Publications by authors named "Eleni Papachristou"

21 Publications

  • Page 1 of 1

Biopharmaceutics 4.0, Advanced Pre-Clinical Development of mRNA-Encoded Monoclonal Antibodies to Immunosuppressed Murine Models.

Vaccines (Basel) 2021 Aug 11;9(8). Epub 2021 Aug 11.

Center of Clinical, Experimental Surgery and Translational Research, Biomedical Research Foundation of the Academy of Athens, 11527 Athens, Greece.

Administration of mRNA against SARS-CoV-2 has demonstrated sufficient efficacy, tolerability and clinical potential to disrupt the vaccination field. A multiple-arm, cohort randomized, mixed blind, placebo-controlled study was designed to investigate the in vivo expression of mRNA antibodies to immunosuppressed murine models to conduct efficacy, safety and bioavailability evaluation. Enabling 4.0 tools we reduced animal sacrifice, while interventions were designed compliant to HARRP and SPIRIT engagement: (a) Randomization, blinding; (b) pharmaceutical grade formulation, monitoring; (c) biochemical and histological analysis; and (d) theoretic, statistical analysis. Risk assessment molded the study orientations, according to the ARRIVE guidelines. The primary target of this protocol is the validation of the research hypothesis that autologous translation of Trastuzumab by in vitro transcribed mRNA-encoded antibodies to immunosuppressed animal models, is non-inferior to classical treatments. The secondary target is the comparative pharmacokinetic assessment of the novel scheme, between immunodeficient and healthy subjects. Herein, the debut clinical protocol, investigating the pharmacokinetic/pharmacodynamic impact of mRNA vaccination to immunodeficient organisms. Our design, contributes novel methodology to guide the preclinical development of RNA antibody modalities by resolving efficacy, tolerability and dose regime adjustment for special populations that are incapable of humoral defense.
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http://dx.doi.org/10.3390/vaccines9080890DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8402437PMC
August 2021

Biocompatibility assessment of resin-based cements on vascularized dentin/pulp tissue-engineered analogues.

Dent Mater 2021 05 7;37(5):914-927. Epub 2021 Mar 7.

Department of Prosthodontics, School of Dentistry, Faculty of Health Sciences, Aristotle University of Thessaloniki (AUTh), Thessaloniki, GR-54124, Greece. Electronic address:

Objectives: A three-dimensional (3D) dentin/pulp tissue analogue, resembling the human natural tissue has been engineered in an in vitro setup, aiming to assess the cytocompatibility of resin-based dental restorative cements.

Methods: Stem Cells from Apical Papilla (SCAP) and Human Umbilical Vein Endothelial Cells (HUVEC) were embedded in Collagen-I/Fibrin hydrogels at 1:3 ratio within 24-well plates. Hanging culture inserts were placed over the hydrogels, housing an odontoblast-like cell layer and a human treated-dentin barrier. Shear modulus of the hydrogels at 3.5 and 5 mg/ml was evaluated by dynamic mechanical analysis. Eluates of two resin-based cements, a dual-cure- (Breeze™, Pentron: Cement-1/C1), and a self-adhesive cement (SpeedCEMplus™, Ivoclar-Vivadent: Cement-2/C2) were applied into the dentin/pulp tissue analogue after pre-stimulation with LPS. Cytocompatibility was assessed by MTT assay, live/dead staining and real-time PCR analysis.

Results: Both hydrogel concentrations showed similar shear moduli to the natural pulp until day (D) 7, while the 5 mg/ml-hydrogel substantially increased stiffness by D14. Both cements caused no significant toxicity to the dentin/pulp tissue analogue. C1 induced stimulation (p < 0.01) of cell viability (158 ± 3%, 72 h), while pre-stimulation with LPS attenuated this effect. C2 (±LPS) caused minor reduction of viability (15-20%, 24 h) that recovered at 72 h for the LPS+ group. Both cements caused upregulation of VEGF, ANGP-1, and downregulation of the respective receptors VEGFR-2 and Tie-1.

Significance: Both resin-based cements showed good cytocompatibility and triggered angiogenic response within the dentin/pulp tissue analogue, indicating initiation of pulp repair responses to the released xenobiotics.
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http://dx.doi.org/10.1016/j.dental.2021.02.019DOI Listing
May 2021

Corrigendum to "Physico-mechanical and finite element analysis evaluation of 3D printable alginate-methylcellulose inks for wound healing applications" [Carbohydr. Polym. 247 (2020) 116666].

Carbohydr Polym 2021 Mar 12;255:117361. Epub 2020 Nov 12.

Laboratory of Pharmaceutical Technology, Department of Pharmacy, School of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki, GR-54124, Greece.

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http://dx.doi.org/10.1016/j.carbpol.2020.117361DOI Listing
March 2021

Hybrid chitosan/gelatin/nanohydroxyapatite scaffolds promote odontogenic differentiation of dental pulp stem cells and in vitro biomineralization.

Dent Mater 2021 01 15;37(1):e23-e36. Epub 2020 Nov 15.

