Incremental Liver Transplant

People waiting for kidney transplants are usually on dialysis - their old kidneys have given up, and the robot sustains them until new ones are available. A person who needs a liver transplant walks around with the old liver doing the best it can - there is no dialysis equivalent. Livers are unusual in that they try to heal - if you quit drinking, or control your hepatitis, your liver will start to grow back. If it is gone past the point of no return, it may not be able to grow back, and you need a new one.

In a kidney transplant, the old kidneys are left in place and the new one hooked up. For a liver transplant, the old one must be removed to make room. I propose that in some cases, the old liver might provide fertile substrate for individual liver cells from a new liver. These would be injected directly into the old one in the hope that they would grow and provide islands of new liver capacity. Perhaps this would hold the line for a little while until the whole new liver comes along - or maybe after a very successful ILT a conventional transplant would not be necessary. Rejection or graft failure would not be such a big deal - you wind up where you started - with a bad liver, but not dead. It might even be possible to repeat ILT a number of times - which would result in a genetically heterogenous liver, but who cares as long as you're not yellow?

The patient who receives ILT would need immunosuppression, just as with a conventional transplant. However the operation would be much safer. In addition, one donor liver might be distributed among a number of recipients in this way: the donor liver is dissolved into its component hepatocytes, which are injected into 10 or more recipients. This idea could be tested using a small portion of a donor liver and a volunteer recipient from the transplant list. Later, when the volunteer actually comes to transplant, his old liver can be examined to see what the ILT did. Of course if it works great, the recipient might never come to transplant!

Donation of liver to be used for ILT might be more like donating bone marrow - several cores of liver are taken from the donor in the same manner as one might do a liver biopsy. The donor spends the night in the hospital to watch for bleeding, then heads home.

A final use for ILT would be for the treatment of inherited metabolic diseases in infants. In many of these diseases, the infant has a fine liver except it is unable to process one particular substance - which then builds up in the blood or elsewhere. These infants would actually be the best candidates for ILT because the existing liver does not have cirrhosis, autoimmune destruction, or some virus already messing with it. It is healthy. A few islands of donor liver within the infant liver should be able to handle metabolism of the substance in question.