Machine Perfusion Enables 24-h Preservation of Vascularized Composite Allografts in a Swine Model of Allotransplantation.

The current gold standard for preserving vascularized composite allografts (VCA) is 4°C static cold storage (SCS), albeit muscle vulnerability to ischemia can be described as early as after 2 h of SCS. Alternatively, machine perfusion (MP) is growing in the world of organ preservation. Herein, we investigated the outcomes of oxygenated acellular subnormothermic machine perfusion (SNMP) for 24-h VCA preservation before allotransplantation in a swine model.

Zebrafish as a high throughput model for organ preservation and transplantation research.

Despite decades of effort, the preservation of complex organs for transplantation remains a significant barrier that exacerbates the organ shortage crisis. Progress in organ preservation research is significantly hindered by suboptimal research tools that force investigators to sacrifice translatability over throughput. For instance, simple model systems, such as single cell monolayers or co-cultures, lack native tissue structure and functional assessment, while mammalian whole organs are complex systems with confounding variables not compatible with high-throughput experimentation.

Continuous versus Pulsatile Flow in 24-Hour Vascularized Composite Allograft Machine Perfusion in Swine: A Pilot Study.

Introduction: Multiple perfusion systems have been investigated on vascularized composite allografts, with various temperatures and different preservation solutions, most using continuous flow (CF). However, physiological flow is pulsatile and provides better outcomes in kidney and lung ex vivo perfusions. The objective of this pilot study is to compare pulsatile flow (PF) with CF in our 24-h subnormothermic machine perfusion protocol for swine hindlimbs.

Pan-caspase inhibition during normothermic machine perfusion of discarded livers mitigates innate immune responses.

Access to liver transplantation is limited by a significant organ shortage. The recent introduction of machine perfusion technology allows surgeons to monitor and assess ex situ liver function prior to transplantation. However, many donated organs are of inadequate quality for transplant, though opportunities exist to rehabilitate organ function with adjunct therapeutics during normothermic machine perfusion.

Partial freezing of rat livers extends preservation time by 5-fold.

The limited preservation duration of organs has contributed to the shortage of organs for transplantation. Recently, a tripling of the storage duration was achieved with supercooling, which relies on temperatures between -4 and -6 °C. However, to achieve deeper metabolic stasis, lower temperatures are required.

Exceeding the Limits of Static Cold Storage in Limb Transplantation Using Subnormothermic Machine Perfusion.

Background:  For 50 years, static cold storage (SCS) has been the gold standard for solid organ preservation in transplantation. Although logistically convenient, this preservation method presents important constraints in terms of duration and cold ischemia-induced lesions. We aimed to develop a machine perfusion (MP) protocol for recovery of vascularized composite allografts (VCA) after static cold preservation and determine its effects in a rat limb transplantation model.

Non-invasive quantification of the mitochondrial redox state in livers during machine perfusion.

Ischemia reperfusion injury (IRI) is a critical problem in liver transplantation that can lead to life-threatening complications and substantially limit the utilization of livers for transplantation. However, because there are no early diagnostics available, fulminant injury may only become evident post-transplant. Mitochondria play a central role in IRI and are an ideal diagnostic target.

Viability testing of discarded livers with normothermic machine perfusion: Alleviating the organ shortage outweighs the cost.

Background: Over 700 donor livers are discarded annually in the United States due to high risk of poor graft function. The objective of this study was to determine the impact of using normothermic machine perfusion to identify transplantable livers among those currently discarded.

Study Design: A series of 21 discarded human livers underwent viability assessment during normothermic machine perfusion.

Subzero non-frozen preservation of human livers in the supercooled state.

Preservation of human organs at subzero temperatures has been an elusive goal for decades. The major complication hindering successful subzero preservation is the formation of ice at temperatures below freezing. Supercooling, or subzero non-freezing, preservation completely avoids ice formation at subzero temperatures.

Cell release during perfusion reflects cold ischemic injury in rat livers.

The global shortage of donor organs has made it crucial to deeply understand and better predict donor liver viability. However, biomarkers that effectively assess viability of marginal grafts for organ transplantation are currently lacking. Here, we showed that hepatocytes, sinusoidal endothelial, stellate, and liver-specific immune cells were released into perfusates from Lewis rat livers as a result of cold ischemia and machine perfusion.

Bulk Droplet Vitrification for Primary Hepatocyte Preservation.

Vitrification is a promising ice-free alternative for classic slow-freezing (at approximately 1 °C/min) cryopreservation of biological samples. Vitrification requires extremely fast cooling rates to achieve transition of water into the glass phase while avoiding injurious ice formation. Although pre-incubation with cryoprotective agents (CPA) can reduce the critical cooling rate of biological samples, high concentrations are generally needed to enable ice-free cryopreservation by vitrification.

Pumping new life into old ideas: Preservation and rehabilitation of the liver using ex situ machine perfusion.

Recent advances in machine perfusion technology have reinvigorated the field of liver transplantation with the possibilities of vastly improving the efficiency and safety of the life-saving procedure. With this improved preservation technology, transplant surgeons are now able to use previously untransplantable donor livers without significantly compromising patient outcomes. Early clinical studies demonstrate the ability to extend preservation times and assess a graft's potential viability using normothermic machine perfusion, in addition to restoring the energy supply in donor livers by supporting metabolism through circulation of vital nutrients and blood-based oxygen carriers.

Supercooling extends preservation time of human livers.

The inability to preserve vascular organs beyond several hours contributes to the scarcity of organs for transplantation. Standard hypothermic preservation at +4 °C (refs. ) limits liver preservation to less than 12 h.

Systems engineering the organ preservation process for transplantation.

Improving organ preservation and extending the preservation time would have game-changing effects on the current practice of organ transplantation. Machine perfusion has emerged as an improved preservation technology to expand the donor pool, assess graft viability and ensure adequate graft function. However, its efficacy in extending the preservation time is limited.

Bulk Droplet Vitrification: An Approach to Improve Large-Scale Hepatocyte Cryopreservation Outcome.

Loss of hepatocyte viability and metabolic function after cryopreservation is still a major issue. Although vitrification is a promising alternative, it has generally been proven to be unsuitable for vitrification of large cell volumes which is required for clinical applications. Here, we propose a novel bulk droplet (3-5 mm diameter) vitrification method which allows high throughput volumes (4 mL/min), while using a low preincubated CPA concentration (15% v/v) to minimize toxicity and loss of cell viability and function.