The Ins And Outs Of Stem Cell And Bone Marrow Transplantation

Introduction

What is stem cell transplant (bone marrow transplant)?

A stem cell transplant or bone marrow transplant is a procedure that replaces damaged or destroyed cells with healthy stem cells taken from bone marrow. Stem cells can be destroyed due to cancer treatment (radiation therapy and chemotherapy), or blood and autoimmune conditions. The transplant can be autologous, where you use your own stem cells, or it can be allogeneic, where you use stem cells from a donor).¹

What are stem cells and what is bone marrow?

Stem cells are special cells that are able to differentiate into other types of cells depending on our body's needs. Think of stem cells as a baby, they have not yet developed into a cell with a specific job, and so, they have the potential to become any cell depending on your body’s needs. They are found in all types of tissues and are essential for healing, maintenance and cell repair after injuries.  

Cancer, cancer treatment, and blood and autoimmune conditions can damage haematopoietic stem cells (stem cells that develop into all types of blood cells).  Haematopoietic stem cells are found in the bone marrow, the bloodstream and peripheral blood.²

Bone marrow is a spongy, soft tissue that fills our bone cavities. It contains hematopoietic stem cells that develop to form white blood cells, red blood cells, and platelets. Because bone marrow is rich in these stem cells, stem cell transplants are usually taken from your bone marrow, which is why the transplant procedure is named interchangeably.  

When haematopoietic stem cells are damaged, they fail to become blood cells, each of which has an important function: 

• Red blood cells: 
  • Carry oxygen from the lungs to the rest of the body
  • Carry carbon dioxide from the cells back to the lungs, where the exchange for oxygen occurs
• White blood cells:
  • Are an essential part of our immune system 
  • Are responsible for fighting bacteria, viruses, and any other pathogens that can threaten your health.
• Platelets:
  • Form clots to slow or prevent bleeding.

Conditions that may require a bone marrow transplant

Bone marrow transplants are carried out when the bone marrow is damaged and no longer able to produce healthy stem cells. Transplants are also carried out to replace destroyed hematopoietic stem cells as a result of intensive cancer treatments with high doses of chemotherapy and/or radiation.

The following blood conditions or cancers can be treated with stem cells transplants:

• Leukaemia
• Severe aplastic anemia
• Lymphoma, Hodgkin and non-Hodgkin lymphoma
• Multiple myeloma
• Certain blood and immune conditions such as sickle cell anemia, thalassemia, and Hurler syndrome

Types of bone marrow transplant

There are different types of bone marrow transplants but the main types are:³

• Autologous 
  • In cases where treatment is expected to damage the bone marrow, stem cells are collected and frozen before the treatment and given back to the patient after the treatment is complete. 
  • The term rescue is often used to describe this type of transplant.

• Allogeneic
  • Stem cells are collected from a genetically matched donor, usually a sibling. 
  • In some rare cases, a parent can be the donor, haploid match is when a parent is the donor and is at least 50% identical to the recipient. 
  • A genetically matched transplant from an unrelated donor can sometimes be the only option, the match can be found through the national bone marrow registries.

• Umbilical cord transplant 
  • Stem cells are taken from the umbilical cord after delivery. These stem cells are more effective than stem cells taken from another donor.
  • The stem cells are collected and frozen immediately after the baby is born to be used if a transplant is needed in the future.

How are stem cells from the donor and the recipient matched?

To determine if someone is a suitable donor for you, you and the donor will be tested for your HLAs (human leukocyte antigens). HLAs are sets of protein markers that are found on most cells of the body. Each person has a unique set of HLAs. The more sets of HLAs you and your donor have in common, the lesser the chances are for your body to reject the transplant.⁴

The process of a stem cell transplant

Whether you are receiving the stem cells from a donor or your own, there are 5 main stages to the complex transplant process, the stages are:⁵

1. Tests and examination

Before the transplant, your healthcare provider will run several tests to ensure you are in good health to endure the transplant. The tests could include an ECG to check your heart health, an echocardiogram to look at the heart and its blood vessels, a total blood count, blood tests, including liver and kidney function tests, and X-rays and CT scans to examine the condition of other organs like your lungs.

