[Primary cutaneous lymphoma-a case series of 163 patients]. / Primär kutane Lymphome ­ eine Fallserie von 163 Patienten.

BACKGROUND: In addition to a broad and clinically diverse spectrum of known primary cutaneous lymphomas, for which an incidence of 1-3:100,000 is postulated, each year further entities are specified and defined. The goal is the presentation of a case series from daily clinical routine. METHODS: Over a period of 6 years and 2 months, patients consulting the Department of Dermatology, Medical Center University of Freiburg, were registered. Subsequently, collectives of mycosis fungoides (MF), Sezary syndrome (SS), CD30+ lymphoproliferative diseases, single cases with rare primary cutaneous lymphomas, and subcollectives of B­cell lymphomas were examined. The high number of MF cases allowed the additional quantitative analyses of the types of therapies used in this group. RESULTS: Yearly 16-25 new diagnoses of primary cutaneous lymphoma are made. The evaluation of 163 primary cutaneous lymphoma revealed 111 cases with MF (68.1%), including 9 particular variants, 15 primary cutaneous CD30+ lymphoproliferative diseases (9.2%) dominated by 10 lymphomatoid papulosis (LyP), in addition to 5 primary cutaneous anaplastic large cell lymphoma (PCALCL), 6 SS (3.68%), and 24 cutaneous B­cell lymphomas (14-72%). Three cases with rare primary cutaneous T/NK cell lymphomas are addressed in detail. In all, 82% of MF cases were stage IA and IB. The descending use of therapies for stage I-III included steroids and diverse UV therapies followed by bexarotene, interferon-α, methotrexate, and extracorporal photophoresis. CONCLUSIONS: Diagnoses of cutaneous lymphomas belong to a vast spectrum of differential diagnoses. This registry describes frequent findings and shows rare variants. You can only diagnose what you know; accordingly, a collection of case reports, which we wish to encourage, can help in processing and specification of entities.

Basophils Trigger Fibroblast Activation in Cardiac Allograft Fibrosis Development.

Fibrosis is a major component of chronic cardiac allograft rejection. Although several cell types are able to produce collagen, resident (donor-derived) fibroblasts are mainly responsible for excessive production of extracellular matrix proteins. It is currently unclear which cells regulate production of connective tissue elements in allograft fibrosis and how basophils, as potential producers of profibrotic cytokines, are involved this process. We studied this question in a fully MHC-mismatched model of heart transplantation with transient depletion of CD4(+) T cells to largely prevent acute rejection. The model is characterized by myocardial infiltration of leukocytes and development of interstitial fibrosis and allograft vasculopathy. Using depletion of basophils, IL-4-deficient recipients and IL-4 receptor-deficient grafts, we showed that basophils and IL-4 play crucial roles in activation of fibroblasts and development of fibrotic organ remodeling. In the absence of CD4(+) T cells, basophils are the predominant source of IL-4 in the graft and contribute to expansion of myofibroblasts, interstitial deposition of collagen and development of allograft vasculopathy. Our results indicated that basophils trigger the production of various connective tissue elements by myofibroblasts. Basophil-derived IL-4 may be an attractive target for treatment of chronic allograft rejection.

Cyclosporine A Inhibits the T-bet-Dependent Antitumor Response of CD8(+) T Cells.

Transplant recipients face an increased risk of cancer compared with the healthy population. Although several studies have examined the direct effects of immunosuppressive drugs on cancer cells, little is known about the interactions between pharmacological immunosuppression and cancer immunosurveillance. We investigated the different effects of rapamycin (Rapa) versus cyclosporine A (CsA) on tumor-reactive CD8(+) T cells. After adoptive transfer of CD8(+) T cell receptor-transgenic OTI T cells, recipient mice received either skin grafts expressing ovalbumin (OVA) or OVA-expressing B16F10 melanoma cells. Animals were treated daily with Rapa or CsA. Skin graft rejection and tumor growth as well as molecular and cellular analyses of skin- and tumor-infiltrating lymphocytes were performed. Both Rapa and CsA were equally efficient in prolonging skin graft survival when applied at clinically relevant doses. In contrast to Rapa-treated animals, CsA led to accelerated tumor growth in the presence of adoptively transferred tumor-reactive CD8(+) OTI T cells. Further analyses showed that T-bet was downregulated by CsA (but not Rapa) in CD8(+) T cells and that cancer cytotoxicity was profoundly inhibited in the absence of T-bet. CsA reduces T-bet-dependent cancer immunosurveillance by CD8(+) T cells. This may contribute to the increased cancer risk in transplant recipients receiving calcineurin inhibitors.

