Publications (25)102.97 Total impact
-
Article: Expansion and differentiation of germline-derived pluripotent stem cells on biomaterials.
[show abstract] [hide abstract]
ABSTRACT: Stem cells with broad differentiation potential, such as the recently described germline-derived pluripotent stem cells (gPS cells), are an appealing source for tissue engineering strategies. Biomaterials can inhibit, support or induce proliferation and differentiation of stem cells. Here we identified (i) polymers which maintain self-renewal and differentiation potential of gPS cells for feeder-free expansion and (ii) polymers supporting the cardiomyogenic fate of gPS cells by analyzing a panel of polymers of an established biomaterial bank previously used to assess growth of diverse stem cell types. Identification of cytocompatible gPS cell/biomaterial combinations required analysis of several parameters including morphology, viability, cytotoxicity, apoptosis, proliferation and differentiation potential. Pluripotency of gPS cells was visualized by the endogenous Oct4-promoter-driven GFP and by Sox2 and Nanog immunofluorescence. Viability assay, proliferation assay and flow cytometry showed that gPS cells efficiently adhere and are viable on synthetic polymers, such as Resomer® LR704 (poly(L-lactic-D,L-lactic acid), PTFE (poly(tetrafluor ethylene), PVDF (poly(vinylidene fluoride), and on gelatine-coated TCPS (tissue culture polystyrene). Expansion experiments showed that Resomer® LR704 is an alternative substrate for feeder-free gPS cell maintenance. Resomer® LR704, PTFE and PVDF were found to be suitable for gPS cell differentiation. Spontaneous beating in embryoid bodies cultured on Resomer® LR704 occurred already on day 8 of differentiation, much earlier compared to the other surfaces. This indicates that Resomer® LR704 supports spontaneous cardiomyogenic differentiation of gPS cells, which was also confirmed on molecular, protein and functional level.Tissue Engineering Part A 12/2012; · 4.64 Impact Factor -
Article: Late angiotensin II receptor blockade in progressive rat mesangioproliferative glomerulonephritis: new insights into mechanisms.
[show abstract] [hide abstract]
ABSTRACT: Mesangioproliferative glomerulonephritis is the most common nephritis worldwide. We examined the effects of low and high dose telmisartan, an angiotensin II receptor blocker, in rats with progressive anti-Thy1.1 mesangioproliferative glomerulonephritis in a clinically relevant situation of established renal damage. Uninephrectomized nephritic rats were randomized on day 28 to remain untreated (control treatment; CT), or to receive low (0.1 mg/kg/d, LT) or high dose telmisartan (10 mg/kg/d, HT), hydrochlorothiazide + hydralazine (8 + 32 mg/kg/d, HCT + H), or atenolol (100 mg/kg/d, AT). CT and LT rats were hypertensive, whereas HT, HCT + H and AT treatment normalized blood pressures. On day 131, despite similar blood lowering effects, only HT, but not AT or HCT + H, prevented loss of renal function and reduced proteinuria compared to CT. Only HT potently ameliorated glomerulosclerosis, tubulointerstitial damage, cortical matrix deposition, podocyte damage and macrophage infiltration. HT reduced cortical expression of platelet derived growth factor receptor-alpha and -beta as well as transforming growth factor-beta 1. LT exhibited minor but significant efficacy even in the absence of antihypertensive effects. Transcript array analyses revealed a 4-fold downregulation of renal cortical chemokine (C-C motif) receptor 6 (CCR6) mRNA by HT, which was confirmed at the protein level. Silencing of CCR6 did not alter podocyte function in vitro thus pointing at a predominant role in the tubulo-interstitium. In human kidney biopsies CCR6 mRNA and mRNA of its ligand chemokine (C-C motif) ligand 20 was upregulated in patients with progressive IgA nephropathy compared to stable disease. Thus, delayed treatment with high dose telmisartan exerted a pronounced benefit in progressive mesangioproliferative glomerulonephritis which extended beyond that of equivalent blood pressure lowering. We identified downregulation of platelet-derived growth factor receptors and CCR6 as potential mediators of telmisartan-related renoprotection. CCR6 may also regulate the renal outcome in human mesangioprolfierative glomerulonephritis. Copyright © 2012 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.The Journal of Pathology 11/2012; · 6.32 Impact Factor -
Article: Embryonic stem cell-derived M2-like macrophages delay cutaneous wound healing.
