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What is a stem cell transplant?

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

By now you have probably heard the terms ‘stem cell transplant’, ‘bone marrow transplant’ or ‘haemopoietic stem cell transplant’ mentioned a few times, but you might not be 100% sure what it involves.

If you have a condition that affects your bone marrow or blood, it could be the best treatment option for you. 

During a stem cell transplant your medical team will replace your blood stem cells with new, healthy stem cells from a suitable donor. After a period of time they will attach to your bone marrow (called engraftment) and start to make new blood cells. Your new stem cells will be selected from a donor that is closely matched to you – to give you the best possible chance of overcoming your condition.

In this section we answer the following questions:

What are stem cells?

Stem cells are immature cells. All other cells which make up your body develop from stem cells.

Blood stem cells are found in your bone marrow. They are responsible for creating lots of different types of blood cells.

You can find out everything you need to know about stem cells on our What is a stem cell? webpage.

What are the different types of blood cells and what do they do?

  • Red blood cells are the most abundant type of blood cell. They carry oxygen to all the tissues in your body. You might also hear them referred to as ‘erythrocytes’. If you have too few red blood cells or they don’t function properly, it can cause anaemia.
  • White blood cells are the cells that make up your immune system and fight infections. They can be divided into further groups based on the jobs they do, including:
    • Neutrophils, which are one of the first cell types to respond to infections when they occur. Neutrophils are the most abundant type of white blood cell. When they travel to the site of an infection, it often causes inflammation and swelling.
    • Lymphocytes: there are two main types of these white blood cells – T cells identify foreign invaders and recruit other immune cells to help, while B cells produce and secrete antibodies.
    • Plasma cells, which are mature B cells that produce different types of antibodies to help fight infection. When problems occur with their production and development it can lead to myeloma.
  • Platelets help the blood to clot following injury or trauma.

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

Both types of transplant give the same result – the patient receives stem cells that will develop into a new immune system. The main difference is how the cells are collected from the donor.

For 90% of donations, stem cells are collected through the donor’s bloodstream in a process called peripheral blood stem cell collection (PBSC). Their blood is passed through a small tube into a machine that collects the stem cells, and then returns the rest of the blood to the body. It’s a very similar experience to giving blood but takes a little longer.  

For 10% of donations, the stem cells are collected from the donor’s bone marrow. It involves a small surgical procedure, using a needle to collect bone marrow from the donor’s pelvis under general anaesthetic.

The choice of collection method depends on the condition involved, the patient’s general health and age. Your doctor will assess which method is most appropriate for you.

If you would like more information on how stem cells are collected, or if you are a friend or family member who is thinking of joining the register, our ‘How to be an Anthony Nolan stem cell donor’ video can help.

How does the transplant process work?

First, you’ll have treatment to get rid of the abnormal cells that are the cause of your condition using chemotherapy and sometimes radiotherapy. This is called conditioning therapy. The day after this finishes, your new stem cells will be infused into your blood in a similar way to a regular blood transfusion.

When your new stem cells enter your blood, they will move to your bone marrow and start producing new blood cells. Over time, this leads to the development of your new immune system that can recognise and remove any remaining abnormal cells 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 depending on several factors. These include:

However, due to improved treatments and better understanding of what makes a good match, patients are generally living for longer and are able to cope better with side effects such as GvHD (graft versus host disease).

If you would like to know more about how this could affect your own circumstances, please talk to your consultant or medical team about it. They will be able to give you the most accurate information about your situation.

Information published: 22/04/2021
Next review due: 22/04/2024

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