Sickle Cell Bone Marrow Transplant Process

The sickle cell bone marrow transplant process replaces a patient's sickle-producing marrow with healthy stem cells from a matched or half-matched donor. It runs in stages: HLA typing and donor selection, one to two days of pre-transplant evaluation, about seven days of conditioning chemotherapy, a stem cell infusion, 12 to 14 days for the new marrow to engraft, roughly 100 days of close follow-up and about a year on medication.

Dr. Arun Singh Danewa, Senior Consultant – Pediatric-Haemato-Oncology & Bone Marrow Transplant (Unit II), Artemis Hospitals, Gurugram, India, has spent more than ten years treating children with cancer and benign blood disorders, including sickle cell disease, thalassaemia and aplastic anaemia. He titled his September 2026 masterclass "Crushing the Crises: A Sickle Cell BMT Review" and delivered it during Sickle Cell Awareness Month to Jivo Healthcare's partner doctors, many of them in Africa. His central argument was simple: transplant is highly effective, still underused, and works best before the disease has damaged the organs.

This guide follows the transplant from the first blood test to the one-year review. Three companion articles go deeper: whether sickle cell disease is curable, and how supportive care compares with cure, HLA matching, donor safety, conditioning and fertility, and engraftment, chimerism and what "cured" means after transplant.

Why sickle cell disease is a case for cure, not only control

Sickle cell disease is a chronic, disabling condition that can damage every organ from the brain to the bones, not simply an anaemia. A single genetic change makes red cells stiff and sticky; they clog small blood vessels, and each blocked vessel starves an organ of blood. Over a lifetime these episodes accumulate into stroke, lung injury, a spleen that no longer works, kidney failure and collapse of the hip joint.

Treatment therefore runs on two tracks. The first is lifelong supportive care: vaccines, antibiotics, pain control, transfusion and disease-modifying drugs such as hydroxyurea and L-glutamine. These relieve symptoms but do not stop the sickling. The second track is curative, and Dr. Danewa was clear that only two treatments belong on it: bone marrow transplant, also called haematopoietic stem cell transplant (HSCT), and gene therapy. The case for choosing cure where it is available is set out in the companion article on supportive care versus cure.

The idea that a transplant could cure sickle cell disease emerged by accident. In 1983, doctors at St. Jude Children's Research Hospital in the United States transplanted a girl for acute myeloid leukaemia. She also had sickle cell disease, and the transplant cured both conditions. That case showed that replacing the bone marrow removes the source of sickle haemoglobin.

The right age for a sickle cell transplant

The best age for a sickle cell transplant is early childhood, before repeated sickling has damaged the organs. Dr. Danewa summarised it in one line he repeated to the audience: the earlier the transplant, the better the outcome.

• From one year of age, a transplant can be done at any time, and one year is the minimum cited in the literature.
• Between two and five years is his preferred window. Infants can be transplanted (his team has transplanted children with leukaemia at six months to a year when there is no alternative), but an older toddler's organs handle the immunosuppression and the drugs better. A small child's inability to describe symptoms is not, in his view, a reason to wait.
• From about 14 or 15 years, the chances of success fall because the organs are already affected, and complications rise with both full-match and half-match donors. He usually discourages transplant after about 18 or 19.

Early transplant also costs less. A smaller child needs smaller drug doses and has fewer complications, so the financial burden on the family falls along with the clinical risk.

Age is a proxy for organ damage

Age matters only because it tracks organ damage. Dr. Danewa agreed that the deciding question is how much harm the disease has already done: if the organs are working well and a very good donor is available, such as a fully matched sibling, he is willing to transplant adults, has done so before, and is preparing one or two patients around 30 who have fully matched donors. He remains more hesitant about half-match transplants in older patients, where complication rates are higher.

The pre-transplant work-up decides the question. He described a woman in her thirties who came for a matched sibling transplant and was found during evaluation to have one kidney already destroyed by sickling, with reduced function in the other. She came through the transplant and is doing well, but he was candid that such outcomes cannot be counted on, and that the risks must be laid out in writing before consent.

The sickle cell bone marrow transplant process, step by step

A sickle cell transplant follows the same sequence whichever donor is used. The hospital phase usually lasts about three weeks and rarely extends to four.

1. Find the donor

The first test is a high-resolution HLA (human leukocyte antigen) test, which maps the tissue type that donor and patient must share. A full match with a brother or sister is best; an unrelated volunteer from an international registry is next; and almost everyone has a half-match donor in a parent. A sibling who carries the sickle cell trait can still donate. The matching rules, the donor-specific antibody test and what donation involves for the donor are explained in the article on HLA matching and conditioning.

2. Pre-transplant evaluation

Before admission, patient and donor spend one or two days on blood tests and imaging. The team checks whether the kidneys and heart are working normally, whether the brain shows old infarcts, whether there is any infection, and whether the teeth have caries that could seed infection later. Viral markers are part of the screen. The purpose is preparation: knowing which organ is weak lets the team adjust drugs and anticipate complications.

