Large extracellular vesicles derived from human regulatory macrophages (L-EVMreg) attenuate CD3/CD28-induced T-cell activation in vitro

Macrophages belong to the innate immune system, and we have recently shown that in vitro differentiated human regulatory macrophages (Mreg) release large extracellular vesicles (L-EVMreg) with an average size of 7.5 μm which regulate wound healing and angiogenesis in vitro. The aim of this study was to investigate whether L-EVMreg also affect the CD3/CD28-mediated activation of T-cells. Mreg were differentiated using blood monocytes and L-EVMreg were isolated from culture supernatants by differential centrifugation. Activation of human T-cells was induced by CD3/CD28-coated beads in the absence or presence of Mreg or different concentrations of L-EVMreg. Inhibition of T-cell activation was quantified by flow cytometry and antibodies directed against the T-cell marker granzyme B. Phosphatidylserine (PS) exposure on the surface of Mreg and L-EVMreg was analyzed by fluorescence microscopy. Incubation of human lymphocytes with CD3/CD28 beads resulted in an increase of cell size, cell granularity, and number of granzyme B-positive cells (P < 0.05) which is indicative of T-cell activation. The presence of Mreg (0.5 × 106 Mreg/ml) led to a reduction of T-cell activation (number of granzyme B-positive cells; P < 0.001), and a similar but less pronounced effect was also observed when incubating activated T-cells with L-EVMreg (P < 0.05 for 3.2 × 106 L-EVMreg/ml). A differential analysis of the effects of Mreg and L-EVMreg on CD4+ and CD8+ T-cells showed an inhibition of CD4+ T-cells by Mreg (P < 0.01) and L-EVMreg (P < 0.05 for 1.6 × 106 L-EVMreg/ml; P < 0.01 for 3.2 × 106 L-EVMreg/ml). A moderate inhibition of CD8+ T-cells was observed by Mreg (P < 0.05) and by L-EVMreg (P < 0.01 for 1.6 × 106 L-EVMreg/ml and 3.2 × 106 L-EVMreg/ml). PS was restricted to confined regions of the Mreg surface, while L-EVMreg showed strong signals for PS in the exoplasmic leaflet. L-EVMreg attenuate CD3/CD28-mediated activation of CD4+ and CD8+ T-cells. L-EVMreg may have clinical relevance, particularly in the treatment of diseases associated with increased T-cell activity. KEY MESSAGES: Mreg release large extracellular vesicles (L-EVMreg) with an average size of 7.5 µm L-EVMreg exhibit phosphatidylserine positivity L-EVMreg suppress CD4+ and CD8+ T-cells L-EVMreg hold clinical potential in T-cell-related diseases.

Characterization of large extracellular vesicles (L-EV) derived from human regulatory macrophages (Mreg): novel mediators in wound healing and angiogenesis?

BACKGROUND

Large extracellular vesicles (L-EV) with a diameter between 1 and 10 µm are released by various cell types. L-EV contain and transport active molecules which are crucially involved in cell to cell communication. We have shown that secretory products of human regulatory macrophages (Mreg) bear pro-angiogenic potential in-vitro and our recent findings show that Mreg cultures also contain numerous large vesicular structures similar to L-EV with so far unknown characteristics and function.

AIM OF THIS STUDY

To characterize the nature of Mreg-derived L-EV (L-EV_Mreg) and to gain insights into their role in wound healing and angiogenesis.

METHODS

Mreg were differentiated using blood monocytes from healthy donors (N = 9) and L-EV_Mreg were isolated from culture supernatants by differential centrifugation. Characterization of L-EV_Mreg was performed by cell/vesicle analysis, brightfield/transmission electron microscopy (TEM), flow cytometry and proteome profiling arrays. The impact of L-EV_Mreg on wound healing and angiogenesis was evaluated by means of scratch and in-vitro tube formation assays.

RESULTS

Mreg and L-EV_Mreg show an average diameter of 13.73 ± 1.33 µm (volume: 1.45 ± 0.44 pl) and 7.47 ± 0.75 µm (volume: 0.22 ± 0.06 pl) respectively. Flow cytometry analyses revealed similarities between Mreg and L-EV_Mreg regarding their surface marker composition. However, compared to Mreg fewer L-EV_Mreg were positive for CD31 (P < 0.01), CD206 (P < 0.05), CD103 (P < 0.01) and CD45 (P < 0.05). Proteome profiling suggested that L-EV_Mreg contain abundant amounts of pro-angiogenic proteins (i.e. interleukin-8, platelet factor 4 and serpin E1). From a functional point of view L-EV_Mreg positively influenced in-vitro wound healing (P < 0.05) and several pro-angiogenic parameters in tube formation assays (all segment associated parameters, P < 0.05; number of meshes, P < 0.05).

CONCLUSION

L-EV_Mreg with regenerative and pro-angiogenic potential can be reproducibly isolated from in-vitro cultured human regulatory macrophages. We propose that L-EV_Mreg could represent a putative therapeutic option for the treatment of chronic wounds and ischemia-associated diseases.

