Durable Mixed Chimerism May Permit Subsequent Immunosuppression-Free Intestinal Transplantation - a Proof-of-Principle Study.

Intestinal transplantation (ITx) is the definitive treatment for intestinal failure but has the highest rejection rate among solid organ transplants, requiring high doses of immunosuppression with high rates of infection, graft-versus-host disease, and malignancy. Transplant tolerance would overcome the need for long-term immunosuppression. Using non-myeloablative conditioning, our laboratory has developed a novel swine model of hematopoietic stem cell transplantation (HSCT) that produces durable mixed chimerism (MC) and immune tolerance without toxicity. We investigated whether durable MC would promote tolerance of subsequently transplanted donor-matched intestinal allografts without immunosuppression. Using miniature swine with defined MHC, we performed HSCT across an MHC-Class-I haplotype mismatch. Immunosuppression was stopped by day 45. MC was evaluated by flow cytometry, and mixed lymphocyte reaction (MLR) assays were used to evaluate cellular responses. Subsequently, orthotopic ITx was performed without immunosuppression using a donor that was MHC-matched to the HSCT donor. Recipients were observed for four weeks and euthanized for tissue collection and mechanistic assays. After HSCT, the recipients developed durable multilineage MC and apparent deletional tolerance. After ITx, recipients showed no clinical or histological signs of rejection, and chimerism was unchanged. These results demonstrate the potential value of generating durable MC to achieve transplant tolerance.

Development of a large animal orthotopic intestinal transplantation model with long-term survival for study of immunologic outcomes.

Introduction: Intestinal transplantation (ITx) is the last remaining therapy for patients with intestinal failure once parenteral nutrition is no longer an option, however its use is limited by immunological complications, including high rates of rejection and morbidity associated with immunosuppression, such as infection and malignancy. We aimed to develop a large animal model of ITx with which to study the immune response to ITx and to design and test tolerance induction regimens. Methods: Learning from prior complications, we developed and progressively improved both surgical methods for the donor and recipient as well as postoperative management strategies. Methods of stoma generation, bowel positioning, vessel preparation, and fluid management were optimized. The immunosuppression strategy mirrored our clinical regimen. Results: As a result of our modifications, results improved from survival less than 1 month to consistent long-term survival with good graft function. We review several techniques that were developed to avoid pitfalls that were encountered, which can be used to optimize outcomes in this model. Discussion: Achieving long-term survival after swine orthotopic ITx permits immunological analysis and pre-clinical trials in a large animal model of ITx.

Volumetric graft changes after liver transplantation: evidence of adaptation to recipient body size.

It is believed that whole liver grafts adjust their size to fit the body size of the recipient after transplantation, despite a lack of evidence. The aim of this study was to test this hypothesis. This was a retrospective cohort study of 113 liver transplantations performed at Karolinska University Hospital. The cohort was divided based on graft volume-to-standard liver volume ratio (GV/SLV) into quartiles of small, mid, and large grafts. Serial volumetric assessment was performed on the day of transplantation and at posttransplant check-ups early (<2 mo) and late (9-13 mo) after transplantation using computed tomography (CT) volumetry. Change in GV/SLV ratio over time was analyzed with ANOVA repeated measures. A multiple regression model was used to investigate the influence of intraoperative blood flow, recipient body size, age, and relative sickness on graft volume changes. Between the three time points, mean GV/SLV ratio adapted to 0.55-0.94-1.00 in small grafts (n = 29, P < 0.001); 0.87-1.18-1.13 in midgrafts (n = 56, P < 0.001); 1.11-1.51-1.18 in large grafts (n = 28, P < 0.001). Regression analysis showed a positive correlation between posttransplant graft growth and portal flow (ß = 1.18, P = 0.005), arterial flow (ß = 0.17, P = 0.001), and recipient body surface area (ß = 59.85, P < 0.001). A negative correlation was observed for graft weight-to-recipient weight ratio (GRWR; ß = -33.12, P < 0.001). Grafts with initial GV/SLV-ratio < 0.6 adapt toward the ideal volume for recipient body size 1 year after transplantation. The disparity between graft size relative to recipient body size, and the portal and arterial perfusion, influence volumetric graft changes.NEW & NOTEWORTHY This is the first and largest human study to verify the hypothesis that whole liver grafts adjust their size to match recipient body size 1 year after transplantation-a phenomenon that has previously only been observed in experimental animal studies and human case reports. The direction of volumetric changes is driven by the disparity between graft size relative to recipient body surface area and weight, as well as the intraoperative portal- and arterial graft perfusion.

