Fred Fändrich

Preimplantation-stage stem cells induce long-term allogeneic graft acceptance without supplementary host conditioning

Hematopoietic stem cells have been successfully employed for tolerance induction in a variety of rodent and large animal studies. However, clinical transplantation of fully allogeneic bone marrow or blood-borne stem cells is still associated with major obstacles, such as graft-versus-host disease or cytoreductive conditioning-related toxicity. Here we show that when rat embryonic stem cell-like cells of WKY origin are injected intraportally into fully MHC-mismatched DA rats, they engraft permanently (>150 days) without supplementary host conditioning. This deviation of a potentially alloreactive immune response sets the basis for long-term graft acceptance of second-set transplanted WKY cardiac allografts. Graft survival was strictly correlated with a state of mixed chimerism, which required functional thymic host competence. Our results provide a rationale for using preimplantation-stage stem cells as vehicles in gene therapy and for the induction of long-term graft acceptance.

A genome-wide association scan identifies the hepatic cholesterol transporter ABCG8 as a susceptibility factor for human gallstone disease

With an overall prevalence of 10–20%, gallstone disease (cholelithiasis) represents one of the most frequent and economically relevant health problems of industrialized countries. We performed an association scan of >500,000 SNPs in 280 individuals with gallstones and 360 controls. A follow-up study of the 235 most significant SNPs in 1,105 affected individuals and 873 controls replicated the disease association of SNP A-1791411 in ABCG8 (allelic P value PCCA = 4.1 × 10−9), which was subsequently attributed to coding variant rs11887534 (D19H). Additional replication was achieved in 728 German (P = 2.8 × 10−7) and 167 Chilean subjects (P = 0.02). The overall odds ratio for D19H carriership was 2.2 (95% confidence interval: 1.8–2.6, P = 1.4 × 10−14) in the full German sample. Association was stronger in subjects with cholesterol gallstones (odds ratio = 3.3), suggesting that His19 might be associated with a more efficient transport of cholesterol into the bile.

A prospective randomised, open-labeled, trial comparing sirolimus-containing versus mTOR-inhibitor-free immunosuppression in patients undergoing liver transplantation for hepatocellular carcinoma

BackgroundThe potential anti-cancer effects of mammalian target of rapamycin (mTOR) inhibitors are being intensively studied. To date, however, few randomised clinical trials (RCT) have been performed to demonstrate anti-neoplastic effects in the pure oncology setting, and at present, no oncology endpoint-directed RCT has been reported in the high-malignancy risk population of immunosuppressed transplant recipients. Interestingly, since mTOR inhibitors have both immunosuppressive and anti-cancer effects, they have the potential to simultaneously protect against immunologic graft loss and tumour development. Therefore, we designed a prospective RCT to determine if the mTOR inhibitor sirolimus can improve hepatocellular carcinoma (HCC)-free patient survival in liver transplant (LT) recipients with a pre-transplant diagnosis of HCC.Methods/DesignThe study is an open-labelled, randomised, RCT comparing sirolimus-containing versus mTOR-inhibitor-free immunosuppression in patients undergoing LT for HCC. Patients with a histologically confirmed HCC diagnosis are randomised into 2 groups within 4-6 weeks after LT; one arm is maintained on a centre-specific mTOR-inhibitor-free immunosuppressive protocol and the second arm is maintained on a centre-specific mTOR-inhibitor-free immunosuppressive protocol for the first 4-6 weeks, at which time sirolimus is initiated. A 21/2 -year recruitment phase is planned with a 5-year follow-up, testing HCC-free survival as the primary endpoint. Our hypothesis is that sirolimus use in the second arm of the study will improve HCC-free survival. The study is a non-commercial investigator-initiated trial (IIT) sponsored by the University Hospital Regensburg and is endorsed by the European Liver and Intestine Transplant Association; 13 countries within Europe, Canada and Australia are participating.DiscussionIf our hypothesis is correct that mTOR inhibition can reduce HCC tumour growth while simultaneously providing immunosuppression to protect the liver allograft from rejection, patients should experience less post-transplant problems with HCC recurrence, and therefore could expect a longer and better quality of life. A positive outcome will likely change the standard of posttransplant immunosuppressive care for LT patients with HCC.Trial RegisterTrial registered at http://www.clinicaltrials.gov: NCT00355862(EudraCT Number: 2005-005362-36)

