Bone marrow transplant reduces sickle cell heart damage: Study
Myocardial fibrosis may set stage for serious heart problems
A bone marrow transplant may help reverse heart damage in people with sickle cell disease (SCD), according to a study.
The findings were published in a letter to the editor titled, “Impact of Hematopoietic Cell Transplantation on Myocardial Fibrosis in Young Patients with Sickle Cell Disease,” in Blood.
SCD is a genetic disorder characterized by the presence of abnormally shaped red blood cells. These misshaped cells are prone to get trapped inside blood vessels and to die prematurely, causing patients to develop chronic anemia and complications resulting from blood flow restriction to certain tissues and organs. Over time, this can cause heart damage, which in turn can lead to myocardial fibrosis, or scarring of the heart muscle. This makes the heart stiffer and less efficient at pumping blood, setting the stage for potentially life-threatening heart disease.
Previous research has shown that standard sickle cell treatments, such as hydroxyurea, are generally not effective for reversing heart damage caused by the disease.
A bone marrow transplant, formally known as a hematopoietic stem cell transplant (HCT), is a procedure that works to replace a patient’s blood stem cells with new, healthy cells. This can be curative in sickle cell, as it allows patients to produce new red blood cells that don’t carry the disease-causing mutation. But the impact of HCT on myocardial fibrosis has not been known until now.
Analyzing MRI scans
To learn how HCT can impact myocardial fibrosis, researchers at St. Jude Children’s Research Hospital and their colleagues analyzed heart MRI scans that had been performed in sickle cell patients who were undergoing HCT as part of a clinical trial (NCT04362293).
“One of the questions that we wanted to ask was what happens to the heart muscle after transplant — and to be honest with you, we didn’t expect things to improve,” Akshay Sharma, the study’s first and corresponding author and a bone marrow transplant physician at the St. Jude Department of Bone Marrow Transplantation & Cellular Therapy, said in a St. Jude news story.
A dozen patients had cardiac MRI performed before HCT and then again one year after the procedure. The myocardial extracellular volume (ECV), which measures the space in between cells in the myocardium (heart muscle) and is highly correlated with myocardial fibrosis, was assessed at both timepoints.
“Cardiac MRI is the gold standard to measure cardiac ventricular volume and mass, superior to any other imaging technique,” said study co-author Jason Johnson, MD, a pediatric cardiologist and cardiac imaging expert at Le Bonheur Children’s Hospital and the University of Tennessee Health Science Center.
Johnson added that this imaging technique “has the added benefit of myocardial tissue characterization to identify the presence of fibrosis, edema [swelling], or inflammation that is important to define in sickle cell patients before and after bone marrow transplantation.”
Results showed that the mean ECV decreased by 3.4% in the first year after HCT. In six patients who had two-year follow-up data available, ECV values decreased even further, by 4.8% on average.
“When we looked at the heart with cardiac MRI, we saw a gradual and definitive improvement in the amount of fibrosis in the heart,” Sharma said, adding that this finding “is hopeful news for patients.”
Since myocardial fibrosis can set the stage for serious heart problems, these improvements “may translate into improved cardiac outcomes for these patients,” the researchers said, though they noted that larger studies with longer follow-up times will be needed to prove this definitively.
The study “provides the impetus to study the potential myocardial protective effect of HCT in a larger patient cohort,” the researchers wrote.
About the Author