[show abstract] [hide abstract]
ABSTRACT: In adults, repair of deeply injured skin wounds results in the formation of scar tissue, whereas in embryos wounds heal almost scar-free. Macrophages are important mediators of wound healing and secrete cytokines and tissue remodeling enzymes. In contrast to host defense mediated by inflammatory M1 macrophages, wound healing and tissue repair involve regulatory M2/M2-like macrophages. Embryonic/fetal macrophages are M2-like, and this may promote scar-free wound healing. In the present study, we asked whether atopical application of ex vivo generated, embryonic stem cell-derived macrophages (ESDM) improve wound healing in mice. ESDM were tested side by side with bone marrow-derived macrophages (BMDM). Compared to BMDM, ESDM resembled a less inflammatory and more M2-like macrophage subtype as indicated by their reduced responsiveness to lipopolysaccharide, reduced expression of Toll-like receptors, and reduced bacterial phagocytosis. Despite this anti-inflammatory phenotype in cell culture, ESDM prolonged the healing of deep skin wounds even more than BMDM. Healed wounds had more scar formation compared to wounds receiving BMDM or cell-free treatment. Our data indicate that atopical application of ex vivo generated macrophages is not a suitable cell therapy of dermal wounds.Wound Repair and Regeneration 11/2012; · 2.91 Impact Factor -
Article: Myelin debris regulates inflammatory responses in an experimental demyelination animal model and multiple sclerosis lesions.
[show abstract] [hide abstract]
ABSTRACT: In multiple sclerosis (MS), gray matter pathology is characterized by less pronounced inflammation when compared with white matter lesions. Although regional differences in the cytoarchitecture may account for these differences, the amount of myelin debris in the cortex during a demyelinating event might also be contributory. To analyze the association between myelin debris levels and inflammatory responses, cortical areas with distinct and sparse myelination were analyzed for micro- and astrogliosis before and after cuprizone-induced demyelination in mice. In postmortem tissue of MS patients, leucocortical lesions were assessed for the type and level of inflammation in the cortical and white matter regions of the lesion. Furthermore, mice were injected intracerebrally with myelin-enriched debris, and the inflammatory response analyzed in white and grey matter areas. Our studies show that the magnitude of myelin loss positively correlates with microgliosis in the cuprizone model. In MS, the number of MHC class II expressing cells is higher in the white compared with the grey matter part of leucocortical lesions. Finally, direct application of myelin debris into the corpus callosum or cortex of mice induces profound and comparable inflammation in both regions. Our data suggest that myelin debris is an important variable in the inflammatory response during demyelinating events. Whether myelin-driven inflammation affects neuronal integrity remains to be clarified.Glia 06/2012; 60(10):1468-80. · 4.82 Impact Factor -
Article: Glucagon counteracts interleukin-6-dependent gene expression by redundant action of Epac and PKA.
