Of Stem Cells and Fooling Your Immune System

Current recipients of any donated organ must always contend with bodily rejection of their new organ, and this has usually been done with the aid of immunosuppressive drugs that must be taken daily for the rest of one’s life. In addition to harmful long-term side effects, these drugs have even been known to damage the transplanted organ. However, researchers from Northwestern University and the University of Louisville are currently performing long-term trials on a new method that significantly reduces the need for immunosuppressive drugs. Their method involves using specially processed donor stem cells to trick the recipient’s immune system into accepting the new organ. They are testing this approach specifically on kidney transplants right now, but they believe their technique may be applicable to other types of transplants as well.

At present, in order to qualify for this experimental procedure, the donor and the recipient must have compatible blood types, and the recipient must not possess any antibodies that may cause rejection. After these preliminary checks, bone marrow stem cells are collected from the kidney donor’s blood by means of apheresis. The stem cells are then sent to the University of Louisville for processing. At the same time, the recipient undergoes a “conditioning” regime that includes chemotherapy and radiation treatment targeted at her bone marrow; this is done in order to suppress the recipient’s natural bone marrow so that the donated cells have more room to develop. This pre-transplantation process begins around one month before the operation.

The kidney transplantation is performed at Northwestern’s hospital once the processed stem cells are ready. The donated stem cells are implanted into the recipient’s bone marrow one day after the transplantation procedure. The donated stem cells are naturally prompted to develop more specialized blood cells, most notably immune cells. The ultimate goal is to create a dual bone marrow system inside a single person. Unfortunately, the recipient is not exempt from needing immunosuppressant drugs after this procedure, but the amount of drugs taken are decreased overtime until the patient ceases medication altogether. The researchers hope that patients will only need to take anti-rejection drugs for about one year after the transplantation. Due to the success of their first patient, who received her transplant roughly two years ago and is no longer taking any medication, the researchers are planning to start a second clinical trial as well.

http://www.sciencedaily.com/releases/2012/03/120311145303.htm