How does a Transplant Cure Blood-Related Diseases?

Think of the marrow in your bones as the blood-production facility of your body.  This is the place where the most basic, undifferentiated cells (stem-cells) are born, and this is the place where they eventually turn into all of the mature elements present in the blood now running through your veins.  The most basic of these blood elements are ones you’ve probably heard of; red blood cells (they carry oxygen throughout our body), white blood cells (they fight infections), and platelets (they help your blood to clot in order to heal injuries).

The purpose of a bone-marrow or stem-cell transplant is to grow a new blood supply with uncontaminated mature blood cells.  When a transplant is successful a patient will grow a brand new immune system – just like an infant does during its first year of life.

Of course diseased cells must first be eradicated in order to kill the blood-related disorder you have, otherwise your new immune system will also be compromised.  Unfortunately in this case the cure is perhaps more dangerous than the disease.  Because of this danger, there are two basic parts to the transplant procedure:

1.     Killing off the diseased cells (via very high-dosage radiation and/or chemotherapy).

2.     Replacing the dead/dying immune system with new, uncontaminated cells in order to grow a new, healthy immune system (the actual transplant itself).

In other words, the first part of the procedure – the high-dosage radiation and/or chemotherapy – is done in an attempt to cure your disease.  The dosage levels of this first step are so extreme that your immune system is severely compromised.  The second part of the procedure – the transplant – is needed in order to survive the attempted cure.