[show abstract] [hide abstract]
ABSTRACT: Inflammation is the biological response to injurious stimuli. In the initial phase of the inflammatory process, interleukin-6 (IL-6) is the main inducer of acute phase protein expression in the liver. A prolonged acute phase response is characterised by a disturbed glucose homeostasis and elevated levels of IL-6, insulin, and counterregulatory hormones such as glucagon. Several studies deal with the impact of IL-6 on glucagon-dependent gene expression. In contrast, only very little is known about the influence of G-protein-coupled receptors on IL-6 signalling. Therefore, the aim of this study is to elucidate the regulation of IL-6-induced gene expression by glucagon. We could reveal a novel mechanism of negative regulation of IL-6-induced MAP kinase activation by glucagon in primary murine hepatocytes. IL-6-dependent induction of the ERK-dependent target gene Tfpi2, coding for a Kunitz-type serine protease inhibitor, was strongly down-regulated by glucagon treatment. Studying the underlying mechanism revealed a redundant action of the signalling molecules exchange protein activated by cyclic AMP (Epac) and protein kinase A. The metabolic hormone glucagon interferes in IL-6-induced gene expression. This observation is indicative for a regulatory role of G-protein-coupled receptors in the IL-6-dependent inflammatory response.Biological Chemistry 12/2011; 392(12):1123-34. · 2.96 Impact Factor -
Article: Glucagon counteracts interleukin-6 dependent gene expression by redundant action of Epac and PKA.
[show abstract] [hide abstract]
ABSTRACT: Abstract Inflammation is the biological response to injurious stimuli. In the initial phase of the inflammatory process, interleukin-6 is the main inducer of acute phase protein expression in the liver. A prolonged acute phase response is characterised by a disturbed glucose homeostasis and elevated levels of IL-6, insulin and counterregulatory hormones like glucagon. Several studies deal with the impact of IL-6 on glucagon-dependent gene expression. In contrast, only very little is known about the influence of G-protein coupled receptors on IL-6 signalling. Therefore, the aim of this study is to elucidate the regulation of IL-6-induced gene expression by glucagon. In this study, we could reveal a novel mechanism of negative regulation of IL-6-induced MAP kinase activation by glucagon in primary murine hepatocytes. IL-6-dependent induction of the ERK-dependent target gene Tfpi2, coding for a Kunitz-type serine protease inhibitor, was strongly downregulated by glucagon treatment. Studying the underlying mechanism revealed a redundant action of the signalling molecules exchange protein activated by cAMP (Epac) and protein kinase A (PKA). The metabolic hormone glucagon interferes in IL-6-induced gene expression. This observation is indicative for a regulatory role of G-protein-coupled receptors in the IL-6-dependent inflammatory response.Biological Chemistry 09/2011; · 2.96 Impact Factor -
Article: Replicative senescence of mesenchymal stem cells causes DNA-methylation changes which correlate with repressive histone marks.
[show abstract] [hide abstract]
ABSTRACT: Cells in culture undergo replicative senescence. In this study, we analyzed functional, genetic and epigenetic sequels of long-term culture in human mesenchymal stem cells (MSC). Already within early passages the fibroblastoid colony-forming unit (CFU-f) frequency and the differentiation potential of MSC declined significantly. Relevant chromosomal aberrations were not detected by karyotyping and SNP-microarrays. Subsequently, we have compared DNA-methylation profiles with the Infinium HumanMethylation27 Bead Array and the profiles differed markedly in MSC derived from adipose tissue and bone marrow. Notably, all MSC revealed highly consistent senescence-associated modifications at specific CpG sites. These DNA-methylation changes correlated with histone marks of previously published data sets, such as trimethylation of H3K9, H3K27 and EZH2 targets. Taken together, culture expansion of MSC has profound functional implications - these are hardly reflected by genomic instability but they are associated with highly reproducible DNA-methylation changes which correlate with repressive histone marks. Therefore replicative senescence seems to be epigenetically controlled.Aging 09/2011; 3(9):873-88. · 5.13 Impact Factor -
Article: Effects and mechanisms of angiotensin II receptor blockade with telmisartan in a normotensive model of mesangioproliferative nephritis.
