Françoise Smets

Hepatocyte transplantation in a 4-year-old girl with peroxisomal biogenesis disease: technique, safety, and metabolic follow-up.

Hepatocyte transplantation is an investigational alternative to orthotopic liver transplantation to treat liver based inborn errors of metabolism. We report successful hepatocyte transplantation in a 4-year-old girl with infantile Refsum disease. Hepatocytes were isolated from the left liver segment of two male donors using a classic two-step perfusion method. Fresh cells were transplanted first and then cryopreserved cells, for a total of 2 billion cells. Total bile acids and abnormal dihydroxycoprostanoïc acid markedly decreased in the patients serum, indicating resolution of cholestasis and re-population of liver cells. Pipecholic acid decreased by 40% and c26:c22 fatty acid ratio by 36% after 18 months. Donor chromosomes sequences were detected on biopsy posttransplant, indicating engraftment. Hepatocyte transplantation is a safe and promising technique in the treatment of rare inborn errors of metabolism. Future improvements of cell viability and prevention of apoptosis may increase engraftment and subsequent re-population.

Patients at risk for development of posttransplant lymphoproliferative disorder: plasma versus peripheral blood mononuclear cells as material for quantification of Epstein-Barr viral load by using real-time quantitative polymerase chain reaction

Background. Early diagnosis of Epstein-Barr virus (EBV)-associated posttransplant lymphoproliferative disorder (PTLD) is required to detect a stage of disease that is more likely to respond to treatment. Elevated levels of EBV DNA were found in peripheral blood of patients at the onset of PTLD. Methods. To compare plasma and peripheral blood mononuclear cells (PBMCs) as material for real-time quantitative polymerase chain reaction (RQ-PCR) measurement of Epstein-Barr viral load, we used two sets of primers and probes specific for the BAM HI-K or BAM HI-W region of the EBV genome. Results. Patients with PTLD had a median viral load of 19,200 EBV genomes/&mgr;g DNA (n=9) or 3,225 EBV genomes/100 &mgr;l plasma (n=5), being significantly higher compared with immunosuppressed patients with primary (n=9) or reactivated (n=20) EBV infection or immunosuppressed patients without serological signs of active EBV infection (n=67) (P <0.001). Hence, a value of greater than 5,000 EBV genomes/&mgr;g PBMC DNA was considered as a diagnostic parameter for PTLD with a sensitivity and specificity of 1.00 or 0.89, respectively. When plasma was analyzed, however, a value of greater than 1,000 EBV genomes/100 &mgr;l plasma had both a sensitivity and specificity of 1.00 for the diagnosis of PTLD. During remission of PTLD, viral load was more effectively cleared in plasma compared with PBMCs. In plasma of nonimmunosuppressed individuals, even a qualitative detection of EBV-related sequences was sensitive and specific for the diagnosis of primary EBV infection, whereas for analysis of PBMC DNA a quantitative parameter had to be considered to differentiate healthy individuals (<100 EBV genomes/&mgr;g PBMC DNA) from patients with primary EBV infection (>100 EBV genomes/&mgr;g PBMC DNA). Conclusion. Although both PBMCs and plasma were useful as material for EBV-specific RQ-PCR in immunosuppressed patients and nonimmunosuppressed individuals, the specificity of analysis seemed to be higher if plasma was taken for analysis.

Cryopreserved liver cell transplantation controls ornithine transcarbamylase deficient patient while awaiting liver transplantation.

Liver cell transplantation was performed in a child with urea cycle disorder poorly equilibrated by conventional therapy as a bridge to transplantation. A 14‐month‐old boy with ornithine transcarbamylase (OTC) deficiency received 0.24 billion viable cryopreserved cells/kg over 16 weeks. Tacrolimus and steroids were given as immunosuppressive treatment while the patient was kept on the pre‐cell transplant therapy. Mean blood ammonia level decreased significantly following the seven first infusions, while urea levels started to increase from undetectable values. After those seven infusions, an ammonium peak up to 263 μg/dL, clinically well tolerated, was observed. Interestingly, blood urea levels increased continuously to reach 25 mg/dL, after the last three infusions. Eventually, he benefited from elective orthotopic liver transplantation (OLT) and the post‐surgical course was uneventful. We conclude that use of cryopreserved cells allowed short‐ to medium‐term metabolic control and urea synthesis in this male OTC‐deficient patient while waiting for OLT.

