An unrelated umbilical cord blood transplant is basically a variation of the standard bone marrow transplant. The advantage of an umbilical cord transplant is it is far easier to match to a patient. Bone marrow transplants need nearly exact matches to prevent significant graph (what is being transplanted) versus host (what it is being transplanted into) (GvH) rejection. In simple terms your body recognizes the transplanted material as foreign – like an illness – and your antibodies attack and attempt to kill it. When your body begins to attack things you need – that is very bad. It happens in all types of transplants (heart, liver, kidney, etc.), but when it happens with your blood it can affect every part of your body – not just the transplanted organ. Additionally in cord blood transplants it can happen both ways – the new blood can attack your body or your body can attack your new blood.
The two hospitals best known for cord blood transplants are the University of Minnesota and Duke Medical Center. Duke Medical Center does approximately 100 transplants a year – everything from leukemia to lysosomal storage diseases. There have only been a handful of Tay-Sachs children transplanted. To most success transplant is a child named Jordan Lehman - he was transplanted at 14 month and at age 8 is actually gaining skills. Additionally Hunter Combs is now eight years old after being tranplanted at 14 months. We believe surviving over 8 years of age with Infantile Tay-Sachs disease has never been done before. On the flip side, three Juvenile Tay-Sachs child where tranplanted in late 2005 and early 2006 - only one (Daktoa Bihn) survived the process and is now over 3 years post transplant. And Krystie Karl-Steiger was transplanted in May 2007 at the University of Minnesota - she continues to recover.
The cord blood transplant procedure involves the destruction of the patient's current blood system. That is done with a regimen of chemo therapy and/or radiation over approximately 10 days. Once the chemo is completed there is generally one recovery day and then the cord blood is administered by IV. The cord blood instinctively knows to head for the bone marrow and begins to set up shop. Because the cord blood is so immature – it seems to accept the new host much easier then a standard bone marrow transplant.
Once the cord blood is in, the trick is to manage any GvH and protect the patient that is absent an immune system until the new blood can engrapht and develop its own immune system. The recovery time from a cord blood transplant can include years of medication. Additionally the side effects of many of the drugs and chemo treatments can have devastating effects on the young recipient's organs. While engraphtment is fairly common, the survival rate is still low in Tay-Sachs patients. There is a 20% chance the patient won't even survive the treatment.
The critics of the cord blood transplants treatment point out the harsh nature of the treatment and for Tay-Sachs patients, the difficulty crossing of the blood brain barrier. While the new blood may be healthy and rich in Hex-A enzymes, the blood brain barrier appears to be crossed very slowly (if at all). Due to the rapid progression of the Tay-Sachs disease, time is not on our side.
Finally, doctors point out that cord blood transplants are not an approved treatment for Tay-Sachs disease. If a disease has no treatment or cure - exactly which therapies would be "approved?" We dream of the day when one of these treatments is considered "approved" because it WORKS!
For additional information:
www.ntsad.org/S05/S05therapeutic_approach.htm
www.dukenews.duke.edu/2005/05/cordblood.html
For articles written about Cord Blood Transplants for Tay-Sachs children:
www.freerepublic.com/focus/f-news/1636101/posts
www.cleveland.com/taysachs/ (Four day long feature)
For websites detailing the journey of transplanted Tay-Sachs children:
www.caringbridge.org/visit/alexismarkowich
www.caringbridge.org/visit/dakotabihn
www.caringbridge.org/visit/jashaiasjourney
