Sickle Cell Anaemia Bone Marrow Transplant

A bone marrow transplant is the only established cure for sickle cell anaemia, and India offers it at a much lower cost than the West. Dr. Vikas Dua, Principal Director & Head - Pediatric Hematology, Hemato Oncology & Bone Marrow Transplant, Fortis Memorial Research Institute, Gurgaon, India, puts the chance of cure at 90 to 95% with a fully matched sibling donor and 85 to 90% with a half-matched parent.

This guide is for families and referring doctors, particularly in Africa, considering a sickle cell anaemia bone marrow transplant in India. It sets out who needs one, where the procedure sits among the other blood disorders it treats, how the stem cells are collected and handled, and what to expect in cost and length of stay. Two deeper articles, linked in the sections below, cover finding a bone marrow donor for patients from Africa and cure rates by donor type, age and conditioning regimen.

Why bone marrow transplant is the only cure for sickle cell anaemia

Bone marrow transplant is the only established cure because it replaces the marrow that produces sickle cells; every other treatment controls the disease without removing it. Sickle cell anaemia is a haemoglobinopathy: an inherited disorder of haemoglobin, the oxygen-carrying protein in red blood cells. The abnormal haemoglobin makes red cells rigid and sickle-shaped, so they break down early (haemolysis) and block small blood vessels. Dr. Dua summarised the consequences as pain crises, haemolysis and damage to multiple organs. Left untreated, the disease causes lifelong illness and can be fatal.

Practically any part of the body can be involved. The complications he listed include:

• Pain crises, the recurring episodes of severe pain that define the disease for most families
• Stroke, caused by sickled cells blocking blood flow to the brain
• Acute chest syndrome, a lung complication that can become life-threatening within hours
• Damage to the eyes, kidneys and bones, which accumulates over years

Care has improved considerably. Penicillin prophylaxis, vaccination, hydroxyurea (a daily oral medicine that raises fetal haemoglobin and reduces sickling) and exchange transfusion have all reduced complications. Dr. Dua's point is that none of these is a permanent solution: they help control the disease but do not remove it. A haematopoietic stem cell transplant replaces the patient's blood-forming system with a donor's, so the marrow stops producing sickle cells altogether.

Gene therapy is the other potentially curative route. The first gene therapies for sickle cell disease were approved in the UK and the US in late 2023, but access remains very limited and they are available in only a handful of centres worldwide. For most patients, an allogeneic stem cell transplant from a family donor remains the curative option that can actually be delivered.

Sickle cell anaemia in Africa: the scale of the problem

Sickle cell disease is the most common haemoglobinopathy across Africa, and Nigeria carries the largest burden of any country. India's dominant haemoglobinopathy is different: as Dr. Dua put it, if Nigeria is the sickle cell capital of the world, India is the thalassaemia capital.

Several hundred thousand babies are born with sickle cell disease every year. Dr. Dua noted that about 75% of them are born in sub-Saharan Africa, and that the number is rising each year. Global projections show the annual number of affected births continuing to grow towards 2050, driven largely by population growth in the most affected regions.

The inheritance pattern explains why the disease clusters in families and communities. Sickle cell anaemia is autosomal recessive: a child is affected only if both parents pass on the sickle gene. Each parent who carries one copy (sickle cell trait, written "AS") is usually healthy. When two carriers have children, each pregnancy carries a 25% chance of a child with sickle cell anaemia ("SS"). Many children in Africa have lived with the disease since birth.

Who needs a bone marrow transplant for sickle cell anaemia

Dr. Dua's criteria for referral are clear. A patient is a transplant candidate if he or she has:

1. A history of stroke
2. A history of acute chest syndrome
3. Frequent pain crises
4. Any other sickle cell complication that continues despite medicines such as hydroxyurea

Timing is the decision families find hardest, and he is direct about it. Every treatment has pros and cons, and transplant carries real risks. But a patient who is not offered a transplant will keep suffering, and organ damage accumulates until a point where even a transplant becomes too risky to perform. "Sooner the better" is the advice his team gives every family: transplant early in life.

There is no strict upper age limit. His centre has transplanted adults, and the oldest sickle cell patient transplanted there was 34 years old at the time and doing well. The results are measurably better in children, however, as the cure-rate figures below show.

Bone marrow transplant in other haematological disorders

Beyond sickle cell anaemia, bone marrow transplant treats a wide range of malignant and non-malignant blood disorders. Two basic types of transplant exist:

• Autologous transplant: the patient is his or her own donor. Stem cells are collected, stored and returned after high-dose chemotherapy.
• Allogeneic transplant: the stem cells come from a donor. This is the type used in sickle cell anaemia and thalassaemia, because the goal is to replace the patient's own defective marrow.