Static and dynamic behaviour of responsive graphene oxide-poly(N-isopropyl acrylamide) composite gels.

Thermoresponsive hydrogels have enormous potential e.g., as sensors, actuators, and pollution control remedies or in drug delivery systems. Nevertheless, their application is often restricted by physical limitations (poor mechanical strength and uncontrolled thermal response). Composite systems may offer a means of overcoming these limitations. This paper presents a systematic study of the structure and dynamics of graphene oxide-poly-(N-isopropylacrylamide) composite systems, and investigates the effect of the nanoparticle filler content on the mechanical and swelling properties of the systems. A combination of macroscopic (swelling and elastic modulus) and microscopic (differential scanning microcalorimetry, small angle neutron scattering and neutron spin-echo spectroscopy) investigations reveals that the architecture of the polymer network is modified by chain nucleation at the surface of the GO platelets, and these form a percolating network inside the gel. Our results show that the elastic modulus of the gels is reinforced by the filler, but the mobility of the polymer chains in the swollen state is practically unaffected. The macroscopic deswelling of the composites, however, is slowed by the kinetics of ordering in the GO network.

mTOR inhibition improves fibroblast growth factor receptor targeting in hepatocellular carcinoma.

BACKGROUND: Systemic therapy has proven only marginal effects in hepatocellular carcinoma (HCC) so far. The aim of this study was to evaluate the effect of targeting fibroblast growth factor receptor (FGFR) on tumour and stromal cells in HCC models. METHODS: Human and murine HCC cells, endothelial cells (ECs), vascular smooth muscle cells (VSMCs), hepatic stellate cells (HSCs), human HCC samples, FGFR inhibitor BGJ398 and mammalian target of rapamycin (mTOR) inhibitor rapamycin were used. Effects on growth, motility, signalling and angiogenic markers were determined. In vivo subcutaneous and syngeneic orthotopic tumour models were used. RESULTS: In tumour cells and ECs, targeting FGFR showed significant inhibitory effects on signalling and motility. Minor effects of FGFR inhibition were observed on VSMCs and HSCs, which were significantly enhanced by combining FGFR and mTOR blockade. In vivo daily (5 mg kg(-1)) treatment with BGJ398 led to a significant growth inhibition in subcutaneous tumour models, but only a combination of FGFR and mTOR blockade impaired tumour growth in the orthotopic model. This was paralleled by reduced tumour cell proliferation, vascularisation, pericytes and increased apoptosis. CONCLUSIONS: Targeting FGFR with BGJ398 affects tumour cells and ECs, whereas only a combination with mTOR inhibition impairs recruitment of VSMCs and HSCs. Therefore, this study provides evidence for combined FGFR/mTOR inhibition in HCC.

Inhibition of innate co-receptor TREM-1 signaling reduces CD4(+) T cell activation and prolongs cardiac allograft survival.

The innate receptor "triggering-receptor-expressed-on-myeloid-cells-1" (TREM-1) enhances downstream signaling of "pattern recognition receptor" (PRR) molecules implicated in inflammatory responses. However the mechanistic role of TREM-1 in chronic heart rejection has yet to be elucidated. We examined the effect of TREM-1(+) antigen-presenting cells (APC) on alloreactive CD4(+) lymphocytes. Bm12 donor hearts were transplanted into wild-type MHC-class-II-mismatched C57BL/6J recipient mice. Progressive allograft rejection of bm12-donor hearts with decreased organ function, severe vasculopathy and allograft fibrosis was evident within 4 weeks. TREM-1(+) CD11b(+) MHC-II(+) F4/80(+) CCR2(+) APC and IFNγ-producing CD4(+) cells were detected during chronic rejection. Peptide inhibition of TREM-1 attenuated graft vasculopathy, reduced graft-infiltrating leukocytes and prolonged allograft survival, while being accompanied by sustained low levels of CD4(+) and CD8(+) cell infiltration. Remarkably, temporary inhibition of TREM-1 during early immune activation was sufficient for long-term allograft survival. Mechanistically, TREM-1 inhibition leads to reduced differentiation and proliferation of IFNγ-producing Th1 cells. In conclusion, TREM-1 influences chronic heart rejection by regulating the infiltration and differentiation of CD4(+) lymphocytes.

