In 2010, Afia Donkor, a young woman from Canada, struggled to walk a few blocks from her home to a subway station in Montreal on her way to the airport. Suitcase in hand, she moved at a snail’s pace as she experienced severe exhaustion due to a flare-up of her sickle cell disease. One step at a time, she finally made it, propelled by the hope of a new treatment that awaited her at the other end of her journey to the United States.
Afia arrived at the National Institutes of Health (NIH) in Bethesda, Maryland, to undergo an experimental procedure: a bone marrow transplant designed to reverse her sickle cell anemia. The genetic disorder causes crescent-shaped red blood cells to form, reducing blood and oxygen flow. The condition can cause fatigue, severe pain, organ damage, stroke, and even death. In the United States, about 90,000 to 100,000 people have the condition, mostly in those of African ancestry; millions worldwide have the disease. To date, there is no widely-available cure.
After a week of preparation, doctors at NIH removed Afia’s bone marrow and replaced it with specially-treated bone marrow obtained from her brother, a healthy, compatible donor who does not have sickle cell disease. Prior to the transplant, her brother underwent a treatment that made his marrow rich in stem cells.
“Stem cells are a type of unspecialized cell that can change into a more specialized cell, such as a healthy red blood cell, under certain conditions,” explained John Tisdale, M.D., a researcher affiliated with both the National Heart, Lung, and Blood Institute (NHLBI) and the National Institute of Diabetes and Digestive and Kidney Diseases. Both are part of the NIH.
“We thought that if we could transfer healthy bone marrow stem cells to an adult sickle cell patient, then the patient would start producing normal red blood cells and the patient would no longer have sickle cell disease,” Dr. Tisdale said. He notes that doctors have previously used stem cell transplants to treat sickle cell disease in children with severe complications, such as stroke, with great success. But recent advances have allowed doctors to extend this procedure to adult patients while lowering the risk of complications, he added.
Like most of the 30 adult patients who have undergone the experimental transplant, the result was a success. Afia’s new bone marrow was soon producing normal red blood cells, not unhealthy sickle-cells, on a continuous basis. As a result, her symptoms—the fatigue, the pain—disappeared.
“I never like to say ‘cured,’ but it feels like a cure,” she said. “It’s amazing. I feel great. As far as I’m concerned, my sickle cell disease is gone.”
Afia, age 33, now works as a lawyer and a volunteer for a religious organization in Ontario. She said that she has not had a pain crisis since the transplant. She’s no longer taking powerful pain medications. She no longer receives blood transfusions that have become common treatment for many sickle cell patients. And while most people who receive stem cell transplants face a lifetime of taking immunosuppressant drugs designed to ward off rejection, she was eventually able to avoid these powerful medications, which can be harmful with prolonged use.
Today, Afia now does things she only dreamed of doing previously. One of those activities is running. After her transplant, Afia started jogging a little bit at a time. By July of 2013, she accomplished what she calls one of the “greatest victories of my life”: she ran nonstop for 2 hours. This was a virtual marathon compared to the walk to the subway that left her breathless.
But Afia cautions that while she feels great, her battle against sickle cell disease is not over. Doctors at NIH are still monitoring her at least once a year for any signs of serious complications. But so far, none have occurred.
Dr. Tisdale points out, however, that not all of the patients undergoing the experimental transplant experience the same positive result. And the procedure is still not widely available to everyone, as doctors have difficulty finding compatible donors for some patients.
The researcher emphasizes that stem cell transplantation for sickle cell disease is still experimental. It appears particularly promising for older, sicker patients, a population that hasn’t seen a compelling breakthrough in quite some time. The NIH is continuing to recruit eligible patients with sickle cell disease into a bone marrow transplantation clinical trial.
In addition, scientists hope that new procedures, such as gene therapy, may also offer lasting treatments for sickle cell disease but provide benefits to a wider range of patients, without the need for finding compatible bone marrow donors. Research toward this goal is underway at NHLBI.
In the meantime, patients like Afia offer a glimpse at what sort of transformations might take place in the future: from being barely able to walk a few steps to running a virtual marathon.