I watched this movie, where they rented hearts to people for a year. I wonder if it is possible to transplant a heart indefinitely from person to person, or does the heart have a lifetime? So, do human organs age and eventually die, or is it possible to transplant organs indefinitely? What is the limiting factor for life of human organs?
First of all, it will be practically impossible to make an estimation of how long a transplanted organ will live and how many times it could be transplanted. However, it is relatively safe to say that it will not live forever.
To be able to receive an organ transplantation, the HLA MHC-complexes of donor and receiver need to be matched very carefully, to limit the host-vs-graft reaction. This limits the number of possible donor-receiver patient pars drastically. So to be able to do a "row transplantation" (one receiver to the next and so on), they need to have matching MHC-complexes.
Otherwise the immune system of the receiver turns against the transplanted organ and will eventually destroy it. To avoid this reaction, transplantation patients also receive drugs, which severely suppress their immune system, thus making other infections potentially dangerous. This reaction will still take place, since you cannot shut down the immune system of the receiver completely (for obvious reasons), though it happens at a much slower rate. Transplanted organs will only live for a certain time (see estimates from a number of transplantations below) and it is possible that people need to receive transplants twice in their life.
For this reason, no doctor will put their patient at risk by giving them an organ which might have a reduced lifetime. The risk of the operation itself is also substantial. Additionally, the original receiver needs to be dead to do this, as he would otherise need another organ in exchange.
What we can do is to take the average number of a lot of transplantations together and calculate some average life-years for a transplant. According to table 2 in this paper ("The Life-Years Saved by a Deceased Organ Donor") the "average benefit by type of transplant (life-years)" is:
- Kidney: 7.2 years
- Liver: 16.9 years
- Lung: 2.1 years
- Heart: 14.5 years
- Kidney-Pancreas: 12.9 years
These numbers are not definite, since the life style of the donor and the receiver as well as infections of the transplated patient (who has a severely suppressed immune system – this is critical) also play an important role in determining the lifetime of the organ.
The median lifetime of an organ transplant is some 5 to 10 years mainly due to chronic rejection mediated by host-versus-graft immune responses. Hence long-term transplants definitely have a limited half life. However, this graft rejection is relatively slow and early explantation and re-implantation in a new host may actually "reset" this process? With re-setting I mean that the new host's immune system must start the slow graft rejection process (immunization) all over again, including antigen recognition and build up of the humoral and cellular immunity (see wiki on graft rejection). So in theory the organ-lifetime may actually surpass the recipient lifetime as mentioned earlier when grafts are explanted and re-implanted. As this scenario has never been tried as far as I am aware - due to the obvious risks associated with repeated complex surgeries - it becomes speculative at this point.
It really depends on the primary disease of the transplant recipient and the organ transplanted. Some diseases cause organ failure and will do damage to the transplanted organ and shorten its survival. There are rejection process in the host that will do all sorts of damage to the graft. There is also surgical complications when trying to ex-plant a transplanted organ and re-implant it into another recipient. However, if you want to know the record of how long an transplanted organ has survived please check this out: http://www.bbc.co.uk/news/uk-england-tyne-37025389