Today, over 60,000 stem cell transplant (SCT) procedures are carried out in more than 600 centers worldwide. SCT is a challenging method of treatment; the complications should not be underestimated.
The modern era of bone marrow transplantation was inaugurated in the 1970’s in the wake of successful experiments and the term STEM CELL TRANSPLANTATION gained currency as stem cells for transplantation were sourced not only from the bone marrow but also from the umbilical cord and peripheral blood. At the end of the day the thing that is transplanted as treatment is a healthy ‘cell’ with the capacity to regenerate new cells. The procedure is now a definitive method of treatment for a large number of hereditary and non-hereditary diseases in children and adults.
Today, over 60,000 stem cell transplant (SCT) procedures are carried out in more than 600 centers worldwide.
SCT is a challenging method of treatment; the complications should not be underestimated. The first step is determining whether the patient’s condition indicates suitability for SCT – not all malignant or hereditary diseases are treatable with SCT. For example, many cases of low risk childhood acute leukemia can only be treated with chemotherapy, while recurrent or high risk cases may be subject to SCT.
After this, the transplantation type, stem cell source and healthy donor are determined, and the patient is prepared for the procedure. Patients are treated in a sterile environment under strictly controlled conditions where they are kept for a period of at least 30-40 days. More problematic cases may remain in the unit for some months.
In SCT, procedures using the patient’s own stem cells are called autologous, those in which a donor’s healthy cells are being used are allogeneic; in the case of twins the term is syngeneic. Autologous SCT procedures are used in the treatment of solid tumor cases; allogeneic procedures are preferred in malignant and genetic disease cases.
Where do the stem cells come from?
We have 3 sources of hematopoietic stem cells:
1- Bone Marrow: The collection process is carried out in the operating theater under epidural or general anesthetic. The latter is preferred in pediatric cases.
2- Peripheral blood (blood circulating in the vessels): Collection is performed using a machine that is attached to the donor.
3- Cord Blood: This is more widely used in pediatric cases as the number of cells is limited and its use is restricted in proportion to the increase in body weight.
Donor Selection
HLA donor compatibility is one of the key limiting factors in SCT procedures. The ideal donor is a tissue type compatible sibling. Advances in technology now allow SCT procedures from partially compatible family member donors. Patients without a compatible relative apply to the world bone marrow bank for a compatible donor; the bank, started in the 1970’s, stores 650,000 umbilical cords from more than 27 million volunteer donors. The transplantation is performed when a suitable donor or cord blood has been found.
In which cases does stem cell transplantation work?
The most frequent case in which SCT procedures are carried out in children is acute leukemia, followed by congenital hemoglobin production dysfunction (e.g. Thalassemia anemia and sickle cell anemia), bone marrow failure, immune system deficiencies, other genetic diseases such as metabolic and bone metabolic conditions, and storage diseases.
Frequently asked questions?
Is blood group compatibility essential?
There is no need for blood compatibility in hematopoietic stem cell transplantations. The physician will carry out the procedure having taken the necessary precautionary measures; in this event the recipient’s blood group will change so that he or she takes on the donor’s blood group.
What are the risks to the donor?
The donor is subject to intensive scanning and evaluation before the transplantation occurs. Risk factors are not so severe that they would prevent the donor agreeing to a procedure that could save the life of a relative or another person. After bone marrow or peripheral blood collection has been completed, the body quicklyreplaces the cells that have been lost.
What are the success rates in stem cell transplantation?
Success depends on many factors including the underlying condition of the patient and the stage of their disease, the patient’s performance during the transplantation procedure, the degree of patient donor compatibility, the type of transplantation, and the gender and age of the donor. The highest success rates are generally seen in cases when the patient’s disease is at an early stage, the patient’s general condition is good, and the donor and recipient are young.
Stem cell transplantation and later…
SCT is a multidisciplinary method of treating life-threatening conditions that are not responsiven to conventional treatment. If the patient is a child, the reasons for the advisability of the treatment, how it is carried out, outcomes, and information on early and long term risks is carefully explained verbally and in writing to the child’s legal guardians (in most cases the child’s parents). The procedure begins only when written consent has been obtained after this briefing. The post-transplantation growth and developmental progress of children, their performance at school and other natters requires special monitoring in a way that is different from adult cases. Nowadays there is a population between the ages of 25 and 30 around the world who haveundergone hematopoietic stem cell transplantation. With the ever longer lifespan of SCT patients, their long term monitoring involves not just medical check-ups but also issues such as psychosocial problems and improving their quality of life.
PROF. DR. BUKET ERER DEL CASTELLO
Pediatric Hematology / Pediatric Health & Diseases / Pediatric Bone Marrow Center
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