Department of Prosthodontics, School of Dentistry, Faculty of Health Sciences, Aristotle University of Thessaloniki (A.U.Th), Greece. Electronic address:

Objective: Hybrid chitosan/gelatin/nanohydroxyapatite (CS/Gel/nHA) scaffolds have attracted considerable interest in tissue engineering (TE) of mineralized tissues. The present study aimed to investigate the potential of CS/Gel/nHA scaffolds loaded with dental pulp stem cells (DPSCs) to induce odontogenic differentiation and in vitro biomineralization.

Methods: CS/Gel/nHA scaffolds were synthesized by freeze-drying, seeded with DPSCs, and characterized with flow cytometry. Scanning Electron Microscopy (SEM), live/dead staining, and MTT assays were used to evaluate cell morphology and viability; real-time PCR for odontogenesis-related gene expression analysis; SEM-EDS (Energy Dispersive X-ray spectroscopy), and X-ray Diffraction analysis (XRD) for structural and chemical characterization of the mineralized constructs, respectively.

Results: CS/Gel/nHA scaffolds supported viability and proliferation of DPSCs over 14 days in culture. Gene expression patterns indicated pronounced odontogenic shift of DPSCs, evidenced by upregulation of DSPP, BMP-2, ALP, and the transcription factors RunX2 and Osterix. SEM-EDS showed the production of a nanocrystalline mineralized matrix inside the cell-based and - to a lesser extent - the cell-free constructs, with a time-dependent production of net-like nanocrystals (appr. 25-30nm in diameter). XRD analysis gave the crystallite size (D=50nm) but could not distinguish between the initially incorporated and the biologically produced nHA.

Significance: This is the first study validating the potential of CS/Gel/nHA scaffolds to support viability and proliferation of DPSCs, and to provide a biomimetic microenvironment favoring odontogenic differentiation and in vitro biomineralization without the addition of any inductive factors, including dexamethasone and/or growth/morphogenetic factors. These results reveal a promising strategy towards TE of mineralized dental tissues.
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http://dx.doi.org/10.1016/j.dental.2020.09.021DOI Listing
January 2021

Physico-mechanical and finite element analysis evaluation of 3D printable alginate-methylcellulose inks for wound healing applications.

Carbohydr Polym 2020 Nov 24;247:116666. Epub 2020 Jun 24.

Laboratory of Pharmaceutical Technology, Department of Pharmacy, School of Health Sciences, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece.

The present study reports on the comprehensive physico-mechanical evaluation of 3D printable alginate-methylcellulose hydrogels with bioactive components (Manuka honey, aloe vera gel, eucalyptus essential oil) using a combined experimental-numerical approach. The 3D printable carbohydrate inks demonstrated good swelling properties under moist conditions and adequate antimicrobial and antibiofilm efficacy against both Gram positive and negative bacteria. The effect of the bioactive compounds on the viscosity and mechanical properties of the 3D printable hydrogels was assessed with rheological, nanoindentation and shear test measurements. All hydrogel compositions showed good biocompatibility on human dermal fibroblasts, stimulating cell growth as confirmed by an in vitro wound healing assay. Finite element analysis simulation was employed to further advance the calculation accuracy of the nanoindentation tests, concluding that combination of an experimental and a numerical technique may constitute a useful method to characterize the mechanical behavior of composite hydrogel films for use in wound healing applications.
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http://dx.doi.org/10.1016/j.carbpol.2020.116666DOI Listing
November 2020

Three-dimensional tissue engineering-based Dentin/Pulp tissue analogue as advanced biocompatibility evaluation tool of dental restorative materials.

Dent Mater 2020 02 30;36(2):229-248. Epub 2019 Nov 30.

Department of Prosthodontics, School of Dentistry, Faculty of Health Sciences, Aristotle University of Thessaloniki (A.U.Th), GR-54124 Thessaloniki, Greece. Electronic address:

Objective: Two-dimensional (2D) in vitro models have been extensively utilized for cytotoxicity assessment of dental materials, but with certain limitations in terms of direct in vitro-in vivo extrapolation (IVIVE). Three-dimensional (3D) models seem more appropriate, recapitulating the structure of human tissues. This study established a 3D dentin/pulp analogue, as advanced cytotoxicity assessment tool of dental restorative materials (DentCytoTool).

Methods: DentCytoTool comprised two compartments: the upper, representing the dentin component, with a layer of odontoblast-like cells expanded on microporous membrane of a cell culture insert and covered by a treated dentin matrix; and the lower, representing a pulp analogue, incorporating HUVEC/SCAP co-cultures into collagen I/fibrin hydrogels. Representative resinous monomers (HEMA: 1-8mM; TEGDMA: 0.5-5mM) and bacterial components (LPS: 1μg/ml) were applied into the construct. Cytotoxicity was assessed by MTT and LDH assays, live/dead staining and real-time PCR for odontogenesis- and angiogenesis-related markers.

Results: DentCytoTool supported cell viability and promoted capillary-like network formation inside the pulp analogue. LPS induced expression of odontogenesis-related markers (RUNX2, ALP, DSPP) without compromising viability of the odontoblast-like cells, while co-treatment with LPS and resin monomers induced cytotoxic effects (live/dead staining, MTT and LDH assays) in cells of both upper and lower compartments and reduced expression angiogenesis-related markers (VEGF, VEGFR2, ANGPT-1, Tie-2, PECAM-1) in a concentration- and time- dependent manner. LPS treatment aggravated TEGDMA-induced and -in certain concentrations (2-4mM)- HEMA-induced cytotoxicity.

