Normothermic machine perfusion of kidneys: current strategies and future perspectives.

PURPOSE OF REVIEW: This review aims to summarize the latest original preclinical and clinical articles in the setting of normothermic machine perfusion (NMP) of kidney grafts. RECENT FINDINGS: Kidney NMP can be safely translated into the clinical routine and there is increasing evidence that NMP may be beneficial in graft preservation especially in marginal kidney grafts. Due to the near-physiological state during NMP, this technology may be used as an ex-vivo organ assessment and treatment platform. There are reports on the application of mesenchymal stromal/stem cells, multipotent adult progenitor cells and microRNA during kidney NMP, with first data indicating that these therapies indeed lead to a decrease in inflammatory response and kidney injury. Together with the demonstrated possibility of prolonged ex-vivo perfusion without significant graft damage, NMP could not only be used as a tool to perform preimplant graft assessment. Some evidence exists that it truly has the potential to be a platform to treat and repair injured kidney grafts, thereby significantly reducing the number of declined organs. SUMMARY: Kidney NMP is feasible and can potentially increase the donor pool not only by preimplant graft assessment, but also by ex-vivo graft treatment.

Ex Vivo Mesenchymal Stem Cell Therapy to Regenerate Machine Perfused Organs.

Transplantation represents the treatment of choice for many end-stage diseases but is limited by the shortage of healthy donor organs. Ex situ normothermic machine perfusion (NMP) has the potential to extend the donor pool by facilitating the use of marginal quality organs such as those from donors after cardiac death (DCD) and extended criteria donors (ECD). NMP provides a platform for organ quality assessment but also offers the opportunity to treat and eventually regenerate organs during the perfusion process prior to transplantation. Due to their anti-inflammatory, immunomodulatory and regenerative capacity, mesenchymal stem cells (MSCs) are considered as an interesting tool in this model system. Only a limited number of studies have reported on the use of MSCs during ex situ machine perfusion so far with a focus on feasibility and safety aspects. At this point, no clinical benefits have been conclusively demonstrated, and studies with controlled transplantation set-ups are urgently warranted to elucidate favorable effects of MSCs in order to improve organs during ex situ machine perfusion.

Beyond the organ: lung microbiome shapes transplant indications and outcomes.

OBJECTIVES: The lung microbiome plays a crucial role in the development of chronic lung diseases, which may ultimately lead to the need for lung transplantation. Also, perioperative results seem to be connected with altered lung microbiomes and its dynamic changes providing a possible target for optimizing short-term outcome after transplantation. METHODS: A literature review using MEDLINE, PubMed Central and Bookshelf was performed. RESULTS: Chronic lung allograft dysfunction (CLAD) seems to be influenced and partly triggered by changes in the pulmonary microbiome and dysbiosis, e.g. through increased bacterial load or abundance of specific species such as Pseudomonas aeruginosa. Additionally, the specific indications for transplantation, with their very heterogeneous changes and influences on the pulmonary microbiome, influence long term outcome.Next to composition and measurable bacterial load, dynamic changes in the allografts microbiome also possess the ability to alter long-term outcomes negatively. This review discusses the "new" microbiome after transplantation and the associations with direct postoperative outcome. With the knowledge of these principles the impact of alterations in the pulmonary microbiome in hindsight to CLAD and possible therapeutic implications are described and discussed. CONCLUSIONS: The aim of this review is to summarize the current literature regarding pre- and postoperative lung microbiomes and how they influence different lung diseases on their progression to failure of conservative treatment. This review provides a summary of current literature for centers looking for further options in optimizing lung transplant outcomes and highlights possible areas for further research activities investigating the pulmonary microbiome in connection to transplantation.

Perfusate Enzymes and Platelets Indicate Early Allograft Dysfunction After Transplantation of Normothermically Preserved Livers.

