Donor intervention and organ preservation: where is the science and what are the obstacles?

Informed consent in research to improve the number and quality of deceased donor organs

Improving the management of potential organ donors in the intensive care unit could meet an important public health goal by increasing the number and quality of transplantable organs. However, randomized clinical trials are needed to quantify the extent to which specific interventions might enhance organ recovery and outcomes among transplant recipients. Among several barriers to conducting such studies are the absence of guidelines for obtaining informed consent for such studies and the fact that deceased organ donors are not covered by extant federal regulations governing oversight of research with human subjects. This article explores the underexamined ethical issues that arise in the context of donor management studies and provides ethical guidelines and suggested regulatory oversight mechanisms to enable such studies to be conducted ethically. We conclude that both the respect that is traditionally accorded to the prior wishes of the dead and the possibility of postmortem harm support a role for surrogate consent of donors in such randomized controlled trials. Furthermore, although recipients will often be considered human subjects under federal regulations, several ethical arguments support waiving requirements for recipient consent in donor management randomized controlled trials. Finally, we suggest that new regulatory mechanisms, perhaps linked to existing regional and national organ donation and transplantation infrastructures, must be established to protect patients in donor management studies while limiting unnecessary barriers to the conduct of this important research.

The European experience

This mini-review on European experiences with tackling the problem of organ shortage for transplantation was based on a literature review of predominantly European publications dealing with the issue of organ donation from deceased donors. The authors tried to identify the most significant factors that have demonstrated to impact on donation rates from deceased donors and subsequent transplant successes. These factors include legislative measures (national laws and European Directives), optimization of the donation process, use of expanded criteria donors, innovative preservation and surgical techniques, organizational efforts, and improved allocation algorithms.

Prolongation of myocardial viability by proteasome inhibition during hypothermic organ preservation

Recently, we provided evidence for a possible role of the cardiac proteasome during ischemia, suggesting that a subset of 26S proteasomes is a cell-destructive protease, which is activated as the cellular energy supply declines. Although proteasome inhibition during cold ischemia (CI) reduced injury of ischemic hearts, it remains unknown whether these beneficial effects are maintained throughout reperfusion, and thus, may have pathophysiological relevance. Therefore, we evaluated the effects of epoxomicin (specific proteasome inhibitor) in a rat heterotopic heart transplantation model. Donor hearts were arrested with University of Wisconsin solution (UW) and stored for 12 h/24 h in 4 °C UW±epoxomicin, followed by transplantation. Efficacy of epoxomicin was confirmed by proteasome peptidase activity measurements and analyses of myocardial ubiquitin pools. After 12hCI, troponin I content of UW was lower with epoxomicin. Although all hearts after 12hCI started beating spontaneously, addition of epoxomicin to UW during CI reduced cardiac edema and preserved the ultrastructural integrity of the post-ischemic cardiomyocyte. After 24hCI in UW±epoxomicin, hearts did not regain contractility. When hearts were perfused with epoxomicin during cardioplegia, the cardiac proteasome was inhibited immediately, all of these hearts started beating after 24hCI in UW plus epoxomicin and cardiac edema and myocardial ultrastructure were comparable to hearts after 12hCI. Epoxomicin did not affect markers of lipid peroxidation or neutrophil infiltration in post-ischemic hearts. These data further support the concept that proteasome activation during ischemia is of pathophysiological relevance and suggest proteasome inhibition as a promising approach to improve organ preservation strategies.