[show abstract] [hide abstract]
ABSTRACT: Renoprotective actions of angiotensin receptor blockers are not well established in normotensive, low-grade proteinuric glomerular diseases. We examined the effect of low-dose telmisartan (LT) and high-dose telmisartan (HT) versus conventional antihypertensive therapy in the rat anti-Thy1.1 model of glomerulonephritis. Rats were randomized on Day 4 after disease induction to no treatment (CT, control), LT or HT or hydrochlorothiazide + hydralazine (HCT + H). All rats remained normotensive: HT and HCT + H reduced blood pressure by 15-20%. LT, HT and HCT + H reduced glomerular endothelial cell proliferation and glomerular and interstitial matrix deposition on Day 14. Only HT reduced podocyte damage and tubular cell dedifferentiation on Day 9 and mesangial cell activation on Day 14. By gene expression analysis arrays, we identified discs-large homolog 1 and angiopoietin-like 4 as potential mediators of the HT effects. In addition, we identified several pathways possibly related to the pleiotropic effects of HT, including growth factor signalling, mammalian target of rapamycin signalling, protein ubiquitination, the Wnt-beta catenin pathway and hypoxia signaling. In summary, treatment with HT, initiated after the induction of disease, ameliorates glomerular and tubulointerstitial damage. We provide the first comprehensive insight into the mechanisms underlying the renoprotective effect of high-dose angiotensin II receptor blockers (ARBs). Our study lays the basis for future investigations on novel pathways affected by ARBs in renal disease.Nephrology Dialysis Transplantation 03/2011; 26(10):3131-43. · 3.40 Impact Factor -
Article: MicroRNA profiling during cardiomyocyte-specific differentiation of murine embryonic stem cells based on two different miRNA array platforms.
[show abstract] [hide abstract]
ABSTRACT: MicroRNA (miRNA) plays a critical role in a wide variety of biological processes. Profiling miRNA expression during differentiation of embryonic stem cells will help to understand the regulation pathway of differentiation, which in turn may elucidate disease mechanisms. The identified miRNAs could then serve as a new group of possible therapeutic targets. In the present paper, miRNA expression profiles were determined during cardiomyocyte-specific differentiation and maturation of murine embryonic stem (ES) cells. For this purpose a homogeneous cardiomyocyte population was generated from a transgenic murine ES cell line. Two high throughput array platforms (Affymetrix and Febit) were used for miRNA profiling in order to compare the effect of the platforms on miRNA profiling as well as to increase the validity of target miRNA identification. Four time points (i.e. day 0, day 12, day 19 and day 26) were chosen for the miRNA profiling study, which corresponded to different stages during cardiomyocyte-specific differentiation and maturation. Fifty platform and pre-processing method-independent miRNAs were identified as being regulated during the differentiation and maturation processes. The identification of these miRNAs is an important step for characterizing and understanding the events involved in cardiomyocyte-specific differentiation of ES cells and may also highlight candidate target molecules for therapeutic purposes.PLoS ONE 01/2011; 6(10):e25809. · 4.09 Impact Factor -
Article: Transcriptome analysis of MSC and MSC-derived osteoblasts on Resomer® LT706 and PCL: impact of biomaterial substrate on osteogenic differentiation.
[show abstract] [hide abstract]
ABSTRACT: Mesenchymal stem cells (MSC) represent a particularly attractive cell type for bone tissue engineering because of their ex vivo expansion potential and multipotent differentiation capacity. MSC are readily differentiated towards mature osteoblasts with well-established protocols. However, tissue engineering frequently involves three-dimensional scaffolds which (i) allow for cell adhesion in a spatial environment and (ii) meet application-specific criteria, such as stiffness, degradability and biocompatibility. In the present study, we analysed two synthetic, long-term degradable polymers for their impact on MSC-based bone tissue engineering: PLLA-co-TMC (Resomer® LT706) and poly(ε-caprolactone) (PCL). Both polymers enhance the osteogenic differentiation compared to tissue culture polystyrene (TCPS) as determined by Alizarin red stainings, scanning electron microscopy, PCR and whole genome expression analysis. Resomer® LT706 and PCL differ in their influence on gene expression, with Resomer® LT706 being more potent in supporting osteogenic differentiation of MSC. The major trigger on the osteogenic fate, however, is from osteogenic induction medium. This study demonstrates an enhanced osteogenic differentiation of MSC on Resomer® LT706 and PCL compared to TCPS. MSC cultured on Resomer® LT706 showed higher numbers of genes involved in skeletal development and bone formation. This identifies Resomer® LT706 as particularly attractive scaffold material for bone tissue engineering.PLoS ONE 01/2011; 6(9):e23195. · 4.09 Impact Factor -
Article: Inflammatory cytokine release of astrocytes in vitro is reduced by all-trans retinoic acid.
