3D scaffolds co-seeded with human endothelial progenitor and mesenchymal stem cells: evidence of prevascularisation within 7 days

Blood supply is a critical issue in most tissue engineering approaches for large defect healing. As vessel ingrowth from surrounding tissues is proven to be insufficient, current strategies are focusing on the neo-vascularisation process. In the present study, we developed an in vitro pre-vascularised construct using 3D polyurethane (PU) scaffolds, based on the association of human Endothelial Progenitor Cells (EPC, CD34+ and CD133+) with human Mesenchymal Stem Cells (MSC). We showed the formation of luminal tubular structures in the co-seeded scaffolds as early as day 7 in culture. These tubular structures were proven positive for endothelial markers von Willebrand Factor and PECAM-1. Of special significance in our constructs is the presence of CD146-positive cells, as a part of the neovasculature scaffolding. These cells, coming from the mesenchymal stem cells population (MSC or EPC-depleted MSC), also expressed other markers of pericyte cells (NG2 and αSMA) that are known to play a pivotal function in the stabilisation of newly formed pre-vascular networks. In parallel, in co-cultures, osteogenic differentiation of MSCs occurred earlier when compared to MSCs monocultures, suggesting the close cooperation between the two cell populations. The presence of angiogenic factors (from autologous platelet lysates) in association with osteogenic factors seems to be crucial for both cell populations' cooperation. These results are promising for future clinical applications, as all components (cells, growth factors) can be prepared in an autologous way.

Matrix metalloproteinases: multifunctional effectors of inflammation in multiple sclerosis and bacterial meningitis

Matrix metalloproteinases (MMPs) are a family of Zn2+-dependent endopeptidases targeting extracellular matrix (ECM) compounds as well as a number of other proteins. Their proteolytic activity acts as an effector mechanism of tissue remodeling in physiologic and pathologic conditions, and as modulator of inflammation. In the context of neuro-inflammatory diseases, MMPs have been implicated in processes such as (a) blood-brain barrier (BBB) and blood-nerve barrier opening, (b) invasion of neural tissue by blood-derived immune cells, (c) shedding of cytokines and cytokine receptors, and (d) direct cellular damage in diseases of the peripheral and central nervous system. This review focuses on the role of MMPs in multiple sclerosis (MS) and bacterial meningitis (BM), two neuro-inflammatory diseases where current therapeutic approaches are insufficient to prevent severe disability in the majority of patients. Inhibition of enzymatic activity may prevent MMP-mediated neuronal damage due to an overactive or deviated immune response in both diseases. Downregulation of MMP release may be the molecular basis for the beneficial effect of IFN-beta and steroids in MS. Instead, synthetic MMP inhibitors offer the possibility to shut off enzymatic activity of already activated MMPs. In animal models of MS and BM, they efficiently attenuated clinical disease symptoms and prevented brain damage due to excessive metalloproteinase activity. However, the required target profile for the therapeutic use of this novel group of compounds in human disease is not yet sufficiently defined and may be different depending on the type and stage of disease. Currently available MMP inhibitors show little target-specificity within the MMP family and may lead to side-effects due to interference with physiological functions of MMPs. Results from human MS and BM indicate that only a restricted number of MMPs specific for each disease is up-regulated. MMP inhibitors with selective target profiles offer the possibility of a more efficient therapy of MS and BM and may enter clinical trials in the near future.

Ringier (Familie)

Famille de pasteurs, politiciens et entrepreneurs de Zofingue, attestée pour la première fois en 1527, lorsque leur aïeul Jean, tonnelier originaire de Nîmes, obtint la bourgeoisie de Zofingue. Michael (1521-1605), avoyer, l'un de ses cinq fils, est l'ancêtre de la branche des imprimeurs et éditeurs. Après lui, de nombreux R. consolidèrent durablement l'influence de la famille. A partir du XVIIIe s., divers membres firent des carrières politiques, tels Samuel (1706-1786), avoyer, et Rudolf Friedrich (1805-1886), président de la ville. Les R. furent aussi très liés à l'Eglise. Le fils de Michael, Moritz (1557-1615), fut pasteur et doyen à Zofingue. Jusqu'au XIXe s., la famille compta une trentaine d'ecclésiastiques, essentiellement des pasteurs officiant sur le territoire bernois, tels Johann Heinrich ( -> 3) et Michael ( -> 8). Les conseillers Beat (1712-1778) et Niklaus (1734-1766) furent les premiers R. actifs dans la production protoindustrielle de drap. D'autres négociants suivirent jusqu'au milieu du XIXe s. L'architecte Niklaus Emanuel (1744-1815) construisit l'hôtel de ville de Zofingue (1792-1795) de style baroque tardif. Johann Rudolf ( -> 4) se distingua sous la République helvétique (1798-1803). Samuel (1767-1826), conseiller municipal de Zofingue, créa les armoiries du canton d'Argovie en 1803. Les R. s'affirmèrent sur le plan cantonal avec Karl Ludwig ( -> 6), chancelier, et Arnold ( -> 1), conseiller d'Etat et plusieurs fois landamman, et sur le plan fédéral avec Johann Rudolf ( -> 5), conseiller national, et Gottlieb ( -> 2), conseiller aux Etats et chancelier de la Confédération. Johann Rudolf (1803-1874) fonda, en 1833, l'imprimerie Ringier à Zofingue, reprise par son fils Franz Emil (1837-1898). A partir de 1898, Paul August ( -> 9), représentant de la troisième génération d'imprimeurs, agrandit l'entreprise dont il fit la principale imprimerie et maison d'édition de Suisse. Cette expansion se poursuivit après 1960 sous son fils Hans (1906-2003). Avec les fils de celui-ci, Christoph (naissance1941, dans la firme jusqu'en 1991) et Michael (naissance1949), Ringier devint, à partir de 1985, une entreprise multinationale et multimédia. Bibliographie – F. Schoder, Ortsbürger von Zofingen, 1962 – P. Meier, T. Häussler, Zwischen Masse, Markt und Macht, 2009

