So, what happens if you are found to be a match for a patient in need? In this event, you will be contacted by a registry representative, and if you are still able and willing to be a donor, guided through the whole donation process by a case manager. First, a nurse or other health care worker will determine if you are generally in good health. Your blood will be tested for infectious diseases and a physician will perform a physical exam to make sure you are healthy enough to donate stem cells; these steps ensure the safety of both the donor and the recipient. At this time, potential risks and benefits will be explained to you, and with your consent, the donation process will go ahead.
There are two ways to donate stem cells; which one is chosen depends on the needs of the patient. Peripheral blood stem cell (PBSC) donation is now the preferred method: HSCs released from the marrow into the bloodstream are collected in a painless process much like an extended session of blood donation. Prior to the procedure, donors receive once-daily injections for five days of a medication that stimulates the body’s production and release of HSCs. Then, over a 4-6 hour period at an outpatient clinic, blood is drawn out of one arm and run through a machine that separates and collects the required stem cells, and returns the rest of the blood through the other arm in a continuous circuit. All the while, donors are free to read, watch a movie, or do pretty much anything else they choose. Most donors experience just mild bone pain, headache, and/or nausea from the injections, and these symptoms subside shortly after donation. Between 5-15% of PBSC donors require placement of a central catheter in a large vein to complete the process.
The older method, bone marrow donation, involves using a special needle to collect liquid marrow from the donor’s hipbone. Rest your hands on your hips—the spots on the back of your hipbones under where your thumbs rest are the areas from which marrow is collected. This procedure is performed under anesthesia (so it is painless), and takes two to three hours from start to finish. Donors typically arrive at the hospital in the morning and leave by afternoon. Though there are risks involved with any medical procedure, most people only experience some hip discomfort at the puncture sites; mild painkillers are usually sufficient. Just 3-5% of your body’s total marrow is withdrawn, and this will completely regenerate in 4-6 weeks. Bone marrow donation, however, is only used about 20% of the time these days.
Thus, both PBSC and bone marrow donation are safe and simple procedures that can save the lives of patients with a wide variety of illnesses. In leukemia patients, stem cell transplant increases the long-term survival rate by 2-3 times over chemotherapy alone. In addition to blood cancers, SCT can potentially cure other bone marrow diseases like thalassemias—some of which are common in South Asians—and sickle cell anemia; disorders of the immune system, such as SCID (“bubble boy disease”); and inborn errors of metabolism, including adrenoleukodystrophy (see “Lorenzo’s Oil”).
Since its inception in 1987, the NMDP has facilitated transplants for more than 35,000 people. The Canadian registry has made possible more than 2,000 transplants since 1988. But, according to the NMDP, at any given time physicians are searching for donors on behalf of 6,000 patients worldwide. So, regardless of your ethnic background, by registering as a donor, you could become (as OneMatch says) an “extreme lifesaver”.
A third, even easier way of donating stem cells applies to expectant mothers. Usually, when a baby is born and the umbilical cord is clipped and cut, the cord and placenta are discarded as medical waste. However, scientists have found that blood from the cord is a rich source of HSCs, and cord blood use is growing in both adult and pediatric populations. Physicians may consider umbilical cord blood a good choice particularly for patients who need an unrelated donor and have an uncommon HLA type or are in urgent need of a transplant.
A cord blood unit is collected at the time of delivery, so parental consent must be provided to doctors and midwives well beforehand. In the U.S., the NMDP is affiliated with more than 20 cord blood banks that facilitate cord blood collection and storage. In Canada, OneMatch expects to implement a public cord blood program within the next year. Until then, Canadians can register with the Alberta Cord Blood Bank, which operates coast-to-coast, or with Héma-Québec, which collects cord blood at several Montréal hospitals.