EnGraft: a multicentre, open-label, randomised, two-arm, superiority study protocol to assess bioavailability and practicability of Envarsus® versus Advagraf™ in liver transplant recipients.

BACKGROUND: Graft rejection and chronic CNI toxicity remain obstacles to organ transplant success. Current formulations of tacrolimus, such as Prograf® and Advagraf™, exhibit limitations in terms of pharmacokinetics and tolerability, related in part to suboptimal bioavailability. As dosing non-compliance can result in graft rejection, the once daily formulation of tacrolimus, Advagraf™, was developed (vs 2x/day Prograf®). Benefits of Advagraf™ are counterbalanced by delayed achievement of therapeutic trough levels and need for up to 50% higher doses to maintain Prograf®-equivalent troughs. Envarsus® is also a prolonged-release once-daily tacrolimus formulation, developed using MeltDose™ drug-delivery technology to increase drug bioavailability; improved bioavailability results in low patient drug absorption variability and less pronounced peak-to-trough fluctuations. In phase III de novo kidney transplant studies, Envarsus® proved non-inferior to twice-daily tacrolimus; however, no phase IV studies show superiority of Envarsus® vs Advagraf™ in de novo liver transplant (LTx) recipients. METHODS: The EnGraft compares bioavailability and tests superiority of Envarsus® (test arm) versus Advagraf™ (comparator arm) in de novo LTx recipients. A total of 268 patients from 15 German transplant centres will be randomised 1:1 within 14 days post-LTx. The primary endpoint is dose-normalised trough level (C/D ratio) measured 12 weeks after randomisation. Secondary endpoints include the number of dose adjustments, time to reach first defined trough level and incidence of graft rejections. Additionally, clinical and laboratory parameters will be assessed over a 3-year period. DISCUSSION: C/D ratio is an estimate for tacrolimus bioavailability. Improving bioavailability and increasing C/D ratio using Envarsus could reduce renal dysfunction and other tacrolimus-related toxicities; previous trials have shown that a higher C/D ratio (i.e. slower tacrolimus metabolism) is not only associated with improved renal function but also linked to reduced neurotoxic side effects. A higher C/D ratio could improve clinical outcomes for LTx recipients; EnGraft has begun, with one third of patients recruited by January 2022. TRIAL REGISTRATION: This trial has been registered (4 May 2020) in the EU Clinical Trials Register, EudraCT-Nummer: 2020-000796-20. Additionally, this trial has been registered (22 January 2021) at ClinicalTrials.gov: NCT04720326. The trial received a favourable opinion from the concerned lead ethics committee at the University of Regensburg, under the reference 20-1842-112.

Rapamycin impairs UV induction of mutant-p53 overexpressing cell clusters without affecting tumor onset.

Because of its antitumor effect, the immunosuppressant rapamycin holds great promise for organ transplant recipients in that it may lower their cancer risk. In a mouse model, we showed previously that rapamycin inhibits the outgrowth of primary skin carcinomas induced by UV radiation. However, the tumors that did grow out showed an altered p53 mutation spectrum. Here, we investigated whether this shift in p53 mutations already occurred in the smallest tumors, which were not affected in onset. We found that rapamycin did not alter the mutational spectrum in small tumors and in preceding microscopic clusters of cells expressing mutant-p53. However, rapamycin did reduce the number of these cell clusters. As this reduction did not affect tumor onset, we subsequently investigated whether rapamycin merely suppressed expression of mutated p53. This was not the case, as we could demonstrate that switching from a diet with rapamycin to one without, or vice versa, did not affect the number of existing mutant-p53 expressing cell clusters. Hence, rapamycin actually reduced the formation of mutant-p53 cell clusters. In wild-type and p53-mutant mice, we could not measure a significant enhancement of UV-induced apoptosis, but we did observe clear enhancement in human skin equivalents. This was associated with a clear suppression of HIF1α accumulation. Thus, we conclude that rapamycin reduces the formation of mutant-p53-expressing cell clusters without affecting tumor onset, suggesting that tumors grow out of a minor subset of cell clusters, the formation of which is not affected by rapamycin.