BACKGROUND: Normothermic machine perfusion (NMP) has become a clinically established tool to preserve livers in a near-physiological environment. However, little is known about the predictive value of perfusate parameters toward the outcomes after transplantation. METHODS: Fifty-five consecutive NMP livers between 2018 and 2019 were included. All of the livers were perfused on the OrganOx metra device according to an institutional protocol. Transplant and perfusion data were collected prospectively. RESULTS: Forty-five livers were transplanted after NMP. Five livers stem from donors after circulatory death and 31 (68.9%) from extended criteria donors. Mean (SD) cold ischemia time was 6.4 (2.3) h; mean (SD) total preservation time was 21.4 (7.1) h. Early allograft dysfunction (EAD) occurred in 13 of 45 (28.9%) patients. Perfusate aspartate aminotransferase (P = 0.008), alanine aminotransferase (P = 0.006), lactate dehydrogenase (P = 0.007) and their development over time, alkaline phosphatase (P = 0.013), and sodium (P = 0.016) correlated with EAD. Number of perfusate platelets correlated with cold ischemia time duration and were indicative for the occurrence of EAD. Moreover, von Willebrand Factor antigen was significantly higher in perfusates of EAD livers (P < 0.001), and Δ von Willebrand factor antigen correlated with EAD. Although perfusate lactate and glucose had no predictive value, EAD was more likely to occur in livers with lower perfusate pH (P = 0.008). ΔPerfusate alkaline phosphatase, Δperfusate aspartate aminotransferase, Δperfusate alanine aminotransferase, and Δperfusate lactate dehydrogenase correlated closely with model for early allograft function but not liver graft assessment following transplantation risk score. Bile parameters correlated with extended criteria donor and donor risk index. CONCLUSIONS: Biomarker assessment during NMP may help to predict EAD after liver transplantation. The increase of transaminases and lactate dehydrogenase over time as well as platelets and vWF antigen are important factors indicative for EAD.

Dealing With Liver Transplantation during Coronavirus Disease 2019 Pandemic: Normothermic Machine Perfusion Enables for Donor, Organ, and Recipient Assessment: A Case Report.

The coronavirus disease 2019 (COVID-19) pandemic has changed life on a global scale. The numbers of transplantations have plummeted as a result of fear of disease transmission, recipient coronavirus disease 2019 infection, priority shift, and resource limitations. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) complicates transplantation because donor testing, (re)allocation of limited resources, and recipient testing may exceed permissible ischemia times. Normothermic machine perfusion (NMP) helps safely prolong liver preservation up to 38 hours. Additional time is essential under the current circumstances. Here we present the case of a 29-year-old liver transplant recipient in whom prolonged liver preservation required for SARS-CoV-2 screening was accomplished through NMP. Donor and recipient test results for SARS-CoV-2 were negative, and intensive care unit capacity was eventually available. The surgical procedure and postoperative course were uneventful. NMP can extend preservation times in liver transplantation while awaiting SARS-CoV-2 test results and available intensive care unit capacity.

A Retrospective Propensity Score Matched Analysis Reveals Superiority of Hypothermic Machine Perfusion over Static Cold Storage in Deceased Donor Kidney Transplantation.

Hypothermic machine perfusion (HMP) has been introduced as an alternative to static cold storage (SCS) in kidney transplantation, but its true benefit in the clinical routine remains incompletely understood. The aim of this study was to assess the effect of HMP vs. SCS in kidney transplantation. All kidney transplants performed between 08/2015 and 12/2019 (n = 347) were propensity score (PS) matched for cold ischemia time (CIT), extended criteria donor (ECD), gender mismatch, cytomegalovirus (CMV) mismatch, re-transplantation and Eurotransplant (ET) senior program. A total of 103 HMP and 103 SCS instances fitted the matching criteria. Prior to PS matching, the CIT was longer in the HMP group (17.5 h vs. 13.3 h; p < 0.001), while the delayed graft function (DGF) rates were 29.8% and 32.3% in HMP and SCS, respectively. In the PS matched groups, the DGF rate was 64.1% in SCS vs. 31.1% following HMP: equivalent to a 51.5% reduction of the DGF rate (OR 0.485, 95% CI 0.318-0.740). DGF was associated with decreased 1- and 3-year graft survival (100% and 96.3% vs. 90.8% and 86.7%, p = 0.001 and p = 0.008) or a 4.1-fold increased risk of graft failure (HR = 4.108; 95% CI: 1.336-12.631; p = 0.014). HMP significantly reduces DGF in kidney transplantation. DGF remains a strong predictor of graft survival.