Increasing practice and acceptable outcomes of high-MELD living donor liver transplantation in the USA.

Recent deceased-donor allocation changes in the United States may have increased high-Model for End-Stage Liver Disease (MELD) living donor liver transplantation (LDLT); however, outcomes in these patients remain poorly defined. We aimed to examine the impact of the MELD score on LDLT outcomes. Using UNOS data (January 1, 2010-December 31, 2021), LDLT recipients were identified and stratified into low-MELD (<15), intermediate-MELD (15-24), and high-MELD (≥25) groups. We compared outcomes between MELD-stratified LDLT groups and between MELD-stratified LDLT and donation after brain death liver transplantation recipients. We used Kaplan-Meier analysis to compare graft survival rates and multivariable Cox proportional hazards modeling to identify factors associated with graft outcomes. Of 3558 LDLTs, 1605 (45.1%) were low-MELD, 1616 (45.4%) intermediate-MELD, and 337 (9.5%) high-MELD. Over the study period, the annual number of LDLTs increased from 282 to 569, and the proportion of high-MELD LDLTs increased from 3.9% to 7.7%. Graft survival was significantly higher in low-MELD versus high-MELD LDLT recipients (adjusted HR = 1.36, 95% CI: 1.03-1.79); however, 5-year survival exceeded 70.0% in both groups. We observed no significant difference in graft survival between high-MELD LDLT and high-MELD donation after brain death liver transplantation recipients (adjusted HR: 1.25, 95% CI:0.99-1.58), with a 5-year survival of 71.5% and 77.3%, respectively. Low LDLT center volume (<3 LDLTs/year) and recipient life support requirement were both associated with inferior graft outcomes among high-MELD LDLT recipients. While higher MELD scores confer graft failure risk in LDLT, high-MELD LDLT outcomes are acceptable with similar outcomes to MELD-stratified donation after brain death liver transplantation recipients. Future practice guidance should consider the expansion of LDLT recommendations to high-MELD recipients in centers with expertise to help reduce donor shortage.

A contemporary analysis of 20,086 deceased donor liver biopsies.

BACKGROUND: Pre-transplant deceased donor liver biopsy may impact decision making; however, interpretation of the results remains variable and depends on accepting center practice patterns. METHODS: In this cohort study, adult recipients from 04/01/2015-12/31/2020 were identified using the UNOS STARfile data. The deceased donor liver biopsies were stratified by risk based on degree of fibrosis, macrovesicular fat content, and level of portal infiltration (low-risk: no fibrosis, no portal infiltrates, and <30% macrosteatosis; moderate-risk: some fibrosis or mild infiltrates and <30% macrosteatosis; high-risk: most fibrosis, moderate/marked infiltrates, or ≥30% macrosteatosis). Graft utilization, donor risk profile, and recipient outcomes were compared across groups. RESULTS: Of the 51,094 donor livers available, 20,086 (39.3%) were biopsied, and 34,606 (67.7%) were transplanted. Of the transplanted livers, 14,908 (43.1%) were biopsied. The transplanted grafts had lower mean macrovesicular fat content (9.3% transplanted vs. 26.9% non-transplanted, P < 0.001) and less often had any degree of fibrosis (20.9% vs. 39.9%, P < 0.001) or portal infiltration (51.3% vs. 58.2%, P < 0.001) versus non-transplanted grafts. Post-transplant recipient LOS (14.2 days high-risk vs. 15.2 days low-risk, P = 0.170) and 1-year graft survival (90.5% vs. 91.7%, P = 0.137) did not differ significantly between high- versus low-risk groups. Kaplan-Meier survival estimates further revealed no differences in the 5-year graft survival across risk strata (P = 0.833). Of the 5178 grafts biopsied and turned down, PSM revealed 1338 (26.0%) were potentially useable based on biopsy results and donor characteristics. CONCLUSION: Carefully matched deceased donor livers with some fibrosis, inflammation, or steatosis ≥30% may be suitable for transplantation. Further study of this group of grafts may decrease turndowns of potentially useable organs.

