Sunday, April 15

Daily health news - Umbilical cord blood stem cells

What is 'umbilical cord blood'?

The blood left over in the umbilical cord (funiculus umbilicalis) and in the placenta after child birth is umbilical cord blood. It is composed of normal components and also hematopoietic (blood-forming) stem cells (HSCs). After child birth, the mother's body expels placenta and the attached umbilical cord. The end of umbilical cord attached to the baby is clamped and cut. Earlier placenta and umbilical cord were discarded without second thought as afterbirth waste.
After the discovery of immense uses of HSCS contained in this blood in 1970s, blood from the placenta and umbilical cord is being collected, frozen and stored widely.
Another promising development is the use of cord tissue (Wharton’s Jelly). This tissue is very rich in Mesenchymal stem cells (MSC).
MSC stem cells differentiate and grow to form tissues like bone, cartilage and connective tissue.

What are stem cells?

Stem cells differ from the other organ tissues of the body.
Their function is not defined and they can keep on dividing creating more stem cells.
Under specific conditions they can also become specialised by the process called differentiation.
Stem cells are present in embryonic tissues, bone marrow, adipose (fat) tissue, peripheral blood, menstrual (endometrial regenerative tissue) and umbilical blood.

What are blood stem cells?

These are hematopoietic stem cells (HSCs) found in the bone marrow and cord and are capable of growing and differentiating into mature tissue components of circulative system. Apart from maturing into red blood corpuscles, white corpuscles and platelets, they even have the potential to give rise to other organs.
Harvesting bone marrow stem cells has to be done under anesthesia and the donor has to suffer postoperative pain.
These hematopoietic stem cells are also found in the umbilical cord blood.
An excellent source of stem cells when compared to bone marrow, cord blood has wide uses in transplantation and regenerative medicine.
The occurrence of the fatal graft versus host disease (GVHD), in which the donor tissue attacks the recipient's tissues, is less frequent with cord blood than with bone marrow.

Use of umbilical cord blood stem cells

Many blood related and genetic diseases like leukaemia, lymphoma, thalassemia, severe anemia, severe combined immunodeficiency (SCID or "bubble boy disease") and aplastic anemia require radiation and chemotherapy for getting rid of the diseased tissues.
The next step is infusion of healthy and disease-free stem cells to grow up into functional tissues sans the disease.
In such cases bone marrow transplants have been used extensively from healthy donors.
When compared to bone marrow, umbilical blood yields more number of stem cells and the procedure to store these stem cells for future use is also easier.
The collected umbilical blood is processed to harvest the stem cells and stored cryogenically in liquid nitrogen.
When the disease is familial, the stored product from healthy member can be used for treating diseased siblings or relatives.
Further properly collected, screened and matched collection from any donor can be used for treating diseased recipient individuals.
Much promising research works are going on in treatment of brain injury, treatment of type 1 diabetes and treating conditions such as hearing loss and paralysis with umbilical cord blood.
Cardiovascular repair and corrections are other promising fields of regenerative medicine.

Banking of umbilical cord blood stem cells

After clamping and detaching the umbilical cord from the newborn, the blood is syringed out from the placenta and collected in a bag similar to standard blood collection method. On an average about 75 ml of blood is collected from the placenta.
The collected fluid is frozen and cryopreserved in liquid nitrogen for future use.

The cryopreservation process comes with some risks like loss of water from the preserved tissue and the resultant extracellular ice formation with damage to cellular membranes.
Vitrification technique is used to overcome the ice formation, by adding cryoprotectants and rapid cooling.
Further the collected sample has to be screened for HIV 1, HIV 2, Hepatitis B, Hepatitis C, syphilis, Creutzfeldt-Jakob disease (CJD), Variant Creutzfeldt-Jakob disease (vCJD), Human T-lymphotropic virus (HTLV) and Cytomegalovirus (CMV).

Shortcomings and controversies in umbilical cord blood stem cells banking

Private umbilical cord blood banking is controversial among the parents as well as the medical community.
Preserving cord blood for future use of the baby is prohibitively costly.
Parents may be mislead into storing this tissue without the actual necessity.
Only a small percentage of babies may be requiring the stored umbilical blood stem cells in the future.
If the private bank becomes nonviable or closes the shop, the fate of the stored product is at great risk.
Apart from difficulties involved in shifting it to a new bank there may be loss of quality. Added expenditure and problems involved may even negate the very purpose of storing.
However there is great support for public banking for umbilical blood from all sections of the communities.
This has to be done by the State and if effectively done will become a priceless resource.
A national grid of umbilical cord blood stem cells banks can be an ideal solution, wherein everyone can deposit into and everyone can draw from.

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Current topic: Umbilical cord blood stem cells
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