• A 3D co-culture of three human cell lines to model the inflamed intestinal mucosa for safety testing of nanomaterials.

      Susewind, Julia; de Souza Carvalho-Wodarz, Cristiane; Repnik, Urska; Collnot, Eva-Maria; Schneider-Daum, Nicole; Griffiths, Gareth Wyn; Lehr, Claus-Michael; Helmholtz-Institut für Pharmaceutische Forschung Saarland, Universitätscampus E8.1, 66123 Saarbrücken, Germany. (2016)
      Oral exposure to nanomaterials is a current concern, asking for innovative biological test systems to assess their safety, especially also in conditions of inflammatory disorders. Aim of this study was to develop a 3D intestinal model, consisting of Caco-2 cells and two human immune cell lines, suitable to assess nanomaterial toxicity, in either healthy or diseased conditions. Human macrophages (THP-1) and human dendritic cells (MUTZ-3) were embedded in a collagen scaffold and seeded on the apical side of transwell inserts. Caco-2 cells were seeded on top of this layer, forming a 3D model of the intestinal mucosa. Toxicity of engineered nanoparticles (NM101 TiO2, NM300 Ag, Au) was evaluated in non-inflamed and inflamed co-cultures, and also compared to non-inflamed Caco-2 monocultures. Inflammation was elicited by IL-1β, and interactions with engineered NPs were addressed by different endpoints. The 3D co-culture showed well preserved ultrastructure and significant barrier properties. Ag NPs were found to be more toxic than TiO2 or Au NPs. But once inflamed with IL-1β, the co-cultures released higher amounts of IL-8 compared to Caco-2 monocultures. However, the cytotoxicity of Ag NPs was higher in Caco-2 monocultures than in 3D co-cultures. The naturally higher IL-8 production in the co-cultures was enhanced even further by the Ag NPs. This study shows that it is possible to mimic inflamed conditions in a 3D co-culture model of the intestinal mucosa. The fact that it is based on three easily available human cell lines makes this model valuable to study the safety of nanomaterials in the context of inflammation.
    • Advanced in vitro lung-on-chip platforms for inhalation assays: From prospect to pipeline.

      Artzy-Schnirman, Arbel; Hobi, Nina; Schneider-Daum, Nicole; Guenat, Olivier T; Lehr, Claus-Michael; Sznitman, Josué; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (Elsevier, 2019-09-06)
      With rapid advances in micro-fabrication processes and the availability of biologically-relevant lung cells, the development of lung-on-chip platforms is offering novel avenues for more realistic inhalation assays in pharmaceutical research, and thereby an opportunity to depart from traditional in vitro lung assays. As advanced models capturing the cellular pulmonary make-up at an air-liquid interface (ALI), lung-on-chips emulate both morphological features and biological functionality of the airway barrier with the ability to integrate respiratory breathing motions and ensuing tissue strains. Such in vitro systems allow importantly to mimic more realistic physiological respiratory flow conditions, with the opportunity to integrate physically-relevant transport determinants of aerosol inhalation therapy, i.e. recapitulating the pathway from airborne flight to deposition on the airway lumen. In this short opinion, we discuss such points and describe how these attributes are paving new avenues for exploring improved drug carrier designs (e.g. shape, size, etc.) and targeting strategies (e.g. conductive vs. respiratory regions) amongst other. We argue that while technical challenges still lie along the way in rendering in vitro lung-on-chip platforms more widespread across the general pharmaceutical research community, significant momentum is steadily underway in accelerating the prospect of establishing these as in vitro "gold standards"
    • Advancing human pulmonary disease models in preclinical research: opportunities for lung-on-chips..

      Artzy-Schnirman, Arbel; Lehr, Claus-Michael; Sznitman, Josué; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (Taylor&Francis, 2020-03-11)
      [No abstracr available]
    • Antibiotic-free nanotherapeutics: Ultra-small, mucus-penetrating solid lipid nanoparticles enhance the pulmonary delivery and anti-virulence efficacy of novel quorum sensing inhibitors.