2. Harvesting stem cells 

The stem cells can be collected through a minor procedure to collect bone marrow from the hip bone. It could also be harvested from the blood of the umbilical cord of a newborn.

3.  Conditioning treatment 

You may need to receive radiation or chemotherapy sessions right before the transplant to destroy any existing ‘sick’ bone marrow and cancer cells, this also helps to prevent your immune system from rejecting the transplant. 

A central line will be placed to receive all the medications you need. Your healthcare provider will explain the possible temporary side effects of the conditioning medication like nausea, hair loss and fatigue. The conditioning phase takes about 2 weeks, and you will likely be hospitalised.

4. The transplant 

One or two days after the conditioning treatment, you will receive the transplant through the central line. The process usually takes several hours. It’s a painless procedure and doesn’t require any kind of anaesthesia or sedation.

5.   Recovery 

You will have to stay in the hospital for a few weeks for careful monitoring of your condition and to wait and see if the transplant is successful. 

You will be given fluid, blood and platelet transfusions as your blood and platelet counts will be relatively low until the stem cells renew. You will also be isolated in a germ-free environment to prevent infection because white blood cell count will be low too.

If the transplant was from a donor you will need to take immunosuppressants. Even after leaving the hospital, you can still be at risk of infection and your provider will supply you with instructions on how you can avoid that. Taking care of yourself, committing to a healthy diet, and taking all the time you need to recover are key to a pleasant healing process. 

Follow-ups are crucial after transplants to ensure your body is adapting well, and to spot any alarming signs early.

Complications of stem cell transplant

It is necessary to know all the possible complications before starting the transplant process and should be weighed against the benefits. The complications are reduced when you receive the stem cells from a family member or use your own cells.

Complications mostly happen after allogeneic transplants, and they include:

• Infections
• Graft versus host disease (GvHD): 
  • A disorder that occurs when your immune cells recognise the recipient’s cells as foreign and start attacking them. 
  • Symptoms include nausea, rash, dry skin, dry mouth, dry eyes, shortness of breath and joint pain.⁶

Inform your treatment team about any complications or signs of GvHD, medications can be given to suppress your immune system and stop it from attacking the new cells.

FAQs

Who is a good candidate for a bone marrow transplant?

A full assessment will be done to determine if you are a good candidate. Your general health and your body’s ability to manage the side effects are very important. It also depends on your blood condition because not all blood diseases can be treated with bone marrow transplantation. The type of treatment you received for your condition can also affect the success of the transplant. Finally, if you can’t use your own stem cells, then the availability of a perfect match is an essential step before starting the process.

How do you know if the stem cell transplant has worked?

Your blood cells count will go up after the stem cells are given the time to renew and differentiate inside your body. If you have cancer, the main reason for a stem cell transplant is to cure or control your cancer, and that is another way of knowing if your transplant was successful.

Summary

• Stem cell transplant, is a procedure used to treat various blood conditions, including certain types of cancer, blood disorders, and autoimmune diseases. 
• It involves the transplantation of healthy stem cells to replace damaged or diseased cells in the body. 
• These stem cells can be obtained from the bone marrow, peripheral blood, or umbilical cord blood, they can come from a donor or from the patient themselves. 
• The process involves several stages, including harvesting the stem cells from the donor, conditioning the patient's body to accept the new cells, and then infusing the stem cells into the patient's bloodstream. 
• Once transplanted, the stem cells can migrate to the bone marrow and begin producing new, healthy blood cells. 
• While stem cell transplant can be a life-saving treatment for many patients, it also carries risks, such as infections, and graft-versus-host disease, and complications related to the conditioning phase of the transplant. 
• Therefore, careful patient selection and close monitoring are essential to ensure the best possible outcomes.

You can visit The NHS blood and transplant and Anthony Nolan website to see all the information you may need about stem cells and bone marrow transplant.