[show abstract] [hide abstract]
ABSTRACT: In the central nervous system inflammation is mediated by microglia and astrocytes. To investigate its regulation, murine astrocyte cultures were treated with bacterial lipopolysaccharides (LPS) and analyzed with Affymetrix gene array, qRT-PCR and ELISA. Cells responded to LPS with a strong upregulation of pro-inflammatory cytokines and chemokines. Treatment with the transcriptional activator retinoic acid (RA) suppressed mRNA expression and protein release of several important cytokines (IL-1β 4%, IL-6 21%, TNFα 30%, IL-12p40 42%, and IL-12p35/p40 27%; p<0.01). The data are consistent with the hypothesis that all-trans RA takes part in endogenous anti-inflammatory feedback loops in the CNS.Journal of neuroimmunology 12/2010; 229(1-2):169-79. · 2.84 Impact Factor -
Article: TTC staining of damaged brain areas after MCA occlusion in the rat does not constrict quantitative gene and protein analyses.
[show abstract] [hide abstract]
ABSTRACT: In models of ischemic stroke, TTC (2,3,5-triphenyltetrazolium chloride) staining is commonly applied for the fast and reliable visualization of hypoxic brain tissue and for defining the size of cerebral infarction and penumbra. Deciphering molecular processes of pathogenesis within the penumbra is of particular interest for the development of therapeutic strategies. The aim of this study was to assess whether TTC-stained tissues can easily and in a reliable quantitative manner be processed for further molecular and biochemical analyses. We applied phenol-based RNA isolation, protein lysis by conventional RIPA buffer, and combined RNA/protein isolation with NucleoSpinRNA/Protein-Kit. Gene and protein expression analyses were performed by RT-rtPCR and Western-blotting. Middle cerebral arteria occlusion (MCAO) in rats was performed following a standardized experimental procedure. After MCAO, TTC staining revealed massive cell death in cortical and sub-cortical areas. TTC processing did not affect the quality of tissue RNA and protein. The expression of housekeeping and regulatory genes and proteins revealed no difference between control and TTC-stained groups. The expression of known stroke-regulated genes such as TNFalpha and IL1beta revealed similar induction profiles after TTC staining as described in the literature. TTC staining allows the precise delineation of lesioned and primarily non-lesioned brain areas for subsequent dissection of selected tissue pieces for molecular analysis. Our study demonstrates that TTC-stained tissues in stroke animal models can be used for quantitative gene and protein expression analyses without constriction. Pathomechanisms of ongoing tissue damage within the penumbra region can now be investigated in detail.Journal of neuroscience methods 03/2010; 187(1):84-9. · 2.30 Impact Factor -
Article: Identification of a 21q22 duplication in a Silver-Russell syndrome patient further narrows down the Down syndrome critical region.