Long‐Term Culture and Differentiation of Rat Embryonic Stem Cell‐Like Cells into Neuronal, Glial, Endothelial, and Hepatic Lineages

The in vitro differentiation of mouse embryonic stem cells into different somatic cell types such as neurons, endothelial cells, or myocytes is a well‐established procedure. Long‐term culture of rat embryonic stem cells is known to be hazardous, and attempts to differentiate these cells in vitro so far have been unsuccessful. We herein describe stable long‐term culture of an alkaline phosphatase‐positive rat embryonic stem cell‐like cell line (RESC) and its differentiation into neuronal, endothelial, and hepatic lineages. RESCs were characterized by typical growth in single cells as well as in embryoid bodies when cultured in the presence of leukemia inhibitory factor. RESC expressed stage‐specific‐embryonic antigen‐1 and the major histocompatibility complex class I molecule. For neuronal differentiation, cells were incubated with medium containing 10−6 M retinoic acid for 14 days. For endothelial differentiation, RESCs were grown on Matrigel for 14 days, and for induction of hepatocyte‐specific antigen expression, RESCs were grown in medium supplemented with fibroblast growth factor‐4. Differentiated cells exhibited typical morphological changes and expressed neuronal (nestin, mitogen‐activated protein‐2, synaptophysin), glial (S100, glial fibrillary acid protein), endothelial (panendothelial antibody, CD31) and hepatocyte‐specific (α‐fetoprotein [αFP], albumin, α‐1‐antitrypsin, CK18) antigens. In addition, expression of hepatocyte‐specific genes (αFP, transthyretin, carbamoyl‐phosphate synthetase, and coagulation factor‐2) was detected by reverse transcription polymerase chain reaction. We were able to culture RESCs under stable, long‐term conditions and to initiate programmed differentiation of RESCs to endothelial, neuronal, glial, and hepatic lineages in the rat species.

Generation of human hepatocytes by stem cell technology: definition of the hepatocyte.

Since 1999, numerous articles have reported the generation of hepatocytes from different types of extrahepatic stem or precursor cells. This opens exciting new possibilities for pharmacology and toxicology, as well as for cell therapy. Hepatocyte marker expression, including albumin, cytokeratin 18, c-met, α-fetoprotein and cytochrome P450 3A4 and -2B6, has been observed after transplantation of different types of human stem cells into the liver of laboratory animals or in vitro after incubation with cytokines. These intriguing observations have prompted scientists to classify stem cell-derived cell populations as hepatocytes. However, this conclusion may be premature. It has been shown that factors of the liver microenvironment can induce expression of a limited number of hepatocyte marker genes in nonhepatic cell types. To conclude on the grounds of a limited number of markers that these cells are true hepatocytes is not indicated. In this case one should carefully evaluate crucial hepatocyte-defining enzymatic properties. The present article: i) reviews studies describing the fate of extrahepatic human stem and precursor cells in livers of laboratory animals, including the possibility of cell fusion; and ii) critically discusses the phenotype of stem cells after application of various differentiation protocols aimed at generating human hepatocytes. In addition, the necessary criteria needed for defining a true hepatocyte are suggested. Establishing the necessary properties for stem cell-derived hepatocytes is timely and reasonable, and thus avoids further misleading semantic confusion. Finally, it is essential to understand that the definition of a bona fide hepatocyte should not be limited to qualitative assays, such as reverse transcriptase polymerase chain reaction and immunohistochemistry, but has to include a quantitative analysis of enzymatic activities, which allows direct comparison with primary hepatocytes. Although the stem cell-derived-hepatocyte does not yet exist there is a good chance that this aim may be achieved in the future.

