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Bone marrow transplants may prevent or improve blood vessel damage in the brains of adults with sickle cell disease, new research suggests, offering a potentially promising treatment for people at high risk of stroke because of the inherited blood cell disorder.

Sickle cell disease is characterized by abnormally shaped red blood cells (sickle-shaped), which can cause blood vessels in the brain to bulge or narrow. It is a major risk factor for stroke in children and adults. Around 100,000 Americans may have sickle cell disease, according to the Centers for Disease Control and Prevention.

Bone marrow – found in the center of bones – contains stem cells that can transform into red or white blood cells or platelets. Prior research has shown bone marrow transplants can help prevent blood vessel damage in children with sickle cell disease. The new study looked at how it would affect blood vessels in adults.

"We were surprised that bone marrow transplant reversed some of the changes in brain vessels," lead study author Dr. John Lynch said in a news release. He is an associate research physician in the stroke branch at the National Institute of Neurological Disorders and Stroke, a division of the National Institutes of Health in Bethesda, Maryland.

"We thought that bone marrow transplantation would stop the changes from getting worse; however, we did not think it would reverse the changes," he said.

The will be presented Wednesday at the American Stroke Association's International Stroke Conference in Dallas. They are considered preliminary until the full results are published in a peer-reviewed journal.

In the study, researchers analyzed brain scan images for 87 adults with sickle cell disease who were enrolled in NIH studies and received bone marrow transplants from 2004 to 2019. They compared changes in blood vessels before and after transplantation during more than three years of follow-up. Study participants were 32 years old on average, and more than half were men.

Before the transplants, 17% of participants showed evidence of narrowed blood vessels and 13% had bulging blood vessels. After transplant, blood vessel abnormalities improved in 62% of the participants. And those who had no blood vessel issues prior to transplants remained free of them during follow-up.

"Our study is unique in that we examined adults with sickle cell disease for a long period of time, and we were able to compare the differences in blood vessels and brain tissue over time," Lynch said. "We suspect that the reduction in the number of sickle cells and the improvement of the cells' oxygen-carrying capacity led to a reduction in the number of strokes after bone marrow transplantation."

The study did not compare the findings to people with sickle cell disease who did not receive bone marrow transplants. Some participants were followed for a shorter time than others.

"Our hope is that bone marrow transplantation may be considered more often for people with sickle cell disease and that other less invasive and potentially lifesaving treatments may be developed for people with sickle cell disease," Lynch said.

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