Nano-chitin reinforced agarose hydrogels: Effects of nano-chitin addition and acidic gas-phase coagulation.

Hydrogels based on natural polymers such as agarose usually show low applicability due to their weak mechanical properties. In this work, we developed a dual cross-linked agarose hydrogel by adding different amounts of TEMPO-oxidized nano-chitin (0-0.2 %) to agarose hydrogel matrices and then physically cross-linked under acidic gas-phase coagulation. The prepared hydrogels were characterized by FTIR, XRD, TGA, and SEM. The effects of nano-chitin addition and acidic gas-phase coagulation on the properties of agarose hydrogels, such as gel strength, swelling degree, rheological properties, and methylene blue (MB) adsorption capacity, were also studied. Structural characterizations confirmed that nano-chitin was successfully introduced into agarose hydrogels. The gel strength, storage modulus, and MB adsorption capacity of agarose hydrogels gradually increased with the increasing nano-chitin addition, whereas the swelling degree decreased. After acidic gas-phase coagulation, agarose/nano-chitin nanocomposite hydrogels exhibited improved gel strength and storage modulus, while the swelling degree and MB adsorption capacity were slightly reduced. The combination of oxidized nano-chitin and acidic gas-phase coagulation is expected to be an effective way to improve the properties of natural polymer hydrogels.

Nanoparticles for Stem Cell Tracking and the Potential Treatment of Cardiovascular Diseases.

Stem cell-based therapies have been shown potential in regenerative medicine. In these cells, mesenchymal stem cells (MSCs) have the ability of self-renewal and being differentiated into different types of cells, such as cardiovascular cells. Moreover, MSCs have low immunogenicity and immunomodulatory properties, and can protect the myocardium, which are ideal qualities for cardiovascular repair. Transplanting mesenchymal stem cells has demonstrated improved outcomes for treating cardiovascular diseases in preclinical trials. However, there still are some challenges, such as their low rate of migration to the ischemic myocardium, low tissue retention, and low survival rate after the transplantation. To solve these problems, an ideal method should be developed to precisely and quantitatively monitor the viability of the transplanted cells in vivo for providing the guidance of clinical translation. Cell imaging is an ideal method, but requires a suitable contrast agent to label and track the cells. This article reviews the uses of nanoparticles as contrast agents for tracking MSCs and the challenges of clinical use of MSCs in the potential treatment of cardiovascular diseases.

Surface morphology and protective effect of Hericium erinaceus polysaccharide on cyclophosphamide-induced immunosuppression in mice.

The aim of this study was to investigate the surface morphological features and in vivo immunomodulatory activities of a hetero polysaccharide fraction (HEP-W) from Hericium erinaceus. SEM and AFM images revealed that HEP-W displayed a flexible random coil conformation, and these flexible winding chains further formed continuous fiber network structure. Meanwhile, Congo red assay and XRD further proved that HEP-W mainly exhibited amorphous structure with non-triple-helical conformation in solution. In vivo immunomodulatory experiments demonstrated that HEP-W possessed protective effects against cyclophosphamide-induced immunosuppression in mice by significantly enhancing immune organ index, splenocyte proliferation, NK cell activity, IL-2 production as well as improving the macrophage phagocytosis. These findings suggest that HEP-W could be explored as a natural and effective immunomodulatory agent.

Immune-enhancing activities of chondroitin sulfate in murine macrophage RAW 264.7 cells.

As a representative sulfated glycosaminoglycan (GAG), chondroitin sulfate (CS) has been reported playing vital roles in the immune response in vivo and in vitro. However, limited information is available about their immune-enhancing activity. This study was to achieve more precise understandings about the immuno-stimulating activity of CS. In in vitro experiments, CS was found to significantly promote the pinocytic, phagocytic activity and ROS production of RAW264.7 cells at the dose range of 100-1000 µg/mL compared with the untreated group (p < 0.05). Further experiments showed that CS could increase the secretion levels of NO, TNF-α, IL-6 and IL-10 via activating the corresponding mRNA expression in macrophages through the toll-like receptor 2 (TLR2). These results indicated that CS could function as an immunostimulator to enhance the immune responses and might be a potential candidate for application in immunological diseases or functional foods.

Structure characterization of a novel polysaccharide from Hericium erinaceus fruiting bodies and its immunomodulatory activities.

