Understanding stem cell transplants



You’ve just found out that either you, or someone close to you, needs a stem cell transplant. It’s natural to feel worried, confused or daunted by what’s going to happen next and you might have lots of unanswered questions.

Finding out information about transplant can be empowering and help build your confidence to tackle the situation head on.

In this section we will help you understand what stem cells do and why they are so important. There is information on how we search our registry for stem cell donors and possible alternatives if a donor can’t be found straightaway. We also look at options in the rare circumstance that funding for a transplant isn’t initially available.    

We will provide answers to the following questions:

What is 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 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:

Stem cells are the body’s primary cells. All other cells, tissue, organs and bones develop from stem cells. Blood stem cells live in our bone marrow, the soft tissue found in the middle of our bones. Blood stem cells are responsible for creating lots of different types of blood cells. They all have a unique job to do that keeps our blood healthy. Our blood stem cells need to produce exactly the right amount of each type of blood cell. If this carefully-controlled process goes wrong, it can result in your blood having too many cells that are not fully developed. This can in turn lead to blood cancers or blood disorders.

Red blood cells: 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: the cells that make up your immune system and fight infections. They can be divided into further groups based on the jobs they do.


Neutrophils: 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: 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: they help the blood to clot following injury or trauma

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.

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.

Stem cell transplant success rates vary widely depending on several factors. These include:

  • The patient’s age
  • The blood cancer or blood disorder they have
  • The type of transplant
  • Their general health prior to transplant.


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.

Different types of stem cell transplant

There are two main types of stem cell transplant. They are different because the stem cells you receive are collected from different sources.


  • If you have an autologous (or autograft) transplant, you will receive your own stem cells that were collected before your treatment started.


  • If you have an allogeneic (or allograft) transplant, you will receive your stem cells from somebody else. This might be someone you know, such as a sibling or family member, or it could be someone who has signed up to oregister. 


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

Autologous transplants

An autologous stem cell transplant allows doctors to give you very high doses of chemotherapy and/or radiotherapy to treat your condition – you might hear this called high dose therapy.

This therapy removes the abnormal cells that cause your condition but it also causes damage to your bone marrow and immune system. The transfusion of your own stem cells back into your blood allows your immune system to re-build itself over time. The stem cells move back into your bone marrow where they start making new blood cells, which aids your recovery.


After your transplant you will not develop graft vs host disease (GvHD) because you receive your own stem cells, so they won’t react to the other cells in your body. However, you are likely to still experience some short-term side effects and you will be at risk of developing infections as your body recovers from the treatment.


An autologous transplant could be a treatment option for you if:

  • You have blood cancer, such as myeloma or lymphoma.
  • Other treatments, such as chemotherapy, have not worked.
  • You have a certain type of cancer that will respond well to high dose chemotherapy, such as germ cell tumours.
  • You have a blood disorder that affects your immune system, such as severe autoimmune diseases like multiple sclerosis or Crohn’s disease. However, this is only in rare cases when other treatment options haven’t worked.

Cord blood transplants

If a sibling or unrelated donor is not available, you could be offered either a cord blood or haploidentical transplant instead.  


Cord blood, rich in stem cells, can be collected once a baby and the placenta have been safely delivered by the mother. It’s collected from the umbilical cord once it has been cut. The procedure is completely safe for both mother and baby. The blood is then frozen and stored in a cord bank until needed.


Cord blood stem cells don’t need to be as well matched with your tissue type compared to other sources of stem cells. This is because they are not as mature as blood stem cells, which means it can be easier to find a suitable cord match.

Haploidentical transplants

A haploidentical transplant uses stem cells from a family member whose tissue type or HLA is half matched to yours. Parents are always a half-match for their children, and vice versa. Siblings have a 50% chance of being a half-match for each other.


This means that you have a greater choice of potential donors – almost all people have at least one potential haploidentical match in their family.


Haploidentical transplants are becoming more common but unfortunately, they are not suitable for everyone. Your transplant team will be able to give you more information about your best possible option.

Matched unrelated donor (MUD) transplants

If you don’t have the option of a sibling match, and your transplant centre feels that it’s a suitable option, you could be given an MUD transplant. This is when your new stem cells come from a stranger whose tissue type matches your own.  


You can find out more about how we search for unrelated donors in one of the next sections.

Sibling transplants

Your siblings are the people most likely to be a match for you. This is because they have the same parents as you, so there’s a 25% chance of them having your tissue type. If you have any brothers or sisters, your hospital will test them before anyone else.


