Enhancing the accuracy of mid-infrared spectroscopy-based liver steatosis quantification using digital image analysis as a reference.

The assessment of liver steatosis is crucial in both hepatology and liver transplantation (LT) surgery. Steatosis can negatively impact the success of LT. Steatosis is a factor for excluding donated organs for LT, but the increasing demand for transplantable organs has led to the use of organs from marginal donors. The current standard for evaluating steatosis is a semi-quantitative grading based on the visual examination of a hematoxylin and eosin (H&E)-stained liver biopsy, but this method is time-consuming, subjective, and lacks reproducibility. Recent research has shown that infrared (IR) spectroscopy could be used as a real-time quantitative tool to assess steatosis during abdominal surgery. However, the development of IR-based methods has been hindered by the lack of appropriate quantitative reference values. In this study, we developed and validated digital image analysis methods for the quantitation of steatosis in H&E-stained liver sections using univariate and multivariate strategies including linear discriminant analysis (LDA), quadratic DA, logistic regression, partial least squares-DA (PLS-DA), and support vector machines. The analysis of 37 tissue samples with varying grades of steatosis demonstrates that digital image analysis provides accurate and reproducible reference values that improve the performance of IR spectroscopic models for steatosis quantification. A PLS model in the 1810-1052 cm-1 region using first derivative ATR-FTIR spectra provided RMSECV = 0.99%. The gained improvement in accuracy critically enhances the applicability of Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) to support an objective graft evaluation at the operation room, which might be especially relevant in cases of marginal liver donors to avoid unnecessary graft explantation.

Comparing the direct assessment of steatosis in liver explants with mid- and near-infrared vibrational spectroscopy, prior to organ transplantation.

A fast and accurate assessment of liver steatosis is crucial during liver transplantation surgery as it can negatively impact its success. Recent research has shown that near-infrared (NIR) and attenuated total reflectance-Fourier transform mid-infrared (ATR-FTIR) spectroscopy could be used as real-time quantitative tools to assess steatosis during abdominal surgery. Here, in the frame of a clinical study, we explore the performance of NIR and ATR-FTIR spectroscopy for the direct assessment of steatosis in liver tissues. Results show that both NIR and ATR-FTIR spectroscopy are able to quantify the % of steatosis with cross-validation errors of 1.4 and 1.6%, respectively. Furthermore, the two portable instruments used both provided results within seconds and can be placed inside an operating room evidencing the potential of IR spectroscopy for initial characterization of grafts in liver transplantation surgery. We also evaluated the complementarity of the spectral ranges through correlation spectroscopy.

Quantitative Prediction of Steatosis in Patients with Non-Alcoholic Fatty Liver by Means of Hepatic MicroRNAs Present in Serum and Correlating with Hepatic Fat.

Non-alcoholic fatty liver disease (NAFLD) is the most prevalent form of chronic liver disease worldwide, but a reliable non-invasive method to quantify liver steatosis in primary healthcare is not available. Circulating microRNAs have been proposed as biomarkers of severe/advanced NAFLD (steatohepatitis and fibrosis). However, the use of circulating miRNAs to quantitatively assess the % of liver fat in suspected NAFLD patients has not been investigated. We performed global miRNA sequencing in two sets of samples: human livers from organ donors (n = 20), and human sera from biopsy-proven NAFLD patients (n = 23), both with a wide range of steatosis quantified in their liver biopsies. Partial least squares (PLS) regression combined with recursive feature elimination (RFE) was used to select miRNAs associated with steatosis. Moreover, regression models with only 2 or 3 miRNAs, with high biological relevance, were built. Comprehensive microRNA sequencing of liver and serum samples resulted in two sets of abundantly expressed miRNAs (418 in liver and 351 in serum). Pearson correlation analyses indicated that 18% of miRNAs in liver and 14.5% in serum were significantly associated with the amount of liver fat. PLS-RFE models demonstrated that 50 was the number of miRNAs providing the lowest error in both liver and serum models predicting steatosis. Comparison of the two miRNA subsets showed 19 coincident miRNAs that were ranked according to biological significance (guide/passenger strand, relative abundance in liver and serum, number of predicted lipid metabolism target genes, correlation significance, etc.). Among them, miR-10a-5p, miR-98-5p, miR-19a-3p, miR-30e-5p, miR-32-5p and miR-145-5p showed the highest biological relevance. PLS regression models with serum levels of 2−3 of these miRNAs predicted the % of liver fat with errors <5%.

