Allogeneic Stem-Cell Transplant
An allogeneic stem-cell transplant replaces diseased bone marrow with blood-forming stem cells from a matched donor — a sibling, an unrelated donor, or in some cases a half-matched relative. After conditioning chemotherapy, the donor cells are infused to build a new immune system that can also help fight residual cancer.
Medically reviewed by the Florence Healthcare medical team · Last reviewed June 2026
Overview
An allogeneic stem-cell transplant — also called an allogeneic bone marrow transplant — uses blood-forming stem cells donated by another person to replace bone marrow that is diseased or has been affected by cancer. The donor is chosen through HLA tissue-typing, which compares specific markers on your cells with the donor's to find the closest possible match; the better the match, the lower the risk of complications. The donor may be a matched sibling, a matched unrelated donor from an international registry, or in some cases a half-matched (haploidentical) family member. Because the new immune system comes from someone else, donor immune cells can recognise and attack any remaining cancer — an effect known as graft-versus-tumour — but the same cells can also react against your healthy tissues, called graft-versus-host disease, which the team works to prevent and manage.
For international patients, a dedicated coordinator manages the entire journey — donor-search logistics, scheduling, travel, accommodation and interpretation — as a single point of contact. Before you travel, our haematology team can review your medical records, pathology and prior treatment remotely and provide a second opinion on whether transplant is appropriate and what type of donor may be suitable. You receive a transparent, itemised cost estimate covering the work-up, donor search, conditioning, the transplant admission and the expected period of monitoring, so there are no surprises after arrival.
Who is a candidate?
- You have a blood cancer such as acute or chronic leukaemia (AML, ALL, CML) that is best treated by replacing the bone marrow
- You have myelodysplastic syndrome, severe aplastic anaemia, or an inherited blood disorder such as thalassaemia or sickle-cell disease
- A suitable donor can be identified through HLA typing — a matched sibling, a matched unrelated donor, or a half-matched relative where appropriate
- Your heart, lungs, liver and kidneys are healthy enough to tolerate conditioning chemotherapy
- Earlier treatments have not produced a lasting remission, or your condition carries a high risk of relapse without transplant
- You and your family understand the intensive nature of the procedure and can commit to a prolonged stay and follow-up
What happens
- 1
Evaluation & donor matching
You undergo detailed testing of your disease and organ function, and HLA tissue-typing is performed on you and potential donors. Siblings are tested first; if none match, an international registry search or a half-matched family donor is considered where suitable.
- 2
Conditioning
Over several days you receive conditioning chemotherapy, sometimes with radiotherapy, to clear diseased marrow and suppress your immune system so the donor cells can take hold. The intensity is tailored to your diagnosis, age and fitness.
- 3
Stem-cell infusion
On transplant day the donor stem cells are given through a central line, much like a blood transfusion. The infusion itself is painless and requires no anaesthesia; the cells travel to the bone marrow and begin to settle in.
- 4
Engraftment & immune recovery
You stay in protective isolation for several weeks while the new marrow starts producing blood cells. Blood counts are monitored closely, and medication is given to prevent infection and graft-versus-host disease as your immune system gradually rebuilds over the following months.
Benefits
- Offers a potential cure for leukaemias, myelodysplastic syndrome and certain inherited blood disorders
- Donor immune cells can attack residual cancer through the graft-versus-tumour effect, lowering relapse risk
- Provides an entirely new, healthy blood and immune system rather than only suppressing disease
- Can replace defective marrow in non-cancer conditions such as thalassaemia, sickle-cell disease and aplastic anaemia
- Drawing on matched unrelated and haploidentical donors widens the chance of finding a suitable match
- Lifelong follow-up can be coordinated remotely after you return home
Risks & considerations
- Allogeneic transplant is an intensive, high-risk treatment: despite every precaution, severe graft-versus-host disease, serious infection during the period of low immunity, or the effects of conditioning can make a patient seriously unwell, and there is a real risk to life from the treatment itself — your team weighs this carefully against the benefit for your condition
- Graft-versus-host disease, where donor immune cells react against your own tissues such as the skin, gut and liver — prevented and treated with immunosuppressive medication
- A prolonged period when blood counts are very low, raising the risk of serious infection and bleeding
- Side effects of conditioning chemotherapy or radiotherapy, including fatigue, mouth sores, nausea and possible effects on fertility
- Risk that the donor cells fail to engraft, or that the original disease returns
- Need for prolonged protective isolation and, for a time, immunosuppressive drugs that increase infection risk
Conditions this treats
Where it is performed
This procedure is performed by our Comprehensive Transplant Center.
Learn more before you decide
Provider-reviewed guides on the related conditions, symptoms and tests in our Health Library.
Allogeneic Stem-Cell Transplant — frequently asked questions
Matching is based on HLA tissue-typing, a blood test that compares immune markers between you and a potential donor. Siblings are tested first because they are most likely to match. If no relative is suitable, an international donor registry is searched for a matched unrelated donor, and in some cases a half-matched (haploidentical) family member can be used where appropriate. Your coordinator keeps you informed at each stage of the search.
Graft-versus-host disease (GVHD) happens when the donor's immune cells recognise your body as foreign and react against tissues such as the skin, gut or liver. It can be mild or more serious and may appear early or months later. Most graft-versus-host disease can be controlled, but in its severe forms it can be life-threatening, which is why prevention, close monitoring and early treatment matter so much. The team reduces the risk by choosing the closest possible match and giving immunosuppressive medication around the transplant, and treats any GVHD that develops with additional medicines while monitoring you closely.
Cost and length of stay depend on your diagnosis, the type of donor and how your recovery progresses, so we do not quote a fixed figure in advance. After our team reviews your records, you receive a transparent, itemised estimate covering the work-up, donor search, conditioning, the transplant admission and the expected monitoring period, together with an indicative timeline for your stay in Istanbul.
Yes. You can send your medical records, pathology reports and details of previous treatment, and our haematology team will review them and provide a remote second opinion on whether an allogeneic transplant is appropriate, what type of donor may be suitable and what the next steps would be — all before you make any decision to travel.
Related treatments
Considering allogeneic stem-cell transplant?
Share your reports for a medical second opinion and a transparent, itemized cost estimate — usually within 48 hours.