Programmable cells of monocytic origin as a source of osteochondroprogenitors: Effect of growth factors on osteogenic differentiation

We have demonstrated previously that peripheral blood monocytes can be converted in vitro to a multipotent stem cell-like cell termed programmable cell of monocytic origin (PCMO) and subsequently into cells with chondrocyte-like phenotype. Here, we investigated whether PCMO could also be differentiated into osteoblast-like cells using growth factors with known osteoinductive potency. Following stimulation with BMP-2, BMP-7, IGF-1 or TGF-β1 for 7 and 14 days, PCMOs were analyzed for mRNA expression of collagen types I and V, alkaline phosphatase, osteocalcin, runt-related transcription factor-2 (Runx2) and Osterix (Osx) by quantitative RT-PCR (qPCR) and the levels of collagen I in culture supernatants by ELISA. The expression of osteoblastic markers was evident, albeit at a different extent in cultures of PCMOs after treatment with the above-mentioned growth factors. Culture supernatants from PCMOs stimulated for 6-10 days with BMP-2, BMP-7, IGF-1 or TGF-β1 contained high levels of collagen type I, together with earlier data indicating synthesis and proper secretion. The findings suggest that PCMOs can transform into cells that are phenotypically similar to osteoblasts and identify these cells as osteochondroprogenitors. The possibility of differentiating PCMOs from peripheral blood in sizable quantities could be a novel way to obtain autologous bone-like substitutes without donor-site morbidity.

Isolation and characterisation of human gingival margin-derived STRO-1/MACS(+) and MACS(-) cell populations

Recently, gingival margin-derived stem/progenitor cells isolated via STRO-1/magnetic activated cell sorting (MACS) showed remarkable periodontal regenerative potential in vivo. As a second-stage investigation, the present study's aim was to perform in vitro characterisation and comparison of the stem/progenitor cell characteristics of sorted STRO-1-positive (MACS⁺) and STRO-1-negative (MACS⁻) cell populations from the human free gingival margin. Cells were isolated from the free gingiva using a minimally invasive technique and were magnetically sorted using anti-STRO-1 antibodies. Subsequently, the MACS⁺ and MACS⁻ cell fractions were characterized by flow cytometry for expression of CD14, CD34, CD45, CD73, CD90, CD105, CD146/MUC18 and STRO-1. Colony-forming unit (CFU) and multilineage differentiation potential were assayed for both cell fractions. Mineralisation marker expression was examined using real-time polymerase chain reaction (PCR). MACS⁺ and MACS⁻ cell fractions showed plastic adherence. MACS⁺ cells, in contrast to MACS⁻ cells, showed all of the predefined mesenchymal stem/progenitor cell characteristics and a significantly higher number of CFUs (P<0.01). More than 95% of MACS⁺ cells expressed CD105, CD90 and CD73; lacked the haematopoietic markers CD45, CD34 and CD14, and expressed STRO-1 and CD146/MUC18. MACS⁻ cells showed a different surface marker expression profile, with almost no expression of CD14 or STRO-1, and more than 95% of these cells expressed CD73, CD90 and CD146/MUC18, as well as the haematopoietic markers CD34 and CD45 and CD105. MACS⁺ cells could be differentiated along osteoblastic, adipocytic and chondroblastic lineages. In contrast, MACS⁻ cells demonstrated slight osteogenic potential. Unstimulated MACS⁺ cells showed significantly higher expression of collagen I (P<0.05) and collagen III (P<0.01), whereas MACS⁻ cells demonstrated higher expression of osteonectin (P<0.05; Mann–Whitney). The present study is the first to compare gingival MACS⁺ and MACS⁻ cell populations demonstrating that MACS⁺ cells, in contrast to MACS⁻ cells, harbour stem/progenitor cell characteristics. This study also validates the effectiveness of the STRO-1/MACS⁺ technique for the isolation of gingival stem/progenitor cells. Human free gingival margin-derived STRO-1/MACS⁺ cells are a unique renewable source of multipotent stem/progenitor cells.

Pluripotency gene expression and growth control in cultures of peripheral blood monocytes during their conversion into programmable cells of monocytic origin (PCMO): evidence for a regulatory role of autocrine activin and TGF-β

Previous studies have shown that peripheral blood monocytes can be converted in vitro to a stem cell-like cell termed PCMO as evidenced by the re-expression of pluripotency-associated genes, transient proliferation, and the ability to adopt the phenotype of hepatocytes and insulin-producing cells upon tissue-specific differentiation. However, the regulatory interactions between cultured cells governing pluripotency and mitotic activity have remained elusive. Here we asked whether activin(s) and TGF-β(s), are involved in PCMO generation. De novo proliferation of PCMO was higher under adherent vs. suspended culture conditions as revealed by the appearance of a subset of Ki67-positive monocytes and correlated with down-regulation of p21WAF1 beyond day 2 of culture. Realtime-PCR analysis showed that PCMO express ActRIIA, ALK4, TβRII, ALK5 as well as TGF-β1 and the βA subunit of activin. Interestingly, expression of ActRIIA and ALK4, and activin A levels in the culture supernatants increased until day 4 of culture, while levels of total and active TGF-β1 strongly declined. PCMO responded to both growth factors in an autocrine fashion with intracellular signaling as evidenced by a rise in the levels of phospho-Smad2 and a drop in those of phospho-Smad3. Stimulation of PCMO with recombinant activins (A, B, AB) and TGF-β1 induced phosphorylation of Smad2 but not Smad3. Inhibition of autocrine activin signaling by either SB431542 or follistatin reduced both Smad2 activation and Oct4A/Nanog upregulation. Inhibition of autocrine TGF-β signaling by either SB431542 or anti-TGF-β antibody reduced Smad3 activation and strongly increased the number of Ki67-positive cells. Furthermore, anti-TGF-β antibody moderately enhanced Oct4A/Nanog expression. Our data show that during PCMO generation pluripotency marker expression is controlled positively by activin/Smad2 and negatively by TGF-β/Smad3 signaling, while relief from growth inhibition is primarily the result of reduced TGF-β/Smad3, and to a lesser extent, activin/Smad2 signaling.