Delayed graft function in pediatric living donor kidney transplantation.

BACKGROUND: Pediatric recipients of living donor kidneys have a low rate of delayed graft function (DGF). We examined the incidence, risk factors and outcomes of DGF in pediatric patients who received a living donor allograft. METHODS: The STARfile was queried to examine all pediatric patients transplanted with a living donor kidney between 2000 and 2020. Donor and recipient demographic data were examined, as were survival and outcomes. Recipients were stratified into DGF and no DGF groups. DGF was defined as the need for dialysis within the first week after transplant. RESULTS: 6480 pediatric patients received a living donor (LD) kidney transplant during the study period. 269 (4.2%) developed DGF post-transplant. Donors were similar in age, creatinine, and cold ischemia time. Recipients of kidneys with DGF were similar in age, sensitization status and HLA mismatch. Focal segmental glomerulosclerosis (FSGS) was the most common diagnosis in recipients with DGF, and allograft thrombosis was the most common cause of graft loss in this group. Small recipients (weight < 15 kg) were found to have a significantly higher rate of DGF. Length of stay doubled in recipients with DGF, and rejection rates were higher post-transplant. Recipients of LD kidneys who developed DGF had significantly worse 1 year allograft survival (67% vs. 98%, p < .0001). CONCLUSIONS: Pediatric living donor kidney transplant recipients who experience DGF have significantly poorer allograft survival. Optimizing the donor and recipient matching to avoid compounding risks may allow for better outcomes.

Normothermic machine perfusion for older transplant recipients.

INTRODUCTION: Elderly patients (≥65 years old) are increasingly undergoing liver transplantation and are more likely to be removed from the waitlist. Normothermic machine perfusion (NMP) holds promise in expanding the number of livers available for transplant and improving outcomes for marginal donors and recipients. We aimed to determine the impact of NMP on outcomes in elderly recipients at our institution and nationally using the UNOS database. METHODS: The use of NMP on outcomes in elderly recipients was reviewed using both the UNOS/SRTR database (2016-2022) and institutional data (2018-2020). Characteristics and clinical outcomes were compared between the NMP and static cold (control) groups within both populations. RESULTS: Nationally, using the UNOS/SRTR database, we identified 165 elderly recipients from 28 centers who received a liver allograft undergoing NMP and 4270 that underwent traditional cold static storage. NMP donors were older (48.3 vs. 43.4 years, p < 0.01), had similar rates of steatosis (8.5% vs 8.5%, p = 0.58), were more likely to be from a DCD (41.8% vs 12.3%, p < 0.01), and had a higher donor risk index (DRI; 1.70 vs. 1.60, p < 0.02). NMP recipients had similar age but had a lower MELD score at transplant (17.9 vs. 20.7, p = 0.01). Despite increased marginality of the donor graft, NMP recipients had similar allograft survival and decreased length of stay, even after accounting for recipient characteristics including MELD. Institutional data showed that 10 elderly recipients underwent NMP and 68 underwent cold static storage. At our institution, NMP recipients had a similar length of stay, rates of complications, and readmissions. CONCLUSIONS: NMP may mitigate donor risk factors that are relative contraindications for transplantation in elderly liver recipients, increasing the donor pool. The application of NMP in older recipients should be considered.

Short-term kidney transplant outcomes from severe acute respiratory syndrome coronavirus 2 lower respiratory tract positive donors.

