Christian Lautenschläger

Drug delivery strategies in the therapy of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a frequently occurring disease in young people, which is characterized by a chronic inflammation of the gastrointestinal tract. The therapy of IBD is dominated by the administration of anti-inflammatory and immunosuppressive drugs, which suppress the intestinal inflammatory burden and improve the disease-related symptoms. Established treatment strategies are characterized by a limited therapeutical efficacy and the occurrence of adverse drug reactions. Thus, the development of novel disease-targeted drug delivery strategies is intended for a more effective therapy and demonstrates the potential to address unmet medical needs. This review gives an overview about the established as well as future-oriented drug targeting strategies, including intestine targeting by conventional drug delivery systems (DDS), disease targeted drug delivery by synthetic DDS and disease targeted drug delivery by biological DDS. Furthermore, this review analyses the targeting mechanisms of the respective DDS and discusses the possible field of utilization in IBD.

PEG-functionalized microparticles selectively target inflamed mucosa in inflammatory bowel disease

INTRODUCTION The systemic therapy of inflammatory bowel diseases (IBD) by oral administration of anti-inflammatory and immunosuppressive agents is characterized by an increased probability of adverse drug reactions. A successful treatment with a simultaneous reduction in adverse events may be achieved by the administration of micro- and nanosized targeted drug delivery systems, which accumulate selectively in inflamed mucosal areas without systemic absorption. We described in a first in vivo study in IBD patients a significantly enhanced, but minor accumulation of non-functionalized poly(lactic-co-glycolic acid) (PLGA) microparticles in ulcerous lesions very recently. AIM The aim of this study was therefore the assessment of an increased targeting potential of different non-, chitosan- and polyethylene glycol (PEG)-functionalized PLGA micro- and nanoparticles to inflamed intestinal mucosa compared to healthy mucosa. MATERIALS AND METHODS For the quantification of nano- and microparticles, fluoresceinamine-labeled-PLGA was synthesized by carbodiimide reaction. Fluorescent chitosan-, PEG-, and non-functionalized PLGA micro- and nanoparticles with mean hydrodynamic diameters of 3000 nm and 300 nm were prepared by solvent evaporation technique. The targeting efficiencies in terms of particle translocation and deposition were investigated in Ussing chamber experiments. Healthy and inflamed macrobiopsies were received from routine endoscopic examinations of patients with IBD as well as control patients. RESULTS One-hundred and one Ussing chamber experiments of patients with IBD (Crohns disease: n=7 and ulcerative colitis: n=9) as well as healthy control patients (n=5) were performed. Histomorphological and electrophysiological investigations of inflamed mucosal tissues confirmed a significant alteration of mucosal barrier integrity in IBD patients (TER: healthy: 34.1 Ω cm(2); inflamed: 21.6 Ωc m(2); p=0.034). In summary, nanoparticles showed an increased translocation and deposition compared to microparticles in healthy and in inflamed mucosa. Chitosan-functionalized particles adhered onto the tissue surface and thus showed the lowest particle translocation and deposition in healthy and inflamed tissues. PEG-functionalized nanoparticles showed the highest translocation through healthy (2.31%) and inflamed mucosa (5.27%). Moreover, PEG-functionalized microparticles showed a significantly increased translocation through inflamed mucosa (3.33%) compared to healthy mucosa (0.55%; p=0.045). Notably, the particle deposition of PEG-functionalized microparticles was significantly increased in inflamed mucosa (10.8%) compared to healthy mucosa (4.1%; p=0.041). CONCLUSIONS Based on the targeted translocation and deposition to inflamed intestinal mucosa, PEG-functionalized PLGA microparticles were qualified as an innovative drug delivery system. These particles may serve as a selective treatment strategy to inflamed mucosal areas in IBD with the potential to improve therapeutic efficacy and to reduce adverse events.

A blue fluorescent labeling technique utilizing micro- and nanoparticles for tracking in LIVE/DEAD® stained pathogenic biofilms of Staphylococcus aureus and Burkholderia cepacia.