Toward Rapid Screening of Liver Grafts at the Operating Room Using Mid-infrared Spectroscopy.

The estimation of steatosis in a liver graft is mandatory prior to liver transplantation, as the risk of graft failure increases with the level of infiltrated fat. However, the assessment of liver steatosis before transplantation is typically based on a qualitative or semiquantitative characterization by visual inspection and palpation and histological analysis. Thus, there is an unmet need for transplantation surgeons to have access to a diagnostic tool enabling an in situ fast classification of grafts prior to extraction. In this study, we have assessed an attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic method compatible with the requirements of an operation room for the evaluation of the lipid contents in human livers. A set of 20 human liver biopsies obtained from organs intended for transplantation were analyzed by expert pathologists, ATR-FTIR spectroscopy, lipid biochemical analysis, and UPLC-ESI(+/-)TOFMS for lipidomic profiling. Comparative analysis of multisource data showed strong correlations between ATR-FTIR, clinical, and lipidomic information. Results show that ATR-FTIR captures a global picture of the lipid composition of the liver, along with information for the quantification of the triradylglycerol content in liver biopsies. Although the methodology performance needs to be further validated, results support the applicability of ATR-FTIR for the in situ determination of the grade of liver steatosis at the operation room as a fast, quantitative method, as an alternative to the qualitative and subjective pathological examination.

Improved in vivo efficacy of clinical-grade cryopreserved human hepatocytes in mice with acute liver failure.

Clinical hepatocyte transplantation short-term efficacy has been demonstrated; however, some major limitations, mainly due to the shortage of organs, the lack of quality of isolated cells and the low cell engraftment after transplantation, should be solved for increasing its efficacy in clinical applications. Cellular stress during isolation causes an unpredictable loss of attachment ability of the cells, which can be aggravated by cryopreservation and thawing. In this work, we focused on the use of a Good Manufacturing Practice (GMP) solution compared with the standard cryopreservation medium, the University of Wisconsin medium, for the purpose of improving the functional quality of cells and their ability to engraft in vivo, with the idea of establishing a biobank of cryopreserved human hepatocytes available for their clinical use. We evaluated not only cell viability but also specific hepatic function indicators of the functional performance of the cells such as attachment efficiency, ureogenic capability, phase I and II enzymes activities and the expression of specific adhesion molecules in vitro. Additionally, we also assessed and compared the in vivo efficacy of human hepatocytes cryopreserved in different media in an animal model of acute liver failure. Human hepatocytes cryopreserved in the new GMP solution offered better in vitro and in vivo functionality compared with those cryopreserved in the standard medium. Overall, the results indicate that the new tested GMP solution maintains better hepatic functions and, most importantly, shows better results in vivo, which could imply an increase in long-term efficacy when used in patients.

A score model for the continuous grading of early allograft dysfunction severity.