OBJECTIVE: In this study, we aim to assess short-term allograft outcomes following deceased donor kidney transplantation from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) lower respiratory tract (LRT) nucleic acid testing (NAT) positive donors. METHODS: From September to December 2021, SARS-CoV-2 NAT positive organ donors, whose solid abdominal organs were transplanted at our academic medical center were identified. Donors were stratified into having tested positive for SARS-CoV-2 in an upper respiratory tract (URT) or LRT sample. For this study, the SARS-CoV-2 LRT NAT positive deceased kidney donors and their respective recipients were examined. Donor and recipient demographic data, coronavirus disease 2019 (COVID-19)-related history, patient outcomes, as well as postoperative graft function were evaluated. RESULTS: Thirteen SARS-CoV-2 positive deceased donors were identified. Of these, eight were LRT NAT positive and yielded nine kidneys. These allografts were successfully transplanted into vaccinated and unvaccinated recipients. All recipients received standard induction immunosuppression and did not receive any prophylactic therapy for SARS-CoV-2. Two recipients had delayed graft function. At 1-month post-transplant, there was no clinical evidence of donor-derived COVID-19 or graft loss, and all recipients were free from dialysis. CONCLUSION: We describe the first case series of SARS-CoV-2 LRT NAT positive deceased kidney donors for vaccinated and unvaccinated recipients with excellent short-term allograft outcomes and no clinical evidence of donor-derived COVID-19 post-transplantation. Given the increasing prevalence of SARS-CoV-2 in the population, utilization of SARS-CoV-2 LRT NAT positive deceased donors could be considered an acceptable source of organs for renal transplantation, especially as multi-center experiences and longer-term follow-up emerge.

Normothermic Machine Perfusion in pediatric liver transplantation: A survey of attitudes and barriers.

BACKGROUND: NMP provides a superior strategy for the assessment and preservation of marginal donor livers and has demonstrated increased utilization and enhances organ quality when used in adult liver transplantation. We aimed to evaluate the interest of incorporating the use of NMP in pediatric liver transplantation. METHODS: An anonymous online survey was distributed to pediatric transplant surgeons and hepatologists across the United States. Respondent demographic information, attitudes toward NMP in pediatric liver transplantation, and barriers to utilization were examined. RESULTS: Thirty-two providers (18 transplant surgeons and 14 hepatologists) completed the survey, yielding a response rate of 64%. Half (50%) of respondents indicated prior exposure to NMP. Overall, 96% of respondents believed there was benefit to using NMP in pediatric liver transplantation. DCD (68%) and post-cross-clamp (75%) grafts were the greatest opportunity for NMP use. A role in splitting livers ex vivo (71%) was also seen as a potential major opportunity. Cost was perceived as a barrier to implementation (36%), followed by institutional factors (32%). Cost tolerance was significantly greater in respondents residing in OPTN regions with greater than median wait times (63% vs. 11% in OPTN regions with greater vs. shorter wait times, p = .010). CONCLUSIONS: There is significant interest within the pediatric liver transplant community for NMP to expand the donor pool. Interest appears particularly strong in regions where wait times for suitable pediatric donors are prolonged.

Simultaneous ex vivo normothermic preservation of liver and heart grafts from a donation after circulatory death donor.

Normothermic machine perfusion of organs is growing in popularity and has been used for both abdominal and thoracic organ preservation before transplantation. The use of normothermic machine perfusion for donation after cardiac death organs can reduce cold ischemia time and help prevent ischemia-related complications. We present a successful case of a donation after cardiac death procurement with both liver and heart allografts preserved by normothermic machine perfusion. Both allografts were perfused without complications and transplanted successfully. As the technology continues to become more prevalent, the situation described will become more commonplace, and we offer a view of the future in transplantation.

Amino acid and lipid profiles following pig-to-primate liver xenotransplantation.

