Umbilical Cord Blood Banking Why? What?How?
Stem cells are undifferentiated precursors of the various types of cells that form different organs. They are also called pluripotent cells. They are found in large numbers in the placenta, embryonic tissues , gonads and to a small extent in cord blood. However, cord blood is richest in some partially differentiated stem cells, namely haemopoetic stem cells, which give rise to the three types of mature blood cells….1)Red blood cells(erythrocytes) 2)White blood cells(Leukocytes) 3)Platelets( Thrombocytes).In extra- uterine life, these haemopoetic stem cells are found in the bone marrow and the lymphatic tissue.
Mature blood cells(with the exception of some leukocytes) have a short life span and are continuously replenished throughout life by the haemopoetic stem cells.If these stem cells are affected, either due to internal or external causes,it results in life threatening disease.The main modality of treatment lies in replenishing the damaged stem cells ,after removing the offending factor,whenever possible.
Until the 1980s, bone marrow transplant remained the sole way of replenishing damaged stem cells,but after the discovery of stem cell rich cord blood,and its successful transfusion in 1988,this method gradually came into vogue.Soon, methods of preserving cord blood also improved,giving rise to modern umbilical cord blood banking.
The why and what of cord blood banking: Today, cord blood is used in the treatment of various disorders like Fanconi syndrome,lymphomas,leukemias,aplastic anemia and inherited disorders of metabolism.
With the advances in regenerative medicine,stem cells in cord blood can be `tweaked` or manipulated to form pluripotent cells with the potential to treat a plethora of diseases like Type1 Diabetes Mellitus,Osteoporosis,Heart Disease,and some Pediatric cancers with ongoing research in the treatment of Cerebral Palsy,other Pediatric brain injuries and Parkinsons Disease.
Cord blood transfusion has the following advantages …………………….
1)In case of autologus transfusios, there is 100% compatibility,as the transfused blood is the patient`s own.If it has been preserved for private use, there is no waiting period for a donor to become available.
2)Greater concenterations of stem cells are present per unit of cord blood as compared to bone marrow,resulting in lesser requirement.
3)In case of the recipient being a first degree relative of the donor,there are greater chances of compatibility…..75% chance for siblings and 50% for parents.A lower histocompatibility score (4/6)suffices as compared to the higher one (6/6)required for bone marrow transplant.This is because cord blood cells are not as differentiated as compared to adult bone marrow.
4)Again,due to the lesser differentiation,even pooled cord blood samples can be used with greater safety and efficacy.
5)Since the collection is generally non-invasive,there is no morbidity for the donor.
6)In the case of ethnic minorities prone to certain inborn metabolic errors, there are greater chances of finding compatible donors.
7)Least chances of Graft-versus-host disease.
In view of all the different merits cord blood transfusion has,it is imperative that it is properly preserved at or in some cases before birth ,so that it can be utilized,should the need arise.This is what umbilical cord blood banking entails.
How is it done? Cord blood is withdrawn from the umbilical vein,either before or at birth.After the birth of the baby, the umbilical cord blood is withdrawn after the cord stops pulsating, thus ensuring that the baby is not deprived of any blood, which might lead to anemia.Generally, 75 to 140 ml is withdrawn.This blood is then subjected to screening for viruses like HIV,HepB and HepC virus.A cryopreservant is then added and the blood is preserved at -90 degrees centigrade.It is then placed in liquid nitrogen which further cools it to -196 degrees centigrade, ensuring that the blood has a shelf life of 20 years.
Cord blood may be stored under two programs:1)Public cord blood storage storage program: Spearheaded in Tata Memorial Hospital in Mumbai,in 1990.Under this program, the donated cord blood is used for the benefit of the public at large.Several samples may be pooled together and a large bank of stem cells becomes available.
2)Private cord blood storage program:Private storage of cord blood in a cryo-banking facility for use of the individual or family, should the need arise.Several such facilities are operational in India such as 1)Reliance Lifesciences,Delhi 2)Lifecell, Chennai 3)Cord life sciences 4)Cryobanks International 5)Histostem, Mumbai.
These private facilities provide storage for specific period, ranging upto 20 years on the payment of a sum,either in installments or as a single payment, which ranges from around INR 75,000 to 1,00,000.
Fraught with possibilities though cord blood banking seems,there are a few disadvantages, especially to the private banking programs. They are as follows:
1)Hasty clamping of the cord can result in depletion of bood to the new-born
2)Although viral contamination of the cord blood is rare,bacterial contamination is known to occur, if proper asepsis is not maintained.
3)Chances of an individual requiring cord blood transfusion is rare. If the blood is banked privately,it seems unwarranted to pay a large sum for something which may not be required in an individual`s health lifetime.
4)In childhood cancers, some forms of leukemia and some immunological disorders,autologous transfusions and transfusions from siblings maybe useless as they may carry the same genetic defect.
5)Samples in private banking programs may not be large enough to cover the needs if multiple transfusions are required.
6)Cord blood is rich in haemopoetic stem cells and not embryonic stem cells and as such, is not `blanket therapy` for any disease requiring new cell generation.
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