell disease (SCD), according to a three-year study of adults who underwent the procedure at the National Institutes of Health (NIH).
Damage to lung tissue and worsened lung function is a major complication and leading cause of death in people with sickle cell disease, a debilitating blood disorder. The new study, published in the Annals of the American Thoracic Society, helps answer whether less intensive types of transplants, which tend to be better tolerated by many adults, by themselves either cause or promote further harm to the lungs.
Researchers say at least one-third of the sickle cell stem cell transplants performed are low-intensity. While they are slightly less effective than the standard transplants, adults who often have more pre-existing organ damage than children tend to do better with them and also experience a lower risk for complications such as graft-versus-host disease. The current study examined if these transplants offered other benefits for adults with already vulnerable lungs.
For the research, the team studied 97 patients with sickle cell disease who underwent a low-intensity, or non-myeloablative, blood stem cell transplant between 2004-2019 at the NIH’s Clinical Center in Bethesda, Maryland. Participants were then followed for up to three years.
The researchers conducted a variety of pulmonary function tests, including forced expiratory volume in one second (FEV-1), which measures the amount of air exhaled in the first second after forced exhalation. Another was a lung diffusion test, or diffusing capacity of the lungs for carbon monoxide (DLCO), which measures how much oxygen moves from the lungs to the blood when exhaling. They also conducted a six-minute walk distance test, which measured how far a patient could walk and their oxygen levels during a set time.
After three years, overall lung function among the patients remained stable. FEV-1 levels remained relatively unchanged post-transplant compared to pre-transplant, indicating that lung function did not worsen over time. Notably, DLCO levels and six-minute walk distance improved significantly following transplant.
