Involvement of lipid rafts of rabbit red blood cells in morphological changes induced by methylated beta-cyclodextrins

Strategies for Taste Masking of Orodispersible Dosage Forms: Time, Concentration, and Perception

Orodispersible dosage forms, characterized as quick dissolving and swallowing without water, have recently gained great attention from the pharmaceutical industry, as these forms can satisfy the needs of children, the elderly, and patients suffering from mental illnesses. However, poor taste by thorough exposure of the drugs' dissolution in the oral cavity hinders the effectiveness of the orodispersible dosage forms. To bridge this gap, we put forward three taste-masking strategies with respect to the intensity of time, concentration, and perception. We further investigated the raw material processing, the composition of auxiliary material, formulation techniques, and process control in each strategy and drew conclusions about their effects on taste masking.

Calcium phosphate-adsorbable and acid-degradable carboxylated polyrotaxane consisting of β-cyclodextrins suppresses osteoclast resorptive activity

Recently, the potential of β-cyclodextrin-thread acid-degradable polyrotaxane (AdPRX) has been emphasized as a therapeutic agent for cholesterol-related metabolic disorders. In this study, we investigated whether carboxymethyl carbamate-modified AdPRX (CMC-AdPRX) can be used for adsorption to calcium phosphate to treat bone diseases. We first synthesized CMC-AdPRX and used it to coat the calcium phosphate plate. RAW264.7 cells were then differentiated into osteoclasts via a receptor activator of nuclear factor-κB ligand, and the number of osteoclasts and the area of absorption lacunae were determined. The number of tartrate-resistant acid phosphatase-positive multinucleated cells was reduced on the CMC-AdPRX-coated plate. The area of the absorption lacunae was smaller with CMC-AdPRX than with AdPRX, which was not carboxy-modified. Our results suggest that CMC-AdPRX can adsorb to calcium phosphate and act on differentiated osteoclasts to suppress their functional expression.

Differential mode of cholesterol inclusion with 2-hydroxypropyl-cyclodextrins increases safety margin in treatment of Niemann-Pick disease type C

BACKGROUND AND PURPOSE

Niemann-Pick disease type C (NPC) is a lysosomal storage disorder with disrupted intracellular cholesterol trafficking. A cyclic heptasaccharide, 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), is a cholesterol solubilizer that is being developed to treat NPC, but its ototoxicity and pulmonary toxicity remain important issues. We have characterized 2-hydroxypropyl-γ-cyclodextrin (HP-γ-CD), a cyclic octasaccharide with a larger cavity than HP-β-CD, as a candidate drug to treat NPC. However, the molecular target of HP-γ-CD with respect to NPC and its potential for clinical application are still unclear.

EXPERIMENTAL APPROACH

We investigated the mode of interaction between HP-γ-CD and cholesterol by phase-solubility analysis, proton NMR spectroscopy and molecular dynamics simulations. We then evaluated the therapeutic effects of HP-γ-CD compared with HP-β-CD using cellular and murine NPC models. Mouse auditory and pulmonary function tests were also conducted.

KEY RESULTS

HP-γ-CD solely formed a 1:1 inclusion complex with cholesterol with an affinity similar to that of HP-β-CD. In vitro, HP-γ-CD and HP-β-CD amelioration of NPC-related manifestations was almost equivalent at lower concentrations. However, at higher concentrations, the cholesterol inclusion mode of HP-β-CD shifted to the highly soluble 2:1 complex whereas that of HP-γ-CD maintained solely the 1:1 complex. The constant lower cholesterol solubilizing ability of HP-γ-CD conferred it with significantly reduced toxicity compared with HP-β-CD, but equal efficacy in treating a mouse model of NPC.

CONCLUSIONS AND IMPLICATIONS

HP-γ-CD can serve as a fine-tuned cholesterol solubilizer for the treatment of NPC with a wider safety margin than HP-β-CD in terms of ototoxicity and pulmonary toxicity.