Human resident liver myeloid cells protect against metabolic stress in obesity.

Although multiple populations of macrophages have been described in the human liver, their function and turnover in patients with obesity at high risk of developing non-alcoholic fatty liver disease (NAFLD) and cirrhosis are currently unknown. Herein, we identify a specific human population of resident liver myeloid cells that protects against the metabolic impairment associated with obesity. By studying the turnover of liver myeloid cells in individuals undergoing liver transplantation, we find that liver myeloid cell turnover differs between humans and mice. Using single-cell techniques and flow cytometry, we determine that the proportion of the protective resident liver myeloid cells, denoted liver myeloid cells 2 (LM2), decreases during obesity. Functional validation approaches using human 2D and 3D cultures reveal that the presence of LM2 ameliorates the oxidative stress associated with obese conditions. Our study indicates that resident myeloid cells could be a therapeutic target to decrease the oxidative stress associated with NAFLD.

Prevalence, management and efficacy of treatment in portal vein obstruction after paediatric liver transplantation: protocol of the retrospective international multicentre PORTAL registry.

INTRODUCTION: Portal vein obstruction (PVO) consists of anastomotic stenosis and thrombosis, which occurs due to a progression of the former. The aim of this large-scale international study is to assess the prevalence, current management practices and efficacy of treatment in patients with PVO. METHODS AND ANALYSIS: The Portal vein Obstruction Revascularisation Therapy After Liver transplantation registry will facilitate an international, retrospective, multicentre, observational study, with 25 centres around the world already actively involved. Paediatric patients (aged <18 years) with a diagnosed PVO between 1 January 2001 and 1 January 2021 after liver transplantation will be eligible for inclusion. The primary endpoints are the prevalence of PVO, primary and secondary patency after PVO intervention and current management practices. Secondary endpoints are patient and graft survival, severe complications of PVO and technical success of revascularisation techniques. ETHICS AND DISSEMINATION: Medical Ethics Review Board of the University Medical Center Groningen has approved the study (METc 2021/072). The results of this study will be disseminated via peer-reviewed publications and scientific presentations at national and international conferences. TRIAL REGISTRATION NUMBER: Netherlands Trial Register (NL9261).

Results of Liver Retransplantation After Rescue Hepatectomy: A Single-Center Study.

BACKGROUND Liver retransplantation (reLT) is a well-accepted treatment for liver graft failure in selected patients. A rescue hepatectomy (RH), on the contrary, is a rare and controversial procedure in which a deteriorating liver graft causing failure of other organ systems is removed to stabilize the patient's condition before a new liver graft is available. MATERIAL AND METHODS In this retrospective cohort study, we evaluated the outcomes of the 104 patients who were listed for a first single-organ reLT in our center during the period 2000-2019, to compare the results after RH to other reLTs. RESULTS In the study population, RH was performed on 8 patients, while 7 of these received a new graft (8% of all first time reLTs) and 1 died before reLT. All RHs were performed within 1 week after the first transplantation. The median anhepatic time after RH was 36 hours (range 14-99). The 1-year patient survival rate was 57% for reLTs with RH and 69% for acute reLTs without RH that were performed within 14 days after the first transplantation (P=0.66). The 5-year survival rate was 50% in the RH and 47% in the non-RH group (P=1.0). CONCLUSIONS The use of RH prior to reLT results in a similar outcome to reLTs without RH. Therefore, RH should be considered in patients with a severe clinical instability caused by a deteriorating liver graft. However, further studies are needed to establish guidelines based on objective parameters for when RH should be performed.

Molecular adsorbent recirculating system treatment in patients with post-hepatectomy liver failure: Long-term results of a pilot study.

