Citations

Background: Normothermic machine perfusion (NMP) may reduce preservation injury in donation-after-circulatory-death (DCD) liver transplantation, but its association with patient-centered recovery and longer-term graft survival remains uncertain. Study Design: We retrospectively analyzed 306 consecutive adult DCD liver transplant recipients at a single center from January 2019 through December 2022, comparing NMP (n=95) with static cold storage (SCS; n=211). The primary endpoint was days alive and out of hospital at 365 days (DAOH365). Quasi-Poisson regression evaluated factors associated with DAOH365, and Cox regression evaluated graft survival. Propensity-matched and calendar-year sensitivity analyses assessed measured confounding. Results: Median DAOH365 was 357.0 (352.0, 360.0) days with NMP versus 353.0 (336.0, 359.0) with SCS (p<0.001), but preservation strategy was not independently associated with DAOH365 (adjusted rate ratio 1.02; p=0.331). NMP recipients had less early allograft dysfunction (35.8% vs 59.7%; p<0.001), ischemic cholangiopathy (4.2% vs 23.7%; p<0.001), and retransplantation within 2 years (0.0% vs 6.6%; p=0.007). Two-year patient survival did not differ significantly. NMP was associated with improved twoF-year graft survival (HR 2.9, 95% CI 1.23–6.87; p=0.015), an association maintained in propensity-matched and calendar-year sensitivity analyses. Adjusted total 1-year costs did not differ (p=0.512). Conclusions: In this single-center DCD cohort, NMP was associated with superior 2-year graft survival but not independently with DAOH365. These hypothesis-generating findings support multicenter prospective evaluation of NMP using both graft survival and patient-centered recovery endpoints.

ABSTRACT Background With increasing use of donation after circulatory death (DCD) donor grafts, the need for accurate risk‐stratification tools in liver transplantation has become critical. Machine perfusion has been shown to improve both graft and patient survival. However, existing prediction models were developed in the static cold storage (SCS) era and their accuracy when using machine perfusion remains unknown. Our study aims to study if current scoring systems can predict graft and patient survival for DCD livers preserved using normothermic machine perfusion (NMP). Methods This was a retrospective study of patient and graft survival in a two‐center U.S. DCD NMP cohort ( n = 532) between January 2022 and December 2024. Predicted graft and patient survival rates were obtained from established risk scoring systems, including the United Kingdom DCD risk score (UK‐DCD), Early Allograft Dysfunction (EAD) Olthoff score, Liver Graft Assessment Following Transplantation (L‐GrAFT 7 ) score, Donor Risk Index (DRI), Balance of Risk (BAR) score, and Survival Outcomes Following Liver Transplant (SOFT) score. Model discrimination was assessed using receiver operating characteristic (ROC) curves (C‐statistics). Survival outcomes across risk strata were estimated and compared using Kaplan‐Meier (KM) analysis. Results Across scoring systems, predicted survival consistently underestimated actual graft and patient survival in the NMP DCD cohort. The DRI, SOFT, EAD and L‐GrAFT 7 did not demonstrate predictive value. UK‐DCD predicted ≤85% and <40% 1‐year graft survival for its high‐risk and “futile” groups, whereas observed rates were 93.7% and 86.8%. BAR low‐risk predicted >60% 5‐year survival but 94.2% was observed; the high‐risk group predicted <60% and observed was 53.3%. Despite underestimations and generally poor C‐statistics, in KM stratification, high‐risk groups still showed statistical differences in the UK‐DCD categories ( p = 0.007), and in SOFT score groups ( p < 0.001). No statistical difference was seen in BAR ( p = 0.36), DRI ( p = 0.36), EAD ( p = 0.12), or L‐GrAFT 7 ( p = 0.75). Conclusion Existing liver transplant risk scores show limited predictive value for donor‐related risk factors in the NMP era, whereas recipient‐related factors remain somewhat predictive, despite overestimating risk. Early allograft dysfunction metrics were not reliable predictors of short or long‐term outcomes. Future risk models should integrate machine‐perfusion parameters and refined donor variables to reflect outcomes more accurately in contemporary DCD liver transplantation.