Human skin fibroblasts: From mesodermal to hepatocyte-like differentiation†

The phenotypic homology of fibroblasts and mesenchymal stem cells (MSCs) has been recently described. Our study investigated the in vitro potential of human skin fibroblasts to differentiate into mesodermal (osteocyte and adipocyte) and endodermal (hepatocyte) cell lineages by comparison with human bone marrow (hBM) MSCs. The endodermal potential of fibroblasts was then explored in vivo in a mouse model of liver injury. Fibroblasts were able to acquire osteocyte and adipocyte phenotypes as assessed by cytochemistry and gene expression analyses. After exposure to a specific differentiation cocktail, these cells presented hepatocyte‐like morphology and acquired liver‐specific markers on protein and gene expression levels. Furthermore, these fibroblast‐derived hepatocyte‐like cells (FDHLCs) displayed the ability to store glycogen and synthesize small amounts of urea. By gene expression analysis, we observed that fibroblasts remained in a mesenchymal‐epithelial transition state after hepatocyte differentiation. Moreover, FDHLCs lost their hepatocyte‐like phenotype after dedifferentiation. In vivo, human fibroblasts infused directly into the liver of hepatectomized severe combined immunodeficient (SCID) mice engrafted in situ and expressed hepatocyte markers (albumin, alpha‐fetoprotein, and cytokeratin 18) together with the mesodermal marker fibronectin. Despite lower liver‐specific marker expression, the in vitro and in vivo differentiation profile of fibroblasts was comparable to that of mesenchymal‐derived hepatocyte‐like cells (MDHLCs). In conclusion, our work demonstrates that human skin fibroblasts are able to display mesodermal and endodermal differentiation capacities and provides arguments that these cells share MSCs features both on the phenotypic and functional levels. (HEPATOLOGY 2007;46:1574–1585.)

Cell transplantation in the treatment of liver diseases.

Abstract:  The liver performs multiple functions that are essential for life, the most crucial being its role in the body metabolism. Impairment of this function, because of liver insufficiency, can be partially restored by medical management but OLT remains the ultimate therapeutic treatment. Because not always indicated or available, other alternatives are proposed such as LCT. Compared to OLT, this procedure is less invasive, less expensive, and fully reversible. More than 50 patients have thus far benefited of this technique and are reviewed here. Indications were multiple including inborn errors of metabolism, FHF, acute on chronic diseases, and decompensated end‐stage cirrhosis. Documented results were encouraging, especially for metabolic disorders, with medium‐term efficacy up to two yr. Related complications were exceptional. On this basis, LCT has entered its phase of clinical application and current indications and protocols are detailed. Ongoing lines of research are discussed, including cell quality, stem cell field, and rejection prevention. Further improvement of the procedure is therefore expected and should lead to broader applications of LCT.

Saccharomyces boulardii Produces in Rat Small Intestine a Novel Protein Phosphatase that Inhibits Escherichia coli Endotoxin by Dephosphorylation

Using a polyclonal antibody raised against a highly conserved sequence of 38 amino acids containing the activation site (VTDSAAGAT) common to mammalian and yeast alkaline phosphatases (AP), we identified in decapsidated Saccharomyces boulardii a protein phosphatase detected by autoradiography as a single signal (63 kD). Using an affinity chromatography column, the protein phosphatase could be concentrated 39.1-fold and presented as a doublet of two subunits. Compared with rat and bovine purified intestinal AP, the enzyme from S. boulardii had a greater ability to dephosphorylate the lipopolysaccharide (LPS) of Escherichia coli 055B5. When tested in vivo, intraperitoneal injection of intact LPS to rats produced, after 9 h, 100 ng/mL of circulating tumor necrosis factor-α with inflammatory lesions and apoptotic bodies in the liver and the heart, whereas rats injected with partially dephosphorylated LPS produced only 40 ng/mL tumor necrosis factor-α without organic lesions. In conclusion, S. boulardii is able to inhibit toxicity of E. coli surface endotoxins by the release of a protein phosphatase exhibiting a great capacity of dephosphorylation.

Cryopreservation of human hepatocytes alters the mitochondrial respiratory chain complex 1.

Transplantation of human hepatocytes has recently been demonstrated as a safe alternative to partially correct liver inborn errors of metabolism. Cryopreservation remains the most appropriate way of cell banking. However, mitochondrial-mediated apoptosis has been reported after cryopreservation and little is known on the involved molecular mechanisms. The aim of this study was to investigate mitochondrial functions of freshly isolated and cryopreserved/thawed hepatocytes from mice and humans. We report here that cryopreservation induced a dramatic drop of ATP levels in hepatocytes. The oxygen consumption rate of cryopreserved/thawed hepatocytes was significantly lower compared to fresh cells. In addition, the uncoupling effect of 2,4-dinitrophenol was lost, in parallel with a reduction of mitochondrial membrane potential. Furthermore, a decrease in mitochondrial respiratory rate was evidenced on permeabilized hepatocytes in the presence of substrate for the respiratory chain complex 1. Interestingly, this effect was less marked with a substrate for complex 2. Electron microscopy examination indicated that mitochondria were swollen and devoid of cristae after cryopreservation. These changes could explain the cytosolic release of the proapoptotic protein cytochrome c in cryopreserved cells. Nevertheless, no caspase 9-3 activation and only few apoptotic and necrotic cells were found, indicating that the subsequent cell death program was not yet evidenced. Our results demonstrate that cryopreservation of hepatocytes induced alteration of the mitochondrial machinery. They also suggest that, in addition to technical progress in the cryopreservation procedure, protection of the respiratory chain complex 1 should be considered to improve the quality of cryopreserved hepatocytes.

