New Techniques for Optimization of Donor Lungs/Hearts

Devices for donor lung preservation

INTRODUCTION

Lung transplantation is the gold standard for the treatment of end stage lung disease but is limited by donor availability. Recently, the donor pool has seen significant expansion with liberalization of donor criteria. However, extended criteria donors can require additional time to prepare for implantation, necessitating additional preservation time of donor lungs.

AREAS COVERED

We present a review of current lung transplant storage strategies including new methodologies and technological advancements. The current standard, static cold storage, is a simple and cost-effective method of preserving grafts, but offers little flexibility with limited ability to mitigate ischemic-reperfusion injury, inflammation, and hypothermic tissue damage. Novel ex vivo lung perfusion (EVLP) devices, TransMedics OCS and XVIVO perfusion systems, extend preservation time by perfusing, and ventilating donor lungs while simultaneously allowing for evaluation of lung viability. Perfusate, preservation solutions, additives, temperature regulation, and assessment of organ damage are all critical components when evaluating the success and outcomes of these devices.

EXPERT OPINION

EVLP devices are more costly and often require additional resources and personnel support compared to static cold storage, but may provide the opportunity to extend preservation time, perform functional assessment, mitigate ischemic injury, and optimize extended criteria donors.

Methane supplementation improves graft function in experimental heart transplantation

BACKGROUND

Maintenance of cell viability during cold storage is a key issue in organ transplantation. Methane (CH₄) bioactivity has recently been recognized in ischemia/reperfusion conditions; we therefore hypothesized that cold storage in CH₄-enriched preservation solution can provide an increased defense against organ dysfunction during experimental heart transplantation (HTX).

METHODS

The hearts of donor Lewis rats were stored for 60 minutes in cold histidine-tryptophan-ketoglutarate (Custodiol [CS]) or CH₄-saturated CS solution (CS-CH₄) (n = 12 each). Standard heterotopic HTX was performed, and 60 minutes later, the left ventricular (LV) pressure-volume relationships LV systolic pressure (LVSP), systolic pressure increment (dP/dtmax), diastolic pressure decrement, and coronary blood flow (CBF) were measured. Tissue samples were taken to detect proinflammatory parameters, structural damage (by light microscopy), endoplasmic reticulum (ER) stress, and apoptosis markers (CCAAT/enhancer binding protein [C/EBP] homologous protein, GRP78, glycogen synthase kinase-3β, very low-density lipoprotein receptor, caspase 3 and 9, B-cell lymphoma 2, and bcl-2-like protein 4), whereas mitochondrial functional changes were analyzed by high-resolution respirometry.

RESULTS

LVSP and dP/dtmax increased significantly at the largest pre-load volumes in CS-CH₄ grafts as compared with the CS group (114.5 ± 16.6 mm Hg vs 82.8 ± 4.6 mm Hg and 3,133 ± 430 mm Hg/s vs 1,739 ± 169 mm Hg/s, respectively); the diastolic function and CBF (2.4 ± 0.4 ml/min/g vs 1.3 ± 0.3 ml/min/g) also improved. Mitochondrial oxidative phosphorylation capacity was more preserved (58.5 ± 9.4 pmol/s/ml vs 27.7 ± 6.6 pmol/s/ml), and cytochrome c release was reduced in CS-CH₄ storage. Signs of HTX-caused myocardial damage, level of ER stress, and the transcription of proapoptotic proteins were significantly lower in CS-CH₄ grafts.

CONCLUSION

The addition of CH₄ during 1 hour of cold storage improved early in vitro graft function and reduced mitochondrial dysfunction and activation of inflammation. Evidence shows that CH₄ reduced ER stress-linked proapoptotic signaling.