ABSTRACT Despite the annual increase in liver transplants, a persistent disparity between suitable donors and recipients continues to challenge the transplant community. The introduction of machine perfusion emerged as a novel approach to organ preservation. This technique, which utilizes extended criteria donor grafts, is expected to reduce rejection rates and expand the donor pool. Its principle, like that of any ex vivo machine perfusion, is based on the continuous supply of nutrients and oxygen to maintain cellular metabolism while interrupting anaerobic processes. This helps prevent conditions such as ischemia-reperfusion injury, early graft dysfunction, and ischemic cholangiopathy, which can lead to graft loss and the need for retransplantation. There are two main modes of ex vivo machine perfusion: hypothermic and normothermic, differentiated by the operating temperature. Utilizing ex situ perfusion machines presents a promising opportunity to increase liver graft usage and reduce waitlist times. However, it is crucial to evaluate how much this technology would raise the overall cost of transplants. In Brazil, implementing a machine perfusion program may encounter unique challenges not seen in other countries. These challenges include limited access to the healthcare system for high-risk liver transplant candidates, long waiting lists, inadequate support for organ donors, reliance solely on deceased brain-dead donors, since donation after cardiac death is not ethically accepted, and geographical barriers.

Objective: To determine whether normothermic machine perfusion (NMP) mitigates the historical survival disadvantage of donation after circulatory death (DCD) liver transplantation compared with donation after brain death (DBD) livers. Summary Background Data: NMP has improved outcomes in DCD LT compared with static cold storage (SCS), but whether it eliminates the historical disparity relative to DBD transplantation remains uncertain. Methods: We performed a retrospective cohort study of adult LT at a high-volume US center between 2019 and 2024. Outcomes of DCD-NMP grafts were compared with DCD-SCS, DBD-SCS, and DBD-NMP grafts. Primary outcomes were 1-year graft and patient survival. Secondary outcomes included early allograft dysfunction (EAD), hepatic artery thrombosis (HAT), primary nonfunction (PNF), biliary anastomotic strictures (BAS), and ischemic cholangiopathy (IC). Results: Among 1338 liver transplants (DBD-SCS n=527; DBD-NMP n=142; DCD-SCS n=255; DCD-NMP n=414), DCD-NMP grafts had a significantly higher donor risk profile ( P <0.001) yet demonstrated survival comparable to DBD transplantation. One-year graft survival was 94% for DCD-NMP versus 93% for DBD grafts and 86% for DCD-SCS, and 1-year patient survival was 98% for DCD-NMP versus 94% to 95% for DBD grafts and 93% for DCD-SCS. In adjusted models, DCD-SCS was associated with increased hazards of graft loss (adjusted hazard ratio: 2.48; P <0.001) and death (adjusted hazard ratio: 2.39; P =0.004), whereas DBD groups did not differ from DCD-NMP. Incidence of EAD was lower with DCD-NMP (21.7%) than DCD-SCS (50.2%) and similar to DBD grafts (21.1%–26.4%); HAT and PNF were rare (≤1.3%). At 1 year, BAS occurred in 36% of DCD grafts versus 17% to 23% of DBD grafts. IC occurred in 7.7% of DCD-NMP compared with 22% of DCD-SCS and ≤1.5% of DBD grafts. Retransplantation due to IC was infrequent overall (1.3%), but more common in DCD-SCS (4.7%) than DCD-NMP (1.0%) and DBD grafts (≤0.4%). Conclusions: NMP enables safe utilization of DCD liver allografts and achieves graft and patient survival comparable to DBD LT, mitigating the historical disadvantage of DCD grafts. These findings support routine integration of NMP into clinical practice and efforts to standardize its implementation.