Clinical management of patients receiving cell-based immunoregulatory therapy

Administering immunoregulatory cells as medicinal agents is a revolutionary approach to the treatment of immunologically mediated diseases. Isolating, propagating, and modifying cells before applying them to patients allows complementation of specific cellular functions, which opens astonishing new possibilities for gain-of-function antigen-specific treatments in autoimmunity, chronic inflammatory disorders, and transplantation. This critical review presents a systematic assessment of the potential clinical risks posed by cell-based immunotherapy, focusing on treatment of renal transplant recipients with regulatory macrophages as a concrete example.

Markers of operational immune tolerance after pediatric liver transplantation in patients under immunosuppression

A prospective identification of the estimated 20-50% of pediatric LTX recipients developing operational tolerance would be of great clinical advantage. So far markers of immune tolerance - T-cell subpopulations or gene expression profiles - have been investigated only retrospectively in successfully weaned patients. Fifty children aged 8-265 months (median 89) were investigated 1-180 months (median 44) after LTX under ongoing immunosuppression. T-cell subpopulations were measured during regular post-transplant visits using FACS (Vδ1- vs. Vδ2-γδ-T cells and Tregs). A Vδ1/Vδ2-γδ-T-cell ratio ≥1.42 previously reported in operational tolerance was found in 12 of 50 (24%) patients. In analogy, a Treg count ≥44 per μL was found in 35 of 50 (70%) patients and a Treg proportion ≥2.23% of CD3(+) -T cells in 39 of 50 (78%) patients. Only 9 of 50 patients (18%) fulfilled both criteria. The parameters Vδ1/Vδ2-γδ-T-cell ratio and Tregs were not significantly correlated to each other or with donor type or immunosuppression. Vδ1/Vδ2-γδ-T-cell ratio was more stable in serial examinations compared with Treg analyses. The observed proportion of 18% pediatric LTX patients with potential operational tolerance is in accordance with previous reports. However, clinical experience shows that rejections may happen even after long-time weaning of immunosuppression. This suggests that operational tolerance is a dynamic process, with uncertain prediction by Vδ1/Vδ2-γδ-T-cell ratio and/or Tregs under immunosuppression.

EGF and HB-EGF enhance the proliferation of programmable cells of monocytic origin (PCMO) through activation of MEK/ERK signaling and improve differentiation of PCMO-derived hepatocyte-like cells

Background

Hepatocyte-like cells (NeoHepatocytes) generated from a peripheral blood monocyte-derived stem cell-like cell (the PCMO) are a promising alternative for primary hepatocytes in cell transplantation studies to cure liver diseases. However, to be therapeutically effective NeoHepatocytes are needed in large quantities. It was the aim of the present study to investigate i) whether the proportion of actively proliferating NeoHepatocytes can be enhanced by supplementing the PCMO differentiation medium (containing M-CSF, IL-3, and human serum) with either EGF or HB-EGF and ii) which signaling pathway underlies the promitotic effect.

Results

EGF and HB-EGF enhanced cell proliferation of PCMOs as demonstrated by increased expression of cycle control genes (ABL, ANAPC2, CDC2, CDK4, CDK6), phosphorylation of the retinoblastoma protein, and increased PCMO cell numbers after stimulation with EGF or HB-EGF. EGF also raised the number of monocytes expressing the proliferation marker Ki67. PCMOs expressed the EGF receptors EGFR (ERBB1) and ERBB3, and expression of both increased during PCMO generation. Phosphoimmunoblotting of PCMOs indicated that both EGF and HB-EGF activated MEK-1/2 and ERK1/2 in a concentration-dependent fashion with the effect of EGF being more prominent. EGF treatment further decreased expression of p47^phox and increased that of Nanog indicating enhanced dedifferentiation and pluripotency, respectively. Treatment with both EGF and HB-EGF resulted in NeoHepatocytes with improved functional parameters.

Conclusions

The results suggested that the addition of EGF or HB-EGF to PCMO differentiation medium superactivates MEK/ERK signaling which then increases both PCMO proliferation, number, and functional differentiation of PCMO-derived NeoHepatocytes.

Cutting Edge: Immunological consequences and trafficking of human regulatory macrophages administered to renal transplant recipients

Regulatory macrophages (M regs) were administered to two living-donor renal transplant recipients. Both patients were minimized to low-dose tacrolimus monotherapy within 24 wk of transplantation and subsequently maintained excellent graft function. After central venous administration, most M regs remained viable and were seen to traffic from the pulmonary vasculature via the blood to liver, spleen, and bone marrow. By 1 y posttransplantation, both patients displayed patterns of peripheral blood gene expression converging upon the IOT-RISET signature. Furthermore, both patients maintained levels of peripheral blood FOXP3 and TOAG-1 mRNA expression within the range consistent with nonrejection. It is concluded that M regs warrant further study as a potential immune-conditioning therapy for use in solid-organ transplantation. The results of this work are being used to inform the design of The ONE Study, a multinational clinical trial of immunomodulatory cell therapy in renal transplantation.