Increased expression of the auxiliary beta2-subunit of ventricular L-type Ca2+ channels leads to single-channel activity characteristic of heart failure

BACKGROUND: Increased activity of single ventricular L-type Ca(2+)-channels (L-VDCC) is a hallmark in human heart failure. Recent findings suggest differential modulation by several auxiliary beta-subunits as a possible explanation. METHODS AND RESULTS: By molecular and functional analyses of human and murine ventricles, we find that enhanced L-VDCC activity is accompanied by altered expression pattern of auxiliary L-VDCC beta-subunit gene products. In HEK293-cells we show differential modulation of single L-VDCC activity by coexpression of several human cardiac beta-subunits: Unlike beta(1) or beta(3) isoforms, beta(2a) and beta(2b) induce a high-activity channel behavior typical of failing myocytes. In accordance, beta(2)-subunit mRNA and protein are up-regulated in failing human myocardium. In a model of heart failure we find that mice overexpressing the human cardiac Ca(V)1.2 also reveal increased single-channel activity and sarcolemmal beta(2) expression when entering into the maladaptive stage of heart failure. Interestingly, these animals, when still young and non-failing ("Adaptive Phase"), reveal the opposite phenotype, viz: reduced single-channel activity accompanied by lowered beta(2) expression. Additional evidence for the cause-effect relationship between beta(2)-subunit expression and single L-VDCC activity is provided by newly engineered, double-transgenic mice bearing both constitutive Ca(V)1.2 and inducible beta(2) cardiac overexpression. Here in non-failing hearts induction of beta(2)-subunit overexpression mimicked the increase of single L-VDCC activity observed in murine and human chronic heart failure. CONCLUSIONS: Our study presents evidence of the pathobiochemical relevance of beta(2)-subunits for the electrophysiological phenotype of cardiac L-VDCC and thus provides an explanation for the single L-VDCC gating observed in human and murine heart failure.

Mechanism of Ca(v)1.2 channel modulation by the amino terminus of cardiac beta2-subunits

L-type calcium channels are composed of a pore, alpha1c (Ca(V)1.2), and accessory beta- and alpha2delta-subunits. The beta-subunit core structure was recently resolved at high resolution, providing important information on many functional aspects of channel modulation. In this study we reveal differential novel effects of five beta2-subunits isoforms expressed in human heart (beta(2a-e)) on the single L-type calcium channel current. These splice variants differ only by amino-terminal length and amino acid composition. Single-channel modulation by beta2-subunit isoforms was investigated in HEK293 cells expressing the recombinant L-type ion conducting pore. All beta2-subunits increased open probability, availability, and peak current with a highly consistent rank order (beta2a approximately = beta2b > beta2e approximately = beta2c > beta2d). We show graded modulation of some transition rates within and between deep-closed and inactivated states. The extent of modulation correlates strongly with the length of amino-terminal domains. Two mutant beta2-subunits that imitate the natural span related to length confirm this conclusion. The data show that the length of amino termini is a relevant physiological mechanism for channel closure and inactivation, and that natural alternative splicing exploits this principle for modulation of the gating properties of calcium channels.

In vitro release of dimethyloxaloylglycine and l-mimosine from bovine bone mineral.

