OPN N-glycosylation promoted bone destruction.

OBJECTIVES: Exploring the role of OPN N-glycosylation in osteoblasts and osteoclasts. METHODS: Immunohistochemistry was used to detect the expression of OPN in mice with apical periodontitis. The asparagine at position 79 of the OPN protein was mutated to glutamine, and the above plasmids were transfected into osteoblasts and osteoclasts. The effect of OPN N-glycosylation on proliferation of osteoblasts and osteoclasts was detected by CCK8 assays. Western blotting was used to detect the expression of OPN N-glycosylation on osteoclasts and osteoblasts. Detection of N-glycosylation of OPN activated the NF-κB signaling pathway to regulate osteoblasts and osteoclasts. RESULTS: OPN increased the expression in a mice model of apical periodontitis. The expression curve of OPN resembled a reverse V shape. The OPN N-glycosylation site was identified as 79 by MS. N-glycosylation of OPN promoted the proliferation of osteoclasts. But the N79 glycosylation site of mutant OPN could not increase the proliferation of osteoblasts. OPN N-glycosylation modulated the expression of osteoclast- and osteoblast-associated factors through the NF-κB signaling pathway. N-glycosylation of OPN promoted nuclear translocation of NF-κB in osteoclasts and osteoblasts. CONCLUSIONS: The N-glycosylation site of OPN is 79. N-glycosylation of OPN played an important role in the biological function of OPN protein.

Regulation of stem cell fate using nanostructure-mediated physical signals.

One of the major issues in tissue engineering is regulation of stem cell differentiation toward specific lineages. Unlike biological and chemical signals, physical signals with adjustable properties can be applied to stem cells in a timely and localized manner, thus making them a hot topic for research in the fields of biomaterials, tissue engineering, and cell biology. According to the signals sensed by cells, physical signals used for regulating stem cell fate can be classified into six categories: mechanical, light, thermal, electrical, acoustic, and magnetic. In most cases, external macroscopic physical fields cannot be used to modulate stem cell fate, as only the localized physical signals accepted by the surface receptors can regulate stem cell differentiation via nanoscale fibrin polysaccharide fibers. However, surface receptors related to certain kinds of physical signals are still unknown. Recently, significant progress has been made in the development of functional materials for energy conversion. Consequently, localized physical fields can be produced by absorbing energy from an external physical field and subsequently releasing another type of localized energy through functional nanostructures. Based on the above concepts, we propose a methodology that can be utilized for stem cell engineering and for the regulation of stem cell fate via nanostructure-mediated physical signals. In this review, the combined effect of various approaches and mechanisms of physical signals provides a perspective on stem cell fate promotion by nanostructure-mediated physical signals. We expect that this review will aid the development of remote-controlled and wireless platforms to physically guide stem cell differentiation both in vitro and in vivo, using optimized stimulation parameters and mechanistic investigations while driving the progress of research in the fields of materials science, cell biology, and clinical research.

Biomaterial Cues Regulated Differentiation of Neural Stem Cells into GABAergic Neurons through Ca2+/c-Jun/TLX3 Signaling Promoted by Hydroxyapatite Nanorods.

Directed differentiation enables the production of a specific cell type by manipulating signals in development. However, there is a lack of effective means to accelerate the regeneration of neurons of particular subtypes for pathogenesis and clinical therapy. In this study, we find that hydroxyapatite (HAp) nanorods promote neural differentiation of neural stem cells due to their chemical compositions. Lysosome-mediated degradation of HAp nanorods elevates intracellular calcium concentrations and accelerates GABAergic neurogenesis. As a mechanism, the enhanced activity of a Ca2+ peak initiated by HAp nanorods leads to the activation of c-Jun and thus suppresses the expression of GABAergic/glutamatergic selection gene TLX3. We demonstrate the capability of HAp nanorods in promoting the differentiation into GABAergic neurons at both molecular and cellular function levels. Given that GABAergic neurons are responsible for various physiological and pathological processes, our findings open up enormous opportunities in efficient and precise stem cell therapy of neurodegenerative diseases.

