Low-intensity blood stem cell transplants, utilizing milder conditioning agents than standard transplants, appear safe for lung health and may improve lung function in adults with sickle cell disease (SCD), according to a three-year NIH study published in the Annals of the American Thoracic Society.
Impact on Lung Function
Lung damage is a major complication in SCD, a debilitating blood disorder. The study addressed concerns about whether less intensive transplants could further harm the lungs. Dr. Parker Ruhl, lead researcher and pulmonologist at NIH, stated, "By using a low-intensity blood stem cell transplant for sickle cell disease, we may be able to stop the cycle of lung injury and prevent continued damage."
Transplant Procedures and Benefits
Historically, bone marrow and blood stem cell transplants were the only cure for SCD, but high-dose chemotherapy requirements posed health risks. Low-intensity transplants are considered slightly less effective but better tolerated by adults with pre-existing organ damage, reducing the risk of graft-versus-host disease. Researchers aimed to determine if these transplants offered additional benefits for vulnerable lungs.
Study Details and Findings
The study involved 97 SCD patients who underwent low-intensity blood stem cell transplants at the NIH Clinical Center between 2004 and 2019, with follow-ups for up to three years. Researchers conducted pulmonary function tests, including forced expiratory volume in one second (FEV-1), and diffusing capacity of the lungs for carbon monoxide (DLCO), along with a six-minute walk distance test.
After three years, overall lung function remained stable. FEV-1 levels were relatively unchanged post-transplant, while DLCO levels and six-minute walk distance improved significantly. These results suggest that low-intensity transplants do not compromise lung health and may offer functional improvements.
Future Research
Ruhl emphasized the need for larger studies with longer follow-up periods, including data from other clinical centers and patients who received standard transplants. The team will continue to monitor NIH patients and report on longer-term outcomes. The study's techniques may also be applied to evaluate lung function in patients undergoing new genetic therapies for SCD, following FDA approvals in December 2023.