Differential roles of Smad2 and Smad3 in the regulation of TGF-β1-mediated growth inhibition and cell migration in pancreatic ductal adenocarcinoma cells: control by Rac1

BACKGROUND

Progression of pancreatic ductal adenocarcinoma (PDAC) is largely the result of genetic and/or epigenetic alterations in the transforming growth factor-beta (TGF-β)/Smad signalling pathway, eventually resulting in loss of TGF-β-mediated growth arrest and an increase in cellular migration, invasion, and metastasis. These cellular responses to TGF-β are mediated solely or partially through the canonical Smad signalling pathway which commences with activation of receptor-regulated Smads (R-Smads) Smad2 and Smad3 by the TGF-β type I receptor. However, little is known on the relative contribution of each R-Smad, the possible existence of functional antagonism, or the crosstalk with other signalling pathways in the control of TGF-β1-induced growth inhibition and cell migration. Using genetic and pharmacologic approaches we have inhibited in PDAC cells endogenous Smad2 and Smad3, as well as a potential regulator, the small GTPase Rac1, and have analysed the consequences for TGF-β1-mediated growth inhibition and cell migration (chemokinesis).

RESULTS

SiRNA-mediated silencing of Smad3 in the TGF-β responsive PDAC cell line PANC-1 reduced TGF-β1-induced growth inhibition but increased the migratory response, while silencing of Smad2 enhanced growth inhibition but decreased chemokinesis. Interestingly, siRNA-mediated silencing of the small GTPase Rac1, or ectopic expression of a dominant-negative Rac1 mutant largely mimicked the effect of Smad2 silencing on both TGF-β1-induced growth inhibition, via upregulation of the cdk inhibitor p21WAF1, and cell migration. Inhibition of Rac1 activation reduced both TGF-β1-induction of a Smad2-specific transcriptional reporter and Smad2 C-terminal phosphorylation in PDAC cells while Smad3-specific transcriptional activity and Smad3 C-terminal phosphorylation appeared increased. Disruption of autocrine TGF-β signalling in PANC-1 cells rendered cells less susceptible to the growth-suppressive effect of Rac1 inhibition, suggesting that the decrease in "basal" proliferation upon Rac1 inhibition was caused by potentiation of autocrine TGF-β growth inhibition.

CONCLUSIONS

In malignant cells with a functional TGF-β signalling pathway Rac1 antagonizes the TGF-β1 growth inhibitory response and enhances cell migration by antagonistically regulating Smad2 and Smad3 activation. This study reveals that Rac1 is prooncogenic in that it can alter TGF-β signalling at the R-Smad level from a tumour-suppressive towards a tumour-promoting outcome. Hence, Rac1 might represent a viable target for therapeutic intervention to inhibit PDAC progression.

Differential roles of Src in transforming growth factor-ß regulation of growth arrest, epithelial-to-mesenchymal transition and cell migration in pancreatic ductal adenocarcinoma cells

Both transforming growth factor (TGF)-ß and the non-receptor tyrosine kinase Src play major roles during tumorigenesis by regulating cell growth, epithelial-to-mesenchymal transition (EMT), migration/invasion and metastasis, but little is known about the signaling crosstalk between them. To interfere with Src function in vitro and in vivo many studies have employed the pharmacologic Src inhibitors PP2 and PP1. Both agents have recently been shown to be powerful inhibitors of TGF-ß receptor type I/ALK5 and type II. As this situation prohibited any definite conclusions with respect to the relative contribution of TGF-ß vs. Src signaling, we decided to reappraise a potential role of Src in TGF-ß1-mediated cellular responses using RNA and dominant-negative (dn) interference to block Src expression and function, respectively. In TGF-ß-responsive pancreatic ductal adenocarcinoma (PDAC) cells, we show that Src is activated by TGF-ß1 and that its specific inhibition strongly attenuated basal proliferation and enhanced TGF-ß1-mediated growth arrest. However, Src inhibition was unable to impair TGF-ß1-controlled EMT as evidenced by cell morphology and regulation of the epithelial marker E-cadherin. Despite its dispensibility for TGF-ß-induced EMT, specific inhibition of Src dramatically reduced basal and TGF-ß1-induced cell migration in Panc-1 cells as measured with a novel real-time migration assay (xCELLigence DP system). Biochemically, dnSrc inhibition failed to block TGF-ß1/ALK5-induced activation of Smad2 and Smad3, but partially inhibited transcriptional activation of TGF-ß/Smad-responsive reporter genes, and effectively blocked basal and TGF-ß1-induced activation of p38 MAPK. Together, the data provide evidence for a role of Src in the regulation of basal proliferation as well as in basal and TGF-ß1-mediated cell motility but not EMT in TGF-ß-responsive pancreatic (tumor) cells.

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

Background

The 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/Design

The 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 2^1/2 -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.