      Nafee, Noha; Husari, Ayman; Maurer, Christine K; Lu, Cenbin; de Rossi, Chiara; Steinbach, Anke; Hartmann, Rolf W; Lehr, Claus-Michael; Schneider, Marc (2014-10-28)
      Cystic fibrosis (CF) is a genetic disease mainly manifested in the respiratory tract. Pseudomonas aeruginosa (P. aeruginosa) is the most common pathogen identified in cultures of the CF airways, however, its eradication with antibiotics remains challenging as it grows in biofilms that counterwork human immune response and dramatically decrease susceptibility to antibiotics. P. aeruginosa regulates pathogenicity via a cell-to-cell communication system known as quorum sensing (QS) involving the virulence factor (pyocyanin), thus representing an attractive target for coping with bacterial pathogenicity. The first in vivo potent QS inhibitor (QSI) was recently developed. Nevertheless, its lipophilic nature might hamper its penetration of non-cellular barriers such as mucus and bacterial biofilms, which limits its biomedical application. Successful anti-infective inhalation therapy necessitates proper design of a biodegradable nanocarrier allowing: 1) high loading and prolonged release, 2) mucus penetration, 3) effective pulmonary delivery, and 4) maintenance of the anti-virulence activity of the QSI. In this context, various pharmaceutical lipids were used to prepare ultra-small solid lipid nanoparticles (us-SLNs) by hot melt homogenization. Plain and QSI-loaded SLNs were characterized in terms of colloidal properties, drug loading, in vitro release and acute toxicity on Calu-3 cells. Mucus penetration was studied using a newly-developed confocal microscopy technique based on 3D-time-lapse imaging. For pulmonary application, nebulization efficiency of SLNs and lung deposition using next generation impactor (NGI) were performed. The anti-virulence efficacy was investigated by pyocyanin formation in P. aeruginosa cultures. Ultra-small SLNs (<100nm diameter) provided high encapsulation efficiency (68-95%) according to SLN composition, high burst in phosphate buffer saline compared to prolonged release of the payload over >8h in simulated lung fluid with minor burst. All types and concentrations of plain and QSI-loaded SLNs maintained the viability of Calu-3 cells. 3D time-lapse confocal imaging proved the ability of SLNs to penetrate into artificial sputum model. SLNs were efficiently nebulized; NGI experiments revealed their deposition in the bronchial region. Overall, nanoencapsulated QSI showed up to sevenfold superior anti-virulence activity to the free compound. Most interestingly, the plain SLNs exhibited anti-virulence properties themselves, which was shown to be related to anti-virulence effects of the emulsifiers used. These startling findings represent a new perspective of ultimate significance in the area of nano-based delivery of novel anti-infectives.
    • Aspherical and Spherical InvA497-Functionalized Nanocarriers for Intracellular Delivery of Anti-Infective Agents.

      Castoldi, Arianna; Empting, Martin; De Rossi, Chiara; Mayr, Karsten; Dersch, Petra; Hartmann, Rolf; Müller, Rolf; Gordon, Sarah; Lehr, Claus-Michael; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (Springer, 2018-12-05)
      The objective of this work was to evaluate the potential of polymeric spherical and aspherical invasive nanocarriers, loaded with antibiotic, to access and treat intracellular bacterial infections. Aspherical nanocarriers were prepared by stretching of spherical precursors, and both aspherical and spherical nanocarriers were surface-functionalized with the invasive protein InvA497. The relative uptake of nanocarriers into HEp-2 epithelial cells was then assessed. Nanocarriers were subsequently loaded with a preparation of the non-permeable antibiotic gentamicin, and tested for their ability to treat HEp-2 cells infected with the enteroinvasive bacterium Shigella flexneri. InvA497-functionalized nanocarriers of both spherical and aspherical shape showed a significantly improved rate and extent of uptake into HEp-2 cells in comparison to non-functionalized nanocarriers. Functionalized and antibiotic-loaded nanocarriers demonstrated a dose dependent killing of intracellular S. flexneri. A slight but significant enhancement of intracellular bacterial killing was also observed with aspherical as compared to spherical functionalized nanocarriers at the highest tested concentration. InvA497-functionalized, polymer-based nanocarriers were able to efficiently deliver a non-permeable antibiotic across host cell membranes to affect killing of intracellular bacteria. Functionalized nanocarriers with an aspherical shape showed an interesting future potential for intracellular infection therapy.
    • Bacteriomimetic invasin-functionalized nanocarriers for intracellular delivery.

