Cold Ischemia on Gene Expression and Protein Expression for Human Kidney Transplants

Kidney transplantation had been established as a superior form of treatment for patients with end stage renal failure. Over the past decades, advances in surgical technique and immunosupression have markedly improved early graft function performance resulting in a current one year kidney graft survival rate of over 97%. However, despite these successes, long term graft survival is still limited and a constant rate of chronic graft lost results in the further expansion of an already laden transplant waiting list.

Cold storage as a form of organ preservation was an important breakthrough in the expansion of cadaveric donor usage. Preservation time allows for optimum tissue matching of individuals and adequate pre-operative preparation. Cold depresses metabolic rate and helps in counteracting the harmful effects of lack of oxygen during storage but concurrently it also introduces changes that exposes kidney to significant injury on subsequent re-establishment of circulation and warming. Previous work by Dr. Declan Healy, funded by the Punchestown Kidney Research Fund showed that cold storage is associated with decrease expression of stress proteins HSP70, HSP90, HSP27 and cell survival protein Bcl-2 which contribute to increased cell death during reperfusion. He also showed that prior heat shock resulted in the maintenance of these proteins and this partially protects against cell death during reperfusion. It is clear from Declans work, which has been published and presented at the American Society of Nephrology, that other proteins which are altered during storage need to be identified and then could be manipulated to prevent kidney damage during storage giving better long term survival.

Our new objective is to obtain a more global view of the molecular alterations occurring during cold storage in order to find other targets for manipulation to improve on the current preservation method. Following ethical approval by the Beaumont Hospital Ethics Committee, Kidney biopsy samples are taken from the kidney of consenting patients before and after cold storage. These tissues will be examined for alterations in gene expression high throughput gene microarray technology. We will then be able to identify candidate genes in addition to the already identified HSP which may be decreased and could explain the kidneys increased susceptibility to damage during cold storage. Equally as important we would propose to manipulate the expression of these proteins and hopefully help further preserve the kidney during storage resulting in a longer term graft survival times and taking the pressure off the already laden transplant waiting list.

Newman Scholar