Significance: DentCytoTool represents a promising tissue-engineering-based cytotoxicity assessment tool, providing more insight into the mechanistic aspects of interactions of dental materials to the dentin/pulp complex.
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http://dx.doi.org/10.1016/j.dental.2019.11.013DOI Listing
February 2020

In vitro cellular toxicity induced by extractable organic fractions of particles exhausted from urban combustion sources - Role of PAHs.

Environ Pollut 2018 Dec 19;243(Pt B):1166-1176. Epub 2018 Sep 19.

Department of Genetics, Faculty of Medicine, Demokrition University of Thrace, GR-68100, Alexandroupolis, Greece.

The bioactivity of the extractable organic matter (EOM) of particulate matter (PM) exhausted from major urban combustion sources, including residential heating installations (wood-burning fireplace and oil-fired boiler) and vehicular exhaust from gasoline and diesel cars), was investigated in vitro by employing multiple complementary cellular and bacterial assays. Cytotoxic responses were investigated by applying the MTT ((3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide)) bioassay and the lactate dehydrogenase (LDH) release bioassay on human lung cells (MRC-5). Sister Chromatids Exchange (SCE) genotoxicity was measured on human peripheral lymphocytes. Lipid peroxidation potential via reactive oxygen species (ROS) was evaluated on E. coli bacterial cells by measuring the malondialdehyde (MDA) end product. Furthermore, the DNA damage induced by the organic PM fractions was evaluated by the reporter (β-galactosidase) gene expression assay in the bacterial cells, and, by examining the fragmentation of chromosomal DNA on agarose gel electrophoresis. The correlations between the source PM-induced biological endpoints and the PM content in polycyclic aromatic hydrocarbons (PAHs), as typical molecular markers of combustion, were investigated. Fireplace wood smoke particles exhibited by far the highest content in total and carcinogenic PAHs followed by oil boilers, diesel and gasoline emissions. However, in all bioassays, the total EOM-induced toxicity, normalized to PM mass, was highest for diesel cars equipped with Diesel Particle Filter (DPF). No correlation between the toxicological endpoints and the PAHs content was observed suggesting that cytotoxicity and genotoxicity are probably driven by other extractable organic compounds than the commonly measured unsubstituted PAHs. Clearly, further research is needed to elucidate the role of PAHs in the biological effects induced by both, combustion emissions, and ambient air particles.
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http://dx.doi.org/10.1016/j.envpol.2018.09.075DOI Listing
December 2018

Detailed Molecular Surveillance of the HIV-1 Outbreak Among People who Inject Drugs (PWID) in Athens During a Period of Four Years.

Curr HIV Res 2017 ;15(6):396-404

Department of Hygiene, Epidemiology and Medical Statistics, Medical School, National and Kapodistrian University of Athens, Athens, Greece.

Background: New diagnoses of HIV-1 infection among people who inject drugs (PWID) increased significantly during 2011 in Athens.

Objective: Our aim was to investigate the patterns of HIV epidemic spread among PWID and to estimate the transmission dynamics for the major local transmission networks (LTNs).

Methods: We analyzed sequences from 2,274 HIV-infected subjects sampled in Greece during 01/01/2011-31/10/2014. Of specimens in our sample, 874 sequences were isolated from HIV-infected PWID. Phylodynamic analysis was performed using birth-death serial skyline models.

Results: Phylogenetic analysis revealed that the majority of sequences from PWID (N=746, 85.4%) fell within four LTNs: CRF14_BG (N=456, 58.3%), CRF35_AD (N=149, 19.1%), subtype B (N=118, 15.1%) and A1 (N=59, 7.5%). In addition to PWID, we also found that sequences from 36 non-PWID belonged to the LTNs corresponding to cross-group transmissions. Based on the estimated plots of the effective reproductive number (Re) over time, subtype A1 and CRF35_AD LTNs showed a sharp increase before and during 2011 (maximum value of Re=3.0 and Re=4.6, respectively). For subtype B and CRF14_BG LTNs, the Re was increasing until the end of 2012 (maximum value of Re=3.2 and Re=3.0, respectively).

Conclusion: HIV transmissions within subtype A1 and CRF35_AD LTNs increased sharply during the early stage of the outbreak, in contrast to subtype B and CRF14_BG. A significant reduction in the number of infections was estimated on all transmission networks from the beginning of 2013 onwards. Prevention measures that took place in the Athens metropolitan area at the end of 2012 including also the ARISTOTLE program may explain this decrease.
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http://dx.doi.org/10.2174/1570162X15666171120104048DOI Listing
April 2019

Odontogenic differentiation and biomineralization potential of dental pulp stem cells inside Mg-based bioceramic scaffolds under low-level laser treatment.

Lasers Med Sci 2017 Jan 26;32(1):201-210. Epub 2016 Oct 26.

Department of Fixed Prosthesis and Implant Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, GR-54124, Greece.