      Labouta, Hagar Ibrahim; Menina, Sara; Kochut, Annika; Gordon, Sarah; Geyer, Rebecca; Dersch, Petra; Lehr, Claus-Michael; Helmholtz Institute for Pharmaceutical Research Saarland (HIPS);Saarland University, Building A4.1, 66123 Saarbruecken, Germany. (2015-12-28)
      Intracellular bacteria invade mammalian cells to establish an infectious niche. The current work models adhesion and subsequent internalization strategy of pathogenic bacteria into mammalian cells to design a bacteriomimetic bioinvasive delivery system. We report on the surface functionalization of liposomes with a C-terminal fragment of invasin (InvA497), an invasion factor in the outer membrane of Yersinia pseudotuberculosis. InvA497-functionalized liposomes adhere to mammalian epithelial HEp-2 cell line at different infection stages with a significantly higher efficiency than liposomes functionalized with bovine serum albumin. Covalent attachment of InvA497 results in higher cellular adhesion than liposomes with physically adsorbed InvA497 with non-specific surface protein alignment. Uptake studies in HEp-2 cells indicate active internalization of InvA497-functionalized liposomes via β1-integrin receptor-mediated uptake mechanism mimicking the natural invasion strategy of Y. pseudotuberculosis. Uptake studies in Caco-2 cells at different polarization states demonstrate specific targeting of the InvA497-functionalized liposomes to less polarized cells reflecting the status of inflamed cells. Moreover, when loaded with the anti-infective agent gentamicin and applied to HEp-2 cells infected with Y. pseudotuberculosis, InvA497-functionalized liposomes are able to significantly reduce the infection load relative to non-functionalized drug-loaded liposomes. This indicates a promising application of such a bacteriomimetic system for drug delivery to intracellular compartments.
    • Bioinspired Liposomes for Oral Delivery of Colistin to Combat Intracellular Infections by Salmonella enterica.

      Menina, Sara; Eisenbeis, Janina; Kamal, Mohamed Ashraf M; Koch, Marcus; Bischoff, Markus; Gordon, Sarah; Loretz, Brigitta; Lehr, Claus-Michael; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (Wiley-VCH, 2019-07-22)
      Bacterial invasion into eukaryotic cells and the establishment of intracellular infection has proven to be an effective means of resisting antibiotic action, as anti-infective agents commonly exhibit a poor permeability across the host cell membrane. Encapsulation of anti-infectives into nanoscaled delivery systems, such as liposomes, is shown to result in an enhancement of intracellular delivery. The aim of the current work is, therefore, to formulate colistin, a poorly permeable anti-infective, into liposomes suitable for oral delivery, and to functionalize these carriers with a bacteria-derived invasive moiety to enhance their intracellular delivery. Different combinations of phospholipids and cholesterol are explored to optimize liposomal drug encapsulation and stability in biorelevant media. These liposomes are then surface-functionalized with extracellular adherence protein (Eap), derived from Staphylococcus aureus. Treatment of HEp-2 and Caco-2 cells infected with Salmonella enterica using colistin-containing, Eap-functionalized liposomes resulted in a significant reduction of intracellular bacteria, in comparison to treatment with nonfunctionalized liposomes as well as colistin alone. This indicates that such bio-invasive carriers are able to facilitate intracellular delivery of colistin, as necessary for intracellular anti-infective activity. The developed Eap-functionalized liposomes, therefore, present a promising strategy for improving the therapy of intracellular infections.
    • Biological barriers - Advanced drug delivery, in vitro modelling, and their implications for infection research.