As outcomes in clinical liver transplantation steadily improve, demand continues to exceed supply, leading to a substantial disparity in organ availability. The translation of porcine liver xenotransplantation (LXT) into a clinical reality aims to address this dilemma. Our laboratory has previously established an applicable model of α-1,3-galactosyltransferase knockout (GalT-KO) pig-to-primate LXT with continuous human coagulation factor infusion and costimulation blockade. This report aims to further investigate the post-LXT lipid and amino acid metabolism profile in our longest surviving recipients (25 and 29 days). Experimental samples and control samples, consisting of pre-transplant porcine and baboon serum and plasma, were analyzed for standard lipid profiles and for amino acid levels. Lipid profiles of LXT recipients remained stable following xenotransplantation compared to donor porcine baseline levels. Amino acid concentrations also remained similar to baseline controls, with the exception of a 3-fold increase in l-ornithine and more than a 10-fold decrease in l-arginine post-transplant when compared to both porcine and baboon baseline levels. The observed changes in l-arginine are consistent with prior studies investigating the effects of graft preservation injury following liver transplantation. These results indicate that the porcine liver can maintain most biochemical profiles stably post-operatively in baboons and suggest that arginine supplementation post-LXT may potentially be useful for further prolongation of xenograft survival.

High risk, high reward: An analysis of outcomes for candidates awaiting hepatic re-transplantation.

 Background. Liver re-transplantation (re-OLT) remains the only feasible option for patients with graft failure following liver transplantation. Sparse resources and a growing waitlist mandate that available grafts are allocated properly. We studied the differences in patient demographics, characteristics, and survival for those listed for re-OLT in a region with prolonged wait times. MATERIAL AND METHODS: We performed a single-center retrospective study, from 2005 to 2013, of adult candidates listed for liver re-OLT at a tertiary care center within United Network for Organ Sharing (UNOS) region 1. RESULTS: Of the 48 patients listed for re-OLT, 1(2%) improved while waiting, 14(29%) died while waiting, and 33(69%) underwent re-OLT. Those re-transplanted represented 11% of the center's adult liver transplant volume during the same time period. Comparing those who died while waiting to those who achieved re-OLT, there was no significant difference in age (median 52 vs. 48 years, p=0.56) or MELD at second listing (median 29 vs. 26, p = 0.90). Waitlisted candidates who failed to achieve re-transplant died on average of 15.5 days (IQR 36 days) days after re-listing. Those re-transplanted achieved 3-year survival of 70% and there was no significant difference in 3-year survival of those re-transplanted within or beyond 90 days of first transplant (70% vs. 69.5%, p = 0.28). CONCLUSIONS: In conclusion, re-OLT is the only viable option for candidates with nonreversible liver graft failure. Inability to achieve re-OLT leads to nearly assured and expeditious death. Despite technical challenges, in experienced hands excellent long term survival following re-OLT can be achieved.

Readmission following liver transplantation: an unwanted occurrence but an opportunity to act.

BACKGROUND: Liver transplant (LT) patients are at high risk for readmission. This study sought to identify predictors of readmission following liver transplantation and to evaluate their impact on survival in a region with prolonged waiting list times. METHODS: A single center review of adult deceased donor LT's from 2005 to 2015 was performed, with linkage to the UNOS Standard Transplant Analysis and Research registry. Readmission was defined as hospitalization within 90 days of discharge. Logistic regression was used to identify independent predictors of readmission and Kaplan-Meier analysis for survival. RESULTS: 325 patients underwent LT with an overall 90-day readmission rate of 46%. Upon adjusted analysis, predictors of readmission were age (OR 0.97 per year), male gender (OR 0.48), hospital length of stay (OR 1.03 per day), and hepatitis C liver failure (OR 2.37). Readmitted patients demonstrated a significantly lower 5-year survival (75% vs. 88%, p = 0.008) with only one patient (0.7%) dying during initial readmission. CONCLUSIONS: Nearly half of all patients are readmitted after LT. As readmission portents decreased survival, an emphasis should be placed on identifying and optimizing those at increased risk. If readmission does occur, however, it presents an opportunity to intervene, as virtually no patients died during initial readmission.

Role of Locoregional Therapy and Predictors for Dropout in Patients with Hepatocellular Carcinoma Listed for Liver Transplantation.