Relevance of maintenance triple-drug immunosuppression to bridle the amplification of rat cytomegalovirus infection after experimental lung transplantation.

Immunosuppressive therapy required to treat rejection after lung transplantation (LTx) contributes significantly to the pathogenesis of cytomegalovirus (CMV) infection and disease. In a weak allogeneic left LTx model in the rat (Fisher 344 [F344] to Wistar Kyoto [WKY] rats) we analyzed the influence of acute CMV infection on postoperative day (POD) 3, with application of standard triple-drug immunosuppression (TD-IS) (cyclosporin A, azathioprine, prednisolone) on late outcome after LTx. Native right lungs and syngeneic grafts (WKY to WKY) served as controls. Rats were sacrificed on POD 15, 30, 60, and 100. TD-IS completely prevented acute and chronic rejection in non-infected rats. Allografts of CMV-infected rats treated with TD-IS showed only mild perivascular infiltrations in 6/10 rats (POD 15 and 30), which persisted up to POD 100 in 4/10 rats. In the long-term course, mild isolated interstitial and alveolar changes were found in 40% of these animals. In conclusion, rat CMV infection partially neutralized the immunosuppressive effect of TD-IS. However, an amplification of CMV infection under TD-IS can be controlled and does not result in fatal outcome.

[Necrobiosis lipoidica. Variants on a theme]. / Necrobiosis lipoidica. Kasuistische Vielfalt einer Diagnose.

A 69-year-old patient presented with different skin lesions all of which belonged to group of necrobiosis lipoidica. The initial histologic diagnosis was actinic granuloma O'Brien. A subsequent biopsy was interpreted as granulomatous necrobiosis lipoidica. The history of these necrobiotic variants is reviewed and exemplarily depicted with this case. Necrobiosis lipoidica is part of the spectrum of granulomatous skin disorders. Although its etiology is unclear, an association with diabetes mellitus is often discussed. Multiple therapeutic options exist, but standardized guidelines for treatment are missing.

Hepatocellular carcinoma progression during bridging before liver transplantation.

BACKGROUND: Recipient selection for liver transplantation in hepatocellular carcinoma (HCC) is based primarily on criteria affecting the chance of long-term success. Here, the relationship between pretransplant bridging therapy and long-term survival was investigated in a subgroup analysis of the SiLVER Study. METHODS: Response to bridging, as defined by comparison of imaging at the time of listing and post-transplant pathology report, was categorized into controlled versus progressive disease (more than 20 per cent tumour growth or development of new lesions). RESULTS: Of 525 patients with HCC who had liver transplantation, 350 recipients underwent pretransplant bridging therapy. Tumour progression despite bridging was an independent risk factor affecting overall survival (hazard ratio 1.80; P = 0.005). For patients within the Milan criteria (MC) at listing, mean overall survival was longer for those with controlled versus progressive disease (6.8 versus 5.8 years; P < 0.001). Importantly, patients with HCCs outside the MC that were downsized to within the MC before liver transplantation had poor outcomes compared with patients who never exceeded the MC (mean overall survival 6.2 versus 6.6 years respectively; P = 0.030). CONCLUSION: Patients with HCCs within the MC that did not show tumour progression under locoregional therapy had the best outcomes after liver transplantation. Downstaging into the limits of the MC did not improve the probability of survival.Prognostic factors determining the long-term success of liver transplantation in patients with hepatocellular carcinoma are still under discussion. A subgroup analysis of the SiLVER trial showed that disease control under bridging therapy is strongly associated with improved prognosis in terms of overall survival. However, in tumours exceeding the limits of the Milan criteria, downstaging did not restore the probability of survival compared with that of patients within the Milan criteria.

