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With almost 15,000 babies born with blood dyscrasia each year, India has the largest number of Thalassaemia patients in the world. After decades of dedicated research, stem cell technology is finally set to change this narrative. Selecting the source of stem cells for transplantation is one of the key clinical questions today. When faced with the dilemma of cord blood vs bone marrow transplant, the choice is never straightforward, but a delicate balance between engraftment kinetics, immune match and a good long-term outcome. This review covers a clinical perspective of both stem cell sources and shows that there is no set choice between the two; the source selection depends solely on the physiology and genetics of the child.
Types of Thalassaemia
Thalassaemia is an inherited blood disorder that results from defects in the production of haemoglobin. This disease is classified into Alpha and Beta Thalassaemia depending on which protein chain is affected by mutation.
Thalassaemia may be asymptomatic in the case of Thalassaemia Minor, where the individual inherits the disorder from one parent. Thalassaemia intermedia causes anaemia, but does not require frequent blood transfusions. Thalassaemia Major is a disease in which the production of haemoglobin is compromised as both parents pass the defect, and the child suffers from severe anaemia. This is often Transfusion-dependent thalassemia (TDT), where the patient needs regular lifelong blood transfusions. Allogenic hematopoietic stem cell transplant (HSCT) is a life-altering event for patients with Thalassaemia Major.
The Role of HSCT in Thalassaemia
Patients with Thalassaemia Major suffer from chronic blood transfusions and iron chelation for life. HSCT offers them their normal Haematopoietic system through which they can produce normal red blood cells. When considering the thalassaemia treatment options, physicians often weigh cord blood stem cell transplant against bone marrow transplantation. Nevertheless, success often depends on the quality of the stem cell graft and the degree of Human Leukocyte Antigen (HLA) match between the donor and the recipient.
Role of Cord Blood in Transplantation
Cord blood is defined as the blood found in the umbilical cord after the baby has been born. This blood is a potent source of both stem and progenitor cells of hematopoiesis. Umbilical cord blood (UCB) is an indispensable treatment option, replacing discarded biological waste products and a useful stem cell source.
For a Thalassemic patient without a full human leukocyte antigen (HLA)- matched related donor, UCB stands out as the best stem cell source for thalassemia treatment. Its main therapeutic advantages over bone marrow (BM) can be found in its biological features as well as its logistical advantages. Unlike BM, which is harvested via an invasive surgical procedure from a donor and requires pre-operative HLA-matching between donor and recipient, umbilical cord blood is collectable at birth, processed and cryopreserved, hence it is ready for rapid use when required, as in rapidly deteriorating diseases like transfusion-dependent Thalassemia Major.
Important Benefits of Cord Blood Transplantation (CBT)
There are a variety of immunological and physiological features that promote cord blood transplant for thalassaemia in India:
Low incidence of Graft-Versus-Host Disease (GVHD)
UCB is comprised of more immature hematopoietic stem cells, which have been shown to result in a reduced incidence and severity of both acute and chronic GVHD compared to bone marrow. This immunological tolerance is ideal because UCB can be used with decreased reliance on HLA-match between donor and recipient. This makes cord blood stem cell therapy for thalassaemia in India an attractive prospect for a child with a marginally sub-optimal HLA match.
Enhanced Proliferative Capacity
The advantages of siblings’ cord blood banking can be gauged from the fact that the regenerative potential of haematopoietic stem cells found in UCB results in efficient recovery of the recipient’s haematopoiesis. Thus, helping them regain their haematopoietic independence.
Expedited Availability
Stem cells are cryopreserved in cord blood banks. The benefits of cord blood banking can be better perceived when a quick withdrawal makes early intervention possible. This reduces risks, resulting in favourable outcomes.
Navigating the Choices
UCB has emerged as a crucial, accessible, and therapeutic alternative source of stem cells for children suffering from Thalassaemia Major. A paediatrician haematologist-oncologist determines which transplant is safer for children with thalassaemia based on individual circumstances.
Age and Weight of Patient
Cord blood units can be a suitable choice for infants and younger children due to reduced risk of GvHD.
HLA Match Availability
Cord blood units are widely used as the stem cell transplant for thalassaemia in cases where HLA matching is not found. Only a 10/10 HLA-matched related or unrelated donor is suitable for bone marrow transplants.
Clinical Urgency
If the child’s status is critical, immediate availability from the cord blood bank should be favoured over a potentially longer wait time for bone marrow donors.
Conclusion
Achieving a cure for thalassaemia with stem cells has evolved into an individualised medicine approach. Factors such as the risk of GvHD, the availability of an exact match donor, and the critical treatment window determine the best Thalassaemia management plan using UCB stem cells.