Spicule movement on RBCs during echinocyte formation and possible segregation in the RBC membrane

We use phase contrast microscopy of red blood cells to observe the transition between the initial discocyte shape and a spiculated echinocyte form. During the early stages of this change, spicules can move across the surface of the cell; individual spicules can also split apart into pairs. One possible explanation of this behaviour is that the membrane forms large scale domains in association with the spicules. The spicules are formed initially at the rim of the cell and then move at speeds of up to 3 μm/min towards the centre of the disc. Spicule formation that was reversed and then allowed to proceed a second time resulted in spicules at reproducible places, a shape memory effect that implies that the cytoskeleton contributes towards stopping the spicule movement. The splitting of the spicules produces a well-defined shape change with an increase in membrane curvature associated with formation of the daughter pair of spicules; the total boundary length around the spicules also increases. Following the model in which the spicules are associated with lipid domains, these observations suggest an experimental procedure that could potentially be applied to the calculation of the line tension of lipid domains in living cells.

Cyclodextrin-Based Formulations: A Non-Invasive Platform for Targeted Drug Delivery

Cyclodextrins (CDs) are recognized as promising pharmaceutical excipients due to their unique ability to form water-soluble inclusion complexes with various poorly soluble compounds. The numerous investigations on CDs and their use in nanomedicine have received considerable attention in the last three decades, leading to the rapid development of new CD-containing formulations that significantly facilitate targeted drug delivery and controlled drug release, with consequent improvements in drug bioavailability. This MiniReview highlights the efficacy and recent uses of CDs for non-invasive drug delivery. Using ophthalmic and nasal drug delivery as examples, an overview of chemical properties, mechanisms of CDs on drug solubilization, stabilization and permeation, along with their toxicological profiles relevant to nasal and ocular administration, are provided and discussed. The recent development and application of CD-based nanocarrier systems for targeted drug delivery are summarized.

Polyrotaxane-based systemic delivery of β-cyclodextrins for potentiating therapeutic efficacy in a mouse model of Niemann-Pick type C disease

Niemann-Pick type C (NPC) disease is a fatal metabolic disorder characterized by the lysosomal accumulation of cholesterol. Although 2-hydroxypropyl β-cyclodextrin (HP-β-CD) promotes the excretion of cholesterol and prolongs the life span in animal models of NPC disease, it requires extremely high dose. We developed acid-labile β-CD-based polyrotaxanes (PRXs) comprising multiple β-CDs threaded along a polymer chain capped with acid-cleavable stopper molecules for potentiating therapeutic efficacy of β-CD in NPC disease. The acid-labile PRXs dissociate under the acidic lysosomes and release threaded β-CDs in lysosomes, which promotes cholesterol excretion in NPC disease model cells at lower concentration than HP-β-CD. In this study, the therapeutic effect of the PRXs in a mouse model of NPC disease was investigated. Weekly administration of the PRXs significantly prolonged the life span and suppressed neurodegeneration in mice, even at a dose of 500mg/kg, a markedly lower dose than previously reported for HP-β-CD. Detailed analysis of tissue cholesterol revealed that PRX treatment markedly suppressed the tissue accumulation of cholesterol in the NPC mouse model, but did not alter cholesterol content in wild-type mice. Acid-labile PRX is therefore a promising candidate for potentiating the efficacy of β-CD in the treatment of NPC disease.

Acid-Induced Intracellular Dissociation of β-Cyclodextrin-Threaded Polyrotaxanes Directed toward Attenuating Phototoxicity of Bisretinoids through Promoting Excretion

In the retinal pigment epithelium of patients with age-related macular degeneration (AMD), excess N-retinylidene-N-retinylethanolamine (A2E), a dimer of all-trans-retinal, accumulats to induce inflammatory cytokine secretion and phototoxic effects. Therefore, the reduction of intracellular A2E is a promising approach for the prevention and treatment of AMD. In this study, acid-labile β-cyclodextrin (β-CD)-threaded polyrotaxanes (PRXs) were synthesized and investigated their effects on the removal of A2E accumulated in retinal pigment epithelium cells (ARPE-19) in comparison to nonlabile PRXs and 2-hydroxypropyl β-CD (HP-β-CD) were examined. GC-MS and HPLC studies strongly suggest that the acid-labile PRXs dissociated into their constituent molecules in cells by lysosomal acidification and threaded β-CDs were considered to be released from the PRXs. The released β-CDs formed an inclusion complex with A2E, which promoted the excretion of A2E. Indeed, the acid-labile PRXs effectively reduced intracellular A2E level at approximately a 10-fold lower concentration than HP-β-CD. Accompanied with A2E removal, the toxicity and phototoxicity of A2E were attenuated by treatment with acid-labile PRXs. Because the nonlabile PRX failed to reduce intracellular A2E level and attenuate phototoxicity, intracellular release of threaded β-CDs from the acid-labile PRX might contribute to reducing intracellular A2E. We conclude that acid-labile PRXs are promising candidates for the treatment of macular diseases through the removal of toxic metabolites.