[show abstract] [hide abstract]
ABSTRACT: Several duplications of chromosome 21q helped to narrow down the Down syndrome (DS) critical region (DSCR) to chromosomal band 21q22 with an approximate length of 5.4 Mb. Recently, it has been suggested that the facial gestalt of DS has been linked to the distal part of the DSCR whereas the proximal region harboring DSCR1/RCAN and DSCAM should be associated with the cardiac abnormalities. Here, we report on a patient with Silver-Russell syndrome (SRS) and a paternally inherited 0.46 Mb duplication in 21q22 affecting the KCNE1 and DSCR1/RCAN genes. The identification of an involvement of KCNE1 was interesting because it encodes the beta-subunit of the KvLQT1 channel as the slow component of the cardiac delayed rectifier K(+) current. Since duplication of the KCNQ1 gene encoding the alpha-subunit of the same channel was reported recently in another SRS patient, we screened both genes for mutations in a cohort of SRS patients without detecting pathologic variants. We presume that the duplication of the two functionally linked genes in different patients with the same disorder is a coincidental finding. However, the lack of DS typical clinical features in our case allows us to further narrow down the DSCR in 21q22. We conclude that DSCR1/RCAN is not sufficient for generating phenotypic features associated with DS but our observation does not contradict a possible role for DSCR1/RCAN in mediating DYRK1A-based effects.American Journal of Medical Genetics Part A 02/2010; 152A(2):356-9. · 2.39 Impact Factor -
Article: Human spongiosa mesenchymal stem cells fail to generate cardiomyocytes in vitro.
[show abstract] [hide abstract]
ABSTRACT: Human mesenchymal stem cells (hMSCs) are broadly discussed as a promising cell population amongst others for regenerative therapy of ischemic heart disease and its consequences. Although cardiac-specific differentiation of hMSCs was reported in several in vitro studies, these results were sometimes controversial and not reproducible. In our study we have analyzed different published protocols of cardiac differentiation of hMSCs and their modifications, including the use of differentiation cocktails, different biomaterial scaffolds, co-culture techniques, and two- and three-dimensional cultures. We also studied whether 5'-azacytidin and trichostatin A treatments in combination with the techniques mentioned above can increase the cardiomyogenic potential of hMSCs. We found that hMSCs failed to generate functionally active cardiomyocytes in vitro, although part of the cells demonstrated increased levels of cardiac-specific gene expression when treated with differentiation factors, chemical substances, or co-cultured with native cardiomyocytes. The failure of hMSCs to form cardiomyocytes makes doubtful the possibility of their use for mechanical reparation of the heart muscle.Journal of Negative Results in BioMedicine 11/2009; 8:11. · 1.47 Impact Factor -
Article: Submicroscopic chromosomal imbalances in idiopathic Silver-Russell syndrome (SRS): the SRS phenotype overlaps with the 12q14 microdeletion syndrome.
[show abstract] [hide abstract]
ABSTRACT: Silver-Russell syndrome (SRS) is a heterogeneous disorder associated with intrauterine and postnatal growth restriction, body asymmetry, a relative macrocephaly, a characteristic triangular face and further dysmorphisms. In about 50% of patients, genetic/epigenetic alterations can be detected: >38% of patients show a hypomethylation of the IGF2/H19 imprinting region in 11p15, whereas the additional 10% carry a maternal uniparental disomy of chromosome 7. In single cases, cytogenetic aberrations can be detected. Nevertheless, there still remain 50% of SRS patients without known genetic/epigenetic alterations. To find out whether submicroscopic imbalances contribute to the aetiology of SRS, 20 idiopathic SRS patients were screened with the Affymetrix GeneChip Human Mapping 500 K array set. Apart from known apathogenic copy number variations, we identified one patient with a 12q14 microdeletion. The 12q14 microdeletion syndrome is characterised by dwarfism but it additionally includes mental retardation and osteopoikilosis. The deletion in our patient is smaller than those in the 12q14 microdeletion carriers but it also affects the LEMD3 and the HMGA2 genes. LEMD3 haploinsufficiency and point mutations have been previously associated with osteopoikilosis but radiographs of our patient at the age of 16 years did not reveal any hint for osteopoikilosis lesions. Haploinsufficiency of HMGA2 is probably responsible for aberrant growth in 12q14 microdeletion syndrome. However, in this study, a general role of HMGA2 mutations for SRS was excluded by sequencing of 20 idiopathic patients. In conclusion, our results exclude a common cryptic chromosomal imbalance in idiopathic SRS patients but show that chromosomal aberrations are relevant in this disease. Thus, molecular karyotyping is indicated in SRS and should be included in the diagnostic algorithm.Journal of Medical Genetics 09/2009; 47(5):356-60. · 6.36 Impact Factor -
Article: Delivery of microRNA-126 by apoptotic bodies induces CXCL12-dependent vascular protection.