Early allograft dysfunction (EAD) dramatically influences graft and patient outcomes. A lack of consensus on an EAD definition hinders comparisons of liver transplant outcomes and management of recipients among and within centers. We sought to develop a model for the quantitative assessment of early allograft function [Model for Early Allograft Function Scoring (MEAF)] after transplantation. A retrospective study including 1026 consecutive liver transplants was performed for MEAF score development. Multivariate data analysis was used to select a small number of postoperative variables that adequately describe EAD. Then, the distribution of these variables was mathematically modeled to assign a score for each actual variable value. A model, based on easily obtainable clinical parameters (ie, alanine aminotransferase, international normalized ratio, and bilirubin) and scoring liver function from 0 to 10, was built. The MEAF score showed a significant association with patient and graft survival at 3-, 6- and 12-month follow-ups. Hepatic steatosis and age for donors; cold/warm ischemia times and postreperfusion syndrome for surgery; and intensive care unit and hospital stays, Model for End-Stage Liver Disease and Child-Pugh scores, body mass index, and fresh frozen plasma transfusions for recipients were factors associated significantly with EAD. The model was satisfactorily validated by its application to an independent set of 200 patients who underwent liver transplantation at a different center. In conclusion, a model for the quantitative assessment of EAD severity has been developed and validated for the first time. The MEAF provides a more accurate graft function assessment than current categorical classifications and may help clinicians to make early enough decisions on retransplantation benefits. Furthermore, the MEAF score is a predictor of recipient and graft survival. The standardization of the criteria used to define EAD may allow reliable comparisons of recipients' treatments and transplant outcomes among and within centers.

Human neonatal hepatocyte transplantation induces long-term rescue of unconjugated hyperbilirubinemia in the Gunn rat.

Crigler-Najjar type 1 disease is a rare inherited metabolic disease characterized by high levels of unconjugated bilirubin due to the complete absence of hepatic uridine diphosphoglucuronate-glucuronosyltransferase activity. Hepatocyte transplantation (HT) has been proposed as an alternative treatment for Crigler-Najjar syndrome, but it is still limited by the quality and the low engraftment and repopulation ability of the cells used. Because of their attachment capability and expression of adhesion molecules as well as the higher proportion of hepatic progenitor cells, neonatal hepatocytes may have an advantage over adult cells. Adult or neonatal hepatocytes were transplanted into Gunn rats, a model for Crigler-Najjar disease. Engraftment and repopulation were studied and compared by immunofluorescence (IF). Additionally, the serum bilirubin levels, the presence of bilirubin conjugates in rat serum, and the expression of uridine diphosphate glucuronosyltransferase 1 family polypeptide A1 (UGT1A1) in rat liver samples were also analyzed. Here we show that neonatal HT results in long-term correction in Gunn rats. In comparison with adult cells, neonatal cells showed better engraftment and repopulation capability 3 days and 6 months after transplantation, respectively. Bilirubinemia decreased in the transplanted animals during the whole experimental follow-up (6 months). Bilirubin conjugates were also present in the serum of the transplanted animals. Western blots and IF confirmed the presence and expression of UGT1A1 in the liver. This work is the first to demonstrate the advantage of using neonatal hepatocytes for the treatment of Crigler-Najjar in vivo.

Metabolomics discloses donor liver biomarkers associated with early allograft dysfunction.

BACKGROUND & AIMS: Early allograft dysfunction (EAD) dramatically influences graft and patient outcome after orthotopic liver transplantation and its incidence is strongly determined by donor liver quality. Nevertheless, objective biomarkers, which can assess graft quality and anticipate organ function, are still lacking. This study aims to investigate whether there is a preoperative donor liver metabolomic biosignature associated with EAD. METHODS: A comprehensive metabolomic profiling of 124 donor liver biopsies collected before transplantation was performed by mass spectrometry coupled to liquid chromatography. Donor liver grafts were classified into two groups: showing EAD and immediate graft function (IGF). Multivariate data analysis was used to search for the relationship between the metabolomic profiles present in donor livers before transplantation and their function in recipients. RESULTS: A set of liver graft dysfunction-associated biomarkers was identified. Key changes include significantly increased levels of bile acids, lysophospholipids, phospholipids, sphingomyelins and histidine metabolism products, all suggestive of disrupted lipid homeostasis and altered histidine pathway. Based on these biomarkers, a predictive EAD model was built and further evaluated by assessing 24 independent donor livers, yielding 91% sensitivity and 82% specificity. The model was also successfully challenged by evaluating donor livers showing primary non-function (n=4). CONCLUSIONS: A metabolomic biosignature that accurately differentiates donor livers, which later showed EAD or IGF, has been deciphered. The remarkable metabolomic differences between donor livers before transplant can relate to their different quality. The proposed metabolomic approach may become a clinical tool for donor liver quality assessment and for anticipating graft function before transplant.

