Prolonged hypothermic machine perfusion enables daytime liver transplantation - an IDEAL stage 2 prospective clinical trial

Abstract

Background: Liver transplantation is traditionally performed around the clock to minimize organ ischemic time. However, the prospect of prolonging preservation times holds the potential to streamline logistics and transform liver transplantation into a semi-elective procedure, reducing the need for nighttime surgeries. Dual hypothermic oxygenated machine perfusion (DHOPE) of donor livers for 1-2 h mitigates ischemia-reperfusion injury and improves transplant outcomes. Preclinical studies have shown that DHOPE can safely extend the preservation of donor livers for up to 24 h.

Methods: We conducted an IDEAL stage 2 prospective clinical trial comparing prolonged (≥4 h) DHOPE to conventional (1-2 h) DHOPE for brain-dead donor livers, enabling transplantation the following morning. Liver allocation to each group was based on donor hepatectomy end times. The primary safety endpoint was a composite of all serious adverse events (SAE) within 30 days after transplantation. The primary feasibility endpoint was defined as the number of patients assigned and successfully receiving a prolonged DHOPE-perfused liver graft. Trial registration at: WHO International Clinical Trial Registry Platform, number NL8740.

Findings: Between November 1, 2020 and July 16, 2022, 24 patients were enrolled. The median preservation time was 14.5 h (interquartile range [IQR], 13.9-15.5) for the prolonged group (n = 12) and 7.9 h (IQR, 7.6-8.6) for the control group (n = 12; p = 0.01). In each group, three patients (25%; 95% CI 3.9-46%, p = 1) experienced a SAE. Markers of ischemia-reperfusion injury and oxidative stress in both perfusate and recipients were consistently low and showed no notable discrepancies between the two groups. All patients assigned to either the prolonged group or control group successfully received a liver graft perfused with either prolonged DHOPE or control DHOPE, respectively.

Interpretation: This first-in-human clinical trial demonstrates the safety and feasibility of DHOPE in prolonging the preservation time of donor livers to enable daytime transplantation. The ability to extend the preservation window to up to 20 h using hypothermic oxygenated machine preservation at a 10 °C temperature has the potential to reshape the landscape of liver transplantation.

Funding: University Medical Center Groningen, the Netherlands.

Keywords: Clinical trial; Hypothermic machine perfusion; IDEAL stage 2; Liver transplantation; Machine perfusion; Machine preservation.

Fig. 1

Consort flow diagram for all recipients enrolled in the trial. DCD, donation after circulatory death; DHOPE, dual hypothermic oxygenated machine perfusion; MELD, model for end-stage liver disease.

Fig. 2

Cold ischemia, preservation, and recipient transplant surgery times according to the treatment group. Cold ischemia time (CIT), dual hypothermic oxygenated machine perfusion (DHOPE) preservation time, and recipient transplant surgery duration is plotted for each individual procedure for the control group (n = 12), and for the prolonged preservation intervention group (n = 12). Donor hepatectomy end time (which determined the assignment to each study arm) as well as the recipient reperfusion time is indicated for each case. Two liver retransplantations in each group are indicated with an asterisk.

Fig. 3

Preservation times and perfusate markers duringdual hypothermic oxygenatedmachine perfusion(DHOPE)according to the treatment group. Preservation times (A) are plotted individually for the control group (n = 12), and for the prolonged preservation intervention group (n = 12). The middle line is the median, the lower and upper whisker represent the first and third quartiles. Individual values during perfusion are presented for lactate (B), cell-free DNA (cfDNA; C), tumor necrosis factor alpha (TNF-a; D), interleukin 6 (IL-6; E), thiobarbituric acid reactive substances (TBARS; F), intercellular adhesion molecule 1 (ICAM-1; G), high-mobility group box 1 (HMGB-1; H), hyaluronic acid (I), D-dimer (J), and von Willebrand Factor (K). Individual levels of adenosine triphosphate (ATP) of liver biopsies at baseline (before start DHOPE) and at the end of perfusion (end DHOPE) (L).

Fig. 4

Serum markers before and after reperfusion in the recipient according to the treatment group. Indocyanine green (ICG) plasma disappearance rates after reperfusion (A) are plotted individually for the control group (n = 12), and for the prolonged preservation intervention group (n = 12). The middle line is the median, the lower and upper whisker represent the first and third quartiles. Lactate clearance in the recipient during the first 24 h after reperfusion with median and 95% confidence interval (B). Individual values before surgery (anesthesia), 5 min after reperfusion, and at end of surgery are presented for cell-free DNA (cfDNA; C), intercellular adhesion molecule 1 (ICAM-1; D), thiobarbituric acid reactive substances (TBARS; E), high-mobility group box 1 (HMGB-1; F), interleukin 6 (IL-6; G), tumor necrosis factor alpha (TNF-a; H), D-dimer (I), hyaluronic acid (J), tissue plasminogen activator (tPA; K), and von Willebrand Factor (L).

Fig. 5

Postoperative biochemistry after transplantation in the recipient and histological analysis of liver biopsies after reperfusion according to the treatment group. Values for alanine aminotransferase (ALT; A), aspartate aminotransferase (AST; B), international normalized ratio (INR; C), total bilirubin (D), gamma glutamyl transferase (yGT; E), and alkaline phosphatase (ALP; F) are plotted individually for the control group (n = 12), and for the prolonged preservation intervention group (n = 12) up to 10 days after transplantation. The middle line is the median, the lower and upper whisker represent the 95% confidence interval. Representative images from histological assessment of liver biopsies after reperfusion in the recipient are depicted for the control group and the prolonged preservation group (G–I). Hematoxylin and eosin (HE) stain showed some subcapsular neutrophils and minimal hepatocellular injury in controls as well as in the prolonged group (G). Von Willebrand Factor (VWF) staining showed no significant vascular endothelial cell activation in control (H) or prolonged perfusion groups. Caspase-3 staining did not reveal apoptosis in any of the groups (I).