BACKGROUND: Post-hepatectomy liver failure (PHLF) is the leading cause of postoperative mortality following major liver resection. Between December 2012 and May 2015, 10 consecutive patients with PHLF (according to the Balzan criteria) following major/extended hepatectomy were included in a prospective treatment study with the molecular adsorbent recirculating system (MARS). Sixty- and 90-day mortality rates were 0% and 10%, respectively. Of the nine survivors, four still had liver dysfunction at 90 days postoperatively. One-year overall survival (OS) of the MARS-PHLF cohort was 50%. The present study aims to assess long-term outcome of this cohort compared to a historical control cohort. METHODS: To compare long-term outcome of the MARS-PHLF treatment cohort with PHLF patients not treated with MARS, the present study includes all 655 patients who underwent major hepatectomy at Karolinska University Hospital between 2010 and 2018. Patients with PHLF were identified according to the Balzan criteria. RESULTS: The cohort was split into three time periods: pre-MARS period (n = 192), MARS study period (n = 207), and post-MARS period (n = 256). The 90-day mortality of patients with PHLF was 55% (6/11) in the pre-MARS period, 14% during the MARS study period (2/14), and 50% (3/6) in the post-MARS period (p = 0.084). Median OS (95% confidence interval (CI)) was 37.8 months (29.3-51.7) in the pre-MARS cohort, 57 months (40.7-75.6) in the MARS cohort, and 38.8 months (31.4-51.2) in the post-MARS cohort. The 5-year OS of 10 patients included in the MARS study was 40% and the median survival 11.6 months (95% CI: 3 to not releasable). In contrast, for the remaining 21 patients fulfilling the Balzan criteria during the study period but not treated with MARS, the 5-year OS and median survival were 9.5% and 7.3 months (95% CI, 0.5-25.9), respectively (p = 0.138)). CONCLUSIONS: MARS treatment may contribute to improved outcome of patients with PHLF. Further studies are needed.The initial pilot study was registered at ClinicalTrials.gov (NCT03011424).

Novel Benchmark Values for Redo Liver Transplantation: Does the Outcome Justify the Effort?

OBJECTIVE: To define benchmark cutoffs for redo liver transplantation (redo-LT). BACKGROUND: In the era of organ shortage, redo-LT is frequently discussed in terms of expected poor outcome and wasteful resources. However, there is a lack of benchmark data to reliably evaluate outcomes after redo-LT. METHODS: We collected data on redo-LT between January 2010 and December 2018 from 22 high-volume transplant centers. Benchmark cases were defined as recipients with model of end stage liver disease (MELD) score ≤25, absence of portal vein thrombosis, no mechanical ventilation at the time of surgery, receiving a graft from a donor after brain death. Also, high-urgent priority and early redo-LT including those for primary nonfunction (PNF) or hepatic artery thrombosis were excluded. Benchmark cutoffs were derived from the 75th percentile of the medians of all benchmark centers. RESULTS: Of 1110 redo-LT, 373 (34%) cases qualified as benchmark cases. Among these cases, the rate of postoperative complications until discharge was 76%, and increased up to 87% at 1-year, respectively. One-year overall survival rate was excellent with 90%. Benchmark cutoffs included Comprehensive Complication Index CCI ® at 1-year of ≤72, and in-hospital and 1-year mortality rates of ≤13% and ≤15%, respectively. In contrast, patients who received a redo-LT for PNF showed worse outcomes with some values dramatically outside the redo-LT benchmarks. CONCLUSION: This study shows that redo-LT achieves good outcome when looking at benchmark scenarios. However, this figure changes in high-risk redo-LT, as for example in PNF. This analysis objectifies for the first-time results and efforts for redo-LT and can serve as a basis for discussion about the use of scarce resources.

Protein intake early after liver transplantation and postoperative outcome: An observational study comparing two nutritional protocols.

OBJECTIVES: Patients undergoing liver transplantation (LT) are at risk for eating difficulties. Adequate nutritional support is important to promote enhanced recovery and to reduce postoperative complications. The aim of this study was to evaluate two nutritional protocols and their effect on total protein intake during the first 7 d after LT. METHODS: Adult patients were monitored daily for energy and protein intake during the first week after LT. Patients with ≥3 d of monitoring were included in the study. Two patient groups were studied: protocol A (pA) based on enteral nutrition (EN) provided from postoperative days 1 through 4 (historical control); and protocol B (pB), which was based on high volume of EN and high-protein oral nutritional supplements (ONS). Outcome measures were hospital length of stay and grade of complications according to Clavien-Dindo within the first 3 mo after transplantation. RESULTS: Seventy patients were included in the study (pA n=34, pB n= 36). The median age was 59 y and 70% were men. During postoperative week 1, patients with pB had a higher daily protein intake (95 g versus 77 g, P < 0.01) and met a higher proportion of estimated protein requirements (80% versus 70%, P < 0.05). There were no differences in severe postoperative outcomes between the two groups. CONCLUSIONS: A nutritional protocol with a higher rate of EN and high-protein ONS resulted in a higher protein intake early after LT. However, there was no difference in severe postoperative outcomes between the two nutritional protocols.