Discussion

If 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 Register

Trial registered at http://www.clinicaltrials.gov: NCT00355862

(EudraCT Number: 2005-005362-36)

Human regulatory macrophages

Regulatory macrophages (M regs) are a novel type of suppressor macrophage which may be a particularly suitable cell for inducing tolerance of solid organ transplants. In this article, we provide a detailed description of the generation of human M regs from peripheral blood monocytes and methods for the assessment of their phenotype. The uniqueness of the human M reg is best appreciated when the M reg is compared to macrophages in other states of activation; therefore, protocols are provided for generating five comparator macrophage types which have been used as cell type-specificity controls in our work.

Investigation of the colorectal cancer susceptibility region on chromosome 8q24.21 in a large German case-control sample

Human chromosome 8q24.21 has been implicated as a susceptibility region for colorectal cancer (CRC) as a result of genome-wide association and candidate gene studies. To assess the impact of molecular variants at 8q24.21 upon the CRC risk of German individuals and to refine the disease-associated region, a total of 2,713 patients with operated CRC (median age at diagnosis: 63 years) were compared with 2,718 sex-matched control individuals (median age at inclusion: 65 years). Information on microsatellite instability in tumors was available for 901 patients. Association analysis of SNPs rs10505477 and rs6983267 yielded allelic p-values of 1.42 x 10(-7) and 2.57 x 10(-7), respectively. For both polymorphisms, the odds ratio was estimated to be 1.50 (95% CI: 1.29-1.75) under a recessive disease model. The strongest candidate interval, outside of which significance dropped by more than 4 orders of magnitude, was delineated by SNPs rs10505477 and rs7014346 and comprised 17 kb. In a subgroup analysis, the disease association was found to be more pronounced in MSI-stable tumors (odds ratio: 1.71). Our study confirms the role of genetic variation at 8q24.21 as a risk factor for CRC and localizes the corresponding susceptibility gene to a 17 kb candidate region.

Postoperative intravenous infusion of donor-derived transplant acceptance-inducing cells as an adjunct immunosuppressive therapy in a porcine pulmonary allograft model

There is very limited published information testifying to the safety and possible complications of cell-based therapies. Accurately assessing the potential risks of translating novel, cell-based immunosuppressive protocols into clinical trials is therefore extremely difficult. This report describes the use of a pulmonary allograft model in outbred miniature pigs as a preliminary step in the development of a safe, clinically feasible, cell-based immunosuppressive protocol. Single lung transplants were performed in 22 MHC Class I-mismatched donor-recipient pairs, which were randomized between four treatment groups. For the first 28 days postoperatively, all animals were immunosuppressed with methylprednisilone and tacrolimus, with or without preoperative irradiation; subsequently, pharmacological immunosuppression was stopped in all treatment groups. Animals in two groups also received a central venous infusion of donor-derived 'transplant acceptance-inducing cells' (TAICs) on the seventh and 14th days postoperatively. Allograft survival was monitored by sequential chest X-rays, bronchoscopies and transbronchial biopsy histologies. No acute adverse events were associated with the administration of TAICs and there was no evidence of accelerated graft rejection. The observations presented in this report represent an important first step towards the development of a clinically applicable protocol for the use of TAIC therapy in lung transplantation.

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.

[Long-term survival of curatively operated gastric cancer: influence of the gender and splenectomy]

BACKGROUND

Despite advances in operative technique long-term survival of curatively operated gastric cancer patients still remains poor with 5-year-survival of 25 %. Gender differences have been recognized in patients with colorectal carcinoma with a higher 5-year-survival of women. The long time-survival of the individual patient is closely dependent on his immunofunction. If a splenectomy has to be carried out, the postoperative immunofunction will be affected considerably. Thus, the question arises as to how far gender and splenectomy influence the long time-survival after curative gastric cancer surgery.

METHODS

In a retrospective analysis of 505 patients with gastric cancer who had been treated between the years 1992 and 2002, a curative resection, i. e. R0, could be performed in 243 patients (48.1 %) with a definite classified tumour stadium according to the UICC (1997). The sociodemographic, operative, histomorphologic and postoperative data of each patient were collected, stratified by gender and compared using log-rank-test (survival) and chi-square-test (distribution). Multivariate analysis was performed by cox regression. The level of significance was set at p < 0.05.

RESULTS

The sociodemographic, histopathologic and operative data between the two genders were comparable. The morbidity between men and women was not significant. However the rate of postoperative sepsis was higher in men (p < 0.05). With regard to the long-term survival, no difference could be shown between the two groups. However, splenectomy had a significant effect on long time-survival. Women with preserved spleen had a significantly improved five-year-survival rate as compared to women undergoing splencetomy and men with preserved spleen (p < 0.05). Multivariate analysis revealed only the tumour stage as a predictor for long time-survival in men, whereas in women the extend of lymphadenectomy and sepsis also influenced long time-survival.

CONCLUSION

Long time-survival of curatively operated gastric cancer patients is gender dependent in terms of splenectomy. Therefore, gender differences should be taken into account in analysing long-term data of oncological patients.