[Current status and future perspectives of hepatocyte transplantation]. / Estado actual y perspectivas futuras del trasplante de hepatocitos.

The imbalance between the number of potential beneficiaries and available organs, originates the search for new therapeutic alternatives, such as Hepatocyte transplantation (HT).Even though this is a treatment option for these patients, the lack of unanimity of criteria regarding indications and technique, different cryopreservation protocols, as well as the different methodology to assess the response to this therapy, highlights the need of a Consensus Conference to standardize criteria and consider future strategies to improve the technique and optimize the results.Our aim is to review and update the current state of hepatocyte transplantation, emphasizing the future research attempting to solve the problems and improve the results of this treatment.

Long-term outcome of 'long-term liver transplant survivors'.

There are few studies focusing on long-term complications in liver transplant (LT) recipients. The aim of this study was to define the outcome of LT recipients having survived at least 10 years from LT. Of 323 adult LT done between 1991 and 1997, the 167(52%) alive >10 years post-LT (baseline time) formed the study population. Long-term outcome measures included the following: immunosuppression, metabolic complications [obesity, arterial hypertension (AH), diabetes, dislypidemia], cardiovascular events (CVE), chronic renal dysfunction-CRD, and de novo tumors. Median age at LT was 50 years. Most common indication was postnecrotic cirrhosis (89%), mostly because of HCV (46%). At study-baseline (10 years post-LT), 29% were obese and AH, diabetes, dislypidemia, and CRD were present in 75%, 30%, 42%, and 36%, respectively. In most cases, these complications were already present 1 year post-LT; less than one quarter developed them onward. The 6 year cumulative survival since baseline reached 84% (n = 24 deaths), with most deaths related to recurrent graft diseases (mostly HCV) followed by de novo tumors or CVE. 1, 3, 5 and 10 years cumulative rates of CVE and de novo tumors since baseline were 2%, 5%, 10% and 17%, and 1%, 3%, 6% and 13%, respectively. Chronic renal impairment was independently associated with survival and development of CVE since baseline. The medium-term survival of 'long-term survivors', i.e. patients alive 10 years after LT is good, but metabolic complications and CRD are common and continue to increase afterwards. Cardiovascular events and de novo tumors increase gradually over time and represent a major cause of late mortality.

Comparison of results of combined liver-kidney transplantation vs. isolated liver transplantation.

INTRODUCTION: Combined liver-kidney transplantation (LKT) is the best therapeutic option for patients with end-stage liver and kidney disease. OBJECTIVES: To analyze baseline characteristics and clinical outcome of LKT compared to isolated liver transplantation (LT). MATERIAL AND METHODS: The study included 16 LKT performed between 1998 and 2006 and 32 LT matched by age, sex, date and indication for transplantation. Demographic, pretransplant, post-transplant and survival variables were analyzed. RESULTS: As planned by the study design, mean age, distribution by sex and indication for LT were similar between groups. The most common indication for LT was HCV- and/or alcohol-induced cirrhosis. The most common indication for KT was renal failure, in most cases secondary to glomerulonephritis. Twelve patients (69%) were on dialysis before LKT. Hepatocellular carcinoma and diabetes mellitus pre-transplantation were similar between groups. However pretransplant arterial hypertension (AHT) was higher in LKT than LT (50% vs. 19%; p = 0.02). In the post-transplant: reoperation due to bleeding, bacterial infections, liver rejection, AHT and median creatinine levels at 1st and 3rd years were similar in LKT and LT. In contrast, early post-transplant dialysis was higher in LKT than LT (31% vs. 3%; p = 0.01). Survival rates at 1st, 3rd, 5th and 7th years were similar in both groups (87.5%, 74%, 74% and 66% vs. 81%, 75%, 75% and 75% in LT and LKT, respectively). CONCLUSIONS: LKT is an effective therapeutic option in patients with end-stage liver and kidney disease. Most early and late complications and long-term survival are similar to those observed with LT.

