Allo transplant

What is a allotransplant of hematopoietic stem cells?

Hematopoietic stem cell transplant is a treatment dedicated to several diseases.

It can be performed from the bone marrow or from peripheral stem cells of a living donor, or from an umbilical cord, also called placental blood. Numerous umbilical cords are frozen after being cut, following children birth in approved maternity wards.


The aim of an allotransplant is to replace an ill patient’s marrow by a healthy donors’ for several reasons:

For example:

  • To destroy a marrow with leukemia and replace it by a healthy marrow
  • To replace a marrow that produces ineffective blood cells. Like red blood cells for patient with thalassemia or sickle cell patients.
  • To replace an ineffective or no longer working marrow in bone marrow depressions and in myelodysplasias.
  • To replace the defective immune system in the treatment of immune deficiencies
  • To bring through a new bone marrow, an defective or missing enzyme in some metabolic diseases
  • To get an anti tumour effect thanks to a new immune system in some solid tumours.

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How do we find donors?

In the first place, we will test if your child and his/her siblings are as close a match as possible by performing a blood test called HLA typing. It is about the white cells type which is different from the blood type that is on the red blood cells.

The probability of siblings to be HLA-matched is ¼. The other family members (parents, cousins …) can’t be HLA-matched.

If no HLA-matched donor can be found within the siblings, we will look into the bone marrow donor file worldwide and on the umbilical cord bank.

There is always a sufficiently HLA-Matched donor or umbilical cord to perform an allotransplant.

How does an allotransplant of hematopoietic stem cells take place?

It includes 4stages, the first three taking place in the access control unit because of the infection risk for the patient.

  • The “conditioning” stage:

The recipient is prepared with chemotherapy or radiotherapy. This conditioning takes from 7 to 10 days and aims at destroying the defective or ill bone marrow.

  • The allotransplant:

The donor’s bone marrow or the placental blood is given to the patient like a transfusion through his catheter in a few hours.

  • The immediate post allotransplant phase:

The aplasia phase which follows the allotransplant is the time required for the donor’s steam cells to set up and get functional to produce blood cells. It takes around from 15 to 40 days. During this phase the patient is exposed to different complications. Following the aplasia, the patient can still have some complications linked to the transplant and pursuing the surveillance at the hospital is required for a changeable time. The average hospitalization time is 2 months.

  • Follow-up at the hospital, then in consultation:

When the marrow is effective and the patient can take his medicines orally, can eat and drink properly, discharge is then consider for a follow-up in the outpatient unit then in consultation.

Long term follow-up:

Your child will not be able to have a community life before 6 months following the transplant until the immune system works accurately again.

He will have to take an immunosuppressant treatment for several months and antibiotics for 1 year. Then, he will no need medication anymore. The different organs will be regularly monitored during the follow-up until your child is a grown-up.

If your child is to receive an allotransplant of hematopoietic cells, you will be informed of the different treatment stages and the different risks by physicians of the access control unit during a “transplant interview” (both parents must be present).

You will have the opportunity to ask all the questions you may need to tackle this new treatment stage of your child.

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