Programmable cells of monocytic origin (PCMO): a source of peripheral blood stem cells that generate collagen type II-producing chondrocytes

The focus of this study was a new adult pluripotent cell derived from human peripheral blood monocytes identified as a "programmable cell of monocytic origin" (PCMO). In contrast to bone marrow-derived stem cells, these cells can be harvested from peripheral venous blood without aspiration of the bone marrow and have multilineage potential comparable to that of mesenchymal stem cells (MSC). The aim of this study was to evaluate the potential of PCMOs to differentiate into collagen type II-producing chondrocytes using various extrinsic cues (TGFbeta-1, IGF-1, BMP-2, and BMP-7). Collagen type I and II proteins were localized using immunohistochemistry and quantified by enzyme-linked immunosorbent assays (ELISA). The shape of the differentiating PCMOs was monitored with electron microscopy. Collagen type I and II messenger RNA expression was analyzed using real-time reverse transcriptase-polymerase chain reaction (RT PCR) and regular RT PCR. Immunohistochemistry revealed a strong accumulation of collagen type II after a 6-week incubation period with BMP-2, BMP-7, TGF-beta, IGF-I, and TGF-beta, and IGF-1. Collagen type I was only mildly induced by the applied stimulants. Electron microscopy findings showed a shift from a monocyte-like structure to a chondrocyte-like structure after 2 weeks of stimulation. Stimulation of PCMOs with BMP-2, BMP-7, TGF-beta, IGF-I, and TGF-beta, and IGF-1 induced a chondrogenic differentiation with continuous expression of collagen type II mRNA and protein over several weeks time. Collagen type I and II expression in undifferentiated PCMOs or in control cells incubated without any stimulant was not detected. PCMOs have the potential to differentiate into collagen type II synthesizing chondrocytes. The ability to reprogram and differentiate PCMOs from peripheral blood into sizable quantities might enable their clinical application in cartilage repair after mechanical injury or in cases of osteoarthritis.

Toward cell-based therapy of type I diabetes

Type 1 diabetes (T1D) is an autoimmune disease that results from the destruction of insulin-producing pancreatic islet cells owing to the aggressive effector function of autoreactive T cells. In addition to lifetime supply of exogenous insulin, whole-pancreas or islet transplantation is presently the only alternative therapy for severely ill patients. Here, we discuss the current status of the development of cell-based therapies that are based on essentially two options, i.e. replacement of islet cells by islet-like cells derived from embryonic or adult stem cells, and re-establishment of immunological tolerance to islet self-antigens through regulatory T cells and/or tolerance-promoting monocyte-derived cells. A combination of both approaches will be required to turn cell-based therapy of T1D into clinical success.

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-gamma-stimulated monocyte-derived cells (IFNgamma-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. IFNgamma-MdC only arise when macrophages are cultivated in the presence of CD40L-expressing CD4+ T cells, M-CSF, and IFN-gamma. IFNgamma-MdC express markers including F4/80, CD11b/c, CD86, and CD274; they are negative for CD4, CD8, Gr1, CD19, CD80, and CD207. Functionally, IFNgamma-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, IFNgamma-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 IFNgamma-MdC represent macrophages in a novel state of activation, possessing multiple T cell-suppressive effects with therapeutic potential for the treatment of autoimmune inflammation.

Genetic investigation of DNA-repair pathway genes PMS2, MLH1, MSH2, MSH6, MUTYH, OGG1 and MTH1 in sporadic colon cancer

Mutations in DNA repair genes have previously been identified as causative factors for hereditary nonpolyposis colon cancer (HNPCC). Recent evidence also supports an association between DNA sequence variation in these genes and sporadic colorectal carcinoma (CRC). Genetic investigation of DNA repair genes PMS2, MLH1, MSH2, MSH6, MUTYH, OGG1 and MTH1, as possible susceptibility factors for sporadic CRC, was done using both a haplotype tagging and a candidate (i.e. coding) single nucleotide polymorphism (SNP) approach. Some 1,068 patients with operated CRC (median age at diagnosis: 59 years) were compared to 738 sex-matched control individuals (median age: 67 years). Haplotype tagging SNPs, previously reported risk variants and all known coding SNPs with a minor allele frequency >0.005 were genotyped in PMS2 (N = 10), MLH1 (N = 11), MSH2 (N = 18), MSH6 (N = 15), MUTYH (N = 7), OGG1 (N = 11) and MTH1 (N = 3). No evidence for an association between CRC and any of the 7 genes was detected, neither with the tagging or coding SNPs nor in a sliding window haplotype analysis (all nominal p-values >0.05). The previously reported risk variants D132H in MLH1 and R154H in OGG1 were not even observed in the German population. Genetic CRC risk factors so far identified in DNA repair genes seem to be rare and population-specific. Their association with the disease could not be replicated in German CRC samples. It remains to be elucidated by more systematic, large-scale experiments whether common variants in the same genes, but present across populations, represent risk factors for sporadic CRC.

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 P(CCA) = 4.1 x 10(-9)), which was subsequently attributed to coding variant rs11887534 (D19H). Additional replication was achieved in 728 German (P = 2.8 x 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 x 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.