This study aimed to investigate the potential of low-level laser irradiation (LLLI) to promote odontogenic differentiation and biomineralization by dental pulp stem cells (DPSCs) seeded inside bioceramic scaffolds. Mg-based, Zn-doped bioceramic scaffolds, synthesized by the sol-gel technique, were spotted with DPSCs and exposed to LLLI at 660 nm with maximum output power of 140 mw at fluencies (a) 2 and 4 J/cm to evaluate cell viability/proliferation by the MTT assay and (b) 4 J/cm to evaluate cell differentiation, using real-time PCR (expression of odontogenic markers) and a p-nitrophenylphosphate (pNPP)-based assay for alkaline phosphatase (ALP) activity measurement. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analysis were used for structural/chemical characterization of the regenerated tissues. Exposure of the DPSCs/scaffold complexes to the proposed LLLI scheme was associated with statistically significant increase of odontogenesis-related markers (bone morphogenetic protein 2 (BMP-2): 22.4-fold, dentin sialophosphoprotein (DSPP): 28.4-fold, Osterix: 18.5-fold, and Runt-related transcription factor 2 (Runx2): 3.4-fold). ALP activity was significantly increased at 3 and 7 days inside the irradiated compared to that in the non-irradiated SC/DPSC complexes, but gradually decreased until 14 days. Newly formed Ca-P tissue was formed on the SC/DPSC complexes after 28 days of culture that attained the characteristics of bioapatite. Overall, LLLI treatment proved to be beneficial for odontogenic differentiation and biomineralization of DPSCs inside the bioceramic scaffolds, making this therapeutic modality promising for targeted dentin engineering.
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http://dx.doi.org/10.1007/s10103-016-2102-9DOI Listing
January 2017

HCV dispersal patterns among intravenous drug users (IDUs) in Athens metropolitan area.

Infect Genet Evol 2016 11 6;45:415-419. Epub 2016 Oct 6.

Department of Hygiene, Epidemiology and Medical Statistics, Medical School, National and Kapodistrian University of Athens, Athens, Greece. Electronic address:

Background: Most of the HCV transmission the recent years in Greece was among IDUs. Our aim was to estimate the prevalence of HCV genotypes and to investigate the patterns of HCV dispersal among IDUs in Athens using current state of the art molecular epidemiology methods.

Methods: HCV sequences were determined from 238 HIV-negative IDUs collected on the basis of the "ARISTOTLE" prevention program carried out in Athens between 2012 and 2013. Phylogenetic trees were inferred on HCV sequences isolated from IDUs in Athens for the most prevalent HCV clades (subtypes 1a and 3a). Phylogenetic analysis was performed by Neighbor-Joining and Bayesian methods using GTR+G as nucleotide substitution model. HCV dispersal patterns were estimated using as references, all globally available HCV sequences for subtypes 1a and 3a.

Results: The prevalence of HCV subtypes was: 3a (59.2%), 1a (21.9%), 4 (13.0%), 1b (5.4%) and 2 (0.5%). Phylogenetic analyses revealed that most sequences (63.5%) οf subtypes 1a and 3a fell within IDU-specific monophyletic groups. The proportion of sequences in monophyletic clades was similar for subtype 3a (62.9%) and 1a (65.3%). For the latter group, monophyletic clades were smaller in size. Multivariable logistic regression analyses showed that monophyletic clustering was marginally associated recent onset of injecting ([AOR]=1.44; 95% CI (0.97-2.13), p=0.068).

Conclusions: The high proportions of HCV sequences within IDU-specific monophyletic clusters suggest that transmissions occurred locally among IDUs in Greece. The numerous clusters for both 1a and 3a provide evidence that both sub-epidemics were the result of multiple introductions among the IDUs. Higher regional clustering was probably associated with a more recent onset of drug use.
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http://dx.doi.org/10.1016/j.meegid.2016.10.003DOI Listing
November 2016

Cytotoxicity and genotoxicity induced in vitro by solvent-extractable organic matter of size-segregated urban particulate matter.

Environ Pollut 2016 Nov 6;218:1350-1362. Epub 2016 Sep 6.

Environmental Pollution Control Laboratory, Department of Chemistry, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece. Electronic address:

Three organic fractions of different polarity, including a non polar organic fraction (NPOF), a moderately polar organic fraction (MPOF), and a polar organic fraction (POF) were obtained from size-segregated (<0.49, 0.49-0.97, 0.97-3 and >3 μm) urban particulate matter (PM) samples, and tested for cytotoxicity and genotoxicity using a battery of in vitro assays. The cytotoxicity induced by the organic PM fractions was measured by the mitochondrial dehydrogenase (MTT) cell viability assay applied on MRC-5 human lung epithelial cells. DNA damages were evaluated through the comet assay, determination of the poly(ADP-Ribose) polymerase (PARP) activity, and the oxidative DNA adduct 8-hydroxy-deoxyguanosine (8-OHdG) formation, while pro-inflammatory effects were assessed by determination of the tumor necrosis factor-alpha (TNF-α) mediator release. In addition, the Sister Chromatid Exchange (SCE) inducibility of the solvent-extractable organic matter was measured on human peripheral lymphocyte. Variations of responses were assessed in relation to the polarity (hence the expected composition) of the organic PM fractions, particle size, locality, and season. Organic PM fractions were found to induce rather comparable Cytotoxicity and genotoxicity of PM appeared to be rather independent from the polarity of the extractable organic PM matter (EOM) with POF often being relatively more toxic than NPOF or MPOF. All assays indicated stronger mass-normalized bioactivity for fine than coarse particles peaking in the 0.97-3 and/or the 0.49-0.97 μm size ranges. Nevertheless, the air volume-normalized bioactivity in all assays was highest for the <0.49 μm size range highlighting the important human health risk posed by the inhalation of these quasi-ultrafine particles.
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http://dx.doi.org/10.1016/j.envpol.2016.09.001DOI Listing
November 2016

