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T Gessler

Publications and source records attributed to T Gessler.

10 recordsLinked to original sources
PubMed2006

Investigation of the proinflammatory potential of biodegradable nanoparticle drug delivery systems in the lung.

Particulate nanocarriers have been praised for their advantageous drug delivery properties in the lung, such as avoidance of macrophage clearance mechanisms and long residence times. However, instilled non-biodegradable polystyrene nanospheres with small diameters and thus large surface areas have been shown to induce pulmonary inflammation. This study examines the potential of biodegradable polymeric nanoparticles composed of poly(lactic-co-glycolic acid) (PLGA) and the novel PLGA derivative, diethylaminopropylamine polyvinyl alcohol-grafted-poly(lactic-co-glycolic acid) (DEAPA-PVAL-g-PLGA), to provoke inflammatory responses in the murine lung after intratracheal instillation. Lactate dehydrogenase (LDH) release, protein concentration, MIP-2 mRNA induction, and polymorphonucleocyte (PMN) recruitment in the bronchial alveolar lavage fluid (BALF) were used to evaluate an inflammatory response in Balb-C mice. Two sizes of polystyrene (PS) nanospheres (diameters: 75 nm and 220 nm) were included in the study for comparison. All nanoparticle suspensions were instilled at concentrations of 1 microg/microl and 2.5 microg/microl, representative of an estimated "therapeutic dose" and a concentrated "dose" of particles. In all experiments, the 75 nm PS particles exhibited elevated responses for the inflammatory markers investigated. In contrast, biodegradable particles of comparable hydrodynamic diameter showed a significantly lower inflammatory response. The most marked differences were observed in the extent of PMN recruitment. While the 75 nm and 220 nm PS nanospheres exhibited 41 and 74% PMN within the total BALF cell population after 24 h, respectively, PMN recruiting in lungs instilled with both types of biodegradable particles did not exceed values of the negative isotonic glucose control. In conclusion, evidence suggests that biodegradable polymeric nanoparticles designed for pulmonary drug delivery may not induce the same inflammatory response as non-biodegradable polystyrene particles of comparable size.

Animals↗
PubMed2005

Nano-carriers for DNA delivery to the lung based upon a TAT-derived peptide covalently coupled to PEG-PEI.

Gene therapy aimed at the respiratory epithelium holds therapeutic potential for diseases such as cystic fibrosis and lung cancer. Polyethylenimine (PEI) has been utilized for gene delivery to the airways. In this study, we describe a new modification of PEI, in which an oligopeptide related to the protein transduction domain of HIV-1 TAT was covalently coupled to 25 kDa PEI (PEI) through a heterobifunctional polyethylenglycol (PEG) spacer resulting in a TAT-PEG-PEI conjugate. Improved DNA reporter gene complexation and protection was observed for small (approximately 90 nm) polyplexes as well as significantly improved stability against polyanions, Alveofact, bronchial alveolar lining fluid and DNase. To determine polyplex toxicity in vitro, MTT assays were performed and, for in vivo testing, the mice bronchial alveolar lavage was investigated for total cell counts, quantity of neutrophils, total protein and TNF-alpha concentration. All parameters suggest significantly lower toxicity for TAT-PEG-PEI. Transfection efficiencies of both PEI and TAT-PEG-PEI polyplexes with DNA were studied under in vitro conditions (A549) and in mice after intratracheal instillation. While luciferase expression in A549 cells was much lower for TAT-PEG-PEI (0.2 ng/mg protein) than for PEI (2 ng/mg), significantly higher transfection efficiencies for TAT-PEG-PEI were detected in mice. Reporter gene expression was distributed through bronchial and alveolar tissue. Thus, TAT-PEG-PEI represents a new approach to non-viral gene carriers for lung therapy, comprising protection for plasmid DNA, low toxicity and significantly enhanced transfection efficiency under in vivo conditions.

Animals↗
PubMed2004

Modified polyethylenimines as non viral gene delivery systems for aerosol therapy: effects of nebulization on cellular uptake and transfection efficiency.

This study examined the effect of nebulization on the cellular uptake and transfection efficiency of polyplexes from four polyethylenimine (PEI) modifications: branched 25 kDa PEI (bPEI), linear 22 kDa PEI (linPEI), pegylated PEI (pegPEI) and biodegradable PEI (bioPEI). Polyplexes were aerosolized with air-jet and ultrasonic nebulizers. The aerosol was collected and used to determine complex size and zeta potential. Fluorescence-assisted cell sorting (FACS) was used to quantify the cellular association of polyplexes in primary alveolar cells (AEC), A549 cells and primary bronchial cells (BEC). Confocal laser scanning microscopic images provided information about the internalization of polyplexes. Transfection efficiencies of polyplexes were quantified via measurement of luciferase expression. All polymers were stable during nebulization, although size increases were observed after air-jet nebulization. FACS studies showed a two- to three-fold increase in polyplex association with BEC compared to A549 cells, while polyplex association with AEC was negligible. BPEI, linPEI and bioPEI polyplexes were internalized, while pegPEI polyplexes remained predominately attached to the cellular membrane. Luciferase expression was detected only in BEC and A549 cells with transfection efficiencies approximately one order of magnitude higher in BEC. All PEI modifications investigated were suitable for aerosol therapy, although cell type and polymer structure significantly influenced the uptake and transfection efficiency of the polyplexes.