Having a sibling transplant can bring up lots of different emotions for everyone involved. Make sure you speak to your transplant team about any concerns you or your family have.


Our Donating to your relative page has more information for siblings and other relatives who are preparing to donate their own stem cells.

Finding a donor for your stem cell transplant

If you’re receiving stem cells donated from someone else – a relative, unrelated donor or cord blood – then doctors need to find a donor whose tissue type matches yours.


At SFS-MDR, we maintain a register of willing volunteers who are ready to donate their stem cells to someone in need of a transplant. We will search for a matching donor, perform the appropriate tests and co-ordinate the stem cells arriving at hospital. For more information on each step of the process, see the links below.

You – Unsurprisingly you will be tested first so that the search for your match can begin. Someone at your hospital or transplant centre will take a blood sample to do a tissue type test. The results will be passed on to us so that we can start searching.

Your siblings – If you have any, your brothers or sisters will be tested next. They have the best chance of being a perfect match for you because they share the same parents. Blood samples will be taken by their local doctor/hospital and sent for tissue typing.

Anyone else? – Usually your wider family and friends will not be tested as it’s very unlikely that they will be a match. If they want to help other people in need of a stem cell transplant, then they may be interested in joining the SFS-MDR.

Once your transplant centre gets in touch, we search all the possible donors in Macedonia to find your best match. If necessary, we will look for possible donors on registries from across the world. 

Shortlisting your donors – our search team will make a shortlist of potential matching donors and send it to your transplant centre within 24 hours. We’ll contact each donor and ensure they’re still available and able to donate. They will then give some blood samples. They will be sent to your transplant centre’s labs, where your blood samples will be tested side by side. We know it’s hard to wait but this process can sometimes take a few weeks.

Choosing your donor– the lab will test the samples to find the best match. After all the factors have been considered, such as your HLA tissue type and what’s best for treating your condition, your medical team will select your donor.

Arranging the donation– when your matched donor has been selected, we’ll get in touch and arrange for them to have further blood tests and a full medical to make sure they’re fit and healthy to donate.

Once they donate, we’ll arrange for the stem cells to get from your donor to you as fast as possible.

What are we looking for?

For a transplant to take place, you need to have a donor whose tissue type matches your own. Matching is based on your human leukocyte antigen (HLA) tissue type. Your HLA is part of what makes you ‘you’ – your individual genetic characteristics.
Your HLA type is made up of many genes, but when it comes to matching, we are most interested in six of them. Each one of these has two different versions (called alleles) making twelve in total. You inherit one version from your mother and one from your father. When it comes to matching you with a donor, if eleven of these genes match up it’s called an 11/12 match. If all twelve match then you’ve got yourself a 12/12 match. It’s important that your doctors find the best possible match because this will give your body the best possible chance of accepting your donor’s stem cells.
We test to see if you are positive for cytomegalovirus (or CMV for short) – a very common virus that often has no side effects. Ideally, we want to find a donor who tests the same for this virus as you do. There is now growing evidence that when a patient and donor have matched CMV status it helps improve transplant success.

Finally, we will consider the age of your donor too. This is because our research has confirmed that transplants are generally more successful when younger donors are selected

Patients are more likely to find a matching donor from someone with a similar ethnic background because our HLA tissue types are inherited – although it’s possible to be a donor for someone of any ethic background. SFS-MDR is hard at work, to encourage people form minority ethnic backgrounds to join their country’s stem cell registers. We are also promoting the use of alternative sources of stem cells and looking at ways to make them more accessible to everyone.
If you have an HLA tissue type that’s rare or less common, it may be harder to find a matching donor, because there may be fewer people with your tissue type.
If a suitable adult donor cannot be found, your transplant team will discuss possible alternatives with you.

Your transplant coordinator will be updated on the progress of the search regularly. If there are any difficulties, they’ll let you know. Depending on your condition, you may need additional treatment to help control your symptoms during this time.
While waiting for a transplant some patients, their friends or families decide they’d like to help raise awareness by encouraging people to sign up to the SFS-MDR.

Тhere are thousands of new potential donors added to registers around the world every day and your doctors and our search team will be focused on finding you the best possible match.

At SFS-MDR, we can’t accept requests to find a donor from individual patients or their families. If you live outside Macedonia, it’s still possible for us to search our registry but the request must come from your country’s own stem cell / bone marrow registry. Your hospital will be able to contact your country’s registry for you.  

We’re not a hospital and we can’t organise the transplants ourselves.