Strategies that target and treat biofilms are widely applied to bacterial cultures using popular live/dead staining techniques with mostly red or green fluorescent markers (eg, with SYTO® 9, propidium iodide, fluorescein). Therefore, visualizing drugs or micro- and nanoparticulate delivery systems to analyze their distribution and effects in biofilms requires a third fluorescent dye that does not interfere with the properties of the live/dead markers. The present study establishes and evaluates a model for tracking polymeric particles in fluorescently stained biological material. To this end, poly(d,l-lactide-co-glycolide) (PLGA)-based micro- and nanoparticles were used as well-established model systems, which, because of their favorable safety profiles, are expected to play important future roles with regard to drug delivery via inhalation. PLGA was covalently and stably labeled with 7-amino-4-methyl-3-coumarinylacetic acid (AMCA), after which blue fluorescent poly(ethylene glycol)-block-PLGA (PEG-PLGA) particles were prepared using a mixture of fluorescent AMCA-PLGA and PEG-PLGA. Because chitosan is known to reduce negative surface charge, blue fluorescent PEG-PLGA-particles with chitosan were also prepared. These micro- and nanoparticles were physicochemically characterized and could be clearly distinguished from live/dead stained bacteria in biofilms using confocal laser scanning microscopy.

Drug-Delivery-Strategien zur gezielten Behandlung von chronisch-entzündlichen Darmerkrankungen

Inflammatory bowel disease (IBD) is a frequently occurring disease in young people, which is characterized by chronic inflammation of the gastrointestinal tract. The therapy of IBD is dominated by the administration of anti-inflammatory and immunosuppressive agents, which suppress the intestinal inflammatory burden and improve the disease-related symptoms. Present treatment strategies are characterized by a limited therapeutical efficacy and the occurrence of adverse drug reactions. The development of novel disease-targeted drug delivery strategies is preferable for a more effective therapy and thus demonstrates the potential to address unmet medical needs. This review gives an overview about drug delivery strategies for the treatment of IBD. Therefore, established intestine-targeting strategies for a selective drug release into the diseased part of the gastrointestinal tract will be presented, including prodrugs, and dosage forms with pH-/time-dependent drug release. Furthermore future-oriented disease-targeting strategies for a selective drug release into the intestinal inflammation will be described, including micro-/nanosized synthetic and biologic drug carriers. This novel therapeutic approach may enable a more effective anti-inflammatory treatment of IBD with reduced risks of adverse reactions.

Novel computer vision algorithm for the reliable analysis of organelle morphology in whole cell 3D images--A pilot study for the quantitative evaluation of mitochondrial fragmentation in amyotrophic lateral sclerosis.

The function of intact organelles, whether mitochondria, Golgi apparatus or endoplasmic reticulum (ER), relies on their proper morphological organization. It is recognized that disturbances of organelle morphology are early events in disease manifestation, but reliable and quantitative detection of organelle morphology is difficult and time-consuming. Here we present a novel computer vision algorithm for the assessment of organelle morphology in whole cell 3D images. The algorithm allows the numerical and quantitative description of organelle structures, including total number and length of segments, cell and nucleus area/volume as well as novel texture parameters like lacunarity and fractal dimension. Applying the algorithm we performed a pilot study in cultured motor neurons from transgenic G93A hSOD1 mice, a model of human familial amyotrophic lateral sclerosis. In the presence of the mutated SOD1 and upon excitotoxic treatment with kainate we demonstrate a clear fragmentation of the mitochondrial network, with an increase in the number of mitochondrial segments and a reduction in the length of mitochondria. Histogram analyses show a reduced number of tubular mitochondria and an increased number of small mitochondrial segments. The computer vision algorithm for the evaluation of organelle morphology allows an objective assessment of disease-related organelle phenotypes with greatly reduced examiner bias and will aid the evaluation of novel therapeutic strategies on a cellular level.

TiO2-containing and ZnO-containing borosilicate glass—a novel thin glass with exceptional antibiofilm performances to prevent microfouling

Biofilm formation, also known as microfouling, on indwelling medical devices such as catheters or prosthetic joints causes difficult to treat and recurrent infections. It is also the initial step for biocorrosion of surfaces in aquatic environment. An efficient prevention of microfouling is preferable but the development of antibiofilm surfaces is enormously challenging. Therefore, soda-lime, aluminosilicate, and three borosilicate glasses with different TiO2 and ZnO compositions were investigated on their feasibility to prevent biofilm formation by standardized in vitro biofilm assays using different pathogenic bacteria. Furthermore, the biocompatibility of these glasses was evaluated using eukaryotic cell lines end erythrocytes. Only two borosilicate glasses, containing TiO2 and ZnO, showed an increased antibiofilm performance inhibiting biofilm adhesion and formation. The biofilm thickness and area were significantly reduced by over 90 % and characterized by diffuse structures. All tested glass types showed neither cytotoxicity nor hemotoxicity. Therefore, the antibiofilm borosilicate-thin glasses are qualified for surface coatings where biofilms are not desirable such as on medical devices.