A robust reprogramming strategy for generating hepatocyte-like cells usable in pharmaco-toxicological studies.

BACKGROUND: High-throughput pharmaco-toxicological testing frequently relies on the use of established liver-derived cell lines, such as HepG2 cells. However, these cells often display limited hepatic phenotype and features of neoplastic transformation that may bias the interpretation of the results. Alternate models based on primary cultures or differentiated pluripotent stem cells are costly to handle and difficult to implement in high-throughput screening platforms. Thus, cells without malignant traits, optimal differentiation pattern, producible in large and homogeneous amounts and with patient-specific phenotypes would be desirable. METHODS: We have designed and implemented a novel and robust approach to obtain hepatocytes from individuals by direct reprogramming, which is based on a combination of a single doxycycline-inducible polycistronic vector system expressing HNF4A, HNF1A and FOXA3, introduced in human fibroblasts previously transduced with human telomerase reverse transcriptase (hTERT). These cells can be maintained in fibroblast culture media, under standard cell culture conditions. RESULTS: Clonal hTERT-transduced human fibroblast cell lines can be expanded at least to 110 population doublings without signs of transformation or senescence. They can be easily differentiated at any cell passage number to hepatocyte-like cells with the simple addition of doxycycline to culture media. Acquisition of a hepatocyte phenotype is achieved in just 10 days and requires a simple and non-expensive cell culture media and standard 2D culture conditions. Hepatocytes reprogrammed from low and high passage hTERT-transduced fibroblasts display very similar transcriptomic profiles, biotransformation activities and show analogous pattern behavior in toxicometabolomic studies. Results indicate that this cell model outperforms HepG2 in toxicological screening. The procedure also allows generation of hepatocyte-like cells from patients with given pathological phenotypes. In fact, we succeeded in generating hepatocyte-like cells from a patient with alpha-1 antitrypsin deficiency, which recapitulated accumulation of intracellular alpha-1 antitrypsin polymers and deregulation of unfolded protein response and inflammatory networks. CONCLUSION: Our strategy allows the generation of an unlimited source of clonal, homogeneous, non-transformed induced hepatocyte-like cells, capable of performing typical hepatic functions and suitable for pharmaco-toxicological high-throughput testing. Moreover, as far as hepatocyte-like cells derived from fibroblasts isolated from patients suffering hepatic dysfunctions, retain the disease traits, as demonstrated for alpha-1-antitrypsin deficiency, this strategy can be applied to the study of other cases of anomalous hepatocyte functionality.

Gut Microbiota and Plasma Bile Acids Associated with Non-Alcoholic Fatty Liver Disease Resolution in Bariatric Surgery Patients.

Bariatric surgery (BS) has several benefits, including resolution of non-alcoholic fatty liver disease (NAFLD) in many patients. However, a significant percentage of patients do not experience improvement in fatty liver after BS, and more than 10% develop new or worsening NAFLD features. Therefore, a question that remains unanswered is why some patients experience resolved NAFLD after BS and others do not. In this study, we investigated the fecal microbiota and plasma bile acids associated with NAFLD resolution in twelve morbidly obese patients undergoing BS, of whom six resolved their steatosis one year after surgery and another six did not. Results indicate that the hallmark of the gut microbiota in responder patients is a greater abundance of Bacteroides, Akkermansia, and several species of the Clostridia class (genera: Blautia, Faecalibacterium, Roseburia, Butyricicoccusa, and Clostridium), along with a decreased abundance of Actinomycetes/Bifidobacterium and Faecalicatena. NAFLD resolution was also associated with a sustained increase in primary bile acids (particularly non-conjugated), which likely results from a reduction in bacterial gut species capable of generating secondary bile acids. We conclude that there are specific changes in gut microbiota and plasma bile acids that could contribute to resolving NAFLD in BS patients. The knowledge acquired can help to design interventions with prebiotics and/or probiotics to promote a gut microbiome that favors NAFLD resolution.