Inhalable dry powder prepared from folic acid-conjugated docetaxel liposomes alters pharmacodynamic and pharmacokinetic properties relevant to lung cancer chemotherapy.

Pulmonary delivery of anti-cancer drugs in the form of nanoparticulate dry powders is considered a promising modality for treating lung cancer. However, it is not known whether the pharmacodynamics and pharmacokinetics of nano-preparations are altered after co-spray drying. In this study, we compared the physicochemical property, anti-cancer activity, tumor targeting and pharmacokinetic behavior of docetaxel-loaded folic acid-conjugated liposomes (LPs-DTX-FA) with those of dry powder prepared by co-spray-drying LPs-DTX-FA. The particle size and PDI after re-dispersion of the powder were increased. The re-dispersed liposomes showed increased cellular uptake via micropinocytosis and exhibited higher cytotoxicity than LPs-DTX-FA. Tumor targeting of re-dispersed liposomes was less effective compared with LPs-DTX-FA but the metabolism of re-dispersed liposomes was decreased. Tracheal administration resulted in a 45-fold higher concentration of docetaxel in the lung of Sprague Dawley rats at 30 min as compared with intravenous administration. Our results indicated that co-spray drying did change the properties, while tracheal administration of the dry powder provided higher drug exposure at the tumor site without increasing the exposure of other organs. Thus, inhaled dry powders might be clinically effective for treatment of lung cancer.

Osteopontin Promotes Bone Destruction in Periapical Periodontitis by Activating the NF-κB Pathway.

BACKGROUND/AIMS: Periapical periodontitis is caused by bacterial infection and results in both one destruction and tooth loss. Osteopontin (OPN) is a secreted phosphorylated glycoprotein that participates in bone metabolism. METHODS: Thirty-three patients with chronic periapical periodontitis and 10 patients who had undergone the orthodontic removal of healthy tooth tissue (control) at the periodontal ligament were investigated, and an animal model of mouse periapical periodontitis was established for an in vivo analysis. The relationship between OPN and bone destruction during periapical periodontitis was analyzed. Osteoblasts and osteoclasts were cultured in vitro and treated with lipopolysaccharide. An inhibitor of NF-κB was used to pretreat the transfected cells. RESULTS: OPN increased osteoclast proliferation and differentiation, but reduced osteoblasts proliferation and differentiation. OPN activated the NF-κB pathway during periapical periodontitis and accelerated the transfer and phosphorylation of P65 from the cytoplasm to the nucleus. CONCLUSION: This study demonstrated that OPN played important roles in the progression of periapical periodontitis, and a dual role in bone metabolism during periapical periodontitis, linking osteoclasts and osteoblasts. The underlying mechanism may be related to the NF-κB pathway.

Boron-bridged RG-II and calcium are required to maintain the pectin network of the Arabidopsis seed mucilage ultrastructure.

The structure of a pectin network requires both calcium (Ca2+) and boron (B). Ca2+ is involved in crosslinking pectic polysaccharides and arbitrarily induces the formation of an "egg-box" structure among pectin molecules, while B crosslinks rhamnogalacturonan II (RG-II) side chain A apiosyl residues in primary cell walls to generate a borate-dimeric-rhamnogalacturonan II (dRG-II-B) complex through a boron-bridge bond, leading to the formation of a pectin network. Based on recent studies of dRG-II-B structures, a hypothesis has been proposed suggesting that Ca2+is a common component of the dRG-II-B complex. However, no in vivo evidence has addressed whether B affects the stability of Ca2+ crosslinks. Here, we investigated the L-fucose-deficient dwarf mutant mur1, which was previously shown to require exogenous B treatment for phenotypic reversion. Imbibed Arabidopsis thaliana seeds release hydrated polysaccharides to form a halo of seed mucilage covering the seed surface, which consists of a water-soluble outer layer and an adherent inner layer. Our study of mur1 seed mucilage has revealed that the pectin in the outer layer of mucilage was relocated to the inner layer. Nevertheless, the mur1 inner mucilage was more vulnerable to rough shaking or ethylene diamine tetraacetic acid (EDTA) extraction than that of the wild type. Immunolabeling analysis suggested that dRG-II-B was severely decreased in mur1 inner mucilage. Moreover, non-methylesterified homogalacturonan (HG) exhibited obvious reassembly in the mur1 inner layer compared with the wild type, which may imply a possible connection between dRG-II-B deficiency and pectin network transformation in the seed mucilage. As expected, the concentration of B in the mur1 inner mucilage was reduced, whereas the distribution and concentration of Ca2+in the inner mucilage increased significantly, which could be the reason why pectin relocates from the outer mucilage to the inner mucilage. Consequently, the disruption of B bridges appears to result in the extreme sensitivity of the mur1 mucilage pectin complex to EDTA extraction, despite the reinforcement of the pectin network by excessive Ca2+. Therefore, we propose a hypothesis that B, in the form of dRG-II-B, works together with Ca2+to maintain pectin network crosslinks and ultimately the mucilage ultrastructure in seed mucilage. This work may serve to complement our current understanding of mucilage configuration.

