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Plasmalogens are a specific glycerophospholipid class containing a vinyl ether moiety at the sn-1-position of the glycerol backbone. The high susceptibility of this vinyl ether bond to oxidative damage and traces of acids may indicate the possible function of plasmalogens in biological systems: The regarded cell-internal antioxidative defense of membranes by protecting other phospholipids or lipoprotein particles against oxidative stress is controversial. Reactive oxygen species preferably affect the vinyl ether function as well as the olefinic acyl residues at the sn-2-position of plasmalogens. This review is dedicated to the role of plasmalogens in different cells and tissues as spermatozoal cells or brain tissue. The first chapter of this review will discuss the molecular structure and chemistry of plasmalogen molecules, their distributions in cells and tissues and the species-specificity. In the second chapter their functions as lipid mediators will be considered and the controversial antioxidative function will be discussed. The supposed function of plasmalogens as "scavengers" for reactive oxygen species (ROS) in biological membranes is challenged by the finding that plasmalogen oxidation products as alpha-hydroxyaldehydes and plasmalogen epoxides accumulate in all chronic diseases as atherosclerosis and myocardial infarction, upon aging as well as in Alzheimers disease and other neuropathological conditions. All these conditions, characterized by increased membrane instability and oxidative damage, will be reviewed in chapter three. Chronically proceeding processes can be described by permanently invading polymorphonuclear neutrophils into inflammatory loci. The degranulation of the azurophilic granula in polymorphonuclear leukocytes causes the release of highly reactive substances, for instance the myeloperoxidase-generated hypochlorous acid (HOCl) acting as effective oxidant. Therefore, special attention will be paid to neutrophil-derived HOCl. The last chapter deals with currently used methods of detecting plasmalogens and their degradation products. Although chromatographic methods will be also discussed, special attention will be given to (31)P NMR spectroscopy and soft ionization techniques of mass spectrometry as electrospray ionization or matrix-assisted laser desorption and ionization time-of-flight mass spectrometry.

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Efficient and safe delivery systems for siRNA therapeutics remain a challenge. Elevated secreted protein, acidic, and rich in cysteine (SPARC) protein expression is associated with tissue scarring and fibrosis. Here we investigate the feasibility of encapsulating SPARC-siRNA in the bilayers of layer-by-layer (LbL) nanoparticles (NPs) with poly(L-arginine) (ARG) and dextran (DXS) as polyelectrolytes. Cellular binding and uptake of LbL NPs as well as siRNA delivery were studied in FibroGRO cells. siGLO-siRNA and SPARC-siRNA were efficiently coated onto hydroxyapatite nanoparticles. The multilayered NPs were characterized with regard to particle size, zeta potential and surface morphology using dynamic light scattering and transmission electron microscopy. The SPARC-gene silencing and mRNA levels were analyzed using ChemiDOC western blot technique and RT-PCR. The multilayer SPARC-siRNA incorporated nanoparticles are about 200 nm in diameter and are efficiently internalized into FibroGRO cells. Their intracellular fate was also followed by tagging with suitable reporter siRNA as well as with lysotracker dye; confocal microscopy clearly indicates endosomal escape of the particles. Significant (60%) SPARC-gene knock down was achieved by using 0.4 pmole siRNA/μg of LbL NPs in FibroGRO cells and the relative expression of SPARC mRNA reduced significantly (60%) against untreated cells. The cytotoxicity as evaluated by xCelligence real-time cell proliferation and MTT cell assay, indicated that the SPARC-siRNA-loaded LbL NPs are non-toxic. In conclusion, the LbL NP system described provides a promising, safe and efficient delivery platform as a non-viral vector for siRNA delivery that uses biopolymers to enhance the gene knock down efficiency for the development of siRNA therapeutics.

Layer-by-layer (LbL)-coated microcarriers offer a good opportunity as transport systems for active agents into specific cells and tissues. The assembling of oppositely charged polyelectrolytes enables a modular construction of the carriers and therefore an optimized integration and application of drug molecules. Here, we report the multilayer incorporation and transport of R 1 -antitrypsin (AT) by colloidal microcarriers. AT is an anti-inflammatory agent and shows inhibitory effects toward its proinflammatory antagonist, human neutrophil elastase (HNE). The highly proteolytic enzyme HNE is released by polymorphonuclear leukocytes (PMNs) during inflammatory processes and can cause host tissue destruction and pain. The high potential of this study is based on a simultaneous intraand extracellular application of AT-functionalized LbL carriers. Carrier application in PMNs results in significant HNE inhibition within 21 h. Microcarriers phagocytosed by PMNs were time dependently decomposed inside phagolysosomes, which enables the step-by-step release of AT. Here, AT inactivates HNE before being released, which avoids a further HNE concentration increase in the extracellular space and, subsequently, reduces the risk of further tissue destruction. Additionally, AT surface-functionalized microcarriers allow the inhibition of already released HNE in the extracellular space. Finally, this study demonstrates the successful application of LbL carriers for a concurrent extra-and intracellular HNE inhibition aiming the rebalancing of protease and antiprotease concentrations and the subsequent termination of chronic inflammations.