Procurement and Evaluation of Hepatocytes for Transplantation From Neonatal Donors After Circulatory Death.

Hepatocyte transplantation is a promising treatment for liver failure and inborn metabolic liver diseases, but progress has been hampered by a scarcity of available organs. Here, hepatocytes isolated from livers procured for a neonatal hepatocyte donation program within a research setting were assessed for metabolic function and suitability for transplantation. Organ donation was considered for infants who died in neonatal intensive care in the Stockholm region during 2015-2021. Inclusion was assessed when a decision to discontinue life-sustaining treatment had been made and hepatectomy performed after declaration of death. Hepatocyte isolation was performed by three-step collagenase perfusion. Hepatocyte viability, yield, and function were assessed using fresh and cryopreserved cells. Engraftment and maturation of cryopreserved neonatal hepatocytes were assessed by transplantation into an immunodeficient mouse model and analysis of the gene expression of phase I, phase II, and liver-specific enzymes and proteins. Twelve livers were procured. Median warm ischemia time (WIT) was 190 [interquartile range (IQR): 80-210] minutes. Median viability was 86% (IQR: 71%-91%). Median yield was 6.9 (IQR: 3.4-12.8) x106 viable hepatocytes/g. Transplantation into immunodeficient mice resulted in good engraftment and maturation of hepatocyte-specific proteins and enzymes. A neonatal organ donation program including preterm born infants was found to be feasible. Hepatocytes isolated from neonatal donors had good viability, function, and engraftment despite prolonged WIT. Therefore, neonatal livers should be considered as a donor source for clinical hepatocyte transplantation, even in cases with extended WIT.

Risk Factors for Development of Biliary Stricture After Liver Transplant in Adult Patients: A Single-Center Retrospective Study.

Identification of risk factors for biliary stricture after liver transplant and its potential prevention is crucial to improve the outcomes and reduce the complications. We retrospectively analyzed donor and recipient characteristics with intraoperative and postoperative parameters to identify the risk factors for development of post-transplant anastomotic and nonanastomotic biliary strictures with additional analysis of the time onset of those strictures. A total of 412 patients were included in this study. Mean (SD) follow-up time was 79 (35) months (range, 1-152 months). Biliary stricture was diagnosed in 84 patients (20.4%). Multivariate analysis indicated that postoperative biliary leakage (odd ratio [OR], 3.94; P = .001), acute cellular rejection (OR, 3.05; P < .001), donor age older than 47.5 years (OR, 2.05; P = .032), preoperative recipient platelet value < 77.5 × 103/mL (OR, 1.91; P = .023), University of Wisconsin solution (OR, 1.73; P = .041)), recipient male sex (OR, 1.78; P = .072), portal/arterial flow ratio > 4 (OR, 1.76; P = .083), and intraoperative bleeding > 2850 mL (OR, 1.70; P = .053) were independent risk factors for biliary stricture regardless of the time of their appearance. Multiple risk factors for biliary stricture were determined in this study. Some of these risk factors are preventable, and implementation of strategies to eliminate some of those factors should reduce the development of post-transplant biliary stricture.

Effects of a Domino Liver Transplantation Program on Patient Survival and Waiting List Time: A Single-Center Retrospective Study.

Explanted livers from patients with familial amyloid polyneuropathy have often been used for domino liver transplantation (DLT). This has expanded the organ pool for liver transplantation. We evaluated the effects of a single-center DLT program on waiting list duration and patient survival. Liver transplants conducted from 2007 to 2017 were analyzed. Selected patients, all liver transplant candidates above the age of 60 years and patients with hepatocellular carcinoma, were offered DLT. Survival, time on waiting list, and operative factors were evaluated. The study group included 485 patients transplanted with grafts from deceased donors (conventional liver transplantation) and 149 patients who were offered and accepted a potential DLT, of whom 34 underwent DLT and 115 did not; these patients received a deceased donor graft (non-DLT). Five-year and overall estimated survival rates respectively were 79% and 54.4% for DLT and 67.6% and 46.7% for non-DLT (P = .67, log rank test). No differences were noted in survival (P = .816) or waiting times (P = 1.0) between DLT and non-DLT groups. As expected, survival time in the conventional liver transplantation group was longer (84.7% and 60.6%, P < .001). Donor age and ischemia time were significantly different between DLT and non-DLT (P < .001). DLT has enabled 6% additional transplantations without affecting waiting time or survival (34/600).

