Stem cells are made in the bone marrow and mature into red blood cells, white blood cells and platelets. When they go rogue and produce defective or cancerous cells, one way to stop them is to "reboot" the bone marrow with a transplant of healthy cells.
You can see why the terms "bone marrow transplant" and "stem cell transplant" are used interchangeably. While there is no difference in the transplant procedure itself, there is a difference in how the cells are harvested. In the past, liquid marrow containing stem cells was collected using a needle inserted into the donor's pelvis. In the majority of cases today, they can be harvested from the blood in a non-surgical procedure done in an outpatient clinic.
The Match Game
The key to a successful transplant is the match between a donor's cells and the patient's, which is typed using human leukocyte antigens (HLA). HLAs are proteins on the surface of white blood cells and other tissues. If there's an HLA match, donor cells are less likely to provoke an attack by the patient's immune system.
The best matches come from siblings or other family members, but people who don't have a suitable relative must find a donor in one of the bone marrow registries. If I needed a transplant and couldn't find a match within my family I would join the 7,500 Americans who are actively searching the national registry for a donor at any given time.
I would have about a 75% chance of finding a match since I'm Caucasian. If I were Hispanic the odds would drop to about 45%, Asian to 40%, African American to 25%. If I were of mixed race they would plummet even lower.
And if I discovered a match in the registry, there's a 35% chance that person could not be located or would change their mind about donating; 66% for African Americans.
These sobering numbers are part of the reason why about 1,000 people die every year while searching for a suitable donor.
Be The Match
Donors must be 18-60 years old and in good health. They can't be pregnant or have a medical condition such as cancer, severe arthritis or asthma, heart or autoimmune disease, or an STD. (If you recently got a tattoo, you may have to wait a year to donate.)
You can get more info on the nuts and bolts of donating from the Be The Match Registry Center near you. They'll have you complete a short health questionnaire and sign a consent form. Then they'll take a swab of cheek cells or a blood sample for HLA typing and your information will be added to a confidential donor database.
If (or when) your HLA type matches someone needing a transplant, you'll be called for further testing. If the match is confirmed, you'll be asked to donate either peripheral blood stem cells or bone marrow depending on what's best for the patient.
This is a volunteer process and you can withdraw at any time. Or, you might get the chance to save a life, which is a wonderful thing and will look great on your permanent record!
Mike Hamel is the author of a dozen books and a popular blog based on his experience with cancer, http://mikehamel.wordpress.com/.