      Schneider, Marc; Loretz, Brigitta; Windbergs, Maike; Schneider-Daum, Nicole; Schaefer, Ulrich F; Lehr, Claus-Michael; Helmholtz Institute for Pharmaceutical Research Saarland (HIPS);Saarland University, Building A4.1, 66123 Saarbruecken, Germany. (2015-09)
    • Calcium Phosphate System for Gene Delivery: Historical Background and Emerging Opportunities.

      Mostaghaci, Babak; Loretz, Brigitta; Lehr, Claus-Michael; Helmholtz Institut f?r Pharmazeutische Forschung Saarland, Universit?tscampus E8.1, 66123 Saarbr?cken, Germany. (2016)
      Calcium phosphate system has been used widely in in vitro gene delivery for almost four decades. Excellent biocompatibility and simple application have motivated the researchers to always consider this system in their transfection experiments. However, there was a major drawback regarding the low transfection efficiency of calcium phosphate. Hence, there have been many efforts in order to increase the gene delivery potential of this system. In this paper, the application of calcium phosphate in gene delivery is introduced. Moreover, the recent progresses in the application of calcium phosphate in the delivery of (oligo)nucleotides and different approaches to improve the properties of this system are reviewed.
    • Cellular delivery of polynucleotides by cationic cyclodextrin polyrotaxanes.

      Dandekar, Prajakta; Jain, Ratnesh; Keil, Manuel; Loretz, Brigitta; Muijs, Leon; Schneider, Marc; Auerbach, Dagmar; Jung, Gregor; Lehr, Claus-Michael; Wenz, Gerhard; et al. (2012-12-28)
      Cationic polyrotaxanes, obtained by temperature activated threading of cationic cyclodextrin derivatives onto water-soluble cationic polymers (ionenes), form metastable nanometric polyplexes with pDNA and combinations of siRNA with pDNA. Because of their low toxicity, the polyrotaxane polyplexes constitute a very interesting system for the transfection of polynucleotides into mammalian cells. The complexation of Cy3-labeled siRNA within the polyplexes was demonstrated by fluorescence correlation spectroscopy. The uptake of the polyplexes (red) was imaged by confocal fluorescence microscopy using the A549 cell line as a model (blue: nuclei, green: membranes). The results prove the potential of polyrotaxanes for further investigations involving knocking down genes of therapeutic interest.
    • Challenges and Strategies in Drug Delivery Systems for Treatment of Pulmonary Infections.

      Ho, Duy-Khiet; Nichols, Brittany L B; Edgar, Kevin J; Murgia, Xabier; Loretz, Brigitta; Lehr, Claus-Michael; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (Elsevier, 2019-09-04)
      Inhalation therapy has been reported as the most effective treatment for respiratory bacterial infections due to the increasing relevance of drug bioavailability. Drug delivery systems (DDS) have the capacity to overcome pulmonary biological barriers limiting the bioavailability of inhaled anti-infectives. This is important to eradicate bacterial infections and to prevent the development of bacterial resistance. Despite substantial efforts in the field, the current state-of-the-art often fails to achieve those goals, and we still observe increasing bacterial resistance. We give a brief insight on benefits and challenges in pulmonary delivery of anti-infectives. In the context of drug delivery development for pulmonary infections, particularly focusing on Pseudomonas aeruginosa (PA) infections, this mini review will critically discuss the main requirements, as well as the recent strategies of drug delivery system synthesis and preparation. Finally, interaction of DDS with crucial pulmonary biological barriers will be of great importance for the success of future applications of the developed DDS.
    • Characterization and evaluation of β-glucan formulations as injectable implants for protein and peptide delivery.