Human treated dentin matrices combined with Zn-doped, Mg-based bioceramic scaffolds and human dental pulp stem cells towards targeted dentin regeneration.

Dent Mater 2016 08 11;32(8):e159-75. Epub 2016 Jun 11.

Department of Fixed Prosthesis & Implant Prosthodontics, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki GR-54124, Greece. Electronic address:

Objective: This study aimed to investigate the potential of Mg-based bioceramic scaffolds combined with human treated-dentin matrices (hTDMs) and dentinogenesis-related morphogens to promote odontogenic differentiation and dentin-like tissue formation by Dental Pulp Stem Cells-DPSCs.

Methods: DPSC cultures were established and characterized by flow cytometry. Experimental cavities were prepared inside crowns of extracted teeth and demineralized by EDTA (hTDMs). Zn-doped, Mg-based bioceramic scaffolds, synthesized by the sol-gel technique, were hosted inside the hTDMs. DPSCs were spotted inside the hTDMs/scaffold constructs with/without additional exposure to DMP-1 or BMP-2 (100ng/ml, 24h). Scanning Electron Microscopy-SEM, live/dead fluorescence staining and MTT assay were used to evaluate cell attachment and viability; Real time PCR for expression of osteo/odontogenic markers; Inductively Coupled Plasma-Atomic Emission Spectrometry-ICP/AES for scaffold elemental release analysis; ELISA for hTDM growth factor release analysis; SEM and X-ray Diffraction-XRD for structural/chemical characterization of the regenerated tissues.

Results: Scaffolds constantly released low concentrations of Mg(2+), Ca(2+), Zn(2+) and Si(4+), while hTDMs growth factors, like DMP-1, BMP-2 and TGFβ-1. hTDMs/scaffold constructs supported DPSC viability, inducing their rapid odontogenic shift, indicated by upregulation of DSPP, BMP-2, osteocalcin and osterix expression. Newly-formed Ca-P tissue overspread the scaffolds partially transforming into bioapatite. Exposure to DMP-1 or BMP-2 pronouncedly enhanced odontogenic differentiation phenomena.

Significance: This is the first study to validate that combining the bioactivity and ion releasing properties of bioceramic materials with growth factor release by treated natural dentin further supported by exogenous addition of key dentinogenesis-related morphogens (DMP-1, BMP-2) can be a promising strategy for targeted dentin regeneration.
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http://dx.doi.org/10.1016/j.dental.2016.05.013DOI Listing
August 2016

Sol-Gel Derived Mg-Based Ceramic Scaffolds Doped with Zinc or Copper Ions: Preliminary Results on Their Synthesis, Characterization, and Biocompatibility.

Int J Biomater 2016 14;2016:3858301. Epub 2016 Feb 14.

Dentistry Department, Laboratory of Fixed Prosthesis and Implant Prosthodontics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece.

Glass-ceramic scaffolds containing Mg have shown recently the potential to enhance the proliferation, differentiation, and biomineralization of stem cells in vitro, property that makes them promising candidates for dental tissue regeneration. An additional property of a scaffold aimed at dental tissue regeneration is to protect the regeneration process against oral bacteria penetration. In this respect, novel bioactive scaffolds containing Mg(2+) and Cu(2+) or Zn(2+), ions known for their antimicrobial properties, were synthesized by the foam replica technique and tested regarding their bioactive response in SBF, mechanical properties, degradation, and porosity. Finally their ability to support the attachment and long-term proliferation of Dental Pulp Stem Cells (DPSCs) was also evaluated. The results showed that conversely to their bioactive response in SBF solution, Zn-doped scaffolds proved to respond adequately regarding their mechanical strength and to be efficient regarding their biological response, in comparison to Cu-doped scaffolds, which makes them promising candidates for targeted dental stem cell odontogenic differentiation and calcified dental tissue engineering.
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http://dx.doi.org/10.1155/2016/3858301DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4769780PMC
March 2016

Redox activity and in vitro bioactivity of the water-soluble fraction of urban particulate matter in relation to particle size and chemical composition.

Environ Pollut 2016 Jan 14;208(Pt B):774-86. Epub 2015 Nov 14.

