The antiatherogenic effect of new biocompatible cationically modified polysaccharides: chitosan and pullulan - the comparison study.

Pullulan and chitosan are biocompatible polysaccharides obtained from natural sources with many biomedical applications. Cationically modified polymers, such as chitosan and pullulan after covalent attachment of glycidyltrimethylammonium chloride (GTMAC), showed beneficial biological properties. In the present study, it was clearly demonstrated and confirmed that both cationically modified polysaccharides (chitosan-GTMAC and pullulan-GTMAC) have the antiatherosclerotic potential by inhibition of atherosclerotic plaque development and controlling the expression of genes involved in lipid metabolism. It has also been shown that the cationically modified chitosan (HTCC) at a dose of 200 mg/kg b.w./day in male apoE-knockout mice acted as hypolipidaemic agent. It was observed that a statistically significant decrease in low-density lipoprotein (LDL) cholesterol level by 32% occurred under the influence of HTCC at a dose of 200 mg/kg b.w./day after 16 weeks of the experiment compared to the control group of apoE(-/-) mice. Moreover, under the influence of cationically modified chitosan administered orally to female apoE-knockout mice at a dose of 300 mg/kg b.w./day for 18 weeks a statistically significant reduction by 33% in the area of atherosclerotic plaque was observed compared to the control group, i.e., apoE-knockout mice whose diet was not supplemented with the cationically modified polysaccharide. Current in vivo studies connected with cationically modified pullulan showed a statistically significant 22% reduction of the area of atherosclerotic plaque in the apoE(-/-) mice fed with a feed containing Pull-GTMAC at a dose of 500 mg/kg b.w./day for 18 weeks in comparison to the control group of apoE-knockout mice. In the in vitro studies it was also shown that cationically modified chitosan acted therapeutically by reduction of the level of the expression of human 3-hydroxy-3-methylglutaryl-CoA reductase (human HMG-CoAR) after 24 hours of incubation with HepG2 cells. However, cationically modified pullulan did not show this effect in the experiment on HepG2 cell line. On the other hand, Pull-GTMAC caused a statistically significant increase in insulin induced gene 1 (INSIG1) expression and increase in mRNA level of LDL receptor in brown fat tissue of female apoE-knockout mice after oral administration with feed at a dose of 300 mg/kg b.w./day for 18 weeks in comparison to the control group of apoE(-/-) mice, that was crearly demonstrated the effect of cationically modified pullulan on the expression of lipid metabolism genes in in vivo conditions. In the present article we have shown for first time that cationically modified pullulan and chitosan have some similarities in their antiatherogenic action but there are also some minor differences in mechanism of their effect on lipid metabolism.

New cationically modified pullulan attenuates atherogenesis and influences lipid metabolism in apoE-knockout mice.

Pullulan is a biocompatible polysaccharide obtained from black, yeast-like fungus Aureobasidium pullulans. This polymer is used to deliver various substances to the liver because of its specificity for this organ. Pullulan is internalized into hepatocytes in the process of asialoglycoprotein receptor mediated endocytosis. Recently, by reaction with glycidyltrimethylammonium chloride (GTMAC) we have successfully synthesized a cationically-modified pullulan (Pull-GTMAC). Pull-GTMAC exhibits some unique beneficial effects not found for its native counterpart. In this article we have reported for the first time that Pull-GTMAC administered orally to apoE-knockout mice (murine model of atherosclerosis) at a dose of 300 mg/kg b.w./day for 18 weeks showed anti-atherosclerotic activity reducing the area of atherosclerotic plaque. We have also found that Pull-GTMAC at a dose of 300 mg/kg b.w./day increases both the average daily mass of feces and the average number of droppings excreted by apoE(-/-) mouse in relation to the control sample derived from the mice fed with feed without the tested compound. However, the raw fat content in the feces of apoE-knockout mice was decreased in the group fed with the diet containing Pull-GTMAC towards control group of animals. Pull-GTMAC caused also statistically significant increase of mRNA level for LDL receptor in the apoE(-/-) mice liver after administration at a dose of 300 mg/kg/b.w./day for 18 weeks. However, the compound had no impact on lipid profile in serum of the tested mice. What is more, the studies on HepG2 cell line indicated an antiproliferative potential of cationically modified pullulan after 24 hour and 48 hour of incubation with the polysaccharide. In this paper we have shown for first time that cationically modified pullulan has antiatherogenic potential and influences on lipid metabolism.

