Bone Marrow Transplants, Stem Cell Transplants: What’s the Difference?

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Topics include: Treatment and Understanding

When discussing MPN treatments, transplant often is discussed.  Terms like stem cell, autologous and bone marrow get thrown around, but what does it all mean?  Dr. David Snyder from City of Hope and Dr. Bart Scott from Seattle Cancer Care Alliance differentiate between the types of transplant and explain how it works, including the role of the donor and the matching process. 

This event was produced in association with City of Hope and sponsored by Patient Empowerment Network through educational grants from Incyte Corporation and Geron Corporation.

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Transcript

Please remember the opinions expressed on Patient Power are not necessarily the views of our sponsors, contributors, partners or Patient Power. Our discussions are not a substitute for seeking medical advice or care from your own doctor. That’s how you’ll get care that’s most appropriate for you. 

Andrew Schorr:

Okay, here’s a question we got. First, just to define things, Dr. Scott, we’ve referred to the term bone marrow transplant. We’ve also said stem cell transplant. Could you just define that, because it’s confusing?

Dr. Scott:

Sure, I like that topic. So allogeneic transplants and autologous transplants, they’re all stem cell transplants, and stem cell is kind of the overlying term and the bone marrow refers to the method in which the stem cells are collected.

So, for related and unrelated donors, there are two principal methods of collecting the stem cells. You can do a GCSF mobilized peripheral blood collection, so you give a drug. It stimulates the stem cells, and it moves the stem cells from the bone marrow into the peripheral blood.

And then you hook the donor up to a machine that’s very similar to a dialysis machine, and you collect the stem cells that way. That’s called a peripheral blood stem cell collection, and we call those transplants peripheral blood stem cell transplants.

Another way to collect stem cells is you can take the donor to the operating room. It’s an in and out procedure. They’re not admitted overnight. But they’re put under general anesthesia, and you do several aspirates, more than several, on each side, which explains why they’re put under general anesthesia.

And you collect the stem cells directly from the bone marrow. I see a lot of faces with downturned mouths, but, you know, it depends on the donor. So, you know, you have to get five days of GCSF, the GCSF can cause bone pain. It can cause headache. It can cause spleen swelling.

So for many patients, and also, it’s another five days, but the bone marrow collection, you can go in and out. And it’s easier, potentially, from the donor’s perspective in regards to scheduling. But stem cell basically refers to all types of transplants, and then peripheral blood and bone marrow refers to how you got it.

And, of course, cord blood is from a cord unit, and I’ll just briefly mention that there are slight differences between the ways you get the stem cells and how the recipient responds to that stem cell infusion. And the difference is that with bone marrow, there appears to be a little bit, well, not a little bit.

There appears to be a lower risk of developing chronic GVHD with unrelated donors. And with peripheral blood, the engraftment, so the time when the stem cells start working and they engraft is a little bit quicker.

There was a randomized trial done looking at unrelated donors, matched unrelated donors, comparing peripheral blood to bone marrow, and the overall survivals were equivalent. But there was a little bit lower rate of chronic GVHD with the bone marrow product as opposed to peripheral blood product.

Andrew Schorr:

Okay, and we have a related question, and that is, what if you have no family member who is a matched donor? Is it, I guess, less successful if you’re having, unrelated matched donor?

Dr. Snyder:           

So it’s interesting that over the last several years, if you look at the numbers of allogeneic transplants done in this country and the source of the donor, whether it’s family, sibling versus unrelated, a couple years ago, I think, maybe three, four years ago, the curves crossed where there’s more unrelated donor transplants compared to sibling donor transplants being done.

And that reflects a couple of trends. One is that, in general, family sizes gets smaller over time. So, if you had, you know, you have a one in four chance of any given sibling being a match. So if you had a family of seven, eight children, obviously you have a better chance of finding a match than if you only had one sibling.

At the same time, the number of volunteers who have registered in the National Marrow Donor Program, it’s really a worldwide registry, keeps climbing. And it’s somewhere around 17 million worldwide.

And though you only have about a one in 20,000 chance of matching with a random individual. If you have 17 million in the registry, that increases the odds, and it does reflect ethnic backgrounds. These HY antigens tend to be, they’re finite numbers and combinations.

They tend to cluster within ethnic groups to the extent that there’s been relative inbreeding, if you will, so that you’re more likely to be successful in finding a match from a pool of people of a similar ethnic background as you.

So, having said all that, if you don’t have a sibling donor, but you find a fully matched, unrelated donor, the outcomes are virtually identical between those two sources.

Dr. Scott:

I want to make a plug for a website. It’s called bethematch.org. And if you have family members who are interested in potentially serving as a donor, that would be a good resource for them.

Please remember the opinions expressed on Patient Power are not necessarily the views of our sponsors, contributors, partners or Patient Power. Our discussions are not a substitute for seeking medical advice or care from your own doctor. That’s how you’ll get care that’s most appropriate for you. 

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Page last updated on October 19, 2015