Steatotic liver: a suitable source for the isolation of hepatic progenitor cells.

BACKGROUND: Alternative and/or complementary sources of cells such as hepatic progenitor cells (HPC) are under investigation for hepatic cell therapy purposes. Steatotic livers are those most commonly rejected for clinical transplantation and are also unsuitable for good quality hepatocyte isolation. AIM: Taken together these two facts, our aim was to investigate whether they could represent a suitable source for the isolation of progenitor cells. METHODS: Rats fed for 7 weeks with methionine-choline deficient diets showing proved steatotic signs (i.e. increase in hepatic lipids; macrovesicular steatosis) and steatotic and normal human liver samples were used to study the expression of HPC markers and to isolate these cells. RESULTS: In the liver of the steatotic rats there was a significant increase in HPC (known as oval cells in rodents) markers such as Thy-1, epithelial cell adhesion molecule (EpCAM) and OV-6 (2-, 3- and 5-fold increase respectively). Additionally, there was an increase in the yield of isolated oval cells compared to control rats. Similarly, studies using human livers clearly confirmed an increase in the expression of HPC markers in the steatotic tissue and a significant rise in the number of isolated progenitor cells (EpCAM+, Thy-1+, OV-6+) (10, 12 and 11.6 × 10(4)  cells/g of tissue respectively). CONCLUSIONS: These data suggest that steatotic livers, discarded for orthotopic liver transplantation and hepatocyte isolation, could be a suitable source for large scale isolation of HPC which might be potential candidates in liver cell therapy.

[Epithelioid hemangioendothelioma: an uncommon liver tumor]. / Hemangioendotelioma epitelioide: un tumor hepatico infrecuente.

We report the case of a female patient who was referred to our unit because of a solid liver tumor, suggestive of metastasis. After biopsy, the patient was diagnosed with epithelioid hemangioendothelioma of the liver. Epithelioid hemangioendothelioma is a rare entity with an unpredictable, potentially fatal, clinical course and outcome. Due to its rarity, this entity should be considered when a solitary hepatic lesion is detected and should be included in the differential diagnosis with liver metastases. We highlight the infrequency of this tumor, its presentation as a solitary hepatic lesion and the indication of surgical treatment. We describe the clinical and pathological characteristics of epithelioid hemangioendothelioma of the liver and report a new case of this entity. The distinct therapeutic options are discussed.

[Hepatic cell transplantation: a new therapy in liver diseases]. / Trasplante celular hepático: un nuevo tratamiento en las enfermedades hepáticas.

Liver transplantation has been remarkably effective in the treatment in patients with end-stage liver disease. However, disparity between solid-organ supply and increased demand is the greatest limitation, resulting in longer waiting times and increase in mortality of transplant recipients. This situation creates the need to seek alternatives to orthotopic liver transplantation.Hepatocyte transplantation or liver cell transplantation has been proposed as the best method to support patients. The procedure consists of transplanting individual cells to a recipient organ in sufficient quantity to survive and restore the function. The capacity of hepatic regeneration is the biological basis of hepatocyte transplantation. This therapeutic option is an experimental procedure in some patients with inborn errors of metabolism, fulminant hepatic failure and acute and chronic liver failure, as a bridge to orthotopic liver transplantation. In the Hospital La Fe of Valencia, we performed the first hepatocyte transplantation in Spain creating a new research work on transplant program.

[Indications and results of liver retransplantation: experience with 1181 patients at the University Hospital La Fe]. / Indicaciones y resultados de retrasplante hepático: experiencia del hospital universitario La Fe (1.181 pacientes).