3. Conditioning

Once the patient is admitted to the bone marrow transplant unit, about seven days of chemotherapy, called conditioning, wipe out the old sickle-producing marrow so that the donor's cells can take its place. The choice of drugs has changed because of fertility, as the companion article describes.

4. Stem cell collection and infusion

A bone marrow transplant is not surgery. Most donors now give stem cells from the bloodstream, through the same type of machine used to collect platelets, in three to four hours, with no cut and no anaesthesia. The patient then receives the cells through a vein, much like a blood transfusion. The stem cells find their own way to the bone marrow and start working there. Dr. Danewa contrasted this with liver and kidney transplantation, where part or all of an organ must be removed from the donor.

5. Engraftment

Dr. Danewa compares the infusion to sowing seeds: they do not sprout at once. The cells circulate, settle in the marrow and begin producing blood over 12 to 14 days. Neutrophils, a type of white blood cell, appear first. Neutrophil engraftment is declared when the count stays above 500 per microlitre for three consecutive days; platelets rise two or three days later, followed by haemoglobin. He calls this the happiest day in a transplant physician's journey, but not the end of the story.

6. The first 100 days

After discharge from the transplant unit, the patient stays near the hospital for frequent outpatient reviews. The first 30, 60 and 100 days are when infections and other complications are most likely, because the new immune system is starting from scratch. Graft-versus-host disease (GVHD), in which the donor's immune cells react against the patient's body, infection and the other risks of this phase, and how chimerism tests (which measure the share of blood-forming cells that come from the donor) track the graft, are covered in the article on engraftment and chimerism.

7. Home, and the one-year mark

If the blood counts and chimerism are satisfactory after about 100 days, the patient can return to their home country with a follow-up plan and come back at one year. Dr. Danewa calls this the beauty of a bone marrow transplant: if all is well, nearly all medication stops after one year. Liver and kidney transplant recipients, by contrast, take anti-rejection drugs for life. At one year the patient must also be revaccinated, because the transplant drugs erase the immune memory of earlier vaccines.

Results and graft failure risk by donor type

Dr. Danewa's team published its own sickle cell transplant experience, gathered over ten years, and reported a success rate of around 80 to 85%. Outcomes depend heavily on the donor. With a fully matched sibling, graft failure (the donor cells ceasing to work) occurs in only about 3 to 5% of cases in his account; with matched unrelated and half-match donors it is somewhat higher, about 5 to 8%, when the conditioning is strong and drug levels and chimerism are monitored closely. After the first year, the chance of graft failure drops below 5%, and after two to three years he regards the cure as almost certain.

A transplant stops further damage but does not reverse damage already done. A patient left wheelchair-bound by a stroke will not walk again because of the transplant; what changes is that no new strokes or crises occur. That is the strongest argument for transplanting early.

Sickle cell transplant cost by donor type

Dr. Danewa put the cost of a sickle cell transplant at most Indian centres at around USD 25,000 for a fully matched sibling donor and around USD 35,000 for a half-match transplant, with variation by centre, the patient's age and any other illnesses. The same transplant in the United States costs several times more, while the drugs and protocols are the same and, in his view, the outcomes almost similar. Indicative package costs for matched sibling, matched unrelated donor and half-match transplants are listed separately.

The real barrier, he argued, is timing rather than total cost. Over a lifetime, the hospital admissions and drugs of supportive care add up to roughly the cost of a transplant; the transplant simply demands the money at once.

Gene therapy as the second curative route

Gene therapy is the other cure. It corrects the patient's own stem cells and returns them, so it avoids the donor search and the graft-versus-host disease of a transplant. The first gene therapies for sickle cell disease have been approved by the US Food and Drug Administration, but their US launch price of about USD 2.2 million puts them beyond the reach of most families in India and Africa. A lower-cost Indian gene therapy is in trials. The details, including the two approved products, are in the companion article on supportive care and cure.

Dr. Danewa's five conclusions

Dr. Danewa closed his lecture with five points for referring doctors:

1. Stem cell transplant for sickle cell disease is highly effective but still underused; awareness is the bottleneck.
2. It should be done before end-organ damage, as early as possible.
3. It is a safe procedure for the donor.
4. Longer follow-up is needed to understand late side effects.
5. The future is bright: gene therapy is now available, and its cost is expected to fall.

The questions doctors and a patient's family put to him after the lecture, on donation limits, cryopreservation, inheritance and graft rejection, are collected on the Live Discussion page for this masterclass.

Related reading

Dr. Danewa's separate masterclass on children's cancers is summarised in his guide to childhood cancer survival rates. Other Jivo Healthcare masterclasses approach sickle cell disease from different angles: Dr. Dharma Choudhary on sickle cell transplant outcomes, Dr. Vikas Dua on sickle cell anaemia bone marrow transplant, Dr. Sukriti Gupta on the disease from screening to cure and Dr. Divya Doval on complications and management. More haematology content sits under the haematology specialty hub.