Early and late effects of the immunosuppressants rapamycin and mycophenolate mofetil on UV carcinogenesis.

Increased skin cancer risk in organ transplant recipients has been experimentally emulated with enhanced UV carcinogenesis from administering conventional immunosuppressants. However, newer generation immunosuppressive drugs, rapamycin (Rapa) and mycophenolate mofetil (MMF), have been shown to impair angiogenesis and outgrowth of tumor implants. To ascertain the overall effect on UV carcinogenesis, Rapa and MMF were admixed into the food pellets of hairless SKH1 mice receiving daily sub-sunburn UV dosages. With immunosuppressive blood levels neither of the drugs affected onset of tumors (<2 mm), but in contrast to MMF, Rapa significantly increased latency of large tumors (>or=4 mm, medians of 190 vs 125 days) and reduced their multiplicity (1.6 vs 4.5 tumors per mouse at 200 days). Interestingly, tumors (>2 mm) from the Rapa-fed group showed a reduction in UV-signature p53 mutations (39% vs 90%) in favor of mutations from putative base oxidation. This shift in mutation spectrum was not essentially linked to the reduction in large tumors because it was absent in large tumors similarly reduced in number when feeding Rapa in combination with MMF, possibly owing to an antioxidant effect of MMF. Significantly fewer tumor cells were Vegf-positive in the Rapa-fed groups, but a correspondingly reduced expression of Hif1alpha target genes (Vegf, Ldha, Glut1, Pdk1) that would indicate altered glucose metabolism with increased oxidative stress was not found. Remarkably, we observed no effect of the immunosuppressants on UV-induced tumor onset, and with impaired tumor outgrowth Rapa could therefore strongly reduce skin carcinoma morbidity and mortality rates in organ transplant recipients.

The rat c-kit ligand, stem cell factor, induces c-kit receptor-dependent mouse mast cell activation in vivo. Evidence that signaling through the c-kit receptor can induce expression of cellular function.

Interactions between products of the mouse W locus, which encodes the c-kit tyrosine kinase receptor, and the Sl locus, which encodes a ligand for c-kit receptor, which we have designated stem cell factor (SCF), have a critical role in the development of mast cells. Mice homozygous for mutations at either locus exhibit several phenotypic abnormalities including a virtual absence of mast cells. Moreover, the c-kit ligand SCF can induce the proliferation and maturation of normal mast cells in vitro or in vivo, and also can result in repair of the mast cell deficiency of Sl/Sld mice in vivo. We now report that administration of SCF intradermally in vivo results in dermal mast cell activation and a mast cell-dependent acute inflammatory response. This effect is c-kit receptor dependent, in that it is not observed when SCF is administered to mice containing dermal mast cells expressing functionally inactive c-kit receptors, is observed with both glycosylated and nonglycosylated forms of SCF, and occurs at doses of SCF at least 10-fold lower on a molar basis than the minimally effective dose of the classical dermal mast cell-activating agent substance P. These findings represent the first demonstration in vivo that a c-kit ligand can result in the functional activation of any cellular lineage expressing the c-kit receptor, and suggest that interactions between the c-kit receptor and its ligand may influence mast cell biology through complex effects on proliferation, maturation, and function.

The rat c-kit ligand, stem cell factor, induces the development of connective tissue-type and mucosal mast cells in vivo. Analysis by anatomical distribution, histochemistry, and protease phenotype.