The signalling imprints of nanoparticle uptake by bone marrow derived dendritic cells.

Nanoparticles (NP) possess remarkable adjuvant and carrier capacity, therefore are used in the development of various vaccine formulations. Our previous studies demonstrated that inert non-toxic 40-50 nm polystyrene NP (PS-NP) can promote strong CD8 T cell and antibody responses to the antigen, in the absence of observable inflammatory responses. Furthermore, instillation of PS-NP inhibited the development of allergic airway inflammation by induction of an immunological imprint via modulation of dendritic cell (DC) function without inducing oxidative stress in the lungs in mice. This is in contrast to many studies which show that a variety of ambient and man-made NP promote lung immunopathology, raising concerns generally about the safe use of NPs in biomedicine. Most NPs are capable of inducing inflammatory pathways in DC largely mediated by signalling via the extracellular signal-regulated kinase 1/2 (ERK). Herein, we investigate whether PS-NPs also activate ERK in DC in vitro. Our data show that PS-NP do not induce ERK activation in two different types of bone marrow derived (BM) DC cultures (expanded with GM-CSF or with GM-CSF together with IL-4). The absence of such signalling was not due to lack of PS-NP uptake by BM-DC as confirmed by confocal microscopy and flow cytometry. The process of NP uptake by DC usually initiates ERK signalling, suggesting an unusual uptake pathway may be engaged by PS-NPs. Indeed, data herein showns that uptake of PS-NP by BM-DC was substantially inhibited by phorbol myristate acetate (PMA) but not cytochalasin D (CCD), suggesting an uptake pathway utilising caveole for PS-NP. Together these data show that BM-DC take up PS-NP via a caveole-dependent pathway which does not trigger ERK signalling which may explain their efficient uptake by DC, without the concomitant activation of conventional inflammatory pathways.

Piezoelectric nylon-11 nanoparticles with ultrasound assistance for high-efficiency promotion of stem cell osteogenic differentiation.

Stem cell differentiation plays a significant role in tissue repair and regeneration. The interaction between stem cells and physical signals mediated by materials has significant influence on the fate of stem cells. The utilization of the stimulation originating from material physical properties to promote stem cell differentiation is being developed and has attracted much attention. However, it is difficult to induce electric signals into tissues noninvasively. In this study, piezoelectric nylon-11 nanoparticles (nylon-11 NPs) with uniform morphology were synthesized in mass production by a simple anti-solvent method. The prepared nylon-11 NPs possessed efficient piezoelectricity and high cytocompatibility. Fluorescent OPDA-coated nylon-11 NPs could image dental pulp stem cells (DPSCs) well, which demonstrated that nylon-11 NPs can be endocytosed easily by DPSCs. With the assistance of ultrasound, nylon-11 NPs could promote the osteogenic differentiation of DPSCs efficiently in a noninvasive way. Meanwhile, nylon-11 NPs could also promote the osteogenic differentiation of DPSCs to a certain extent. Therefore, piezoelectric nylon-11 NPs with the assistance of ultrasound will have enormous potential in tissue engineering, especially in stem cell fate regulation by noninvasive stimulation. This indicates that nanomaterial-mediated physical signals can regulate stem cell differentiation efficiently.