[show abstract] [hide abstract]
ABSTRACT: Apoptosis is a pivotal process in embryogenesis and postnatal cell homeostasis and involves the shedding of membranous microvesicles termed apoptotic bodies. In response to tissue damage, the CXC chemokine CXCL12 and its receptor CXCR4 counteract apoptosis and recruit progenitor cells. Here, we show that endothelial cell-derived apoptotic bodies are generated during atherosclerosis and convey paracrine alarm signals to recipient vascular cells that trigger the production of CXCL12. CXCL12 production was mediated by microRNA-126 (miR-126), which was enriched in apoptotic bodies and repressed the function of regulator of G protein (heterotrimeric guanosine triphosphate-binding protein) signaling 16, an inhibitor of G protein-coupled receptor (GPCR) signaling. This enabled CXCR4, a GPCR, to trigger an autoregulatory feedback loop that increased the production of CXCL12. Administration of apoptotic bodies or miR-126 limited atherosclerosis, promoted the incorporation of Sca-1+ progenitor cells, and conferred features of plaque stability on different mouse models of atherosclerosis. This study highlights functions of microRNAs in health and disease that may extend to the recruitment of progenitor cells during other forms of tissue repair or homeostasis.Science Signaling 01/2009; 2(100):ra81. · 7.50 Impact Factor -
Article: Topographical control of human macrophages by a regularly microstructured polyvinylidene fluoride surface.
[show abstract] [hide abstract]
ABSTRACT: In this study we investigated the influence of surface topography on the inflammatory response of human macrophages. We generated different polyvinylidene fluoride (PVDF) surfaces including (i) a smooth surface of PVDF spherulites as a control, (ii) a randomly nanotextured surface with alumina particles, and (iii) a microstructure using laser ablation. The identical chemistry of all PVDF surfaces was demonstrated by X-ray photoelectron spectroscopy. The topography was evaluated by white light interferometry and X-profile analysis. Macrophages were cultured on the different surfaces including lipopolysaccharide (LPS) treatment as an inflammatory activator. Our results demonstrate that the microstructured surface but not the nanotexured significantly affects the activation of primary human macrophages by inducing a specific cytokine and gene expression pattern. This activation resulted in a subtype of macrophages with pro- but also anti-inflammatory properties. Interestingly, the response on the topography differed from that triggered by LPS, pointing to a different activation state of the cells. Our data clearly show that a particular topography induces an inflammatory response. This suggests that the modification of topography could influence the inflammatory potency of a biomaterial and hence could affect the biocompatibility of implants.Biomaterials 11/2008; 29(30):4056-64. · 7.40 Impact Factor -
Article: Differential expression of influx and efflux transport proteins in human antigen presenting cells.