OBJECTIVE Prolyl hydroxylases (PHD) are oxygen sensors and therefore pharmacological targets to stimulate periodontal regeneration. Here we evaluate the release profile of the PHD inhibitors dimethyloxaloylglycine and l-mimosine from bone substitutes. MATERIALS Dimethyloxaloylglycine and l-mimosine were lyophilised onto bone substitutes including bovine bone mineral, beta-tricalcium phosphate, and hydroxyapatite. Release kinetic was evaluated by bioassays with gingival and periodontal ligament fibroblasts. We determined the capacity of PHD inhibitors to provoke VEGF expression and to repress metabolic activity and proliferation as assessed by immunoassay, MTT conversion and (3)[H]thymidine incorporation, respectively. RESULTS We found that the PHD inhibitors are released from bovine bone mineral as indicated by the increase of VEGF production in gingival and periodontal ligament fibroblasts. Supernatants obtained after 1h also decreased metabolic activity and proliferation of the fibroblasts. A fibrin matrix prolonged the release of PHD inhibitors up to 192h. A similar cellular response was found when supernatants from PHD inhibitors loaded beta-tricalcium phosphate and hydroxyapatite embedded in fibrin were assessed. CONCLUSIONS In conclusion bone substitutes can serve as carriers for PHD inhibitors that maintain their capacity to provoke a pro-angiogenic response in vitro. These findings provide the basis for preclinical studies to evaluate if this release kinetic can stimulate periodontal regeneration.

L-mimosine and dimethyloxaloylglycine decrease plasminogen activation in periodontal fibroblasts

BACKGROUND The use of prolyl hydroxylase inhibitors such as l-mimosine (L-MIM) and dimethyloxaloylglycine (DMOG) to improve angiogenesis is a new approach for periodontal regeneration. In addition to exhibiting pro-angiogenic effects, prolyl hydroxylase inhibitors can modulate the plasminogen activator system in cells from non-oral tissues. This study assesses the effect of prolyl hydroxylase inhibitors on plasminogen activation by fibroblasts from the periodontium. METHODS Gingival and periodontal ligament fibroblasts were incubated with L-MIM and DMOG. To investigate whether prolyl hydroxylase inhibitors modulate the net plasminogen activation, kinetic assays were performed with and without interleukin (IL)-1. Moreover, plasminogen activators and the respective inhibitors were analyzed by casein zymography, immune assays, and quantitative polymerase chain reaction. RESULTS The kinetic assay showed that L-MIM and DMOG reduced plasminogen activation under basal and IL-1-stimulated conditions. Casein zymography revealed that the effect of L-MIM involves a decrease in urokinase-type plasminogen activator activity. In agreement with these findings, reduced levels of urokinase-type plasminogen activator and elevated levels of plasminogen activator inhibitor 1 were observed. CONCLUSION L-MIM and DMOG can reduce plasminogen activation by fibroblasts from the gingiva and the periodontal ligament under basal conditions and in the presence of an inflammatory cytokine.

Effects of Prolyl Hydroxylase Inhibitor L-mimosine on Dental Pulp in the Presence of Advanced Glycation End Products

INTRODUCTION Proangiogenic prolyl hydroxylase (PHD) inhibitors represent a novel approach to stimulate tissue regeneration. Diabetes mellitus involves the accumulation of advanced glycation end products (AGEs). Here we evaluated the impact of AGEs on the response of human pulp tissue to the PHD inhibitor L-mimosine (L-MIM) in monolayer cultures of dental pulp-derived cells (DPCs) and tooth slice organ cultures. METHODS In monolayer cultures, DPCs were incubated with L-MIM and AGEs. Viability was assessed based on formazan formation, live-dead staining, annexin V/propidium iodide, and trypan blue exclusion assay. Vascular endothelial growth factor (VEGF), interleukin (IL)-6, and IL-8 production was evaluated by quantitative polymerase chain reaction and immunoassays. Furthermore, expression levels of odontoblast markers were assessed, and alizarin red staining was performed. Tooth slice organ cultures were performed, and VEGF, IL-6, and IL8 levels in their supernatants were measured by immunoassays. Pulp tissue vitality and morphology were assessed by MTT assay and histology. RESULTS In monolayer cultures of DPCs, L-MIM at nontoxic concentrations increased the production of VEGF and IL-8 in the presence of AGEs. Stimulation with L-MIM decreased alkaline phosphatase levels and matrix mineralization also in the presence of AGEs, whereas no significant changes in dentin matrix protein 1 and dentin sialophosphoprotein expression were observed. In tooth slice organ cultures, L-MIM increased VEGF but not IL-6 and IL-8 production in the presence of AGEs. The pulp tissue was vital, and no signs of apoptosis or necrosis were observed. CONCLUSIONS Overall, in the presence of AGEs, L-MIM increases the proangiogenic capacity, but decreases alkaline phosphatase expression and matrix mineralization.