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Machine Perfusion and the Expanding Role of Ex Vivo Organ Perfusion

Op-Med is a collection of original articles contributed by Doximity members.

This year’s American Transplant Congress, ATC 2021, held during June 4–9, had major themes across all organ systems around machine perfusion and the expanding role of ex vivo organ perfusion to increase donor allograft availability and improve transplant outcomes. This theme is unique in that the concept has evolved where it is mainstream, and the acceptance across organs and continents to expand donor organ availability and quality has taken hold.

The field of ex vivo organ perfusion has been led and championed by the University of Toronto lung transplantation group. Separate presentations by Drs. Shaf Keshavjee and Marcello Cypel from Toronto have highlighted their extensive history of over 750 ex vivo lung perfusions. Their experience is leading the world and has been one of the most aggressive and comprehensive aggregate approaches to organ resuscitation to date. Additional expertise and perspective were provided by separate talks from Drs. Copland, Ardehali, and Sanchez on heart and lung machine perfusion.

The expansion of normothermic ex vivo organ perfusion has a strong foothold in abdominal organs as well. Dr. Peter Friend provided a comprehensive presentation on the evolving role of liver ex vivo perfusion and how to expand donor utilization amongst organs. The expanding role of liver ex vivo perfusion will undoubtedly increase numbers as it demonstrates a lower rate of primary non-function and fewer bile duct complications.

Of particular interest is the expanding role of donation after circulatory death (DCD) donors for heart recoveries. There are two evolving strategies that require coordination and attention to detail. Two approaches to DCD heart donation (ex vivo perfusion and normothermic regional perfusion (NRP)) were discussed in a session moderated by Dr. Pagani from the University of Michigan with compelling talks on the ethics of DCD and NRP by Alexandra Glazier from New England Donor Services and the process and implementation of DCD NRP by Dr. Nader Moazami from NYU Langone Medical Center.

What we are seeing is that these machine perfusion techniques are allowing for marked improvement in allograft assessment. This is also leading to novel approaches to improving organ quality, such as de-fatting techniques in the liver, gene delivery, aggressive treatment of infection through high concentration tailored anti-microbial medications administered directly to the organ. Compelling data from the University of Toronto Lung Transplant Program is changing the conversation around what "acceptable ischemic times" mean. Ex vivo lung perfusion is facilitating longer cold ischemic times with seemingly improved outcomes.

There are evolving discussions around the optimum setting to do ex vivo organ assessment, whether or not that is in the recipient center, through the organ perfusion organization, or external third-party party entities. There are complicated pros and cons of each approach, with resource utilization, cost, risk, and organ allocation all entering the conversation.

In aggregate, these concepts around normothermic ex vivo organ perfusion and NRP are rapidly expanding. These organ assessment platforms allow for a more in-depth assessment and resuscitation of donor allografts. These technologies will continue to evolve to active organ treatment in organs undergoing machine perfusion. This assessment and therapeutic approach will undoubtedly continue to expand organ availability, increase organs able to be transplanted and improve transplant outcomes through less ischemia-reperfusion injury and improved allograft function.

Illustration by Jennifer Bogartz

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