Coordination ability determined transition metal ions substitution of Tb in Tb-Asp fluorescent nanocrystals and a facile ions-detection approach.

Although the synthesis and fluorescent properties of lanthanide-amino acid complex nanostructures have been investigated extensively, limited studies have been reported on metal ions' substitution ability for the lanthanide ions in the complex and their effect on the fluorescent property. In this study, taking biocompatible Tb-aspartic acid (Tb-Asp) complex nanocrystals as a model, the substitution mechanism of metal ions, particularly transition metals, for Tb ions in Tb-Asp nanocrystals and the change in the fluorescent property of the Tb-Asp nanocrystals after substitution were systematically investigated. The experimental results illustrated that metal ions with higher electronegativity, higher valence, and smaller radius possess stronger ability for Tb ions' substitution in Tb-Asp nanocrystals. Based on the effect of substituting ions' concentration on the fluorescent property of Tb-Asp, a facile method for copper ions detection with high sensitivity was proposed by measuring the fluorescent intensity of Tb-Asp nanocrystals' suspensions containing different concentrations of copper ions. The good biocompatibility, great convenience of synthesis and sensitive detection ability make Tb-Asp nanocrystals a very low cost and effective material for metal ions detection, which also opens a new door for practical applications of metal-Asp coordinated nanocrystals.

Coloaded Nanoparticles of Paclitaxel and Piperlongumine for Enhancing Synergistic Antitumor Activities and Reducing Toxicity.

The purpose of this study was to develop a nanocarrier system for codelivery of paclitaxel (PTX) and piperlongumine (PL) and investigate the therapeutic potential of improving efficacy and reducing toxicity. PTX and PL were formulated into poly lactic-co-glycolic acid and D-α-tocopheryl polyethylene glycol succinate via organic solvent evaporation method. The average diameter was 117.1 ± 1.9 nm, and the zeta potential was -43.25 ± 2.76 mV. PL facilitated the cellular uptake of PTX, and the increased cytotoxicity was similarly displayed. The formulation with the PTX/PL concentration ratio at 1:200 showed the best antitumor activity, the IC50 of PTX were 5.10 ± 0.08 nM in HepG2 cells, and 3.79 ± 1.01 nM in Michigan Cancer Foundation-7 cells. Correspondingly, the combination index was 0.79 and 0.76. Furthermore, intracellular uptake of PTX toward HepG2 cells in coencapsulated nanoparticles was significantly more than free solution. In addition, the antitumor effect of PTX/PL-PTNPs in the HepG2 xenograft tumor model suggested that the nanoparticles showed a higher antitumor efficacy with reduced toxicity to other tissues compared with free PTX. In summary, the results indicated that PTX/PL-PTNPs processed well characteristics and enhanced its therapeutic efficacy; thus, this delivery system could be clinically effective for treatment of cancers.

Vaccination strategies to enhance local immunity and protection against Mycobacteriun tuberculosis.

To determine the immunogenicity and protective efficacy of the Mycobacterium tuberculosis 10 kD culture filtrate protein (CFP10), and to evaluate strategies that enhance local immunity, we used C57Bl/6 DR4 mice that were transgenic for human HLA DRB1 0401, because CFP10 contains epitopes for DRB1 0401 but not for C57Bl/6 mice. Intramuscular immunization with a DNA vaccine encoding CFP10 elicited production of IFN-gamma by systemic CD4+ T cells, and one intravenous dose of the CFP10-based DNA vaccine coated with polyethylenimine (PEI) stimulated IFN-gamma production by lung CD4+ cells and reduced the pulmonary bacillary burden. We conclude that CFP10 is a potential vaccine candidate and that coating vaccines with PEI enhances local protective immunity to tuberculosis