      Jacobs, Simone; Bunt, Craig R; Wu, Zimei; Lehr, Claus-Michael; Rupenthal, Ilva D; Biopharmaceutics and Pharmaceutical Technology, Saarland University, Saarbrücken, Germany. (2012-11)
      Injectable implants are biodegradable, syringeable formulations that are injected as liquids, but form a gel inside the body due to a change in pH, ions or temperature.
    • Chemically modified hCFTR mRNAs recuperate lung function in a mouse model of cystic fibrosis.

      Haque, A K M Ashiqul; Dewerth, Alexander; Antony, Justin S; Riethmüller, Joachim; Schweizer, Georg R; Weinmann, Petra; Latifi, Ngadhnjim; Yasar, Hanzey; Pedemonte, Nicoletta; Sondo, Elvira; et al. (Nature publishing group, 2018-11-13)
      Gene therapy has always been a promising therapeutic approach for Cystic Fibrosis (CF). However, numerous trials using DNA or viral vectors encoding the correct protein resulted in a general low efficacy. In the last years, chemically modified messenger RNA (cmRNA) has been proven to be a highly potent, pulmonary drug. Consequently, we first explored the expression, function and immunogenicity of human (h)CFTR encoded by cmRNA
    • Ciprofloxacin-loaded PLGA nanoparticles against Cystic Fibrosis P. aeruginosa Lung Infections.

      Günday Türeli, Nazende; Torge, Afra; Juntke, Jenny; Schwarz, Bianca C; Schneider-Daum, Nicole; Türeli, Akif Emre; Lehr, Claus-Michael; Schneider, Marc; Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1, 66123 Saarbrücken, Germany. (2017-05-02)
      Current pulmonary treatments against Pseudomonasaeruginosa infections in cystic fibrosis (CF) lung suffer from deactivation of the drug and immobilization in thick and viscous biofilm/mucus blend, along with the general antibiotic resistance. Administration of nanoparticles (NPs) with high antibiotic load capable of penetrating the tight mesh of biofilm/mucus can be an advent to overcome the treatment bottlenecks. Biodegradable and biocompatible polymer nanoparticles efficiently loaded with ciprofloxacin complex offer a solution for emerging treatment strategies. NPs were prepared under controlled conditions by utilizing MicroJet Reactor (MJR) to yield a particle size of 190.4±28.6 nm with 0.089 PDI. Encapsulation efficiency of the drug was 79% resulting in a loading of 14%. Release was determined to be controlled and medium-independent in PBS, PBS+0.2% Tween 80 and simulated lung fluid. Cytotoxicity assays with Calu3 cells and CF bronchial epithelial cells (CFBE41o(-)) indicated that complex loaded PLGA NPs were non-toxic at concentrations >MICcipro against lab strains of the bacteria. Antibacterial activity tests revealed enhanced activity when applied as nanoparticles. NPs' colloidal stability in mucus was proven. Notably, a decrease in mucus turbidity was observed upon incubation with NPs. Herewith, ciprofloxacin complex loaded PLGA NPs are introduced as promising pulmonary nano drug delivery systems against P.aeruginosa infections in CF lung.
    • Co-culture of human alveolar epithelial (hAELVi) and macrophage (THP-1) cell lines.