UNLABELLED: Liver retransplantation (LrT) is the only therapeutic option for irreversible failure of a hepatic graft and accounts for 2.9%-24.0% of all liver transplantations (LT). It is technically difficult and has a high level of immediate morbidity and a lower survival than primary LT. Our aim was to determine the rate of LrT and its indications, morbidity, post-operative mortality and actuarial survival in the retransplanted patient. PATIENTS AND METHOD: A historical cohort study of 1181 patients transplanted between 1991 and 2006. RESULTS: Of the 1260 LT performed, 79 were LrT. At the time of the first LT there were no differences between those patients and those that did not require an LrT. The LrT rate was 6.3% and the most frequent causes were: hepatic artery thrombosis (31.6%), recurrence of cirrhosis due the HVC (30.4%) and primary graft (21.5%). The ischemia times, perfusion syndrome and hepatic congestion were no different between the primary LT and the LrT. On the other hand, red cell transfusions were higher in LrT (6.3+/-4.9 vs. 3.5+/-3.0 units, P<0.001). The post-operative morbidity and morbidity (up to 30 days after the LT) was higher in retransplanted patients (68.4% vs. 57.0%, P=0.04 and 25.3% vs. 10.9%, P<0.001; respectively). The actuarial survival at 1 and 5 years was 83% and 69% in those without LrT, 71% and 61% in early LrT and 64% and 34% in delayed LrT (P<0.001). CONCLUSIONS: Despite the increased morbidity and mortality of LrT, it appears that this treatment alternative is still valid in those patients with an early loss of the liver graft. On the other hand, when the graft loss is delayed, it needs to be defined, what would be the minimum acceptable results to indicate LrT and which patients could benefit from this treatment.

Induced pluripotent stem cells for the treatment of liver diseases: challenges and perspectives from a clinical viewpoint.

The only curative treatment for severe end-stage liver disease (ESLD) is liver transplantation (LT) but it is limited by the shortage of organ donors. The increase of the incidence of liver disease has led to develop new therapeutic approaches such as liver cell transplantation. Current challenges that limit a wider application of this therapy include a limited cell source and the poor engraftment in the host liver of cryopreserved hepatocytes after thawing. Induced pluripotent stem cells (iPSCs) that can be differentiated into hepatocyte-like cells (HLCs) are being widely explored as an alternative to human hepatocytes because of their unlimited proliferation capacity and their potential ability to avoid the immune system. Their large-scale production could provide a new tool to produce enough HLCs for treating patients with metabolic diseases, acute liver failure (ALF), those with ESLD or patients not considered for organ transplantation. In this review we discuss current challenges for generating differentiated cells compatible with human application as well as in-depth safety evaluation. This analysis highlights the uncertainties and deficiencies that should be addressed before their clinical use but also points out the potential benefits that will produce a great impact in the field of hepatology.

Comparative prospective study of two liver graft preservation solutions: University of Wisconsin and Celsior.

University of Wisconsin solution (UWS) is the gold standard for graft preservation. Celsior solution (CS) is a new solution not as yet widely used in liver grafts. The aim of this study was to compare the liver function of transplanted grafts stored in these 2 preservation solutions. The primary endpoints were the rates of primary nonfunction (PNF) and primary dysfunction (PDF). We performed a prospective and pseudorandomized study that included 196 patients (representing 104 and 92 livers preserved in UWS and CS, respectively) at La Fe University Hospital (Valencia, Spain) between March 2003 and May 2005. PNF and PDF rates, liver function laboratory parameters, postoperative bleeding, vascular and biliary complications, and patient and graft survival at 3 years were compared for the 2 groups. The 2 groups were similar in terms of donor variables, recipient variables, and surgical techniques. The PNF rates were 2.2% and 1.9% in the CS and UWS groups, respectively (P = not significant), and the PDF rates were 15.2% and 15.5% in the CS and UWS groups, respectively (P = not significant). There were no significant differences in the laboratory parameters for the 2 groups, except for alanine aminotransferase levels in month 3, which were lower in the CS group (P = 0.01). No significant differences were observed in terms of complications. Three-year patient and graft survival rates were as follows for years 1, 2, and 3: 83%, 80%, and 76% (patient) and 80%, 77%, and 73% (graft) for the UWS group and 83%, 77%, and 70% (patient) and 81%, 73%, and 67% (graft) for the CS group (P = not significant). In conclusion, this study shows that CS is as effective as UWS in liver preservation.