Fundamentals of Adult Stem Cells

It�s known that using umbilical cord blood to perform transfusions lowers the risk of graft vs. host disease, but what exactly is GVHD?

GVHD is a potentially fatal complication that occurs following a transplant of stem cells from either a related or allogeneic donor. It is a severe immune system response. The transplanted cells form the recipient�s new immune system after the destruction of the old system by chemotherapy. If this transplanted immune system known as the graft attacks the body of the host recipient, then the patient has GVHD.

 

When transplanting blood stem cells, it�s important to get as close a match as possible to the recipient�s own immune system characteristics or �markers�. If there is a less than perfect match, then T-cells, a white blood cell, can lead an attack on the recipient�s body. T-cells act on foreign materials that enter the body as a defense against disease and infection. Therefore, GVHD is thought to occur due to these white blood cells. Cord blood, because it is more primitive, does not thoroughly attack against diseases and therefore GVHD is less likely to occur.

 

Acute and Chronic GVHD

If the recipient has GVHD, there are two courses the attack could take. In acute GVHD, symptoms will arise within 3 months following the transplant. The recipient will notice a reddish skin rash and skin that peels or blisters. GVHD may even affect the intestines and stomach and the recipient will notice nausea, diarrhea and cramping. If GVHD has affected the liver, the recipient will notice a yellowing of skin.

Chronic GVHD starts affecting the recipient after 3 months. Doctors rate chronic GVHD on a scale; 1 is mild and 4 is severe. In addition to affecting the body in the same ways acute GVHD does, chronic GVHD also affects certain glands in he body; specifically, the salivary glands in the mouth and the mucous glands in the eyes.

 

Preventing and Treating GVHD

To prevent GVHD, doctors will usually administer immunosuppressive drugs, to stifle the attack of the new immune system on the host�s body. These drugs are carefully administered, as they can cause damage to the body. Treatment also involves immunosuppressive drugs, mostly steroids.

 

GVHD and Cord Blood

A study done in 2000 looking at recipients of transplants donated from siblings for cord blood and bone marrow found that cord blood transplants recipients were 59% less likely to develop GVHD.