Antitumor activity of ALK1 in pancreatic carcinoma cells

In this study, the authors investigated the expression of activin receptor-like kinase 1 (ALK1) in pancreatic carcinoma and evaluated its potential role as a tumor suppressor in vitro and in vivo. Endogenous ALK1 expression was demonstrated by immunohistochemistry in both pancreatic tumor tissue and peritumoral normal tissue from 6 patients and by RT-PCR in 8/12 established pancreatic cancer cell lines. Ectopic expression of a constitutively active (ca) ALK1 mutant in TGF-beta sensitive PANC-1 and COLO-357 cells augmented transcriptional activation of a Smad2/3 responsive reporter, and slowed down basal growth in vitro. Both effects were further enhanced by TGF-beta/ALK5 stimulation, suggesting largely independent nuclear Smad signaling by both type I receptors. Upon orthotopic transplantation of PANC-1-caALK1 into immunodeficient mice, tumor size was strongly reduced and was associated with a lower microvessel density in the PANC-1-caALK1-derived tumors. In vitro, this mutant efficiently blocked TGF-beta-induced epithelial-to-mesenchymal transdifferentiation and suppressed TGF-beta/ALK5-mediated activation of the p38 MAPK pathway. Mechanistically, caALK1 silenced MyD118, an immediate TGF-beta target gene whose protein product, GADD45beta, couples Smad signaling to p38 activation. These results show that ALK1 activation in pancreatic tumor cells is antioncogenic by inducing ALK5-independent growth inhibition and by blocking TGF-beta/ALK5-mediated epithelial-to-mesenchymal transdifferentiation and, possibly, invasion and metastatic progression.

Establishment of a novel orthotopic xenograft model of human gallbladder carcinoma

OBJECTIVE

Gallbladder cancer is characterized by high morbidity and mortality. An appropriate human xenograft animal model could serve as a research tool to investigate new therapeutic strategies.

SUMMARY BACKGROUND DATA

To date, the few reports describing a xenograft animal model showed significant limitations. We improved a murine orthotopic human xenotransplantation model by implanting human gallbladder carcinoma cells directly into the lumen of the gallbladder.

METHODS

Mz-ChA-1 cells were orthotopically injected into the gallbladder of Severe Combined Immune Deficiency (SCID) beige mice inducing the growth of solid tumors. The natural course of the disease, tumor growth, and metastases were analyzed. The cytotoxic drug gemcitabine was tested in vitro and in vitro.

RESULTS

All animals revealed solid tumors in the inoculated area with liver infiltration. The median tumor volume in the untreated group was significantly higher than in the gemcitabine-treated group. Immunohistochemical staining revealed expression of human cytokeratin 7 and cytokeratin 8. To analyze tumor cell proliferation, the tumors were stained for the antigen Ki-67, and labeling indices were calculated for both groups. Animals receiving gemcitabine treatment showed significantly lower mean labeling indices. In vitro investigation revealed a significant reduction of DNA synthesis. DNA fragmentation, as a measure of apoptosis, was elevated by roughly 20% within 24 h of treatment. With this, we successfully established an orthotopic xenotransplant animal model and investigated the in vitro and in vivo effects of gemcitabine in human xenografted Mz-ChA-1 gallbladder adenocarcinoma.

CONCLUSION

This model resembles the clinical situation as closely as possible and offers a relevant option for the preclinical testing of new therapeutic strategies.

Dissecting the role of TGF-beta type I receptor/ALK5 in pancreatic ductal adenocarcinoma: Smad activation is crucial for both the tumor suppressive and prometastatic function

In the present study, we have analysed the effects of transforming growth factor-beta (TGF-beta) signaling on the growth behavior of pancreatic carcinoma cells in vitro and on their tumorigenicity in vivo. Ectopic expression of dominant-negative mutants of the TGF-beta type II receptor or type I receptor/activin receptor-like kinase 5 (ALK5) in TGF-beta-sensitive pancreatic ductal adenocarcinoma PANC-1 cells prevented the TGF-beta-induced activation of transfected Smad-responsive reporter genes and growth arrest. The growth-inhibitory effect was mimicked by stable expression of kinase-active ALK5 (ALK5-T204D), and was dependent on ALK5's ability to activate Smad signaling, as a ALK5-derived mutant with an intact kinase domain but deficient in its ability to activate Smads (RImL45) failed to suppress proliferation in the absence of added TGF-beta. Moreover, this mutant often displayed opposite effects to those of ALK5-TD and blocked various ligand-induced responses in vitro, indicating that it acts in a dominant-negative fashion to inhibit endogenous wild-type receptors. ALK5-TD-, but not RImL45-TD-transduced cells underwent epithelial-to-mesenchymal transition, exhibited a higher ratio of thrombospondin-1 to vascular endothelial growth factor-A expression and upregulated various metastasis-associated genes. Upon orthotopic transplantation of PANC-1 clones into immunodeficient mice, ALK5-TD, but not RImL45-TD, greatly reduced tumor size and induced the formation of liver metastases in otherwise non-metastatic PANC-1 cells. These results suggest a causal, dominant role for the endogenous Smad2/3 signaling pathway in the tumor suppressor and prometastatic activities of TGF-beta in pancreatic tumor cells.