      Kletting, Stephanie; Barthold, Sarah; Repnik, Urska; Griffiths, Gareth; Loretz, Brigitta; Schneider-Daum, Nicole; de Souza Carvalho-Wodarz, Cristiane; Lehr, Claus-Michael; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (Springer Nature, 2018-01-01)
      The air-blood barrier is mainly composed of alveolar epithelial cells and macrophages. Whereas the epithelium acts as a diffusional barrier, macrophages represent an immunological barrier, in particular for larger molecules and nanoparticles. This paper describes a new co-culture of human cell lines representing both cell types. Acquiring, culturing and maintaining primary alveolar epithelial cells presents significant logistical and technical difficulties. The recently established human alveolar epithelial lentivirus immortalized cell line, hAELVi, when grown on permeable filters, forms monolayers with high functional and morphological resemblance to alveolar type I cells. To model alveolar macrophages, the human cell line THP-1 was seeded on pre-formed hAELVi monolayers. The co-culture was characterized regarding cellular morphology, viability and barrier function. Macrophages were homogenously distributed on the epithelium and could be kept in co-culture for up to 7 days. Transmission electron microscopy showed loose contact between THP-1 and hAELVi cells. When grown at air liquid interface, both cells were covered with extracellular matrix-like structure, which was absent in THP-1 mono-culture. In co-culture with macrophages, hAELVi cells displayed similar, sometimes even higher, transepithelial electrical resistance than in mono-cultures. When exposed to silver and starch nanoparticles, hAELVi mono-cultures were more tolerant to the particles than THP-1 mono-cultures. Viability in the co-culture was similar to that of hAELVi mono-cultures. Transport studies with sodium fluorescein in the presence/absence of EDTA proved that the co-culture acts as functional diffusion barrier. These data demonstrate that hAELVi-/THP-1 co-cultures represent a promising model for safety and permeability studies of inhaled chemicals, drugs and nanoparticles.
    • Co-Delivery of mRNA and pDNA Using Thermally Stabilized Coacervate-Based Core-Shell Nanosystems.

      Nasr, Sarah S; Lee, Sangeun; Thiyagarajan, Durairaj; Boese, Annette; Loretz, Brigitta; Lehr, Claus-Michael; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (MDPI, 2021-11-13)
      Co-delivery of different species of protein-encoding polynucleotides, e.g., messenger RNA (mRNA) and plasmid DNA (pDNA), using the same nanocarrier is an interesting topic that remains scarcely researched in the field of nucleic acid delivery. The current study hence aims to explore the possibility of the simultaneous delivery of mRNA (mCherry) and pDNA (pAmCyan) using a single nanocarrier. The latter is based on gelatin type A, a biocompatible, and biodegradable biopolymer of broad pharmaceutical application. A core-shell nanostructure is designed with a thermally stabilized gelatin-pDNA coacervate in its center. Thermal stabilization enhances the core's colloidal stability and pDNA shielding effect against nucleases as confirmed by nanoparticle tracking analysis and gel electrophoresis, respectively. The stabilized, pDNA-loaded core is coated with the cationic peptide protamine sulfate to enable additional surface-loading with mRNA. The dual-loaded core-shell system transfects murine dendritic cell line DC2.4 with both fluorescent reporter mRNA and pDNA simultaneously, showing a transfection efficiency of 61.4 ± 21.6% for mRNA and 37.6 ± 19.45% for pDNA, 48 h post-treatment, whereas established commercial, experimental, and clinical transfection reagents fail. Hence, the unique co-transfectional capacity and the negligible cytotoxicity of the reported system may hold prospects for vaccination among other downstream applications.
    • Combining MucilAir™ and Vitrocell Powder Chamber for the In Vitro Evaluation of Nasal Ointments in the Context of Aerosolized Pollen.

      Metz, Julia; Knoth, Katharina; Groß, Henrik; Lehr, Claus-Michael; Stäbler, Carolin; Bock, Udo; Hittinger, Marius; HIPS, Helmholtz-Institute für pharmazeutische Forschung Saarland, Universitätscampus E8.1, 66123 Saarbrücken, Germany. (2018-05-10)
      Hay fever is notoriously triggered when nasal mucosa is exposed to allergenic pollen. One possibility to overcome this pollen exposure may be the application of an ointment with physical protective effects. In this context, we have investigated Bepanthen Eye and Nose Ointment and the ointment basis petrolatum as reference while using contemporary in vitro techniques. Pollen from false ragweed () was used as an allergy-causing model deposited as aerosol using the Vitrocell Powder Chamber (VPC) on Transwell inserts, while being coated with either Bepanthen Eye and Nose Ointment and petrolatum. No pollen penetration into ointments was observed upon confocal scanning laser microscopy during an incubation period of 2 h at 37 &deg;C. The cellular response was further investigated by integrating the MucilAir&trade; cell system in the VPC and by applying pollen to Bepanthen Eye and Nose Ointment covered cell cultures. For comparison, MucilAir&trade; were stimulated by lipopolysaccharides (LPS). No increased cytokine release of IL-6, TNF-&alpha;, or IL-8 was found after 4 h of pollen exposure, which demonstrates the safety of such ointments. Since nasal ointments act as a physical barrier against pollen, such preparations might support the prevention and management of hay fever.
    • Coupling quaternary ammonium surfactants to the surface of liposomes improves both antibacterial efficacy and host cell biocompatibility

