Donor stem cells
Allogeneic Stem Cell Transplant
An allogeneic stem cell transplant is a form of HSCT where healthy blood-forming stem cells are collected from another person. The donor can be a matched sibling, any other family member, volunteer, or in some cases donated umbilical cord blood. It is important to note that in contrast to the autologous transplant where a patient's own cells are transplanted, in the case of the allogeneic procedure, the cells transplanted are new and healthy cells capable of re-creating the bone marrow and the immune system.
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A donor-to-patient pathway
An allogeneic stem cell transplant is a form of HSCT where healthy blood-forming stem cells are collected from another person. The donor can be a matched sibling, any other family member, volunteer, or in some cases donated umbilical cord blood. It is important to note that in contrast to the autologous transplant where a patient's own cells are transplanted, in the case of the allogeneic procedure, the cells transplanted are new and healthy cells capable of re-creating the bone marrow and the immune system.
Allogeneic stem cell transplant is a tried and tested way of treatment for specific forms of blood cancer, bone marrow failure syndromes, genetic disorders of the blood, and autoimmune diseases. For most patients, it is possible to replace the unhealthy bone marrow with normal donor cells and make use of the donor's immune system to get rid of any residual abnormal cells, which is called GVT or GVL effect.
For allogeneic stem cell transplants to be carried out in Malaysia, they should be conducted in designated hematological and transplant centers, whereby the patients will be evaluated in terms of the following stages: donor matching, conditioning, transplantation, and follow-up. Donor compatibility is an important aspect that must be matched in the treatment procedure for a successful outcome.
01 · Who may need it
Who May Need an Allogeneic Stem Cell Transplant?
A stem cell transplantation from another person is indicated in cases where the disease can only be successfully controlled using donor stem cells or the replacement of the bone marrow and immune system is seen as the best hope for disease management. This is because it involves use of donor stem cells hence this therapy is not used where the risk is high.
In Malaysia, patients are thoroughly assessed by haematologists and transplant specialists before recommending an allogeneic transplant to patients. This evaluation takes into consideration the patient’s diagnosis, condition and responses to other treatment methods among other factors.
Conditions Commonly Treated with Allogeneic Transplantation
An allogeneic stem cell transplant may be considered for selected patients with:
- Acute leukaemia.
- Chronic leukaemia.
- Myelodysplastic syndromes (MDS).
- Aplastic anaemia.
- Thalassaemia major.
- Certain inherited bone marrow disorders.
- Selected congenital or acquired immune deficiencies.
Conditions to discuss with a transplant specialist
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02 · Donor selection to recovery
How an Allogeneic Stem Cell Transplant Is Performed
The first step is to identify a proper donor via HLA compatibility testing. After a compatible donor is identified, stem cells are collected from:
Allogeneic stem cell transplantation is a well-coordinated process which involves replacement of the sick blood-forming stem cells with healthy ones from another person. The transplant occurs at specialised haematology and transplant centers in Malaysia, whereby the patients receive services from multidisciplinary teams at all levels of their treatment process.
Step 1: Donor Selection and Stem Cell Harvesting
The first step is to identify a proper donor via HLA compatibility testing. After a compatible donor is identified, stem cells are collected from:
- Peripheral blood (most common route).
- Bone marrow.
- Umbilical cord blood in certain instances.
Step 2: Conditioning Therapy
Conditioning is done prior to receiving donor stem cells and consists of chemotherapy at a high dose, sometimes followed by radiation therapy. This process assists in killing unhealthy cells in the bone marrow, weakening the patient’s immune system so as to prevent rejection of donor cells, and preparing the bone marrow for donor cells.
Step 3: Donor Stem Cell Infusion
Once the process of conditioning therapy is over, then the donor’s stem cells are given back to the patient through an intravenous line. The procedure of giving donor’s stem cells resembles blood transfusion in many ways and is non-surgical. Upon infusing donor’s stem cells into the patient, the latter finds their way to bone marrow of the patient's body where they start forming blood cells.
Step 4: Engraftment and Recovery
At this point when the stem cell transplantation takes place, the patients are carefully watched by the doctors since the donated stem cells start settling into the patient’s bone marrow. This process whereby the donor’s stem cells settle in the bone marrow is known as engraftment.
03 · Benefits and immune risks
Benefits and Risks of an Allogeneic Stem Cell Transplant
Allogeneic stem cell transplant can be considered as one of the methods of treatment of some forms of blood cancer, bone marrow diseases, congenital blood disorders, and disorders of the immune system. The procedure of replacing unhealthy bone marrow with healthy donor cells creates normal blood production and a new immune system in patients. The use of donor cells in the procedure involves some risks that require medical assistance.
Potential Benefits
- Replace diseased or damaged bone marrow with healthy donor stem cells.
- Restore normal production of red blood cells, white blood cells, and platelets.
- Rebuild the immune system in selected inherited or acquired immune disorders.
- Provide long-term disease control or potential cure for certain blood cancers.
- Produce a graft-versus-leukaemia (GVL) or graft-versus-tumour (GVT) effect, where donor immune cells help eliminate remaining abnormal cells.
Potential Risks
- Infection while the immune system is recovering.
- Bleeding caused by low blood cell counts.
- Side effects related to conditioning chemotherapy or radiotherapy.
- Delayed or unsuccessful engraftment.
- Graft-versus-host disease (GVHD), where donor immune cells attack healthy tissues.
Conclusion
Allogenic stem cell transplant is one of the proven treatment options available to a selected few patients suffering from blood cancer, bone marrow failure syndrome, inherited blood diseases, and some immune disorders. With the help of healthy stem cells from a compatible donor, the process enables the restoration of bone marrow function, immune system regeneration, and even a cure or control over the disease for the right patients.
In Malaysia, allogeneic stem cell transplantation is conducted through specialized transplant centres that have specialized teams handling all the procedures right from patient selection, donor selection, conditioning, transplant, and recovery stages. This being an advanced medical procedure, patient and donor selection as well as proper monitoring are necessary for the best results.
Allogeneic transplant questions
Frequently Asked Questions
Allogeneic stem cell transplantation is a medical process involving the use of healthy hematopoietic stem cells collected from a compatible donor to replace sick or malfunctioning bone marrow.
This could involve a matching sibling, another compatible family member, an unrelated voluntary donor found through donor registries, or in some cases, a unit of umbilical cord blood.
This procedure is often used for selected patients suffering from acute and chronic leukemia, aplastic anemia, myelodysplasia, thalassemia, congenital bone marrow disorders, and selected immune system disorders.
Yes. Selected specialized hospitals in Malaysia perform allogeneic stem cell transplantation based on internationally accepted protocols.
GVHD is one of the complications where the immune cells from the donor body recognize the recipient tissues as foreign and initiate an attack on them. Medical practitioners watch the patients very carefully in order to identify the problem and treat it at an early stage.
Every individual will have a different recovery process. Blood recovery starts in about a couple of weeks while immunity recovery takes several months or even more.
Allogeneic transplant
Donor selection shapes the entire treatment pathway.
HLA matching, conditioning, graft-versus-host prevention, and long-term monitoring require specialist care.
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