A hybrid adsorbent/visible light photocatalyst for the abatement of microcystin-LR in water.

A hybrid adsorbent/photocatalyst was obtained and used for the removal of microcystin-LR, a potent toxin, from water via adsorption and photocatalyzed oxidation with singlet oxygen. The combined adsorption/photooxidation processes yielded a 500-fold decrease of the overall MC-LR concentration. The adsorbent/photocatalyst can be easily removed from the reaction system by sedimentation or centrifugation.

Photocrosslinked ultrathin anionic polysaccharide supports for accelerated growth of human mesenchymal stem cells.

OBJECTIVES: Properties of cell culture supports obtained from ultrathin multilayer films containing anionic natural polysaccharides (PSacs) and a synthetic polycation were studied. MATERIALS AND METHODS: Supports were prepared via a layer-by-layer (LbL) self-assembly deposition method. Polymers used were: heparin (Hep), chondroitin sulphate (CS), hyaluronic acid (HA), and ι-carrageenan (Car) as polyanions, and diazoresin (DR) as a polycation. PSac layers were crosslinked with DR layers by irradiation with UV light absorbed by DR resin. RESULTS: DR/PSac films are very efficient cell culture growth supports as found from experiments with human mesenchymal stem cells (hMSCs). Irradiation of the films resulted in changing zeta potential of outermost layers of both DR and PSac to more negative values, and in increased film hydrophobicity, as found from the contact angle measurements. Photocrosslinking of the supports led to their increased stability. CONCLUSIONS: The supports allow for obtaining intact cell monolayers faster than when typical polystyrene tissue culture plates are used. Moreover, these monolayers spontaneously detach permitting formation of new cell layers on these surfaces relatively early during culture, compared to cells cultured on commonly used tissue culture plastic.

The current view on biological potency of cationically modified chitosan.

Chitosan is biocompatible polymer obtained from chitin, the building component of the crustacean shells. In this paper we make an attempt to review the current state of knowledge on some biological effects of chitosan in comparison with those of cationically modified chitosan, N-(2-hydroxypropyl)-3-trimethylammonium chitosan chloride (HTCC) that was recently synthetized by us by covalent attachment of glycidyltrimethylammonium chloride (GTMAC). Biological effects of HTCC and non-modified polymer are very similar. However, HTCC shows some unique beneficial properties which have not been found in its non-modified counterpart. One such example is that HTCC has the ability to bind heparin at physiological pH. HTCC having the degree of substitution almost 63.6% is easily absorbed within 1 hour after oral administration as found in C57BL/6j mice using FITC-labeled polymer. HTCC is distributed to lung, heart, and kidneys. HTCC stimulates and enhances blood platelet aggregation and decreases erythrocyte deformability (RBC). Moreover, HTCC seems to decrease both plasma total cholesterol level and LDL-cholesterol level in apoE-knockout mice fed with a diet containing HTCC. HTCC possibly down-regulates the HMG-CoAR mRNA level after 24 hour incubation with HepG2 cells in vitro.

"Smart" alginate-hydroxypropylcellulose microbeads for controlled release of heparin.

"Smart" (thermosensitive) alginate-hydroxypropylcellulose (Alg/HPC) microbeads for controlled release of heparin were synthesized and the release profiles at various temperatures and for various alginate/HPC compositions were measured. Microbeads of regular spherical shape (ca. 3 microm in diameter) containing efficiently encapsulated heparin were obtained using an emulsification method. The internal structure of the bead was estimated by fluorescence microscopy using dansyl alginate as a labelled component. The microbeads surface structure and morphology were imaged in a dry state using scanning electron microscopy (SEM) and in water using atomic force microscopy (AFM). The microbead surface was shown to be covered by the regular network of pores with a mesh of ca. 30-60 nm. Lower critical solution temperature (LCST) of the Alg/HPC systems was measured spectrophotometrically (cloud point measurements). Heparin release profiles were obtained based on spectrophotometric detection of heparin complex with Azure A. Three-stage sustained release for at least 16 days was observed at 37 degrees C. This was correlated with the size of the pores present at the surface of microbeads. The release profile can be controlled by the temperature and composition of the Alg/HPC microbeads.