What to Expect from Allogeneic Stem Cell Transplantation

Transplanted stem cells can help cure some diseases

Allogeneic stem cell transplantation is a procedure in which stem cells are transplanted from a donor to a recipient. This procedure is a curative treatment for certain blood cell cancers, blood disorders, and immune diseases.

Stem cells are cells that are considered immature, or still developing into specific cell types. They are present in the bone marrow and blood of people of all ages and the umbilical cord of a newborn baby. The cells are transplanted to the recipient intravenously (IV, through a vein). 

What to Know About Allogenic Stem Cell Transplantation - Illustration by Adriana Sanchez

Verywell / Adriana Sanchez

Before receiving the transplanted cells from a donor, the recipient has a pretreatment phase with chemotherapy and/or radiation therapy to destroy their own disease-causing bone marrow cells. The transplanted allogeneic stem cells are then expected to engraft (grow and make healthy cells) into the recipient's bone marrow so the new cells can produce healthy cells.

This type of transplant can cause complications, such as transplant rejection (the recipient rejects the transplant) or graft-vs.-host disease (GvHD, the transplanted immune cells attack the recipient's body).

The risk of these complications can be reduced by finding a closely matched donor. Some complications can be treated with medication.

This article will discuss allogeneic stem cell transplant indications, donor selection, the procedure, and recovery.

Reasons for Allogeneic Stem Cell Transplantation

This procedure is a treatment option for blood cancers and blood diseases that occur when there is a defect in the cells that are produced in the bone marrow. These cells include red blood cells (cells carrying oxygen to provide energy for the body) and white blood cells (immune cells that protect from infection and cancer).

Less commonly, allogenic stem cell transplantation is used to treat autoimmune disorders, in which the body’s immune system attacks the body itself.

Conditions that are sometimes treated with allogeneic stem cell transplantation include:

Sometimes these conditions are effectively treated with medication, and sometimes a stem cell transplant is considered a better option.

Who Is Not a Good Candidate?

You and your doctor will need to discuss your treatment options if you have a blood disease that can be treated with allogenic stem cell transplantation.

The right decision for you depends on factors such as the severity of your condition, other medical issues you might have, and the expected improvement in your quality of life and survival if you have a transplant.

Some issues that may be contraindications for (reasons not to undergo) this procedure include:

  • Your doctors would have to postpone the procedure if you have an active infection.
  • The procedure can make you sick if you have severe heart, lung, kidney, or liver disease.
  • Your condition does not respond to the pretreatment regimen.
  • Treatment of some conditions is guided by age-associated criteria, and you or your child might not qualify based on age.

Overall, it’s important to remember that allogeneic stem cell transplantation is one of many treatment options, and the pros and cons are considered in comparison to the other options.

Types of Allogeneic Stem Cell Transplantation

Allogeneic stem cell transplantation is a transplant that uses stem cells from a donor. There is another type of hematopoietic stem cell transplant, which is autologous stem cell transplantation. Autologous stem cell transplantation is a transplant that uses your own cells to replace your bone marrow cells.

There are advantages and disadvantages to each type, including:

  • Allogeneic stem cell transplantation: You need to find a match, and there is a risk of transplant rejection or graft-vs.-host disease. A strong benefit is that the donor cells are highly unlikely to carry the disease that you are being treated for.
  • Autologous stem cell transplantation: It is not necessary to find a match, and transplant rejection is not a risk. This type of transplant might not be curative if your transplanted cells carry the disorder that you are being treated for.

Donor-Recipient Selection Process 

Compatibility between the donor and recipient is a major factor in the donor selection process for allogenic stem cell transplantation.

One way to determine recipient and donor compatibility is with human leukocyte antigen (HLA) markers. These are markers on your cells that allow your body to recognize itself, so your immune system won’t attack your own body.

When your doctors are selecting a donor for you, they will try to find a donor with a matching HLA type to reduce the risk of transplant rejection and GvHD. 

Types of Donors

There are a few types of donors for allogeneic stem cell transplantation. You and your doctor will have to discuss the best type of donor for you.

