In April of 2016, I got a phone call that changed my life. Canadian Blood Services were calling to tell me that I was a match for a person who needed a stem cell donor. Within six months, I had surgery. Doctors took stem cells from my bone marrow. These stem cells were then urgently shipped to a patient desperately fighting for their life.
Wait - let’s take a step back. What are stem cells? What is a “match?” Exactly how do you donate stem cells? Does it hurt?
What is a stem cell?
A stem cell is an unspecialized cell that can become another type of cell. This happens through a process called differentiation.
There are different types of stem cells. You might have heard or read about embryonic stem cells. Embryonic stem cells are pluripotent. This means that they can differentiate into all the cell types found in your body.
There are not the cells that people can donate. Instead, people can donate hematopoietic stem cells. These are blood stem cells found in the bone marrow, the soft, spongy insides of your bones. Blood stem cells are multipotent, which means that they can become a certain number of different cells. Specifically, they can differentiate into red blood cells, white blood cells, and platelets.
Your blood cells do many of the tasks required to keep you alive. For example, red blood cells bring oxygen to your cells and white blood cells fight infections. However, some people have stem cells that do not work properly. Imagine that a hematopoietic stem cell is like a factory. This factory constantly makes red blood cells, white blood cells, and platelets. In some people, these factories have stopped working. Leukemia is an example of a disease that affects blood stem cells. The stem cells of a person with leukemia are affected so they start to produce cells at an uncontrollable rate. In other words, they become cancerous.
Did you know? Canadian scientists James Till and Ernest McCulloch discovered stem cells in the 1960s.
There are treatment options for patients with faulty stem cells. One of the last and most serious options is a stem cell donation. During a stem cell donation, the patient’s own stem cells are killed with high doses of chemotherapy and radiation and replaced with stem cells from another person. This person is called a match.
What is a match?
A match is a person who has stem cells that are like those of the person with the disease. More specifically, they have common human leukocyte antigens (HLA), which is a type of antigen. Antigens are things that can provoke an attack by the body’s immune system.
A white blood cell can tell what cells it needs to attack based on their HLA markers. You can think of an HLA marker like a sports jersey. If a cell has the same HLA markers as the rest of the body, they are on the same team. If a cell does not have the same HLA markers, it is likely an invader.
This system of identification helps a white blood cell protect the body from viruses and bacteria. However, it can make transplantation difficult. If donated blood cells don’t have the same HLA markers, white blood cells will attack them.
A doctor’s first choice would be to look for a match within the family. However, only 30% of patients find a match amongst their relatives, usually a brother or sister. The remaining 70% of patients rely on unrelated donors to survive, where the probability of a match can vary. One study of the American population found that the chance of finding a match from an unrelated individual varied between 16 % - 75 %. This variation is due to the patients’ racial and ethnic background as well as the racial and ethnic background of the general population.
What is it like to donate stem cells?
I signed up to donate stem cells when I was 17, which is how old you must be to register. When you register for the stem cell registry, you fill out a health questionnaire and swab the inside of your cheek. The health questionnaire helps the registry staff see if you are healthy enough to one day donate stem cells. The cheek swab is used to get your DNA for HLA marker testing.
Most people who register never match with a person in need. However, I got the call when I was 23 years old saying I was a match.
After I got that call, the first thing I had to do was have a blood test to confirm I was a match. If there are multiple matches, this test also helps to decide who is the best match. Next, I had a checkup to make sure that my heart was healthy, and that I had no infections. If you are not in good general health, you are not allowed to donate.
After these tests, I was cleared for donation!
So, what does donating stem cells involve?
There are two methods of donating stem cells. The classic method involves surgery. The quickest way to get these stem cells is to use a big needle and suck up the stem cells from inside your pelvic bone.
However, in most cases, people donate via a relatively new process called apheresis. This process involves taking blood from your body via a needle, separating the blood into different components, and only keeping the stem cells.
I donated stem cells surgically. I went to the hospital early in the morning and was put under general anesthetic. While I was unconscious, the doctors removed bone marrow from my hip bone. I was sound asleep and didn’t feel a thing. Afterwards, I had some side effects, including a sore throat and nausea. Also, my lower back was stiff because that is where they put the needle. Most of these side effects only lasted a few hours, except for the back pain. The back stiffness lasted about three or four days. I was back to school in four days and running within three weeks!
How common are stem cell donations?
In 2016, in Canada, there were almost 1000 people looking for a match. Worldwide, in 2015, there were 50, 000 people looking for matches outside of their family.
There’s a big need for more ethnic diversity within stem cell registries. Scientists have figured out that two people are more likely to have the same HLA markers if they have the same ethnic and racial background.
Want to help?
There are over 80 disorders and diseases that can be treated by a stem cell donation. But even if you don’t want to or can’t donate stem cells, there are other ways you can help others in need! You can donate blood, sign up as a organ donor, volunteer for a stem cell club, or consider working for a stem cell registry.
Did you know? I volunteer with the Stem Cell Club at the University of Toronto. Our job is sign people up on stem cell registries. Organizations like ours have signed up millions of people worldwide to stem cell registries. Once you register, you are making a commitment: If you are a match, you will donate stem cells.
Bone Marrow (Hematopoietic) Stem Cells (2016)
Domen, A. Wagers & I.L. Weissman, National Institutes of Health
International marrow registries together reach 25 million donor milestone (2015)
Canadian Blood Services
Blood Stem Cell Transplant (2014)
Let’s Talk Science
HLA Match Likelihoods for Hematopoietic Stem-Cell Grafts in the U.S. Registry (2014)
L.Gragert, The New England Journal of Medicine 371
Stem Cells - What’s Myth, What’s Truth (2012)
Levac, Let’s Talk Science