PURPOSE: To identify factors associated with removal from the liver transplantation waitlist because of death, deterioration of condition, or exceeding Milan criteria in patients with hepatocellular carcinoma (HCC), with emphasis on the role of locoregional therapy (LRT), defined as percutaneous thermal ablation and drug-eluting embolic chemoembolization, as bridge therapy. MATERIALS AND METHODS: All patients listed for liver transplant at a single institution with exception points for HCC during 2004-2012 were evaluated. The most common cause of cirrhosis was hepatitis C (68%; 121/177). Seventy-one percent (125/177) of patients underwent liver transplantation, and 83% (147/177) underwent at least 1 LRT procedure. Of the 52 patients who did not undergo liver transplantation, 31 (60%) of livers were removed because of progression of HCC. RESULTS: The likelihood of transplant was higher for patients who received LRT (odds ratio [OR], 2.9; confidence interval [CI], 2.2-7.2) and lower for patients with multifocal tumors (OR, 0.25; CI, 0.12-0.52) and with larger tumors (OR, 0.94; CI, 0.90-0.98). Time on the waitlist (OR, 0.99; CI, 0.99-1.0) was not found to correlate with removal. LRT increased the likelihood of liver transplantation, specifically for patients with prolonged wait times. Patients who demonstrated complete response (CR) to LRT on the first follow-up imaging study were more likely to undergo liver transplantation. CONCLUSIONS: LRT increased the likelihood of a patient with HCC achieving liver transplant, particularly in patients facing prolonged waiting times. CR after LRT significantly increased the likelihood of liver transplantation.

A Contemporary Analysis of Mental Well-being Among Living Donor Kidney Applicants.

Background: Living donation is paramount for expanding the donor pool. The aim of this study was to assess changes over time in self-reported mental health of living donor kidney applicants in efforts to inform patient-centered discussions with potential donors. Methods: Kidney donor applications from 2017 through 2021 were compiled. Data included age, gender, race, ethnicity, applicant-recipient relationship, medical history, and medications. Trends over time were analyzed and post hoc analyses were performed. Results: During the study period, 2479 applicants to the living donor kidney program were evaluated; 73% of applicants were female individuals. More than half of applicants were not related to their intended recipient; this fraction increased from 46% in 2017 to 58% in 2021 (P < 0.01). A similar decline in family relations was not present among Black and Latino applicants. Of all applicants, 18% reported depression and 18% reported anxiety; 20% reported taking antidepressants or anxiolytics. Depression and anxiety increased 170% (P < 0.001) and 136% (P < 0.001) from 2018 to 2019, respectively; antidepressant and anxiolytic use rose 138% (P < 0.001) between 2018 and 2020. Conclusions: The profile of living donor applicants has changed in recent years, with approximately 1 in 5 requiring antidepressants or anxiolytics. Predonation counseling and postdonation monitoring are imperative to decrease adverse psychological outcomes for living donors.

Liver Transplantation in Elderly Recipients: Is Age Just a Number?

BACKGROUND: The proportion of older patients on the liver transplant waitlist continues to increase. With limited existing data to guide liver transplant evaluation of elderly patients, we aimed to study selection practices and outcomes of patients ≥70 years old. We hypothesized that 1-year patient and graft survival would not differ between appropriately selected elderly patients and those who are younger. METHODS: All patients referred for liver transplantation between 2018 and 2020 were stratified into elderly (age ≥70) and young (age <70) cohorts. Evaluation data pertaining to medical, surgical, and psychosocial risk assessment were reviewed. Recipient characteristics and post-operative outcomes, primarily 1-year graft and patient survival, were compared, with a median follow-up of 16.4 months. RESULTS: 322 patients underwent transplant out of 2331 referred. Elderly patients represented 230 of these referrals and 20 underwent transplant. The most common reasons for denial of elderly patients were multiple medical comorbidities (49%), cardiac risk (15%) and psychosocial barriers (13%). The median MELD of elderly recipients was lower (19 vs 24, P = .02), and proportion of hepatocellular carcinoma was higher (60% vs 23%, P < .001). There was no difference in 1-year graft (elderly 90.9% vs young 93.3%, P = .72) or patient survival (elderly 90.9% vs young 94.7%, P = .88). DISCUSSION: Liver transplant outcomes and survival are not affected by advanced age in carefully evaluated and selected recipients. Age should not be considered an absolute contraindication for liver transplant referral. Efforts should be made to develop guidelines for risk stratification and donor-recipient matching that optimize outcomes in elderly patients.