Human monocyte-derived neohepatocytes: a promising alternative to primary human hepatocytes for autologous cell therapy.

Background. There is growing interest in new therapeutic options for the treatment of end-stage liver diseases. In addition to mechanical devices supporting liver function, such as bioreactors, the transplantation of hepatocyte-like cells derived from (adult) stem cells offer great perspectives. We have generated hepatocyte-like (NeoHep) cells from terminally differentiated peripheral blood monocytes and, in this study, have evaluated these cells as a possible tool for autologous cell therapy. Methods. Peripheral blood monocytes were cultured under conditions that promote hepatocyte-like differentiation and were characterized for hepatocyte marker expression by reverse-transcriptase polymerase chain reaction, immunohistochemistry, and immunoblotting and for specific secretory and metabolic functions with the appropriate biochemical assays. Results. NeoHep cells resembled primary human hepatocytes with respect to morphology, expression of hepatocyte markers (albumin, cytochrome P450 isoenzymes, asialoglycoprotein receptor, coagulation factor VII), various secretory and metabolic functions (albumin secretion, urea production, lactate formation, and lactate dehydrogenase and aspartate transaminase release), and drug detoxification activities (phase I metabolization of ethoxycoumarin into 7OH-coumarin after stimulation with 3-methylcholanthren, induction of CYP3A4 activity, and phase II metabolization through UDP-glucuronidation of 4-methyl-umbelliferone). Conclusions. These data convincingly show that NeoHep cells display a phenotype and specific in vitro metabolic functions that are quantitatively and qualitatively comparable in part with those of primary human hepatocytes. These cells could thus be clinically applied in an autologous setting for the treatment of end-stage liver diseases or for improving liver function in patients who have undergone critical liver-mass resection.

Sirolimus Use in Liver Transplant Recipients With Hepatocellular Carcinoma: A Randomized, Multicenter, Open-Label Phase 3 Trial.

Background We investigated whether sirolimus-based immunosuppression improves outcomes in liver transplantation (LTx) candidates with hepatocellular carcinoma (HCC). Methods In a prospective-randomized open-label international trial, 525 LTx recipients with HCC initially receiving mammalian target of rapamycin inhibitor–free immunosuppression were randomized 4 to 6 weeks after transplantation into a group on mammalian target of rapamycin inhibitor–free immunosuppression (group A: 264 patients) or a group incorporating sirolimus (group B: 261). The primary endpoint was recurrence-free survival (RFS); intention-to-treat (ITT) analysis was conducted after 8 years. Overall survival (OS) was a secondary endpoint. Results Recurrence-free survival was 64.5% in group A and 70.2% in group B at study end, this difference was not significant (P = 0.28; hazard ratio [HR], 0.84; 95% confidence interval [95% CI], 0.62; 1.15). In a planned analysis of RFS rates at yearly intervals, group B showed better outcomes 3 years after transplantation (HR, 0.7; 95% CI, 0.48-1.00). Similarly, OS (P = 0.21; HR, 0.81; 95% CI, 0.58-1.13) was not statistically better in group B at study end, but yearly analyses showed improvement out to 5 years (HR, 0.7; 95% CI, 0.49-1.00). Interestingly, subgroup (Milan Criteria-based) analyses revealed that low-risk, rather than high-risk, patients benefited most from sirolimus; furthermore, younger recipients (age ⩽60) also benefited, as well sirolimus monotherapy patients. Serious adverse event numbers were alike in groups A (860) and B (874). Conclusions Sirolimus in LTx recipients with HCC does not improve long-term RFS beyond 5 years. However, a RFS and OS benefit is evident in the first 3 to 5 years, especially in low-risk patients. This trial provides the first high-level evidence base for selecting immunosuppression in LTx recipients with HCC.

Macrophages driven to a novel state of activation have anti-inflammatory properties in mice.