Nonbone marrow-derived circulating progenitor cells contribute to postnatal neovascularization following tissue ischemia

Circulating progenitor cells home to sites of postnatal neovascularization and differentiate into endothelial cells but questions remain regarding the source of these cells. Indeed, a recent study suggests that nonbone marrow-derived cells may be even more important than bone marrow-derived cells in the setting of transplant arteriosclerosis. Thus, we aimed to thoroughly investigate the contribution of nonbone marrow-derived progenitor cells for neovascularization. We exclusively identified nonbone marrow-derived progenitor cells by combining a parabiosis model with reverse bone marrow transplantation followed by hindlimb ischemia. In this model, nonbone marrow-derived circulating progenitor cells attributed for 74+/-13% of the circulating progenitor cells that incorporated into the ischemic hindlimb. Increasing evidence suggests that organs such as small intestine and liver contain a considerable number of tissue resident progenitor cells and, thus, represent putative sources for nonbone marrow-derived progenitors. To track organ-derived progenitors, we transplanted sex-mismatched small intestine or liver, respectively, into rats followed by induction of hindlimb ischemia. These experiments show that organ-derived progenitor cells are contributing to postnatal vasculogenesis (intestine: 4.7+/-3.7%; liver: 6.3+/-2.2%). Based on the subsequent observation that liver-derived nonhematopoietic c-kit(+)CD45(-) progenitors are mobilized on induction of hindlimb ischemia, we prospectively isolated and intravenously infused these progenitors from murine livers. The isolated cells demonstrated a marked capacity for enhancing neovascularization and restoring blood flow to the ischemic hindlimb (no cells: 26.4+/-4.8% of normal blood flow; c-kit(+)CD45(-) cells: 67.0+/-8.0% of normal flow; P<0.01). In conclusion, we find that nonbone marrow-derived c-kit(+)CD45(-) progenitors contribute to postnatal neovascularization to an extent that is similar to that of bone marrow-derived progenitor cells. Intestine and liver represent a rich source for mobilized tissue-residing progenitor cells.

Audit of a series of 40 gastrointestinal stromal tumour cases

AIMS

To analyze prognostic factors influencing survival and tumour recurrence after resection of gastrointestinal stromal tumours.

METHODS

Forty patients who underwent surgery for a GIST at our institution were reviewed. Patients were classified on the basis of tumour size, mitotic rate and CD117 positivity. The overall survival and disease free survival were calculated using Kaplan-Meier method considering the extent of surgery comparing local tumour excisions with segmental organ resections.

RESULTS

Tumours were localized in the oesophagus, stomach, duodenum, small bowel and large bowel and rectum. Sixty-five percent of the patients had an intermediate or high risk GIST according to tumour size and mitotic count. In 26/40 patients tumour resection was performed using segmental organ resection, in all other patients local tumour excision was carried out. The mean overall survival was 73 months. Disease free survival was significantly better after local tumour excision compared to segmental organ resection (73 months versus 53 months; p=0.05). Large tumour size (p=0.07) and high mitotic count (p=0.14) were negative prognostic factors for disease free survival, although statistical significance was not reached yet.

CONCLUSION

Primary surgery remains the cornerstone in the treatment of primary and recurrent GIST. Risk adapted surgery is the most important factor to avoid early tumour recurrence. In case of small tumour size segmental organ resections can be avoided favouring local tumour excisions with a low risk of tumour recurrence.

Investigation of the Lith1 candidate genes ABCB11 and LXRA in human gallstone disease

Genetic susceptibility in the causation of gallbladder diseases was recognized as early as 1937. A major gallstone susceptibility locus (Lith1) was identified in 1995 by quantitative trait locus mapping in mice. Two attractive positional and functional candidate genes in LXRA and ABCB11 are located in this interval. ABCB11 is associated with progressive familial cholestasis. This study was undertaken to investigate LXRA and ABCB11 as candidate genes for gallstone disease in humans. Eight hundred and ten patients who underwent cholecystectomy for symptomatic gallstone disease (median age of onset, 50 years) were compared with 718 sex-matched control individuals. Control individuals were sonographically free of gallstones. Haplotype tagging and all known coding single nucleotide polymorphisms (SNPs) were genotyped for ABCB11 (n=29) and LXRA (n=10). The investigated high-risk patient sample provides a power of greater than 80% for the detection of odds ratios down to 1.55. No evidence of association of the two genes in the single point tagging markers, coding variants or in the sliding window haplotype analysis was detected (all nominal single-point P values>or=.08). In conclusion, in the investigated German sample, no evidence of association of ABCB11 and LXRA to gallstone susceptibility was detected. The gallstone trait is not allelic to progressive familial cholestasis at the ABCB11 locus. Systematic fine mapping of the Lith1 region is required to identify the causative genetic variants for gallstone in mice and humans.

Derivation, maintenance, and characterization of rat embryonic stem cells in vitro

The in vitro differentiation of mouse embryonic stem (ES) cells into different somatic cell types such as neurons, endothelial cells, or myocytes is well established, and many mouse ES cell lines have been created so far. The establishment of rat ES cell lines, however, has proven to be difficult. Most attempts to culture rat ES cell lines and maintain them in an undifferentiated state have failed, so researchers were forced to abandon this system and use mouse ES cells. This chapter describes the long-term cultivation of an alkaline phosphatase-positive rat embryonic stem cell-like line (RESC) and their differentiation into neuronal, endothelial, and hepatic lineages. The RESCs can be characterized by typical growth in single cells as well as embryoid bodies when cultivated in the presence of leukemia inhibitory factor. RESC expressed stage-specific-embryonic antigen 1 and the major histocompatibility class 1 molecule. Neuronal differentiation is achieved by standard retinoic acid treatment and endothelial differentiation can be reproducibly induced by growth on or within Matrigel for 14 d. To induce expression of hepatocyte-specific antigens, RESCs were either grown in hepatocyte-conditioned media or in media containing different combinations of growth factors. The characterization of differentiated cells was done primarily by immunohistochemistry, enzyme-linked immunosorbent assay, and polymerase chain reaction.