Mast cell development is a complex process that results in the appearance of phenotypically distinct populations of mast cells in different anatomical sites. Mice homozygous for mutations at the W or S1 locus exhibit several phenotypic abnormalities, including a virtual absence of mast cells in all organs and tissues. Recent work indicates that W encodes the c-kit tyrosine kinase receptor, whereas S1 encodes a c-kit ligand that we have designated stem cell factor (SCF). Recombinant or purified natural forms of the c-kit ligand induce proliferation of certain mast cell populations in vitro, and injection of recombinant SCF permits mast cells to develop in mast cell-deficient WCB6F1-S1/S1d mice. However, the effects of SCF on mast cell proliferation, maturation, and phenotype in normal mice in vivo were not investigated. We now report that local administration of SCF in vivo promotes the development of connective tissue-type mast cells (CTMC) in the skin of mice and that systemic administration of SCF induces the development of both CTMC and mucosal mast cells (MMC) in rats. Rats treated with SCF also develop significantly increased tissue levels of specific rat mast cell proteases (RMCP) characteristic of either CTMC (RMCP I) or MMC (RMCP II). These findings demonstrate that SCF can induce the expansion of both CTMC and MMC populations in vivo and show that SCF can regulate at least one cellular lineage that expresses c-kit, the mast cell, through complex effects on proliferation and maturation.

Clustering of cytokine genes on mouse chromosome 11.

The presence of positionally conserved amino acid residues suggests that the mouse proteins TCA3, P500, MIP1-alpha, MIP1-beta, and JE are members of a single gene family. These proteins are activation specific and can be expressed by both myeloid and lymphoid cells. MIP1-alpha/MIP1-beta and MCAF (the putative human homologue of JE) act as chemotactic and activating agents for neutrophils and macrophages, respectively. The functions of TCA3 and P500 are unknown. We have used interspecies somatic cell hybrids and recombinant inbred mouse strains to show that the genes encoding TCA3, MIP1-alpha, MIP1-beta, and JE (provisionally termed Tca3, Mip-1a, Mip-1b, and Sigje, respectively) map as a cluster on the distal portion of mouse chromosome 11 near the Hox-2 gene complex. DNA sequence analysis indicates that the P500 and TCA3 proteins are encoded by alternative splicing products of one genomic gene. Additionally, the genes encoding TCA3 and JE are found to be strikingly similar with respect to the positions of intron-exon boundaries. Together, these data support the model that the cytokines TCA3, P500, MIP1-alpha, MIP1-beta, and JE are encoded by a single cluster of related genes. The gene encoding IL-5 (Il-5), which acts as a T cell-replacing factor, a B cell growth factor, and an eosinophil differentiation factor, is also mapped to mouse chromosome 11.Il-5 maps approximately 25 cM proximal to the Tca-3 gene and appears tightly linked to a previously described gene cluster that includes Il-3, Il-4, and Csfgm. We discuss the potential relevance of the two cytokine gene clusters described here with particular attention to specific human hematologic malignancies associated with chromosomal aberrations at corresponding locations on human chromosomes 5 and 17.

VEGF: a surrogate marker for peripheral vascular disease.

This study aims to evaluate the value of VEGF as a surrogate marker for peripheral vascular disease (PVD). Prior to treatment, serum VEGF levels were evaluated by enzyme-linked immunosorbent assay (ELISA) in 293 PVD patients. Risk factors and clinical parameters of PVD were documented. Twenty-six age-matched healthy volunteers served as controls. Serum VEGF values strongly correlated with Fontaine stages (p<0.006, stage IV vs. controls). High VEGF values prior to treatment were associated with poor outcome. Serum VEGF appears to indicate the severity of PVD and might serve as a surrogate indicator of disease severity.

Immunosuppression for liver transplantation.

In the last few decades liver transplantation (LTx) has become a reliable life-saving procedure for patients with chronic end-stage liver diseases. LTx has an outstanding success rate in the first few years after allografting, especially considering that many patients are on the brink of survival at the time of transplantation. The success of LTx is owed to the pioneers who developed the surgical procedures and to researchers who discovered the medications to help prevent immunological rejection of allografts. However, several problems continue to impose serious limits on LTx today, including a shortage of donor livers, recurrence of disease (eg, hepatitis, hepatocellular cancer), preservation of long-term allograft function and the side effects of anti-rejection drugs. While the dilemma of organ shortage is not a focus of this review, we will address the latter issues as they relate to the "oldest" and "newest" approaches to immunosuppression, and discuss the prospect that recipients could potentially be made immunologically tolerant to liver transplants. Due to the critical shortage of organs, new strategies to preserve transplanted liver allografts for the longest possible time are of paramount importance.

Mesenchymal stem cells can induce long-term acceptance of solid organ allografts in synergy with low-dose mycophenolate.

