Novel oxygenation technique for hypothermic machine perfusion of liver grafts: Validation in porcine Donation after Cardiac Death (DCD) liver model.

BACKGROUND: Hypothermic oxygenated machine perfusion improves outcomes in Liver Transplantation, but application is limited as O2 is supplied by a stationary circuit. A novel technique of O2 "pre-charge" in a portable pump would broaden use and further mitigate ischemia damage from organ transport. METHODS: Porcine DCD livers were randomized to static cold storage (SCS, n = 8) or hypothermic machine perfusion (HMP). HMP was stratified into HMP-O2 (n = 5), non-O2 open to air HMP-RA (n = 5), and non-O2 with sealed lids or no air HMP-NA (n = 5). HMP-O2 was "pre-charged" using 100% O2 delivered at 10 L/min over 15 min. Perfusate and tissue O2 tension (pO2), liver biopsies, and fluid chemistries were analyzed. RESULTS: "Pre-charge" achieves sustained tissue and perfusate pO2 vs others. HMP-O2 results in decreased markers of hepatocyte injury: ALT (p < 0.05) and LDH (p < 0.05), lower expression of CRP and higher expression of SOD1 vs SCS. This suggests decreased inflammation and improved ROS scavenging. CONCLUSIONS: "Pre-charge" is an effective technique, which allows portability and transport without an O2 source and improves graft parameters.

A novel ex-vivo porcine renal xenotransplantation model using a pulsatile machine preservation system.

BACKGROUND: Animal models to investigate pathophysiology and xenotransplantation require complex techniques and significant animal utilization. The aim of the study was to develop a reliable ex-vivo technique to test xenotransplant interventions. MATERIAL/METHODS: Miniature Swine being utilized for a nonsurvival study acted as donor animals. Kidneys were flushed and rapidly explanted and chilled to 4°C. Kidneys were assigned to be the control (CK) (n=3) and the mate were used as a Xenograft Kidneys (XK) (n=3). Kidneys were perfused on separate Waters RM 3 perfusion devices. Perfusion temperature was 35-37°C and pressure was 100-110/60-70 mmHg at 60 pulses per minute. CKs were reperfused with autologous blood collected at the time of organ procurement. XKs were reperfused using freshly donated whole human blood. Physical characteristics, urine output were recorded. Core needle biopsies were obtained and examined by a blinded pathologist for evidence of antibody mediated rejection. RESULTS: XK kidneys demonstrated homogenous reperfusion which rapidly became patchy at 5-7 minutes. XK kidneys had become complete black and thrombosed by 60-70 minutes. XK biopsies demonstrated peritubular capillaritis. CK kidneys demonstrated homogenous reperfusion and urine production. H&E stain of CKs only demonstrated nonspecific inflammation. CONCLUSIONS: Our ex-vivo porcine xenotransplant model shows early promise as a tool for studying Xeno- associated hyperacute rejection. This technique saves resources and animal utilization.

Hypothermic machine preservation attenuates ischemia/reperfusion markers after liver transplantation: preliminary results.

BACKGROUND: Hypothermic machine perfusion (HMP) has shown significant benefits in renal transplantation but is still in its infancy in liver transplantation. Potential benefits include diminished preservation injury and improved early graft function. METHODS: We analyzed liver tissue and effluent collected during our Phase 1 trial of liver HMP. Liver allografts underwent HMP for 4-7 h using dual centrifugal perfusion with Vasosol solution at 4-8°C were transplanted and compared with cold stored (CS) transplant controls. Histology, reverse transcription-polymerase chain reaction (RT-PCR), and immunohistochemistry on liver biopsies compared histology and expression of early proinflammatory cytokines, IL-8 and TNF-α, and intracellular adhesion molecule-1 (ICAM-1). Gel electrophoresis was used to evaluate effluent protein content representing residual metabolism. RESULTS: We saw no differences between HMP and CS in early histologic findings after reperfusion. RT-PCR of reperfusion biopsy samples in the CS group showed high expression of proinflammatory cytokines and ICAM-1. This up-regulation was significantly attenuated by HMP (ICAM-1; P = 0.0152) (IL-8; P = 0.0014) (TNF-α; P = 0.0284). This was confirmed with immunohistochemistry. Albumin was identified in the perfusate throughout HMP. CONCLUSIONS: HMP significantly reduced proinflammatory cytokine expression compared with CS controls. Further studies of human liver HMP with detailed molecular investigations are now warranted to elucidate benefits of HMP in liver transplantation.

Digital imaging of extended criteria donor livers to facilitate placement and utilization.

The disparity between organ supply and demand has necessitated more aggressive use of livers from extended criteria donors. Organ sharing between donor service areas and transplant centers in other regions is common. Confidence in the graft quality is greatly improved with a digital image taken in conjunction with the recovery surgeon's report and biopsy data. Three cases in which digital images of various levels of quality allowed the recipient's surgery to proceed, minimized the cold ischemia time, and yielded excellent outcomes are described. Another case in which a picture was not available and the liver was discarded after importation is also presented for comparison.

Pulsatile machine perfusion with Vasosol solution improves early graft function after cadaveric renal transplantation.

BACKGROUND: Cold storage is the most common method of preservation in renal transplantation, but pulsatile machine perfusion (MP) is increasingly used for purposes of ex vivo assessment and resuscitation of high risk allografts. Vasosol (VSL) MP solution (MPS) (Pike Laboratories Inc, Eagle, PA) is a novel perfusate with enhanced vasodilatory and antioxidant capacity. We report our experience with VSL in machine preservation of renal allografts. METHODS: Locally procured cadaver kidney pairs undergoing MP were randomized to VSL or control solution (Belzer MPS; Trans-Med, Elk River, MN). En bloc perfusion was performed according to standard MP procedures. Transplantation was performed at 1 of 12 local transplant centers. Donor and recipient data were collected prospectively. RESULTS: Data from 162 transplanted kidneys were analyzed. A total of 82 renal grafts were perfused with VSL, and 80 were perfused with control solution. No organs were lost secondary to the technique of MP. There was no difference in donor or recipient age between groups. Kidneys perfused with VSL exhibited significantly higher rates of immediate function and significantly less delayed graft function (12.2% vs. 21.2%). Discharge creatinine and length of stay were also significantly improved in the VSL group. One-year graft and patient survivals were equivalent (95%) in both groups. CONCLUSIONS: VSL improved early graft function and shortened the length of stay compared with Belzer MPS. Further improvement in preservation solutions in conjunction with pulsatile perfusion shows promise in improving early outcomes after renal transplantation, especially for extended criteria donor kidneys.