Matt is with his family in the garden. Matt received a stem cell transplant.

What is a stem cell transplant?

You might have heard the terms ‘stem cell transplant’, ‘bone marrow transplant’ or ‘haemopoietic stem cell transplant’ mentioned a few times. It’s important to understand what you’re going through. This page explains exactly what is involved in the process of a transplant.

What’s on this page?

What's involved in a stem cell transplant?

During a stem cell transplant, your medical team will replace your damaged blood stem cells with new, healthy stem cells from a suitable donor. It’s a bit like getting a blood transfusion – it’s not an operation.

In time, the new stem cells will attach to your bone marrow in a process called engraftment. After this, the donated stem cells will start to make new blood cells.

What are stem cells?

If you haven’t yet read our page on understanding stem cells, we recommend taking a look at the information to help you learn what stem cells are.

What's the difference between a stem cell transplant and a bone marrow transplant?

The main difference between stem cell and bone marrow transplants is how doctors collect cells from the donor. Both types of transplant give the same result – you receive stem cells that will develop into your new immune system.

The way doctors collect stem cells will usually depend on the condition involved, your general health and age. Your medical team will assess which method is best for you.

How do doctors collect stem cells?

There are two ways of collecting stem cells for a donation:

  • Peripheral blood stem cell collection (PBSC). For around 90% of donations, doctors collect stem cells through a donor’s bloodstream in a process called PBSC. Their blood passes through a small tube into a machine that collects the stem cells and returns the rest of the blood to the body. It’s a similar experience to giving blood but takes a little longer.
  • Bone marrow collection. For around 10% of donations, stem cells are collected directly from the donor’s bone marrow. It involves a small operation under general anaesthetic, using a needle to collect bone marrow from the donor’s pelvis.

How does the stem cell transplant process work?

We’ll explain the process of a stem cell transplant in five main steps:

  1. Finding a stem cell donor. Medical professionals select stem cells from a donor who is closely matched to you. This gives you the best possible chance of overcoming your condition.
  2. Conditioning therapy. You’ll have treatment to get rid of the damaged cells that have caused your condition. This treatment might involve chemotherapy and sometimes radiotherapy. This stage of preparing your body is called conditioning therapy.
  3. Stem cell infusion. The day after your conditioning therapy finishes, your new stem cells will be ‘infused’ into your blood. This is a similar process to a regular blood transfusion.
  4. Blood cell production. When your new stem cells enter your blood, they will move to your bone marrow and start producing new, healthy blood cells.
  5. Building a new immune system. Over time, this leads to the development of your new immune system that can recognise and remove any damaged cells left in your body. It will also protect you against things like bacteria and viruses that can cause infections.

How successful are stem cell transplants?

Stem cell transplant success rates vary widely. Their success depends on several factors, which may include:

However, thanks to improved treatments and better understanding of what makes a good match, people generally live longer and cope better with side effects like graft versus host disease (GvHD).

To find out more about how certain factors could affect the success of your transplant, please talk to your consultant or medical team. They’ll be able to give you the most accurate information about your situation.

Are there different types of stem cell transplants?

There are two main types of stem cell transplant. The stem cells you receive in each type of transplant are collected from different sources:

  • Autologous transplants: You receive your own stem cells that doctors collected before your treatment started. You might also hear it called an autograft or auto.
  • Allogeneic transplants. You receive your stem cells from somebody else. This might be someone you know, like a sibling or family member, or someone who has signed up to the Anthony Nolan register. You might also hear it called an allograft or allo.

If you have an allogeneic transplant, there are further different types of stem cell transplant. We have information pages explaining each type:

The type of transplant you have will depend on the type of blood cancer or blood disorder you have, as well as your age, general health and availability of a suitable donor.

What side effects can I expect from a stem cell transplant?

The side effects of a stem cell transplant vary between different people and might last for a short or long time. Your conditioning therapy often causes side effects, as well as the effects of the transplant itself. It can also depend on the type of transplant you have.

Having a stem cell transplant is a very intensive treatment which can really affect your life physically and emotionally. Your transplant team will explain the risk of complications and side effects, so you can make the best decisions for your care.

You can read more about side effects in our information about recovering after a stem cell transplant.

Short-term side effects


After any type of stem cell transplant, you might experience short-term side effects like:

  • increased risk of infections
  • a sore mouth, known as mucositis
  • liver and kidney problems
  • tiredness
  • feeling or being sick
  • diarrhoea (loose or runny poo)
  • not feeling hungry, or eating less than you would normally.

In terms of mental wellbeing, it’s common to feel a bit low or anxious during the early stages of recovery. This is perfectly normal and understandable. Your transplant team will be on hand to listen to your concerns and may be able to refer you to a therapist for further support.

In terms of mental wellbeing, it’s common to feel a bit low or anxious during the early stages of recovery. This is perfectly normal and understandable. Your transplant team will be on hand to listen to your concerns and may be able to refer you to a therapist for further support.

Long-term side effects


After any type of stem cell transplant, you might experience long-term side effects like:

Your transplant team will monitor you closely and offer treatment and support where they can.

Side effects of specific transplant types


As well as all of the above, which can apply to any type of stem cell transplant, you might experience other side effects depending on your transplant type:

  • Further need for blood and platelet transfusions. This is a potential short-term side effect related mainly to autologous, cord blood and sibling stem cell transplants.
  • Graft versus host disease (GvHD). This is a possible side effect of cord blood, matched unrelated donor (MUD), haploidentical or sibling transplant types. It can be short or long term, and mild or severe. Your transplant team will closely monitor you for signs of GvHD and offer treatment that can help. Read more about GvHD.

Information updated: 23/05/2024

Next review due: 23/05/2027