Aerosols↗
PubMed2004

Modified polyethylenimines as non-viral gene delivery systems for aerosol gene therapy: investigations of the complex structure and stability during air-jet and ultrasonic nebulization.

Polyelectrolyte complexes between DNA and polyethylenimine (PEI) are promising non-viral delivery systems for pulmonary inhalation gene therapy and thus require sufficient stability during nebulization. The structure and stability of four different PEI-DNA polyplexes, namely branched (bPEI), linear (linPEI), poly(ethylene glycol)-grafted PEI (PEGPEI), biodegradable (bioPEI) PEI with DNA, were investigated. Using atomic force microscopy, the morphology of DNA and polyplexes before and after both air-jet and ultrasonic nebulization was characterized. The influence of nebulization on physico-chemical properties, particle size and zeta potential, was studied. Efficient DNA condensation to spherical particles was achieved with bPEI (90 nm) and PEGPEI (110 nm). By contrast, incomplete DNA condensations, seen as flower structures, were observed with linPEI (110 nm) and bioPEI (105 nm). Air-jet nebulization altered the polyplex structure to a greater extent than ultrasonic nebulization and resulted mainly in smaller and non-spherical particles (30-200 nm). Ultrasonic nebulization did not change the spherical structure or particle size of the polyplexes. In particular, the shape and size of the PEGPEI polyplexes did not change. We conclude that ultrasonic nebulization is a milder aerosolization method for gene delivery systems based on PEI. Additionally, PEGPEI-DNA polyplexes seem to be more stable than their counterparts, which may be advantageous in pulmonary inhalation gene therapy.

Aerosols↗
PubMed2003

Surfactant-free, biodegradable nanoparticles for aerosol therapy based on the branched polyesters, DEAPA-PVAL-g-PLGA.

PURPOSE: This study describes the development of surfactant-free, biodegradable nanoparticle systems with varying physicochemical properties and their suitability for pulmonary application via nebulization. METHODS: Nanoparticle suspensions were formulated from the branched polyester, diethylaminopropyl amine-poly(vinyl alcohol)-grafted-poly(lactide-co-glycolide) (DEAPA-PVAL-g-PLGA) alone, as well as with increasing amounts of carboxymethyl cellulose (CMC). Particle size, zeta potential, turbidity, and morphology (atomic force microscopy) were characterized. Three formulations were chosen for further study: Cationic nanoparticles without CMC, cationic nanoparticles with CMC, and anionic nanoparticles with an excess of CMC. Nanoparticle degradation was characterized, as well as stability during nebulization. Nanoparticle-cell interactions were investigated and quantified using confocal laser scanning microscopy and fluorescence spectrometry. RESULTS: Nanoparticles ranged in size from 70-250 nm and displayed zeta potentials of +58.9 to -46.6 mV. Anionic nanoparticles showed the highest stability during nebulization. The degradation rate of each nanoparticle formulation decreased with increasing amounts of CMC. Cell association was highest among cationic nanoparticles (57% and 30%, respectively), although these were not internalized. Despite a lower rate of cell association (3%), anionic nanoparticles were internalized by A549 cells. CONCLUSIONS: Surfactant-free nanoparticles from DEAPA-PVAL-g-PLGA are versatile drug delivery systems; however, only the anionic formulations investigated were proven suitable for aerosol therapy.

Aerosols↗
PubMed2001

Endogenous nitric oxide synthesis and vascular leakage in ischemic-reperfused rabbit lungs.

Pulmonary edema formation resulting from loss of capillary barrier properties is a prominent finding in lung ischemia/reperfusion (I/R) injury. The role of endogenous nitric oxide (NO) in this process is unresolved. We exposed buffer-perfused rabbit lungs to warm I/R and measured air space NO liberation and intravascular accumulation of NO degradation products. In lungs undergoing 210 min of ischemia with normoxic ventilation, with maintenance of positive intravascular pressure to avoid vascular collapse, NO synthesis was moderately reduced during ischemia but was fully restored upon reperfusion, and a moderate leakage response occurred during reperfusion. Pretreatment with the NO synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA) suppressed NO synthesis but did not affect the leakage. During ischemia with anoxic ventilation, NO synthesis was fully abrogated, but again promptly reappeared upon reperfusion and entrance of oxygen into the system. It was with this protocol that the most severe vascular leakage was encountered, which was markedly reduced in the presence of L-NMMA or superoxide dismutase. We conclude that endogenous NO does not play a major role in the induction or mitigation of I/R injury under conditions of normoxic ischemia, but that return of endogenous NO synthesis upon reperfusion after anoxic ischemia contributes substantially to the triggering of vascular leakage, possibly via interaction with superoxide.