Is primary hepatic angiosarcoma in children an indication for liver transplantation?-A single-centre experience and review of the literature.

PHA in the paediatric population is an extremely rare and aggressive malignant soft tissue neoplasm, with less than 50 cases published worldwide. The prognosis is dismal. If the tumour is unresectable, one treatment option is LT. In this article, the current available literature is reviewed and additionally, three cases of paediatric patients with PHA who underwent LT at Karolinska University Hospital, Sweden, are presented. Based on the literature and our own experience, there is undoubtedly possible good outcome of LT due to PHA. On the contrary, no patients have survived PHA without LT. PHA in paediatric patients should be recommended to LT in selected patients. Effect of modern adjuvant chemo and RT should be evaluated further based on international registry for such rare cases of PHA.

The role of the comprehensive complication index for the prediction of survival after liver transplantation.

In the last years, several scoring systems based on pre- and post-transplant parameters have been developed to predict early post-LT graft function. However, some of them showed poor diagnostic abilities. This study aims to evaluate the role of the comprehensive complication index (CCI) as a useful scoring system for accurately predicting 90-day and 1-year graft loss after liver transplantation. A training set (n = 1262) and a validation set (n = 520) were obtained. The study was registered at https://www.ClinicalTrials.gov (ID: NCT03723317). CCI exhibited the best diagnostic performance for 90 days in the training (AUC = 0.94; p < 0.001) and Validation Sets (AUC = 0.77; p < 0.001) when compared to the BAR, D-MELD, MELD, and EAD scores. The cut-off value of 47.3 (third quartile) showed a diagnostic odds ratio of 48.3 and 7.0 in the two sets, respectively. As for 1-year graft loss, CCI showed good performances in the training (AUC = 0.88; p < 0.001) and validation sets (AUC = 0.75; p < 0.001). The threshold of 47.3 showed a diagnostic odds ratio of 21.0 and 5.4 in the two sets, respectively. All the other tested scores always showed AUCs < 0.70 in both the sets. CCI showed a good stratification ability in terms of graft loss rates in both the sets (log-rank p < 0.001). In the patients exceeding the CCI ninth decile, 1-year graft survival rates were only 0.7% and 23.1% in training and validation sets, respectively. CCI shows a very good diagnostic power for 90-day and 1-year graft loss in different sets of patients, indicating better accuracy with respect to other pre- and post-LT scores.Clinical Trial Notification: NCT03723317.

Intrahepatic Microdialysis for Monitoring of Metabolic Markers to Detect Rejection Early After Liver Transplantation.

OBJECTIVES: The clinical and biochemical manifestations of acute rejection after liver transplantation are nonspecific, and a liver biopsy is often needed to verify the diagnosis. This may delay treatment. The aim of this study was to evaluate whether monitoring of intrahepatic glucose, lactate, pyruvate, and glycerol by microdialysis can be used to predict rejection early after liver transplantation. METHODS: Seventy-one patients undergoing liver transplantation were included in the study. The patients were monitored using microdialysis for up to 6 days postoperatively. Patients who developed acute rejection within 1 month were identified according to standard protocol. Area under the curve (AUC) was calculated for 12-hour intervals for glucose, lactate, pyruvate, glycerol, and lactate/pyruvate ratio. Patients with and without rejection were compared with respect to these parameters, as well as standard liver blood investigations and time-zero biopsies. RESULTS: The lactate/pyruvate ratio was higher at 0 to 12 hours in the group with rejection as compared to the group without rejection. Glucose was lower in the group with rejection at 24 to 48 hours. Also, the intrahepatic lactate levels at 48 to 72 hours and pyruvate levels at 60 to 72 hours after liver transplantation, were higher in the rejection group. The lactate/pyruvate ratio at 0 to 12 hours and lactate at 60 to 72 hours were two independent risk factors for rejection within the first month after liver transplantation. No significant differences in glycerol levels could be detected between the two patient groups. CONCLUSIONS: Microdialysis monitoring following liver transplantation may be useful in the detection of the metabolic events that precede rejection. The metabolic patterns detected by microdialysis early after transplantation indicate a possible relation between primary ischemia-reperfusion injury and the development of rejection. Identifying these patterns may help to identify patients at risk for the development of acute rejection and may help select those who may benefit from higher dose of immunosuppression early after liver transplantation.

Liver Transplantation for Acute Intermittent Porphyria.