Donors can include:

  • Related donor: A close relative who is an HLA match might be able to donate stem cells through a blood sample or a bone marrow sample. Your family members would have their blood tested to see if they are a close match. Identical twin siblings are often a strong match, but there is a chance they could also have the disorder you are being treated for.
  • Unrelated donor: An unrelated donor may be a strong HLA match, and your doctor will have resources for finding unrelated donors. 
  • Umbilical cord cells: These are cells that are collected after birth from the cord attaching the fetus to the placenta, from which the fetus gets oxygen and nutrients. Umbilical cords are stored and preserved. You might have a family member who has preserved umbilical stem cells that are a close match for you, or you could receive umbilical stem cells from an unrelated match.  


If you are having a transplant from a donor, they will need to donate their stem cells. Your donor will need to provide either a blood sample or a bone marrow sample.

This is safe, but the process of providing a bone marrow sample can be physically uncomfortable or painful. The donor should be able to produce their own stem cells to compensate for those they have donated to you.

Before the Transplant

If you and your doctor have decided to proceed with allogeneic stem cell transplantation, you will need preliminary tests and preparation before your procedure.

Before the transplant, you will need:

  • Tests to determine your own HLA markers so that you can be matched with a donor
  • Testing to determine whether you can tolerate treatment, which includes complete blood count (CBC), liver function blood tests, electrolyte blood tests, chest X-ray, and electrocardiogram (ECG or EKG) 
  • Pretreatment with medication and/or radiation

Myeloablation is pretreatment that destroys the disease-causing cells in your bone marrow to prepare you for the transplanted cells. Myeloablation can make your immune system very weak, which makes you susceptible to infections. You will be advised to avoid situations that could expose you to infections. 

In some situations, the pretreatment is only partially myeloablative or non-myeloablative.

Transplant Process 

Your transplant procedure is an infusion into a vein. You will have a central line, which is a large intravenous catheter, surgically placed in your chest. This may be done on the day of your transplant infusion or several days beforehand.

When you go for your procedure, your medical team will check your temperature, oxygen saturation, blood pressure, respiratory rate, and heart rate. The cells will be infused over the course of several hours, and your medical team will check on you during this time.

You can stay awake during your infusion, or you can rest. If you experience any discomfort, be sure to tell your medical team as soon as possible.


During and shortly after the infusion, you can experience some side effects, including:

  • Dizziness 
  • Shortness of breath
  • Fever, chills
  • A rash
  • Weakness
  • Tiredness
  • Chest tightness

These issues should resolve, but you should tell your medical team in case you need treatment.

After Transplant

After your procedure, you are expected to have a recovery time that can take several months. You can be susceptible to infections during this recovery time, so your doctor will advise you to avoid exposure to infections. This can include staying away from crowds, avoiding anyone who has a cold, and not eating certain foods.

Some specific issues that your doctor will monitor you for include:

  • Acute graft-vs.-host disease: Within 100 days of the transplant, the transplanted immune cells can attack your body tissues, causing a rash, fevers, and potentially organ failure.
  • Rejection: In some cases, the transplant is rejected or does not engraft. If this happens, you might need another transplant or a different treatment approach for your condition.
  • Chronic graft-vs.-host disease: Chronic GvHD can occur after 100 days of the transplant and can include symptoms of fatigue, difficulty concentrating, and potentially may affect your organ function.
  • Recurrence: There is a risk of disease recurrence after allogeneic stem cell transplant. Depending on your initial condition, your doctor will tell you the warning signs of recurrence and will also monitor you for signs of recurrence.


Generally, an allogeneic stem cell transplant has a good outcome. You can expect to have a recovery period, but the procedure is intended to be curative.

The prognosis and the risk and incidence of complications depend on many factors, including the condition being treated and how closely the donor and recipient match.

Support and Coping

Having a transplant is not an easy process. The physical aspects can be demanding on your body, and the emotional and psychological aspects can be difficult as well. It's important that you know that you are not alone and that there are resources you can reach out to for support.

Talk to your doctor about seeking counseling, support groups, and practical help at home. You might need to get special accommodations if you want to continue to go to work or school. Most importantly, be kind to yourself and give yourself a break and the self-care you need for your physical, emotional, and psychological well-being.


In an allogeneic stem cell transplant, a donor contributes stem cells from their blood, bone marrow, or umbilical cord blood to treat the recipient for conditions such as certain blood cell cancers, blood disorders, and immune diseases.

The donor must be of matching HLA type to the recipient and may be related or unrelated. The recipient undergoes pretreatment with chemotherapy and/or radiation to eliminate their immune cells and stem cells.

The donor cells are transplanted to the recipient intravenously. They then migrate to the bone marrow and can produce a new line of healthy cells.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.