Recurrent episodes of inflammation underlie numerous pathologies, notably those of inflammatory bowel diseases. In this study, we describe a population of macrophages in a novel state of activation that mitigates colitis in mice. The cells responsible for this effect, called IFN-γ-stimulated monocyte-derived cells (IFNγ-MdC), derive from mouse spleen, blood, and bone marrow monocytes and are distinguished from known macrophage populations by mode of generation, cell surface phenotype, and function. IFNγ-MdC only arise when macrophages are cultivated in the presence of CD40L-expressing CD4+ T cells, M-CSF, and IFN-γ. IFNγ-MdC express markers including F4/80, CD11b/c, CD86, and CD274; they are negative for CD4, CD8, Gr1, CD19, CD80, and CD207. Functionally, IFNγ-MdC are defined by their capacity to enrich cocultured T cell populations for CD4+CD25+Foxp3+ regulatory cells; this enrichment, constituting up to 60% or more of residual lymphocytes, is attributed to an expansion, but also to a cell contact and caspase-dependent depletion of activated T cells. In mice, IFNγ-MdC delivered i.v. traffic to gut-associated peripheral lymphoid tissues, including the mesenteric lymph nodes, Peyer’s patches, and colonic mucosa, and promote the clinical and histological resolution of chronic colitis. We conclude that IFNγ-MdC represent macrophages in a novel state of activation, possessing multiple T cell-suppressive effects with therapeutic potential for the treatment of autoimmune inflammation.

Overexpression of phosphatidylinositol 3-kinase in human lung cancer

Abstract. Background: This study was conducted to investigate the expression of phosphatidylinositol 3-kinase (PI3K) and AKT2, a downstream effector, in primary human lung carcinomas of different histological type. Methods: Specimens from 105 human lung carcinomas and their corresponding lymph nodes and liver metastases were examined using immunohistochemistry and Northern-blot assays to study the PI3K p85 and p110 subunits and the AKT2-expression patterns. Results: The p85 and p110 subunits of PI3K were overexpressed at the protein level in 77% and 59% of 80 primary lung carcinomas, respectively, irrespective of the histological type. PI3K overexpression was correlated with tumor grading. In contrast, no overexpression of PI3K subunits was observed in normal lung tissue and benign lung tumors. Consistent with these findings, upregulation of p110 mRNA transcripts was restricted to primary lung carcinomas. Overexpression of AKT2 was observed in 10% of the investigated lung tumor specimens, but in none of the healthy lung sections. A profound increase of PI3K expression was uniformly observed in lung tissue specimens and in corresponding extra-pulmonary lymph-node and liver metastases with low-differentiation grades. Conclusion: PI3K appears to be associated with the process of tumor-cell transformation and proliferation. One of its major downstream effector molecules, AKT2, which contributes to apoptotic cell death, was not upregulated by PI3K overexpression in primary lung carcinomas.

A cell‐based approach to the minimization of immunosuppression in renal transplantation

Five renal transplant recipients were preoperatively treated with transplant acceptance‐inducing cells (TAICs) in a Phase‐I safety study of TAICs as an adjunct immune‐conditioning therapy in living‐donor kidney transplantation. Initially, patients received anti‐thymocyte globulin induction therapy in combination with tacrolimus and steroid immunosuppression. Over the course of 12 weeks, steroids were withdrawn and tacrolimus therapy was minimized. Three of the five patients were able to tolerate low‐dose tacrolimus monotherapy and one patient was withdrawn from all immunosuppression for over 8 months. No acute or delayed adverse events were associated with the infusion of TAICs. Monitoring of the recipient anti‐donor reactivity of TAIC‐treated patients in mixed lymphocyte cultures demonstrated that, during periods of clinically stable graft function, recipient T‐cell proliferation and cytokine secretion in response to stimulation with donor alloantigen was relatively suppressed. Therefore, although the TAIC‐II trial did not provide conclusive evidence of a beneficial effect of preoperative TAIC treatment, the results were encouraging because they suggest that TAICs promote a state of alloantigen‐specific unresponsiveness, which might allow safe minimization of pharmacological immunosuppression.