Cord Blood, Bone Marrow, and PBSC: What Is the Difference?

If you have been reading about joining a donor registry, you have probably run into three phrases that sound a lot alike: bone marrow, PBSC, and cord blood. They can feel confusing, and a little intimidating. The good news is that the core idea is simple, and once you see how the three fit together, the whole picture gets a lot friendlier.

Here is the short answer. Bone marrow, PBSC, and cord blood are three different sources of the same thing: blood-forming stem cells, the cells that rebuild a patient's blood and immune system after treatment for diseases like leukemia and lymphoma. According to the U.S. Health Resources and Services Administration (HRSA), all three are used in transplants. They simply come from different places and are collected in different ways.

One more thing worth saying up front, because it takes the pressure off: as a donor, you do not have to pick which method is used. The patient's transplant team decides that, based on what is safest and most effective for the person they are trying to help.

What are blood-forming stem cells, in plain terms?

Deep inside your bones is a soft, spongy tissue called marrow. That marrow is a kind of factory: it makes the red cells that carry oxygen, the white cells that fight infection, and the platelets that help you stop bleeding. The cells that run that factory are called blood-forming stem cells (you may also see them called hematopoietic stem cells).

For some patients, disease or its treatment damages that factory. A transplant of healthy blood-forming stem cells can give the body a fresh start. Those healthy cells can come from three sources, which is where bone marrow, PBSC, and cord blood come in.

Bone marrow donation: the surgical option

This is the source most people picture when they hear "bone marrow donation," and it is a real surgical procedure, though a routine and well-understood one.

According to NMDP (formerly Be The Match), marrow donation is an outpatient surgery, typically 60 to 90 minutes, done under general or regional anesthesia so the donor feels no pain during the collection. Doctors use a needle to withdraw liquid marrow from the back of the pelvic (hip) bone. The small incisions are less than a quarter-inch and usually do not need stitches. NMDP notes that most donors go home the same day and return to their usual activities within a few days to a week, and the body naturally replaces the donated marrow over the following weeks.

Bone marrow is the less common way adults donate today, but it remains important. NMDP notes it is often the method chosen for pediatric patients and for some patients at higher risk of certain complications.

PBSC donation: the non-surgical option most donors give

PBSC stands for peripheral blood stem cells, and it is the source behind most adult donations. According to NMDP, about 90% of donations are made this way, with the remaining 10% through bone marrow.

Here is the clever part. The same blood-forming stem cells found in your marrow also circulate, in smaller numbers, in your bloodstream. HRSA explains that in the days before a PBSC donation, the donor receives injections of a medication called filgrastim that coaxes more of those cells out of the marrow and into the blood, where they can be collected without surgery.

On donation day, the process looks a lot like giving blood or plasma. NMDP describes it as apheresis: blood is drawn from a vein in one arm, passed through a machine that separates out the blood-forming stem cells, and the rest of the blood is returned through the other arm. There is no operating room and no anesthesia. NMDP reports that PBSC donors tend to recover a little faster than marrow donors.

Cord blood: collected after a baby is born

The third source is different from the first two, because it does not involve an adult donor at all. It comes from the umbilical cord and placenta after a baby is born.

Normally the cord and placenta are discarded after birth. But the blood left inside them is rich in blood-forming stem cells. According to HRSA, expectant parents can choose to donate that cord blood to a public cord blood bank, where it is collected, tested, frozen, and stored so it may later help a patient who needs a transplant. HRSA is clear on an important reassurance: no blood is taken from the baby, only from the cord and placenta after the birth, and public banks cover the cost of collection and storage.

Cord blood is a valuable option in part because it does not have to match a patient quite as precisely as an adult donation does, which can widen a patient's chances of finding something usable.

Who decides which source a patient gets?

This is the question that trips up a lot of well-meaning people, so it is worth stating plainly: the donor does not choose the method, and neither does any charity or registry. NMDP states directly that "the patient's doctor determines the best method for their treatment."

That decision depends on medical factors, the patient's diagnosis and age, their size, their risk of complications, and what the transplant team judges will give the best chance of a good outcome. When you join a registry, you are saying you are willing to help however you are needed. If you are ever identified as a match, the registry and the transplant team will talk you through exactly what is being requested and why, and you can ask any question you like before agreeing.

Where the Jada Bascom Foundation fits in

A quick, honest note about who we are. The Jada Bascom Foundation is a nonprofit that helps people understand donation and find the right registry for their country. We do not run a registry, mail swab kits, test anyone's tissue type, store donor records, or decide who is eligible. Those roles belong to the donor registries and transplant centers. Our job is simply to help you take the first step with clear, trustworthy information, and then point you to the organization that handles the rest.

Understanding the three sources is a great start, because it replaces a vague sense of "that sounds scary" with a clear picture of what is actually involved. For most adults, it means a procedure much like giving blood. For everyone, it means the potential to help rebuild a stranger's blood and immune system.

Ready to take the next step?

The most powerful thing an adult can do is get on the registry, because a patient can only be matched with someone who is already listed. Registries are organized country by country, so the right place to sign up depends on where you live.

[Find the donor registry for your country](/find-your-registry) and learn how to join. It usually starts with a simple cheek swab, and it could be the reason someone gets a second chance.

Frequently asked questions

What is the difference between bone marrow, PBSC, and cord blood?

They are three different sources of the same blood-forming stem cells. Bone marrow is collected surgically from the pelvic bone under anesthesia. PBSC (peripheral blood stem cells) are collected without surgery from a vein in the arm, much like giving blood. Cord blood is collected from the umbilical cord and placenta after a baby is born. According to HRSA, all three are used in transplants.

Which type of donation is most common?

For adult donors, PBSC is by far the most common. According to NMDP (formerly Be The Match), about 90% of donations are made through PBSC and the remaining 10% through bone marrow.

Do I get to choose whether I donate bone marrow or PBSC?

No. NMDP states that the patient's doctor determines the best method based on what is safest and most effective for that patient. When you join a registry, you are agreeing to help in whatever way is needed, and the transplant team will explain exactly what is being requested before you decide.

Is bone marrow donation painful?

According to NMDP, marrow donation is a surgical outpatient procedure done under general or regional anesthesia, so donors feel no pain during the collection itself. The incisions are tiny and usually do not need stitches, and most donors return to normal activities within a few days to a week.

Does the Jada Bascom Foundation run a registry or mail swab kits?

No. The Jada Bascom Foundation is a nonprofit that helps people understand donation and find the right registry for their country. We do not run a registry, mail kits, type anyone's tissue, store donor records, or decide eligibility. Those roles belong to the donor registries and transplant centers we refer people to.

Sources

• HRSA (Blood Stem Cell) — About Transplantation and the three cell sources
• HRSA (Blood Stem Cell) — Donate Cord Blood
• NMDP (formerly Be The Match) — PBSC Donation Process Overview (90% of donations)
• NMDP (formerly Be The Match) — Bone Marrow Donation Overview & Process
• HRSA (Blood Stem Cell) — Frequently Asked Questions