Environmental Pollution Control Laboratory, Department of Chemistry, Aristotle University of Thessaloniki, GR 54124, Thessaloniki Greece. Electronic address:

Chemical and toxicological characterization of the water-soluble fraction of size-segregated urban particulate matter (PM) (<0.49, 0.49-0.97, 0.97-1.5, 1.5-3.0, 3.0-7.2 and >7.2 μm) was carried out at two urban sites, traffic and urban background, during the cold and the warm period. Chemical analysis of the water-soluble PM fraction included ionic species (NO3(-), SO4(2-), Cl(-), Na(+), NH4(+), K(+), Mg(2+), Ca(2+)), water-soluble organic carbon (WSOC), and trace elements (Al, As, Ba, Cd, Cr, Cu, Fe, Pb, Mn, Ni, Zn, Pt, Pd, Rh, Ru, Ir, Ca, and Mg). The dithiothreitol (DTT) assay was employed for the abiotic assessment of the oxidative PM activity. Cytotoxic responses were investigated in vitro by applying the mitochondrial dehydrogenase (MTT) and the lactate dehydrogenase (LDH) bioassays on human lung cells (MRC-5), while DNA damage was estimated by the single cell gel electrophoresis assay, known as Comet assay. The correlations between the observed bioactivity responses and the concentrations of water-soluble chemical PM constituents in the various size ranges were investigated. The results of the current study corroborate that short-term bioassays using lung human cells and abiotic assays, such as the DTT assay, could be relevant to complete the routine chemical analysis and to obtain a preliminary screening of the potential effects of PM-associated airborne pollutants on human health.
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http://dx.doi.org/10.1016/j.envpol.2015.10.058DOI Listing
January 2016

Angiogenic Potential and Secretome of Human Apical Papilla Mesenchymal Stem Cells in Various Stress Microenvironments.

Stem Cells Dev 2015 Nov 2;24(21):2496-512. Epub 2015 Sep 2.

5 Laboratory of Pharmacology, School of Pharmaceutical Sciences, Aristotle University of Thessaloniki (A.U.TH.) , Thessaloniki, Greece .

Stem cells from the apical papilla (SCAP) of human adult teeth are considered an accessible source of cells with angiogenic properties. The aims of this study were to investigate the endothelial transdifferentiation of SCAP, the secretion of pro- and antiangiogenic factors from SCAP, and the paracrine effects of SCAP when exposed to environmental stress to stimulate tissue damage. SCAP were exposed to serum deprivation (SD), glucose deprivation (GD), and oxygen deprivation/hypoxia (OD) conditions, individually or in combination. Endothelial transdifferentiation was evaluated by in vitro capillary-like formation assays, real-time polymerase chain reaction, western blot, and flow cytometric analyses of angiogenesis-related markers; secretome by antibody arrays and enzyme-linked immunosorbent assays (ELISA); and paracrine impact on human umbilical vein endothelial cells (HUVECs) by in vitro transwell migration and capillary-like formation assays. The short-term exposure of SCAP to glucose/oxygen deprivation (GOD) in the presence, but mainly in deprivation, of serum (SGOD) elicited a proangiogenesis effect indicated by expression of angiogenesis-related genes involved in vascular endothelial growth factor (VEGF)/VEGFR and angiopoietins/Tie pathways. This effect was unachievable under SD in normoxia, suggesting that the critical microenvironmental condition inducing rapid endothelial shift of SCAP is the combination of SGOD. Interestingly, SCAP showed high adaptability to these adverse conditions, retaining cell viability and acquiring a capillary-forming phenotype. SCAP secreted higher numbers and amounts of pro- (angiogenin, IGFBP-3, VEGF) and lower amounts of antiangiogenic factors (serpin-E1, TIMP-1, TSP-1) under SGOD compared with SOD or SD alone. Finally, secretome obtained under SGOD was most effective in inducing migration and capillary-like formation by HUVECs. These data provide new evidence on the microenvironmental factors favoring endothelial transdifferentiation of SCAP, uncovering the molecular mechanisms regulating their fate. They also validate the angiogenic properties of their secretome giving insights into preconditioning strategies enhancing their therapeutic potential.
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http://dx.doi.org/10.1089/scd.2015.0197DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4620528PMC
November 2015

Genetic manipulation of RPS5 gene expression modulates the initiation of commitment of MEL cells to erythroid maturation: Implications in understanding ribosomopathies.

Int J Oncol 2015 Jul 21;47(1):303-14. Epub 2015 May 21.

Laboratory of Pharmacology, Department of Pharmaceutical Sciences, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece.

Impairment of ribosome biogenesis contributes to the molecular pathophysiology of ribosomopathies by deregulating cell-lineage specific proliferation, differentiation and apoptosis decisions of haematopoietic progenitor cells. Here, using pro-erythroblast-like murine erythroleukemia (MEL) cells, a model system of erythroid maturation, we aimed to investigate whether genetic manipulation of RPS5 expression affects the capacity of cells to grow and differentiate in culture. Parental MEL cells stably transfected with full length RPS5 cDNA in sense (MEL-C14 culture) or antisense (MEL-antisenseRPS5 culture) orientation, as well as MEL cells transiently transfected with siRNAs specific for RPS5 gene silencing (MEL-RPS5siRNA culture) were assessed for their ability to fully execute their erythroid maturation program in culture. The data obtained thus far indicate that: a) MEL-antisenseRPS5 exhibit a pronounced delay in the initiation of differentiation, as well as an impairment of commitment, since the continuous presence of the inducer in culture is required for the cells to fully execute their erythroid maturation program. b) RNAi-mediating silencing of RPS5 gene expression resulted in the inability of MEL cells to differentiate; however, when these cells were allowed to recapitulate normal RPS5 gene expression levels they regained their differentiation capacity by accumulating high proportion of erythroid mature cells. c) Interestingly the latter, is accompanied by morphological changes of cells and an impairment of their proliferation and apoptosis potential. Such data for the first time correlate the RPS5 gene expression levels with the differentiation capacity of MEL cells in vitro, a fact that might also have implications in understanding ribosomopathies.
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http://dx.doi.org/10.3892/ijo.2015.3017DOI Listing
July 2015

