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Hypothermic machine perfusion (HMP) has become the new gold standard in clinical donor kidney preservation and a promising novel strategy in higher risk donor livers in several countries. As shown by meta-analysis for the kidney, HMP decreases the risk of delayed graft function (DGF) and improves graft survival. For the liver, HMP immediately prior to transplantation may reduce the chance of early allograft dysfunction (EAD) and reduce ischemic sequelae in the biliary tract. Ischemia-reperfusion injury (IRI), unavoidable during transplantation, can lead to massive cell death and is one of the main causes for DGF, EAD or longer term impact. Molecular mechanisms that are affected in IRI include levels of hypoxia inducible factor (HIF), induction of cell death, endothelial dysfunction and immune responses. In this review we have summarized and discussed mechanisms on how HMP can ameliorate IRI. Better insight into how HMP influences IRI in kidney and liver transplantation may lead to new therapies and improved transplant outcomes.

Assessment of specific β-cell death can be used to determine the quality and viability of pancreatic islets prior to transplantation and hence predict the suitability of the pancreas for isolation. Recently, several groups have demonstrated that unmethylated insulin (INS)-DNA is correlated to β-cell death in type 1 diabetes patients and during clinical islet isolation and subsequent transplantation. Here, we present a step-by-step protocol of our novel developed method for quantification of the relative amount of unmethylated INS-DNA using methylation sensitive restriction enzyme digital polymerase chain reaction This method provides a novel and sensitive way to quantify the relative amount of β-cell derived unmethylated INS-DNA in cellular lysate. We therefore suggest that this technique can be of value to reliably determine the purity of an islet preparation and may also serve as a measure of the quality of islets prior to transplantation measuring unmethylated INS-DNA as a reflection of the relative amount of lysed β-cells.

This thesis demonstrates that kidneys from DCD donors can be fully embraced, and that the perception of DCD kidney transplantation being inferior to DBD kidney transplantation – mainly motivated by concerns regarding high incidences of DGF and EGL – is no longer justified. One explanation for this phenomenon is that outcomes of transplanted DCD kidneys have improved over time, with a similar incidence of EGL following DBD and DCD kidney transplantation in the current era. Another explanation is that both donor types have different biological responses to DGF: whilst DGF severely impacts on DBD graft survival, DGF has no impact on DCD graft survival. This difference relates to donor type-specific regulation of resilience and pro-inflammatory pathways benefitting the DCD graft and its outcomes. As such, the persistent high incidence of DGF in DCD grafts should not be regarded an impediment toward the use of these donor kidneys.This thesis additionally explores a series of physiological and methodological contrasts between preclinical and clinical I/R injury, that all may contribute to the impaired translatability of preclinical studies in clinical practice. Awareness of these pitfalls may help to improve study designs in future research, bringing us one step closer towards bridging the translational gap.