The cyclophosphamide spares the donor's stem cells and allows them to establish new blood cells and a new immune system. The nascent immune system is re-trained to see the patient's body as friend, not foe. This prevents the patient from rejecting the transplanted bone marrow - and prevents the newly developing immune system from attacking the patient.
Brodsky compares the drug's effect to rebooting a computer: "Cyclophosphamide is control-alt-delete to the immune system."
With a new immune system, the foundation is laid for the donor stem cells to out-compete the patient's weakened stem cells. Healthy blood cells are created and start circulating - overtaking the sickled blood.
Brodsky said the biggest problem in promoting widespread use of his new procedure may be the cost. Most insurance companies won't cover experimental treatment for genetic disorders, he said.
At the National Heart Lung and Blood Institute, Tisdale and his team began testing a new bone marrow transplant procedure about three years ago. Of eight transplanted adults, seven were cured. The eighth patient survived the transplant but his symptoms returned. Two more are undergoing transplants.
Despite his investment in his own procedure, Tisdale said the Hopkins method - if it works in more patients - would be a "huge" breakthrough because it only requires half matches, while his requires full matches.
The Hopkins procedure has been huge for Pamela Newton.
Newton's mother knew something was wrong with her baby early on. She cried a lot, especially when she was picked up. When she learned to walk, Newton dragged her legs. Her mother took her back and forth to hospitals until she was 5, when a doctor finally ordered the critical blood test. She had sickle cell.
Newton took an extra year to graduate from high school after missing too many classes when she was sick. She dropped out of college when the pain, which she said felt like a heart attack all over her body, made it too hard to focus. By then she needed regular narcotics and used a Demerol pump. She spent 15 years on daily painkillers and sometimes wound up in the hospital twice a month.
By 2006, when she was referred to Brodsky, she was out of options. Twice in the previous year, she had wound up in the intensive-care unit with bleeding on her brain.
Brodsky offered her a bone marrow transplant. He warned her of the risks. He told her she could die.