Wnt/β-catenin signaling regulates Dental Pulp Stem Cells' responses to pulp injury by resinous monomers.

Dent Mater 2015 May 28;31(5):542-55. Epub 2015 Feb 28.

Department of Conservative Dentistry, Periodontology & Preventive Dentistry, School of Dentistry, Hannover Medical School, Hannover D-30625, Germany. Electronic address:

Objectives: Aim of this study was to investigate whether Dental Pulp Stem Cells-DPSCs responses to pulp injury caused by resinous monomers is be mediated through activation of Wnt/β-catenin signaling.

Methods: DPSCs cultures were established from third molars of healthy donors and characterized for stem cell markers with flow cytometry. Cells were exposed to TEGDMA (T: 0.5-2mM) with or without presence of the Wnt-1 ligand (W:25-100ng/ml) or the GSK3β inhibitor Lithium (L:1-10mM), used both as activators of Wnt/β-catenin signaling. Cell viability was evaluated by MTT assay, cell cycle profiles by flow cytometry and expression of key molecules of Wnt/β-catenin signaling by Real-time PCR and Western Blot.

Results: DPSC exposure to TEGDMA caused a concentration-dependent cytotoxicity, accompanied by G1 arrest at lower and G2/M arrest at higher concentrations or after prolonged exposure. Lithium caused a dual effect, by stimulating/inhibiting cell proliferation at lower/higher concentrations respectively and causing a G2/M arrest in a concentration-dependent manner. Wnt signaling could be activated in DPSCs after Lithium or Wnt-1 treatment, as shown by accumulation of β-catenin, its translocation into the nucleus and enhanced expression of key pathway players, like LEF1 and Cyclin D1. Importantly, exposure to TEGDMA caused a more pronounced activation of the pathway, whereas cumulative effects were observed after T/L or T/W co-treatment, indicating a very strong activation of Wnt signaling after treatment of already "activated" (by Lithium or Wnt-1) cells with TEGDMA.

Significance: These findings highlight the important role of Wnt canonical signaling in pulp repair responses to common injuries.
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http://dx.doi.org/10.1016/j.dental.2015.02.004DOI Listing
May 2015

Prevalence of different HPV types and estimation of prognostic risk factors based on the linear array HPV genotyping test.

J Med Virol 2009 Dec;81(12):2059-65

Department of Hygiene Epidemiology and Medical Statistics, School of Medicine, University of Athens, Athens, Greece.

The aim of the study was to evaluate the prevalence and risk factors of HPV in a gynecologic population attending outpatient clinics using two new molecular tests. The Amplicor HPV test and the Linear Array (LA) HPV Genotyping test were used for the detection of HPV DNA in 320 women. Multiple logistic regression was used to identify independent prognostic factors of HPV positivity. The agreement between the two methods in terms of their qualitative results was 89.3% (kappa: 0.63). Based on the LA results, the overall prevalence of HPV DNA was 49.1%, 95% confidence interval (95% CI: 43.5%, 54.7%). The prevalence of high-risk HPV types was 30.3%. The predominant types were HPV-6 (24.8%) and HPV-16 (20.4%). Among women with normal cytology, the prevalence of HPV was much higher in those presenting other findings, such as inflammation, than those without other abnormal findings (49.5% vs. 31.5%). On the basis of multivariate analysis, the risk of HPV infection was higher among women with multiple sexual partners [>3 vs. 1: OR = 3.1, 95% CI: (1.5, 7.2)], Pap smear findings [low/high-grade lesions vs. negative: OR = 2.8, 95% CI: (1.2, 6.5)], the presence of warts [yes vs. no: OR = 3.0, 95% CI: (1.5, 6.3)] and no history of child birth [no vs. yes: OR = 2.6, 95% CI: (1.0, 6.7)]. Younger age was an additional risk factor for HPV infection with carcinogenic genotypes [OR for 1 year increase = 0.93, 95% CI: (0.89, 0.98)].
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http://dx.doi.org/10.1002/jmv.21639DOI Listing
December 2009

The potential role of ribosomal protein S5 on cell cycle arrest and initiation of murine erythroleukemia cell differentiation.

J Cell Biochem 2008 Jul;104(4):1477-90

Laboratory of Biochemistry, School of Chemistry, Aristotle University of Thessaloniki, GR-54124 Thessaloniki, Greece.

