The cord blood is different from regular blood in that it contains a wealth of hematopoietic stem cells (HSCs). There are as many HSCs in new born blood as there are in the bone marrow.
These hematopoietic cells are cells which are able to divide and replicate themselves. When these cells divide, the new cells have the ability to remain as a stem cell, or to become more specialized. They can actually form more red and white blood cells! Even more remarkable is that they appear to be able to form other types of cells such as blood vessels, muscle and bone. At present, other types of stem cells like those from an embryo, fetus, or adult do not appear to be able to do this.
How is cord blood collected? When the cord is clamped and detached from the infant, the cord blood can be captured and preserved using a special kit provided by the cord blood bank. Approximately 100 ml (+/-50 ml) of cord blood can be drained from the cord and placenta either before or after the placenta has been delivered.
The placenta supports the pregnancy by facilitating the regulation of nutrients and hormones between mother and fetus. After the baby is delivered, the placenta (sometimes called the afterbirth) is then delivered and usually discarded.
Once blood collection is complete, the package must be delivered to a cord blood bank, where it undergoes analysis to determine tissue type, and to screen for infectious properties. The red blood cells are then removed and it is cryogenically frozen, typically using liquid nitrogen.
When needed, the cord blood is thawed and the freezing preservatives are removed before transplantation. Cord blood cells have been successfully recovered more than 15 years after collection, and there is little reason to believe that cells cannot be viable beyond the length of a healthy human lifetime.
What is cord blood used for? Currently, hematopoietic stem cells are commonly used in the treatment of cancers, as well as blood and immune system disorders. The obvious extension of HSC research points to the possibility that hematopoietic stem cells may one day be used to replace a wide array of cells, and enable healing to occur in any injury or disease.
Cord blood is not useful for a blood transfusion, as the red blood cells contain fetal hemoglobin which is unable to transport oxygen from the air. After birth, the fetal red blood cells die rapidly and are replaced be normal hemoglobin. Jaundice in the newborn is caused by the degradation of the fetal red blood cells.
As a cancer treatment, cord blood cells, with the red cells removed, can be transplanted intravenously to restore immune system functionality. Compared to a bone marrow transplant, the complexity and complications are greatly reduced.