A porcine ex vivo paracorporeal model of lung transplantation

Technical Advances Targeting Multiday Preservation of Isolated Ex Vivo Lung Perfusion

Indications for ex vivo lung perfusion (EVLP) have evolved from assessment of questionable donor lungs to treatment of some pathologies and the logistics. Yet up to 3 quarters of donor lungs remain discarded across the globe. Multiday preservation of discarded human lungs on EVLP platforms would improve donor lung utilization rates via application of sophisticated treatment modalities, which could eventually result in zero waitlist mortality. The purpose of this article is to summarize advances made on the technical aspects of the protocols in achieving a stable multiday preservation of isolated EVLP. Based on the evidence derived from large animal and/or human studies, the following advances have been considered important in achieving this goal: ability to reposition donor lungs during EVLP; perfusate adsorption/filtration modalities; perfusate enrichment with plasma and/or donor whole blood, nutrients, vitamins, and amino acids; low-flow, pulsatile, and subnormothermic perfusion; positive outflow pressure; injury specific personalized ventilation strategies; and negative pressure ventilation. Combination of some of these advances in an automatized EVLP device capable of managing perfusate biochemistry and ventilation would likely speed up the processes of achieving multiday preservation of isolated EVLP.

Fluorimetric characterisation of metabolic activity of ex vivo perfused pig hearts

Autofluorescence of tissues and organs is an indicator of the physiological state of cells. The aim of the study was to investigate whether fluorimetric determination of the redox state of the ex vivo perfused pig heart can provide fast online detection of progressive changes in heart muscle tissue. Measurements on six organs perfused in a four-chamber working heart model were performed using a spectroscopic method exploiting the specific and different fluorescence lifetimes of intrinsic fluorophores such as NADH and flavins and providing a means of internal signal referencing. It was shown that the redox potential of heart muscle tissue can be assessed by fluorescence measurement. In the steady-state phase of the beating heart, spectroscopic measurements revealed a change in redox state from an initial constant level to a continuous decrease, accompanied by a decrease in heart performance and indications of changes in electrolyte equilibrium (K(+) concentration). At the same time, troponin I levels in the perfusate increased. The results indicate that fluorimetric determination of heart muscle metabolic activity yields reliable information about the functional status of the ex vivo heart and may be advantageous for the optimisation of ex vivo organ models.