Animals↗
PubMed2001

Ultrasonic versus jet nebulization of iloprost in severe pulmonary hypertension.

Inhalation of iloprost, a stable prostacyclin analogue, is a promising perspective in the treatment of pulmonary hypertension. In initial clinical studies, a conventional jet nebulizer system was successfully used to decrease pulmonary vascular resistance and pressure, requiring however, up to twelve inhalations of 12-15 min per day. The aim of this study was to investigate if the application of an equal dose of iloprost at a drastically reduced duration of inhalation with the use of a more efficient ultrasonic nebulizer, leads to comparable haemodynamic effects, without escalation of side effects. The physical features of the jet nebulizer system (Ilo-Neb) and the ultrasonic nebulizer (Multisonic Compact) were characterized by laser diffractometry and a Tc99m-tracer technique. Mass median aerodynamic diameters were 3.2 microm for the jet and 3.9 microm for the ultrasonic nebulizer. Total output (mean+/-SD) was 60+/-7 microL.min(-1) (jet) and 163+/-15 microL.min(-1)(ultrasonic), and efficiency of the devices was 39+/-3% (jet) and 86+/-5% (ultrasonic). Based on these data, a total inhalative dose of 2.8 microg iloprost was delivered by jet nebulization within 12 min and by ultrasonic nebulization within 4 min, in 18 patients with severe primary and secondary pulmonary hypertension (New York Heart Association class III and IV), in a randomized crossover design. Haemodynamics were assessed by right heart catheterization. Inhalation with the ultrasonic device and jet nebulizer, reduced mean+/-SEM pulmonary artery pressure from 54.3+/-2.1 to 47.1+/-2.0 and from 53.5+/-2.2 to 47.0+/-2.2 mmHg, respectively, and mean+/-SEM pulmonary vascular resistance from 1,073+/-109 to 804+/-87 and from 1,069+/-125 to 810+/-83 dyn.s.cm(-5), respectively. Both modes of aerosolization were well tolerated. In conclusion, due to the markedly higher efficiency and output of the ultrasonic device, wastage of drug is largely avoided and the duration of inhalation can be shortened to one-third, with comparable haemodynamic effects and without enforcing side effects.

Administration, Inhalation↗
PubMed1998

Nitric oxide biosynthesis in an exotoxin-induced septic lung model: role of cNOS and impact on pulmonary hemodynamics.

Nitric oxide (NO) is an important vasodilator that is produced by constitutive (cNOS) as well as inducible (iNOS) isoforms of nitric oxide synthase. The pore-forming hemolysin of Escherichia coli (HlyA), an important virulence factor in extraintestinal E. coli infections, was found to be a potent stimulator of NO liberation in isolated endothelial cells, and that it also causes thromboxane generation and related vasoconstriction in rabbit lungs. We investigated the effect of different concentrations of HlyA on pulmonary NO synthesis in buffer-perfused rabbit lungs. NO release into the alveolar as well as the intravascular compartment was monitored on-line by chemiluminescence detection of expired NO and by measurement of (peroxy-)nitrite/nitrate release into the perfusate. HlyA induced a pressor response and an immediate dose-dependent increase of exhalative and intravascular NO liberation, further enhanced by the addition of the NOS substrate L-arginine. The nonspecific NOS inhibitor N(G)-monomethyl-L-arginine (L-NMMA), but not the iNOS selective inhibitors aminoguanidine and 2-(2-aminoethyl)-2-thiopseudourea-dihydrobromide, blocked the HlyA-evoked NO liberation into both the alveolar and the intravascular compartments. Enhancement of NO formation (L-arginine) slightly reduced, and inhibition of NO synthesis (L-NMMA) amplified greatly, the HlyA-elicited vasoconstrictor response. Inhibition of the pressor response by a thromboxane receptor antagonist did not interfere with the exotoxin-elicited NO formation. We conclude (1) that marked NO biosynthesis occurs in this model of the septic lung, (2) that the signal transduction in response to HlyA proceeds via activation of cNOS directly related to exotoxin activity and not to secondary changes in shear stress, and (3) that this vasodilator release mitigates the HlyA-induced pulmonary vasoconstriction. These findings may have important implications for therapeutic approaches using NOS inhibitors in sepsis.

Animals↗