The induction of tolerance towards allogeneic solid organ grafts is one of the major goals in transplantation medicine. Mesenchymal stem cells (MSC) inhibit the immune response in vitro, and thus are promising candidate cells to promote acceptance of transplanted organs in vivo. Such novel approaches of tolerance induction are needed since, to date, graft acceptance can only be maintained through life-long treatment with unspecific immunosuppressants that are associated with toxic injury, opportunistic infections and malignancies. We demonstrate that donor-derived MSC induce long-term allograft acceptance in a rat heart transplantation model, when concurrently applied with a short course of low-dose mycophenolate. This tolerogenic effect of MSC is at least partially mediated by the expression of indoleamine 2,3-dioxygenase (IDO), demonstrated by the fact that blocking of IDO with 1-methyl tryptophan (1-MT) abrogates graft acceptance. Moreover we hypothesize that MSC interact with dendritic cells (DC) in vivo, because allogeneic MSC are rejected in the long-term but DC acquire a tolerogenic phenotype after applying MSC. In summary, we demonstrate that MSC constitute a promising tool for induction of non-responsiveness in solid organ transplantation that warrants further investigation in clinical trials.

Prolongation of heart allograft survival after long-term expression of soluble MHC class I antigens and vIL-10 in the liver by AAV-plasmid-mediated gene transfer.

INTRODUCTION: The essential prerequisite for successful gene therapy in vivo is an effective and long-lasting transfer of the desired gene into the respective cell type or tissue. Over the last decades, many different methods have been developed for this purpose. The use of plasmid DNA seems to be a good alternative to the commonly used viral vectors because its large-scale production is simple, and side effects are low. Unfortunately, most reports describe only short-term expression in vivo, probably due to the lack of genomic integration in the target cell. This problem can possibly be addressed by the use of adeno-associated virus plasmids (AAV plasmids), where the coding sequences are cloned between the AAV-specific inverted terminal repeats. Here, we report our results after allogeneic heart transplantation, which followed AAV-plasmid-mediated gene transfer of the rat soluble major histocompatibility complex class I antigen RT1.A(a) and viral interleukin (vIL)-10 in the "high"-responder Dark Agouti to Lewis rat strain combination. RESULTS: A high and stable long-term expression was achieved by in vivo transfection of the liver using AAV plasmids. Serum levels over 1,000 ng/ml of soluble RT1.A(a) and over 300 pg of vIL-10, respectively, were achieved. Expression levels remained high for up to several months. A mean prolongation of heart allograft survival of 1 to 2 days was demonstrated after transfection of either RT1.A(a) or vIL-10.

The impact of mTOR inhibitors on the development of malignancy.

Although continuous improvements have been made in fighting rejection with immunosuppressive drugs in transplant recipients, this success story has been tempered by an associated high incidence of cancer. The latest projections are that cancer might exceed cardiovascular disease as the leading cause of death among transplant recipients. Indeed, immunosuppression reduces our natural ability to destroy cancer cells and to inhibit viral infections potentially linked to cancer development. Therefore, a strategy to counter the problem of cancer in transplantation is needed. Recently, mammalian target of rapamycin (mTOR) inhibitors have demonstrated potential as both immunosuppressive and anticancer agents. Although mTOR inhibitors prevent organ transplant rejection, this class of drugs has potential anticancer properties that may be useful in the "balance of effects" toward cancer-free survival in transplant recipients. Mechanisms of mTOR inhibitors' anticancer effects are multiple, affecting processes including angiogenesis, cell proliferation, cell survival, and molecular oncogenic signaling. Importantly, experimental work supports the view that tumor inhibition can be accomplished with mTOR inhibitors while protecting allografts against rejection. Most recently, prospective randomized clinical studies have been initiated to test the concept that mTOR inhibitors reduce cancer while simultaneously inhibiting allograft rejection. One such study, the SiLVER trial, examines hepatocellular carcinoma recurrence in mTOR inhibitor-treated liver transplant patients. More robust evidence as to whether cancer risk can be reduced in transplant recipients with mTOR inhibitors may come from such clinical trials.