[show abstract] [hide abstract]
ABSTRACT: Human macrophages (M Phi) express cytochrome P450 enzymes verifying their capacity to metabolize a variety of endogenous and exogenous substances. Here we analysed the mRNA and protein expression of transport proteins involved in the uptake or export of drugs, hormones and arachidonic acid metabolites in dendritic cells (DC) and M Phi compared to their precursors - blood monocytes - using cDNA microarray, RT-PCR, Western-blot and immunostaining techniques. The transport proteins studied included members of the solute carrier organic anion transporter family (SLCO) and the multidrug resistance associated proteins (MRP) 1-6 belonging to the ATP-binding cassette subfamily C (ABCC). We found that only mRNA for SLCO-2B1, -3A1, and -4A1 were present in monocytes, M Phi and DC. Most interestingly the expression of SLCO-2B1 was markedly enhanced in M Phi as compared to monocytes and DC. The presence of mRNA for ABCC1, 3, 4, 5 and 6 in all three cell types was demonstrated. On protein level ABCC1/MRP1 which has been identified as leukotriene C(4) transporter was found to be the most abundant transporter in M Phi and DC. Blocking the ABCC1/MRP1 activity with the specific inhibitor MK571 resulted in a phenotypic change in DC but not in M Phi. Our data show that human blood monocytes and monocyte derived M Phi as well as DC express a specific profile of transporters involved in uptake and export of exogenous molecules like allergens or drugs, but also of endogenous substances in particular of inflammatory lipid mediators like leukotrienes and prostaglandins.Experimental Dermatology 07/2008; 17(9):739-47. · 3.54 Impact Factor -
Article: Expression of enzymes involved in the prostanoid metabolism by cortical astrocytes after LPS-induced inflammation.
[show abstract] [hide abstract]
ABSTRACT: Neuroinflammatory processes are a common epiphenomenon for a number of neurological and neurodegenerative diseases. Besides microglia, astrocytes are implicated in brain inflammation in response to harmful stimuli and pathological processes. Bacterial endotoxins can induce the synthesis and release of proinflammatory mediators, i.e., cytokines and chemokines, by astroglia. In this study, we have investigated the effect of lipopolysaccharide (LPS) treatment on the expression of enzymes of prostanoid synthesis and degradation in cultured mouse cortical astrocytes using an Affymetrix Gene Chip array, quantitative reverse transcriptase polymerase chain reaction (RT-PCR), and an enzyme-immunosorbent assay. LPS treatment induced an upregulation of enzymes responsible for prostaglandin E2 synthesis, a downregulation of enzymes that catalyzes prostaglandin E2 (PGE2) degradation and production of proinflammatory leukotrienes. Changes in enzyme expression were accompanied by a highly significant increase in extracellular PGE2. Our data demonstrate that astrocytes are directly involved in the complex regulation of proinflammatory prostanoids in the CNS under pathological processes, thus being of potential interest as targets for therapeutical interventions. Further studies are required to unravel the different roles and interactions between astroglia and other cells of the brain-intrinsic innate immune system during inflammation.Journal of Molecular Neuroscience 03/2008; 34(2):177-85. · 2.50 Impact Factor -
Article: Assessment of stem cell/biomaterial combinations for stem cell-based tissue engineering.
[show abstract] [hide abstract]
ABSTRACT: Biomaterials are used in tissue engineering with the aim to repair or reconstruct tissues and organs. Frequently, the identification and development of biomaterials is an iterative process with biomaterials being designed and then individually tested for their properties in combination with one specific cell type. However, recent efforts have been devoted to systematic, combinatorial and parallel approaches to identify biomaterials, suitable for specific applications. Embryonic and adult stem cells represent an ideal cell source for tissue engineering. Since stem cells can be readily isolated, expanded and transplanted, their application in cell-based therapies has become a major focus of research. Biomaterials can potentially influence e.g. stem cell proliferation and differentiation in both, positive or negative ways and biomaterial characteristics have been applied to repel or attract stem cells in a niche-like microenvironment. Our consortium has now established a grid-based platform to investigate stem cell/biomaterial interactions. So far, we have assessed 140 combinations of seven different stem cell types and 19 different polymers performing systematic screening assays to analyse parameters such as morphology, vitality, cytotoxicity, apoptosis, and proliferation. We thus can suggest and advise for and against special combinations for stem cell-based tissue engineering.Biomaterials 02/2008; 29(3):302-13. · 7.40 Impact Factor
Top co-authors
Top Journals
Institutions
-
2003–2006
-
Rheinisch-Westfälische Technische Hochschule Aachen
- Interdisziplinäres Zentrum für Klinische Forschung IZKF
Aachen, North Rhine-Westphalia, Germany
-
