Title : Current techniques for the ex vivo perfusion of free tissue flaps systematic review and meta analysis
Abstract:
Background: Access to healthy living tissue in the lab has always been an essential substrate for experimentation across the breadth of medical research. Historically originally limited to live animal studies using small mammals such as rats, and subsequently more anatomically and physiologically analogous animals such as pigs, recent developments in cellular technologies have allowed for the in-vitro production of human tissue, such as the development of spheroid and organoid technologies, which allow for the study of 3D cell structures in a microenvironment that mimics the in-vivo environment. However, they remain unable to completely recreate in-vivo conditions, including issues of scale and maintaining macroscopic tissue architecture.
The advent of technology such as Extra Corporeal Membrane Oxygenation (ECMO) offers the potential for the effective perfusion of large volumes of donor tissue in the lab, which addresses these issues. There is substantial literature looking at subnormothermic perfusion using alternative pump methods with synthetic or substitute perfusates in non-human tissues – however there is a paucity of data assessing the application of this technology to human tissue in a normothermic context with human blood products
Method: A literature review was conducted using the MEDLINE and EMBASE databases, identifying 11 articles comprising a total of 135 specimens (5 human, 130 animal) across 1 systematic review, 1 case series and 7 technical studies. Of these, 1 studies examined human tissue and 2 studies used ECMO as perfusion method. The studies were stratified by tissue type, perfusate, pump type and temperature.
Results: Across all perfusion methods, tissue survived for a range of 12 hours to 7 days, with mean maximum survival of 17 hours in porcine studies and 7 days in the human study. Mean maximum survival 4 days on ECMO perfusion, 17 hours on centrifugal pump and 6 hours on gravity-assisted pump.