Evidence now exists to indicate that some ribosomal proteins besides being structural components of the ribosomal subunits are involved in the regulation of cell differentiation and apoptosis. As we have shown earlier, initiation of erythroid differentiation of murine erythroleukemia (MEL) cells is associated with transcriptional inactivation of genes encoding ribosomal RNAs and ribosomal proteins S5 (RPS5) and L35a. In this study, we extended these observations and investigated whether transfection of MEL cells with RPS5 cDNA affects the onset of initiation of erythroid maturation and their entrance in cell cycle arrest. Stably transfected MEL cloned cells (MEL-C14 and MEL-C56) were established and assessed for their capacity to produce RPS5 RNA transcript and its translated product. The impact of RPS5 cDNA transfection on the RPS5 gene expression patterns and the accumulation of RPS5 protein in inducible transfected MEL cells were correlated with their ability to: (a) initiate differentiation, (b) enter cell cycle arrest at G(1)/G(0) phase, and (c) modulate the level of cyclin-dependent kinases CDK2, CDK4, and CDK6. The data presented indicate that deregulation of RPS5 gene expression (constitutive expression) affects RPS5 protein level and delays both the onset of initiation of erythroid maturation and entrance in cell cycle arrest in inducer-treated MEL cells.
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http://dx.doi.org/10.1002/jcb.21722DOI Listing
July 2008

Evaluation of the clinical sensitivity for the quantification of human immunodeficiency virus type 1 RNA in plasma: Comparison of the new COBAS TaqMan HIV-1 with three current HIV-RNA assays--LCx HIV RNA quantitative, VERSANT HIV-1 RNA 3.0 (bDNA) and COBAS AMPLICOR HIV-1 Monitor v1.5.

J Virol Methods 2006 Feb 27;131(2):168-74. Epub 2005 Sep 27.

Department of Hygiene and Epidemiology, National Retrovirus Reference Center, Athens University Medical School, and General Hospital of Athens G. Gennimatas, Greece.

The COBAS TaqMan HIV-1 test (Roche Diagnostics) was compared with the LCx HIV RNA quantitative assay (Abbott Laboratories), the Versant HIV-1 RNA 3.0 (bDNA) assay (Bayer) and the COBAS Amplicor HIV-1 Monitor v1.5 test (Roche Diagnostics), using plasma samples of various viral load levels from HIV-1-infected individuals. In the comparison of TaqMan with LCx, TaqMan identified as positive 77.5% of the 240 samples versus 72.1% identified by LCx assay, while their overall agreement was 94.6% and the quantitative results of samples that were positive by both methods were strongly correlated (r=0.91). Similarly, in the comparison of TaqMan with bDNA 3.0, both methods identified 76.3% of the 177 samples as positive, while their overall agreement was 95.5% and the quantitative results of samples that were positive by both methods were strongly correlated (r=0.95). Finally, in the comparison of TaqMan with Monitor v1.5, TaqMan identified 79.5% of the 156 samples as positive versus 80.1% identified by Monitor v1.5, while their overall agreement was 95.5% and the quantitative results of samples that were positive by both methods were strongly correlated (r=0.96). In conclusion, the new COBAS TaqMan HIV-1 test showed excellent agreement with other widely used commercially available tests for the quantitation of HIV-1 viral load.
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http://dx.doi.org/10.1016/j.jviromet.2005.07.014DOI Listing
February 2006

Comparison of three current viral load assays for the quantitation of human immunodeficiency virus type 1 RNA in plasma.

J Virol Methods 2004 Oct;121(1):93-9

Department of Hygiene and Epidemiology, Athens University Medical School, 75 Mikras Asias Street, GR-115 27 Athens, Goudi, Greece.

The LCx HIV RNA quantitative assay (Abbott Laboratories, Delkenheim, Germany) was compared with the Versant HIV-1 RNA 3.0 (bDNA) assay (Bayer, Tarrytown, NY) and the COBAS Amplicor HIV-1 Monitor v1.5 test (Roche Diagnostics, Branchburg, NJ), using plasma samples of various viral load levels from HIV-1-infected patients. Considering the lower limit of the linear range of 50 copies/ml of both assays, the detection range of the LCx was 127/151 (84.1%) versus the 131/151 (86.8%) of the bDNA 3.0 assay, while overall agreement between the two assays was 93.4% (141/151). LCx and bDNA 3.0 results were found to be strongly correlated (r = 0.96). The fitted regression line was described by the equation log10(LCx copies/ml) = 0.05 + 1.06 x log10(bDNA 3.0 copies/ml) with 95% CI for the estimated slope and intercept at 1.01, 1.12 and -0.16, 0.26, respectively. Similarly, the detection range of the LCx was 115/148 (77.7%) versus the 128/148 (86.5%) of the Monitor v1.5 test. A 91.2% concordance (135/148) was observed between these two assays at a cut-off of 50 copies/ml. LCx and Monitor v1.5 results were highly correlated (r = 0.96). The fitted regression line was described by the equation log10(LCx copies/ml) = 0.06 + 1.03 x log(10)(Monitor v1.5 copies/ml) with 95% CI for the estimated slope and intercept at 0.97, 1.09 and -0.16, 0.28, respectively.
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http://dx.doi.org/10.1016/j.jviromet.2004.06.007DOI Listing
October 2004
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