      Montefusco-Pereira, Carlos V.; Formicola, Beatrice; Goes, Adriely; Re, Francesca; Marrano, Claudia A.; Mantegazza, Francesco; Carvalho-Wodarz, Cristiane; Fuhrmann, Gregor; Caneva, Enrico; Nicotra, Francesco; et al. (Elsevier BV, 2020-04)
      By functionalizing the surface of PEG-liposomes with linkers bearing quaternary ammonium compounds (QACs), we generated novel bacteria disruptors with anti-adhesive properties and reduced cytotoxicity compared to free QACs. Furthermore, QAC-functionalized liposomes are a promising platform for future drug encapsulation. The QAC (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide (MTAB) was attached to maleimide-functionalized liposomes (DSPE-PEG) via thiol linker. The MTAB-functionalized liposomes were physicochemically characterized and their biological activity, in terms of anti-adherence activity and biofilm prevention in Escherichia coli were assessed. The results showed that MTAB-functionalized liposomes inhibit bacterial adherence and biofilm formation while reducing MTAB toxicity.
    • Crossing biological barriers for advanced drug delivery.

      Schneider, Marc; Windbergs, Maike; Daum, Nicole; Loretz, Brigitta; Collnot, Eva-Maria; Hansen, Steffi; Schaefer, Ulrich F; Lehr, Claus-Michael (2013-06)
      This special issue compiles invited and contributed papers of the 9th International Conference and Workshop "Biological Barriers", 29 February-9 March 2012 at Saarland University, Saarbrücken Germany.
    • A Custom-Made Device for Reproducibly Depositing Pre-metered Doses of Nebulized Drugs on Pulmonary Cells .

      Horstmann, Justus C; Thorn, Chelsea R; Carius, Patrick; Graef, Florian; Murgia, Xabier; de Souza Carvalho-Wodarz, Cristiane; Lehr, Claus-Michael; HIPS, Helmholtz-Institut für Pharmazeutische Forschung Saarland, Universitätscampus E8.1 66123 Saarbrücken, Germany. (Frontiers, 2021-04-21)
      The deposition of pre-metered doses (i.e., defined before and not after exposition) at the air-liquid interface of viable pulmonary epithelial cells remains an important but challenging task for developing aerosol medicines. While some devices allow quantification of the deposited dose after or during the experiment, e.g., gravimetrically, there is still no generally accepted way to deposit small pre-metered doses of aerosolized drugs or pharmaceutical formulations, e.g., nanomedicines. Here, we describe a straightforward custom-made device, allowing connection to commercially available nebulizers with standard cell culture plates. Designed to tightly fit into the approximately 12-mm opening of either a 12-well Transwell® insert or a single 24-well plate, a defined dose of an aerosolized liquid can be directly deposited precisely and reproducibly (4.8% deviation) at the air-liquid interface (ALI) of pulmonary cell cultures. The deposited dose can be controlled by the volume of the nebulized solution, which may vary in a range from 20 to 200 μl. The entire nebulization-deposition maneuver is completed after 30 s and is spatially homogenous. After phosphate-buffered saline (PBS) deposition, the viability and barrier properties transepithelial electrical resistance (TEER) of human bronchial epithelial Calu-3 cells were not negatively affected. Straightforward in manufacture and use, the device enables reproducible deposition of metered doses of aerosolized drugs to study the interactions with pulmonary cell cultures grown at ALI conditions.