24 Confocal Laser Endomicroscopy to Assess Mucosal Microcirculation: A Quantitative Analysis in a Porcine Model of Septic Shock and in Patients With Severe Sepsis

Aim Microcirculatory alterations play a central role in the pathophysiology of sepsis. Even if systemic hemodynamic parameters appear to be adequate, septic patients may suffer from significant intestinal microcirculatory alterations. It has been suggested that these changes play a central role in regard to morbidity and mortality. The present study first assessed the feasibility of In Vivo detection of mucosal microcirculation in different segments of the gastrointestinal tract in an animal model of septic shock using probe-based confocal laser endomicroscopy (pCLE) (Mauna Kea Technologies, Paris, France). Subsequently, we assessed duodenal microcirculation in patients suffering from severe sepsis in the early phase of the disease. Materials and Methods First, anesthetized and mechanically ventilated pigs were observed over 8 hrs. Septic shock was triggered by inducing fecal peritonitis (0.75 g autologous feces per kg body weight). Mucosal microcirculation was assessed simultaneously using pCLE in stomach, duodenum, terminal ileum and rectum at baseline, 4 hours after induction of septic shock as well as 2 hours after treatment of the condition. Second, six patients who presented with a severe sepsis on the intensive care unit were examined regarding their duodenal microcirculation after obtaining informed consent from their nearest relatives. These patients were compared to ten healthy controls. Four to six areas were examined for each site and images were analysed in a blinded fashion offline thereafter in both parts of the study. Mean capillary diameter, capillary length and functional capillary density (FCD) were measured quantitatively. Results Two hours after induction of sepsis in the animal model, FCD was markedly decreased in the duodenal (-20.8, p < 0.001), the ileal (-13.4, p < 0.001), the gastric (-11.9%, p < 0.001), and in the rectal mucosal beds (-5.5, p<0,01). After administration of 30 mg x kg-1 of gelatine (30 kDa) FCD increased in all mucosal compartments to 90.0% (duodenum), 94.4% (ileum), 95.4% (gastric) and 97% (rectum) of baseline values. Interestingly, mean vessel diameter was unchanged in all compartments investigated. In patients suffering from severe sepsis we found a significant decrease in mean vessel diameter (-5.0%, p<0.001) as well as in FCD (-9,4%, p<0.001) of the duodenal mucosa, as well. Conclusions During the early phase of septic shock, pCLE may be able to quantify microcirculatory alterations in the gastrointestinal mucosa. Fluid resuscitation improves but does not completely restore intestinal microcirculation in the septic shock model. pCLE may represent a useful tool in order to assess the efficacy of therapeutic interventions on mucosal microcirculation, possibly even in clinical practice.

Development of an advanced diagnostic concept for intestinal inflammation: molecular visualisation of nitric oxide in macrophages by functional poly(lactic-co-glycolic acid) microspheres

We here describe a new approach to visualise nitric oxide (NO) in living macrophages by fluorescent NO-sensitive microspheres based on poly(lactic-co-glycolic acid) (PLGA). PLGA microspheres loaded with NO550 dye were prepared through a modified solvent-evaporation method. Microparticles were characterized by a mean hydrodynamic diameter of 3000 nm, zeta potential of −26.000 ± 0.351 mV and a PDI of 0.828 ± 0.298. Under abiotic conditions, NO release was triggered through UV radiation (254 nm) of 10 mM sodium nitroprusside dehydrate (SNP). After incubation, AZO550 microspheres exhibited an about 8-fold increased emission at 550 nm compared to NO550 particles. For biotic NO release, RAW 264.7 murine macrophages were activated with lipopolysaccharide (LPS) of Salmonella typhimurium. After treatment with NO550 microparticles, only activated cells caused a green particle fluorescence and could be detected by laser scanning microscopy. NO release was confirmed indirectly with Griess reaction. Our functional NO550 particles enable a simple and early evaluation of inflammatory and immunological processes. Furthermore, our results on particle-based NO sensing and previous studies in targeting intestinal inflammation via (PLGA)-based microspheres demonstrate that an advanced concept for visualizing intestinal inflammation is tangible.