A novel polysaccharide fraction (HEP-S) was extracted and isolated from the fruiting bodies of Hericium erinaceus. Structural characterization revealed that HEP-S had an average molecular weight of 1.83 × 104 Da and consisted of rhamnose, fucose, mannose, glucose and galactose at a molar ratio of 1.47 : 0.93 : 1.36 : 8.68 : 4.08. Periodate oxidation-Smith degradation and NMR analysis showed that the main linkage types of HEP-S were composed of (1→)-α-d-Glc, (1→3,4)-α-d-Glc, (1→6)-α-d-Gal, (1→3,4)-ß-d-Man, (1→3,6)-α-Rha and (1→2)-ß-l-Fuc. The immunomodulatory assay indicated that HEP-S could significantly enhance the pinocytic and phagocytic capacity and promote the secretion of nitric oxide and pro-inflammatory cytokines by activating the corresponding mRNA and protein expression in RAW 264.7 cells involving a toll-like receptor 2 membrane receptor. Besides, HEP-S was also found to improve the adaptive immune function by enhancing T and B lymphocyte proliferation and increasing the interleukin-2, interleukin-4 and interferon-γ secretion in spleen lymphocytes. These results suggested that HEP-S could be used as a potential immunoregulatory agent in functional foods.

Two-Stage Enzymatic Preparation of Eicosapentaenoic Acid (EPA) And Docosahexaenoic Acid (DHA) Enriched Fish Oil Triacylglycerols.

Fish oil products in the form of triacylglycerols generally have relatively low contents of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) and so it is of potential research and industrial interest to enrich the related contents in commercial products. Thereby an economical and efficient two-stage preparation of EPA and DHA enriched fish oil triacylglycerols is proposed in this study. The first stage was the partial hydrolysis of fish oil by only 0.2 wt.‰ AY "Amano" 400SD which led to increases of EPA and DHA contents in acylglycerols from 19.30 and 13.09 wt % to 25.95 and 22.06 wt %, respectively. Subsequently, products of the first stage were subjected to transesterification with EPA and DHA enriched fatty acid ethyl esters (EDEE) as the second stage to afford EPA and DHA enriched fish oil triacylglycerols by using as low as 2 wt % Novozyme 435. EDEEs prepared from fish oil ethyl ester, and recycled DHA and EPA, respectively, were applied in this stage. Final products prepared with two different sources of EDEEs were composed of 97.62 and 95.92 wt % of triacylglycerols, respectively, with EPA and DHA contents of 28.20 and 21.41 wt % for the former and 25.61 and 17.40 wt % for the latter. Results not only demonstrate this two-stage process's capability and industrial value for enriching EPA and DHA in fish oil products, but also offer new opportunities for the development of fortified fish oil products.

Green tea polyphenols induce cell death in breast cancer MCF-7 cells through induction of cell cycle arrest and mitochondrial-mediated apoptosis.

In order to study the molecular mechanisms of green tea polyphenols (GTPs) in treatment or prevention of breast cancer, the cytotoxic effects of GTPs on five human cell lines (MCF-7, A549, Hela, PC3, and HepG2 cells) were determined and the antitumor mechanisms of GTPs in MCF-7 cells were analyzed. The results showed that GTPs exhibited a broad spectrum of inhibition against the detected cancer cell lines, particularly the MCF-7 cells. Studies on the mechanisms revealed that the main modes of cell death induced by GTPs were cell cycle arrest and mitochondrial-mediated apoptosis. Flow cytometric analysis showed that GTPs mediated cell cycle arrest at both G1/M and G2/M transitions. GTP dose dependently led to apoptosis of MCF-7 cells via the mitochondrial pathways, as evidenced by induction of chromatin condensation, reduction of mitochondrial membrane potential (ΔΨm), improvement in the generation of reactive oxygen species (ROS), induction of DNA fragmentation, and activations of caspase-3 and caspase-9 in the present paper.

The effects of dietary thiamin on oxidative damage and antioxidant defence of juvenile fish.

The present study explored the effects of thiamin on antioxidant capacity of juvenile Jian carp (Cyprinus carpio var. Jian). In a 60-day feeding trial, a total of 1,050 juvenile Jian carp (8.20 ± 0.02 g) were fed graded levels of thiamin at 0.25, 0.48, 0.79, 1.06, 1.37, 1.63 and 2.65 mg thiamin kg(-1) diets. The results showed that malondialdehyde and protein carbonyl contents in serum, hepatopancreas, intestine and muscle were significantly decreased with increasing dietary thiamin levels (P < 0.05). Conversely, the anti-superoxide anion capacity and anti-hydroxyl radical capacity in serum, hepatopancreas, intestine and muscle were the lowest in fish fed the thiamin-unsupplemented diet. Meanwhile, the activities of catalase (CAT), glutathione peroxidase, glutathione S-transferase and glutathione reductase, and the contents of glutathione in serum, hepatopancreas, intestine and muscle were enhanced with increasing dietary thiamin levels (P < 0.05). Superoxide dismutase (SOD) activity in serum, hepatopancreas and intestine followed a similar trend as CAT (P < 0.05). However, SOD activity in muscle was not affected by dietary thiamin level (P > 0.05). The results indicated that thiamin could improve antioxidant defence and inhibit lipid peroxidation and protein oxidation of juvenile Jian carp.