Recurrent attacks of acute intermittent porphyria (AIP) result in poor quality of life and significant risks of morbidity and mortality. Liver transplantation (LT) offers a cure, but published data on outcomes after LT are limited. We assessed the pretransplant characteristics, complications, and outcomes for patients with AIP who received a transplant. Data were collected retrospectively from the European Liver Transplant Registry and from questionnaires sent to identified transplant and porphyria centers. We studied 38 patients who received transplants in 12 countries from 2002 to 2019. Median age at LT was 37 years (range, 18-58), and 34 (89%) of the patients were women. A total of 9 patients died during follow-up, and 2 patients were retransplanted. The 1-year and 5-year overall survival rates were 92% and 82%, which are comparable with other metabolic diseases transplanted during the same period. Advanced pretransplant neurological impairment was associated with increased mortality. The 5-year survival rate was 94% among 19 patients with moderate or no neuropathy at LT and 83% among 10 patients with severe neuropathy (P = 0.04). Pretransplant renal impairment was common. A total of 19 (51%) patients had a GFR < 60 mL/minute. Although few patients improved their renal function after LT, neurological impairments improved, and no worsening of neurological symptoms was recorded. No patient had AIP attacks after LT, except for a patient who received an auxiliary graft. LT is a curative treatment option for patients with recurrent attacks of AIP. Severe neuropathy and impaired renal function are common and increase the risk for poor outcomes. If other treatment options fail, an evaluation for LT should be performed early.

Energy expenditure early after liver transplantation: Better measured than predicted.

OBJECTIVE: There is no consensus on how to estimate energy requirements after liver transplantation (LT). The aim of this study was to compare measured resting energy expenditure (REE) with predictive equations and fixed factors, and evaluate whether clinical variables were associated with REE. METHODS: During the period of 2011 through 2018, REE measured with indirect calorimetry and predicted by the Harris and Benedict (HB) equation was compared in patients during the first 30 postoperative days after LT. The fixed factors 25 kcal/kg, 30 kcal/kg, or 35 kcal/kg were used to calculate energy requirements. The accuracy of HB and fixed factors were evaluated with a Bland-Altman analysis and Lin's concordance correlation coefficient. The associations of pre- and postoperative clinical variables with REE were evaluated in a multivariate regression analysis. RESULTS: A total of 143 patients were evaluated and had indirect calorimetry performed on postoperative day 6 (interquartile range: 3) in median. The mean measured REE was 1950 ± 461 kcal (range, 720-3309 kcal) or 24.5 ± 6.1 kcal/kg body weight. Large limits of agreements were observed in the Bland-Altman analyses for both HB and fixed factors. HB was closer than fixed factors with a positive concordance (concordance correlation: 0.350; 95% confidence interval, 0.248-0.445) and Pearsons r2 = 0.261. Measured REE was significantly associated (P < 0.05) with age, sex, Model for End-Stage Liver Disease score before LT, surgery time, and graft cold ischemia time according to the multiple regression analysis. CONCLUSIONS: The low accuracy of HB and fixed factors suggests risks of both under- and overfeeding of individual patients if energy requirement is only based on calculation. REE measurement is recommended after LT to secure accurate and safe nutritional therapy.

Systemic modified messenger RNA for replacement therapy in alpha 1-antitrypsin deficiency.

Alpha 1-antitrypsin (AAT) deficiency arises from an inherited mutation in the SERPINA1 gene. The disease causes damage in the liver where the majority of the AAT protein is produced. Lack of functioning circulating AAT protein also causes uninhibited elastolytic activity in the lungs leading to AAT deficiency-related emphysema. The only therapy apart from liver transplantation is augmentation with human AAT protein pooled from sera, which is only reserved for patients with advanced lung disease caused by severe AAT deficiency. We tested modified mRNA encoding human AAT in primary human hepatocytes in culture, including hepatocytes from AAT deficient patients. Both expression and functional activity were investigated. Secreted AAT protein increased from 1,14 to 3,43 µg/ml in media from primary human hepatocytes following mRNA treatment as investigated by ELISA and western blot. The translated protein showed activity and protease inhibitory function as measured by elastase activity assay. Also, mRNA formulation in lipid nanoparticles was assessed for systemic delivery in both wild type mice and the NSG-PiZ transgenic mouse model of AAT deficiency. Systemic intravenous delivery of modified mRNA led to hepatic uptake and translation into a functioning protein in mice. These data support the use of systemic mRNA therapy as a potential treatment for AAT deficiency.