No Stone Left Unturned: Utilization of an Organ Procurement Organization Donor Surgeon at Procurement Reduces Discards of Marginal Liver Allografts.

BACKGROUND: The recent trend of organ procurement organizations (OPOs) employing independent surgeons for organ procurement has been developed with the goal of improving the supply of suitable organs for transplantation. We investigated the effects that the addition of an OPO-employed, organ-procurement specialist has on liver allograft discard rate, marginal organ utilization, and graft survival. METHODS: Organ Procurement and Transplant Network and OPO data were retrospectively studied between April 1, 2014' and July 31, 2019' within the Southwest Transplant Alliance donor service area. Liver procurements with an OPO-surgeon present (OPO-Present) were compared to those without the involvement of an OPO surgeon (OPO-Absent). Donor and recipient characteristics as well as outcomes were analyzed across groups using propensity score matching. RESULTS: In total 869 OPO-Present liver allografts had similar rates of discard (5.2%) compared to 771 OPO-Absent livers (5.8%). However, after adjusting for donor risk, OPO-Present livers had a lower propensity of discard compared to OPO-Absent (3.4% versus 7.6%, P < 0.05). OPO-Present livers were more likely to be shared nationally (11.0% versus 4.8%, P < 0.001). Outcome analysis showed allograft survival of OPO-Present livers at 5 y was comparable to OPO-Absent livers (79.5% versus 80%, P = 0.34). CONCLUSIONS: The presence of an OPO surgeon was associated with decreased liver allograft discard and increased utilization of marginal donor organs. The OPO surgeon's presence represents a potential strategy to increase organ utilization nationally.

Is there value in volume? An assessment of liver transplant practices in the United States since the inception of MELD.

BACKGROUND: Liver transplantation has increased in volume and provides substantial survival benefit. However, there remains a need for value-based assessment of this costly procedure. METHODS: Model for end stage liver disease era adult recipients were identified using United Network for Organ Sharing Standard Transplant Analysis file data (n = 75,988) and compared across time periods (period A: February 2002 to January 2007; B: February 2007 to January 2013; C: February 2013 to January 2019). Liver centers were divided into volume tertiles for each period (small, medium, large). Value for the index transplant episode was defined as percentage graft survival ≥1 year divided by mean posttransplant duration of stay. RESULTS: All centers increased value over time due to ubiquitous improvement in 1-year graft survival. However, large centers demonstrated the most significant value change (large +17% vs small +7.0%, P < .001) due to a -8.5% reduction in large centers duration of stay from period A to C, while small centers duration of stay remained unchanged (-0.1%). Large centers delivered higher value despite more complex care: older recipients (54.8 ± 10.3 vs 53.0 ± 11.4 years P < .001), fewer model for end stage liver disease exceptions (34.0% vs 38.2%, P < .001), higher rates of candidate portal vein thrombosis (10.1% vs 8.5%, P < .001) and prior abdominal surgery (43.4% vs 37.4%, P < .001), and more marginal donor utilization (donor risk index 1.45 ± 0.38 vs 1.36 ± 0.33, P < .001). Mahalanobis metric matching demonstrated that compared with small centers, large centers progressively shortened recipient duration of stay per transplant in each period (A: -0.36 days, P = .437; B: -2.14 days, P < .001; C: -2.49 days, P < .001). CONCLUSION: There is value in liver transplant volume. Adoption of value-based practices from large centers may allow optimization of health care delivery for this costly procedure.