Dr. Dua divides the indications into two groups.

Malignant (cancerous) indications include blood cancers, myelodysplastic syndromes, lymphomas, brain tumours and neuroblastoma.

Non-malignant indications include aplastic anaemia, inherited bone marrow failure syndromes, immunodeficiencies, sickle cell anaemia, thalassaemia and metabolic disorders.

The field has a long record. The first successful transplant for leukaemia was performed in 1969, and E. Donnall Thomas, who pioneered it, received the Nobel Prize in 1990 for his work on transplantation. The first successful transplant for thalassaemia followed in 1981. Data from the US national donor registry show transplant numbers rising year by year, with alternative-donor and cord blood transplants also increasing.

Transplant is not a universal answer, and Dr. Dua was equally clear on its limits. Asked by doctors on the session, he said there is no role for bone marrow transplant in prostate cancer, and no research supporting it. Nor is there a current indication in cerebral palsy: research is ongoing into whether transplant helps, but there is no clear answer yet.

How successful is a bone marrow transplant for sickle cell anaemia?

The numbers that matter most to families are straightforward. With a fully matched sibling donor, Dr. Dua puts the chance of cure at 90 to 95%, in line with results reported from centres in the US, Belgium and France. With a half-matched (haploidentical) parent as donor, the chance of cure is 85 to 90%. Transplant before the age of 16 gives outcomes of around 95%, against around 80% after 16. These figures, the evidence behind them and the role of the conditioning regimen are covered in sickle cell transplant cure rates by donor, age and regimen.

Finding a donor for patients from Africa

The first step is HLA typing of the patient and siblings: a blood test that compares the tissue-type markers the immune system uses to recognise its own cells. Dr. Dua estimates a 25 to 30% chance that a sibling is a complete match. For patients from Africa, the next option most of the world relies on, an unrelated donor from a registry, is largely closed, because African populations are under-represented in the world's donor registries. The practical answer is a half-matched transplant from the father or mother. The full donor pathway, including cord blood, is set out in bone marrow donors for sickle cell patients from Africa.

How a bone marrow transplant for sickle cell anaemia is carried out

Stem cells can be collected from three sources: the bone marrow, the peripheral blood, or the umbilical cord blood at birth. Whatever the source, they are collected into sterile bags for infusion. For a peripheral blood collection, the donor sits in the blood bank while a machine separates out the stem cells. Dr. Dua stresses that the procedure is safe for the donor: the growth-factor injections given beforehand commonly cause temporary bone aches, but serious complications are rare. That matters when a parent is weighing whether to donate.

Two laboratory steps follow. The team checks that a sufficient stem cell dose has been collected, which his centre does in-house. If the cells are to be used later, they can be cryopreserved (frozen) in the hospital.

Before the infusion, the patient receives conditioning chemotherapy to clear the existing marrow and suppress the immune system so the donor cells can engraft. Chemotherapy is prepared in a biosafety cabinet, and patients stay in positive-pressure rooms, where filtered air flows outwards to keep infection out during the weeks when immunity is lowest. After the transplant, most patients stop all immunosuppressive medicines at about one year.

Sickle cell anaemia bone marrow transplant in India: cost and length of stay

Dr. Dua gave the figures in answer to a doctor from DR Congo. At the time of the session, a matched sibling donor transplant cost roughly US$25,000 and a half-matched transplant around US$35,000. Accommodation and other logistics add about US$10,000, so a family should plan for roughly US$35,000 in total for a full-match transplant and US$45,000 for a half-match. The stay is about three months.

Because a parent is the likely donor when no sibling matches, Dr. Dua advises that parents travel with the patient. The cost of transplant is much lower than in the West, which is why India has become a destination for patients from many parts of the world. For current treatment-cost ranges, see the pages on matched sibling donor bone marrow transplant and haploidentical (half-match) bone marrow transplant.

The transplant programme at Fortis Memorial Research Institute

Dr. Dua's centre had performed more than 1,800 transplants at the time of the session, including more than 150 for sickle cell anaemia. It marked its thousandth transplant about three years earlier. The unit then had 20 beds, with 18 more planned for the following year to bring it to 38. The clinical team includes six paediatric haematologists and six adult haematologists, and the centre performs high-resolution HLA typing in-house.

His experience with patients from Africa goes back about a decade, and for him the measure of the work is personal: as a paediatric haematologist, the drawings his young patients make for him are, in his words, the most rewarding thing for his team.

The questions doctors raised during the session, from cord blood to immunosuppression, are answered in full on the Live Discussion page. More on Dr. Dua's practice is on his doctor profile, and related series are collected under haematology.