Normothermic machine perfusion (NMP) enables preservation and functional assessment of liver allografts, improving outcomes, particularly in marginal organs. However, the TransMedics Organ Care System (OCS) permits only single hepatic artery (HA) cannulation, limiting its use in grafts with variant arterial anatomy. Arterial reconstruction before NMP may overcome this limitation and expand the pool of grafts eligible for perfusion. We conducted a retrospective single-center cohort study of adult liver transplants utilizing OCS from January 2022 to September 2024. Allografts with variant hepatic artery anatomy requiring arterial reconstruction before NMP initiation were identified. Postoperative outcomes, including vascular and biliary complications, were compared between reconstructed and non-reconstructed grafts. Among 541 OCS-preserved grafts, 74 (13.7%) underwent arterial reconstruction. Compared with non-reconstructed grafts, reconstructed grafts had longer cross-clamp to cannulation time (2.8 vs. 2.4 h, p <0.001), but similar rates of early allograft dysfunction (23.0% vs. 20.8%, p =0.65), ischemic cholangiopathy (4.1% vs. 4.1%, p =1.00), and primary nonfunction (0.0% vs. 0.4%, p =1.00). Early (2.7% vs. 0.2%, p =0.05) and late hepatic artery thrombosis (HAT) (4.1% vs. 2.1%, p =0.40) were infrequent and not significantly different between non-reconstructed and reconstructed groups, respectively. Hepatic artery stenosis occurred more often in reconstructed grafts (12.2% vs. 4.1%, p =0.008), though most cases were managed with interventional radiology or surgical revision. Only one reconstructed graft required retransplantation due to vascular complications. Arterial reconstruction before NMP is safe and feasible, enabling successful perfusion and transplantation of liver allografts with variant HA anatomy. These findings support the broader application of NMP in anatomically complex donor livers.

Despite improvements in kidney transplantation rates, the shortage of donor kidneys remains a critical issue, exacerbated by non-utilization of recovered kidneys due to quality concerns, necessitating advancements in perfusion methods to enhance graft outcomes and usage. Although static cold storage remains the default standard for kidney preservation, newer methods like hypothermic machine perfusion have shown improved outcomes, including reduced delayed graft function and better survival rates. Hypothermic oxygenated machine perfusion and normothermic machine perfusion offer some potential clinical benefits but studies to date have demonstrated mixed results. In the United States, LifePort and the XVIVO’s Kidney Assist Transport are the most popular hypothermic perfusion devices, with NMP devices mostly in trials. Combining perfusion with biomarkers such as mitochondrial flavin mononucleotide, neutrophil gelatinase-associated lipocalin, and osteopontin shows promise in assessing kidney viability and predicting post-transplant outcomes, though further research is also needed. Emphasis on repair biomarkers, such as uromodulin and osteopontin, aims to better predict graft outcomes and develop new therapies. While notable advancements have been made in the use of machine perfusion and viability testing for liver transplantation, additional research with larger sample sizes is essential to substantiate these results and enhance kidney transplantation outcomes.

Background. Ex vivo machine perfusion (MP) has transformed organ preservation, offering significant benefits in liver transplantation (LT), particularly with high-risk donor grafts. However, adoption in the United States has been limited. We aimed to examine early adoption trends, surgeon perceptions, and barriers to implementing MP in the United States after Food and Drug Administration approval of MP platforms. Methods. A 23-question electronic survey was distributed to members of the American Society of Transplant Surgeons between October and November 2022, capturing attitudes and practices related to MP adoption. Responses from 96 surgeons representing 77 LT centers across 11 Organ Procurement and Transplantation Network regions were analyzed. Results. Forty-four respondents (48%) reported having an MP program at their institution. Adoption of MP was significantly more common in high-volume centers and those performing ≥20 donation after circulatory death (DCD) transplants annually (P < 0.001). MP utilization received strong support, with 88% endorsing its use for DCD liver allografts and 82% for donation after brain death allografts. Respondents cited MP’s ability to reduce ischemic cholangiopathy, enable graft repair, and facilitate viability assessment as key benefits. Normothermic MP was preferred for high-risk donor profiles, including DCD grafts, older donors, and steatotic livers, and was associated with an increased willingness to accept medically complex grafts compared with static cold storage. Barriers to MP utilization included program costs, personnel demands, and logistical complexities. Centers with higher proportions of privately insured patients were more likely to adopt MP. Despite these challenges, 84% of respondents expressed interest in future MP adoption. Conclusions. MP enhances graft utilization and outcomes, particularly for complex and high-risk donor livers, but widespread US adoption requires addressing financial and logistical barriers. Future efforts should focus on refining cost-effectiveness analyses, collaboration with organ procurement organizations and device companies, and developing standardized training to optimize MP integration and maximize its clinical impact on LT.