Duct of Luschka Bile Leak Following Deceased Donor Liver Transplant.

BACKGROUND Biliary leak is a relatively uncommon but potentially severe complication of liver transplantation. Duct of Luschka (also known as subvesical bile ducts) is a term that refers to a number of accessory biliary ducts. While leaks from Ducts of Luschka are well-described in the field of hepatobiliary surgery, only 2 case reports of such leaks exist in the setting of liver transplant. CASE REPORT We report the first case of a Duct of Luschka biliary leak seen after DCD liver transplant in a 41-year-old woman with cirrhosis secondary to primary sclerosing cholangitis. The patient underwent surgical re-exploration in the immediate postoperative period due to bilious output from a surgical drain. A Duct of Luschka was found intraoperatively at the gallbladder fossa and was oversewn. Apart from immunosuppression-related neutropenia, the patient recovered uneventfully. CONCLUSIONS Given the variability in preoperative detection of subvesical bile ducts, accessory bile duct leak remains an important consideration in the liver transplant perioperative period. The prevalence of Ducts of Luschka and the relative risk of leakage from such subvesical bile ducts in liver transplants compared to cholecystectomies are unclear. Further research into anatomical accessory bile duct variants and preoperative techniques for detecting such ducts is warranted.

Remaining Physiological Barriers in Porcine Kidney Xenotransplantation: Potential Pathways behind Proteinuria as well as Factors Related to Growth Discrepancies following Pig-to-Kidney Xenotransplantation.

Considerable shortages in the supply of available organs continue to plague the field of solid organ transplantation. Despite changes in allocation, as well as the utilization of extended criteria and living donors, the number of patients waiting for organs continues to grow at an alarming pace. Xenotransplantation, cross-species solid organ transplantation, offers one potential solution to this dilemma. Previous extensive research dedicated to this field has allowed for resolution of xenograft failure due to acute rejection, leaving new areas of unresolved challenges as barriers to success in large animal models. Specific to kidney xenotransplantation, recent data seems to indicate that graft compromise can occur due to discrepancies in growth between breeds of donors and significant proteinuria leading to nephrotic syndrome in the recipient. Given these potential limitations, herein, we review potential pathways behind proteinuria, as well as potential causative factors related to growth discrepancies. Control of both of these has the potential to allow xenotransplantation to become clinically applicable in an effort to resolve this organ shortage crisis.

Xenogeneic Heterotopic Auxiliary Liver transplantation (XHALT) promotes native liver regeneration in a Post-Hepatectomy Liver failure model.

The liver's regenerative capacity is unique, but too small a segment can overwhelm its ability to simultaneously regenerate and support the host, resulting in liver dysfunction and death. Here we tested a temporary Xenogeneic Heterotopic Auxiliary Liver Transplant (XHALT) from Gal-KO miniature swine in a baboon model of Post-Hepatectomy Liver Failure (PHLF) by 90%- hepatectomy. Immunosuppression consisted of CVF, ATG, FK 506 and steroids. 90%-hepatectomized animals died within 4-5 days with the clinical picture of PHLF, (high LFTs and bilirubin, ascites, encephalopathy and coagulopathy). The 10% remnants had macroscopic and histological evidence of severe steatosis and absence of hepatocyte replication. In contrast, the addition of XHALT prolonged survival up to 11 days, with the cause of death being sepsis, rather than liver failure. The remnant liver appeared grossly normal, and on histology, there was no evidence of fatty infiltration, but there was pronounced Ki-67 staining. In conclusion, temporary auxiliary xenografts have the potential to support a small for size liver graft while it grows to adequate size or provide an opportunity for organ recovery in acute liver failure.