Characteristics of Epstein-Barr virus primary infection in pediatric liver transplant recipients.

BACKGROUND/AIM: Pediatric liver transplant recipients are at high risk of Epstein-Barr virus infection. However the incidence of clinical symptoms and the graft function at the time of acute infection remains poorly documented. The aim of this study was to monitor the clinical and biochemical events associated with primary Epstein-Barr virus infection. METHODS: Clinical and biological patterns associated with Epstein-Barr virus infection were prospectively searched in 38 liver transplanted children. Polymerase chain reaction and anti-Epstein-Barr virus IgM antibodies were used at regular intervals to detect the timing of primary infection. RESULTS: Five children (13%) had pretransplant immunity, 26 (68.5%) developed primary Epstein-Barr virus infection 15 to 90 days after transplantation and seven (18.5%) remained Epstein-Barr virus negative. The four patients with clinical symptoms at the time of infection subsequently developed post-transplant lymphoproliferative disease. A single post-transplant lymphoproliferative disease occurred in non-symptomatic patients (overall incidence 13%). No mortality was associated with post-transplant lymphoproliferative disease. Two asymptomatic patients had abnormal liver function tests possibly related to primary Epstein-Barr virus infection. CONCLUSION: Epstein-Barr virus primary infection occurs in 80% of seronegative patients within 3 months after OLT. Clinical symptoms are rare and closely associated with post-transplant lymphoproliferative disease. Outside post-transplant lymphoproliferative disease, the consequences of infection are marginal.

Steroid-free, tacrolimus-basiliximab immunosuppression in pediatric liver transplantation: Clinical and pharmacoeconomic study in 50 children†

Corticosteroid‐free immunosuppression (IS) may be potentially beneficial for transplanted patients, particularly children. The purpose of this study was to evaluate the efficacy and cost of such strategy in primary pediatric liver transplantation (LT). Fifty pediatric LT recipients were prospectively treated with a steroid‐free, tacrolimus‐basiliximab–based IS (group TB). A group of 34 children transplanted under a conventional tacrolimus‐steroids regimen served as control series (group TS). Groups TB and TS were compared regarding patient and graft survival, rejection incidence, infectious complications, and growth, as well as cost of the transplant procedure. Patient and graft survivals at 3 years were 96% and 94% in group TB, versus 91% and 88% in group TS (P = 0.380 and P = 0.370, respectively). Rejection‐free graft survival at 3 years was 72% in group TB, versus 41% in group TS (P = 0.007). Patients in group TB had significantly less viral infections than patients in group TS (P = 0.045). Height standard deviation score was significantly enhanced in children from group TB, when compared to group TS. Medical care costs were similar in both groups. Steroid avoidance together with basiliximab immunoprophylaxis was not harmful in terms of allograft acceptance, and even seemed to be beneficial in the long term. Liver Transpl, 2008.

Persistence of a chimerical phenotype after hepatocyte differentiation of human bone marrow mesenchymal stem cells

Abstract.  Objectives: Recent studies have suggested the potential of mesenchymal stem cells (MSCs) to differentiate into a hepatocyte‐like lineage. Here, we evaluate the efficacy of hepatocyte differentiation of MSCs by studying acquisition of hepatocyte‐like features together with alteration of the native mesenchymal phenotype. Material and methods: In vitro, we have investigated protein and mRNA level expression of hepatocyte and mesenchymal markers of mesenchymal‐derived hepatocyte‐like cells (MDHLCs) and we have evaluated their functionality using metabolic assays. In vivo, we investigated co‐expression of hepatocyte (albumin, α‐foetoprotein, cytokeratin 18) and mesenchymal (fibronectin, vimentin) markers after transplantation of MSCs or MDHLCs into severe combined immune deficiency mice. Results: We observed that while in vitro these cells acquired some phenotypic and functional features of mature hepatocytes, they partially preserved their mesenchymal phenotype. After intrasplenic transplantation, engrafted MSCs with isolated expression of fibronectin and α‐foetoprotein were observed. When these cells were injected into the liver, they expressed all analysed markers, confirming the chimaeric co‐expression observed in vitro. Conversely, liver‐engrafted MDHLCs conserved their hepatocyte‐lineage markers but lost their chimaeric phenotype. Conclusions: Hepatocyte differentiation of MSCs predominantly allows the acquisition of phenotypic hallmarks and provides chimaeric cells that maintain expression of initial lineage markers. However, advanced maturation to the hepatocyte‐like phenotype could be obtained in vivo by conditioning MSCs prior to transplantation or by infusing cells into the liver micro‐environment.