Since 1998, advances in cord blood technology have made cord blood transplants a viable alternative to traditional bone marrow transplants in patients requiring a stem cell transplant. While bone marrow transplants continue be a more common procedure, evidence suggests this trend may be changing. But is a cord blood transplant really a more effective procedure? The truth is, it depends on the circumstance.
What are Cord Blood and Bone Marrow Transplants?
Both bone marrow and cord blood stem cell transplants are designed to replace unhealthy cells with healthy ones.
A bone marrow transplant involves the use of bone marrow that is transplanted from a donor into a recipient to cultivate new stem cells. Bone marrow is a spongy tissue located inside the bones. Most commonly, bone marrow is extracted from the breastbone, skull, hips, ribs or spine, as these contain stem cells that produce white blood cells (leukocytes), which fight against infection; red blood cells (erythrocytes), which carry oxygen in order to eliminate waste from the organs and tissue; and platelets, which are responsible for making the blood clot. Bone barrow is removed from the donor under a general anesthetic. It is filtered, treated, and either transplanted immediately into the recipient, or tested, frozen, and stored for later use.
Cord blood is collected from a newborn’s umbilical cord after delivery, so that it may be tested, frozen, and subsequently stored in a cord blood bank for future use.
Cord Blood Transplant vs. Bone Marrow Transplant
There are many different criteria used to evaluate whether or not a cord blood transplant is right for you. When making your decision, it is important that both you and your doctor keep the following in mind:
|Evaluative Criteria||Transplant Preferred|
|Graft Versus Host Disease (GvHD)||Cord Blood Preferred|
|Graft versus host disease is a potentially serious complication for any organ transplant. In fact, it is estimated to be fatal in up to 40% of patients. However, because cord blood is more primitive than bone marrow, there is a lower chance that these cells will attack the recipient's body, resulting in a lower incidence of GvHD.|
|HLA Matching||Cord Blood Preferred|
|Human Leukocyte Antigen (HLA) is a marker your immune system uses to recognize foreign cells. HLA tissue types are inherited, which is why it is recommended that a recipient's bone marrow donor be a family member (ideally a brother or sister). This is a problem because 70% of donors do not have a suitable donor in their family. However, because cord blood stem cells are considered to be "purer" (and therefore more adaptable), there is generally no need to find an HLA match.|
|Rich Source of Stem Cells||Cord Blood Preferred|
|Stem cells are found in greater proportions in umbilical cord blood. In fact, some experts say it contains nearly 10 times the amount of stem cells found in bone marrow.|
|Regenerative Source||Cord Blood Preferred|
|It is believed that stem cells found in cord blood have greater regenerative properties since they are younger than bone marrow.|
|Availability||Cord Blood Preferred|
|Stem cell transplants are in high demand, with over 30,000 individuals in line for the procedure each year. The problem is that waiting for a suitable donor can often inhibit an individual from having the procedure. In fact, for this very reason, 70% of these individuals cannot find a matching donor. Unfortunately, for some individuals, such as those with more severe types of cancer, this lack of treatment can be fatal. Cord blood banking, however, helps to alleviate this issue, as their storage facilities make cord blood readily available for those in need.|
|Pain||Cord Blood Preferred|
|From a donor's perspective, a cord blood transplant presents a much less invasive procedure, as the collection of cord blood stem cells happens directly after birth from the umbilical cord. Bone marrow transplants, on the other hand, are invasive procedures, requiring a general anesthesia so that bone marrow can be removed from the rear of the pelvic bone through a series of injections.|
|Graft Rejection||Bone Marrow Preferred|
|Despite the numerous advantages of cord blood transplants, bone marrow transplants are still preferred in the case of graft rejection-- or a case in which the recipient's body attacks the donor's stem cells. According to a recent study, some 11% of cord blood transplants were rejected, while this was the case in only 2% of bone marrow transplants.|
In addition, cord blood transplants are generally better-suited for those younger than 30 years and, depending upon the quantity of available stem cells, may not be suited for patients over a certain weight. Bone marrow transplants, on the other hand, are not recommended for individuals with kidney, lung, liver, or heart conditions.
Bone Marrow Stem Cells
Cord Blood Stem Cells
Bone marrow stem cells are obtained in a painful and invasive procedure. It involves surgery and general anesthesia.
Collecting cord blood is painless and its stem cells are easily acquired
Patients who had organ transplants using bone marrow stem cells often have Graft vs Host Disease (GvHD)
GvHD is a lot less frequent and even when it occurs, it’s generally easier to treat
A stem cell from bone marrow can differentiate into a limited amount of blood forming cells
A stem cell from cord blood forms more blood cells than a stem cell from the bone marrow
Bone marrow stem cell transplants require the donor perfect match with the recipient
In cord blood stem cell transplants, the donor and recipient can be mismatched making it a lot easier to find a donor.
Latent viral infection (Cytomegalovirus) in the donor is common. It’s present in >50% of U.S. adult bone marrow donors.
Latent viral infection is rare in cord blood donors. Cytomegalovirus (CMV) infection is present in <1% of U.S. cord blood donors
Units of bone marrow harvested must be used freshly i.e it has a shelf life of mere hours
Units of cord blood can be cyropreserved for well over a decade
There is no risk of transplanting a genetic disease
There is a tiny risk that a rare and unrecognised genetic diseases, found in the blood or immune system of the baby, may be transplanted i
For bone marrow stem cell transplants, even when a donor match is found, the donor must be found and re-tested.
Once stored, cord blood is available till whenever it is needed
Bone marrow transplants require a quart or more of bone marrow, mixed with blood
In cord blood transplants, only a small volume is required
“Cord Blood vs. Bone Marrow Transplants.” Stem Cell Transplants: Bone Marrow vs Cord Blood. N.p., n.d. Web. 06 Feb. 2017.