Potential Use of Cyclodextrins as Drug Carriers and Active Pharmaceutical Ingredients

Cyclodextrins (CyDs) are extensively used in various fields, and especially have been widely utilized as pharmaceutical excipients and drug carriers in the pharmaceutical field. Owing to the multi-functional and biocompatible characteristics, CyDs can improve the undesirable properties of drug molecules. This review outlines the current application of CyDs in pharmaceutical formulations, focusing on their use as CyD-based drug carriers for several kinds of drugs. Additionally, CyDs have great potential as active pharmaceutical ingredients against various diseases with few side effects.

Interactions between cyclodextrins and cellular components: Towards greener medical applications?

In the field of host-guest chemistry, some of the most widely used hosts are probably cyclodextrins (CDs). As CDs are able to increase the water solubility of numerous drugs by inclusion into their hydrophobic cavity, they have been widespread used to develop numerous pharmaceutical formulations. Nevertheless, CDs are also able to interact with endogenous substances that originate from an organism, tissue or cell. These interactions can be useful for a vast array of topics including cholesterol manipulation, treatment of Alzheimer's disease, control of pathogens, etc. In addition, the use of natural CDs offers the great advantage of avoiding or reducing the use of common petroleum-sourced drugs. In this paper, the general features and applications of CDs have been reviewed as well as their interactions with isolated biomolecules leading to the formation of inclusion or exclusion complexes. Finally, some potential medical applications are highlighted throughout several examples.

Biocompatible hyperbranched polyglycerol modified β-cyclodextrin derivatives for docetaxel delivery

The development of biocompatible vector for hydrophobic drug delivery remains a longstanding issue in cancer therapy. We design and synthesis a drug delivery system based on HPG modified β-CD (β-CD-HPG) by conjugating HPG branches onto β-CD core and its structure was confirmed by NMR, FTIR, GPC and solubility. In vitro biocompatibility tests showed that HPG modification significantly improved red blood cells morphology alteration and hemolysis cause by β-CD and β-CD-HPG displayed cell safety apparently in a wide range of 0.01-1mg/mL. An anti-cancer drug, docetaxel, was effectively encapsulated into β-CD-HPG which was confirmed by DSC analysis. This copolymer could form nanoparticles with small size (<200nm) and exhibited better DTX loading capacity and controlled release kinetics without initial burst release behavior compared with β-CD. Furthermore, antitumor assay in vitro show that β-CD-HPG/DTX effectively inhibited proliferation of human breast adenocarcinoma cells. Therefore, β-CD-HPG/DTX exhibit great potential for cancer chemotherapy.

Evaluation of antitumor effects of folate-conjugated methyl-β-cyclodextrin in melanoma

Melanoma is a life-threatening disorder and its incidence is increasing gradually. Despite the numerous treatment approaches, conventional systemic chemotherapy has not reduced the mortality rate among melanoma patients, probably due to the induction of toxicity to normal tissues. Recently, we have developed folate-conjugated methyl-β-cyclodextrin (FA-M-β-CyD) and clarified its potential as a new antitumor agent involved in autophagic cell death. However, it remains uncertain whether FA-M-β-CyD exerts anticancer effects against melanomas. Therefore, in this study, we investigated the effects of FA-M-β-CyD on the folate receptor-α (FR-α)-expressing melanoma cell-selective cytotoxic effect. FA-M-β-CyD showed cytotoxic effects in Ihara cells, a human melanoma cell line expressing FR-α. In sharp contrast to methyl-β-cyclodextrin, FA-M-β-CyD entered Ihara cells [FR-α(+)] through FR-α-mediated endocytosis. Additionally, FA-M-β-CyD elicited the formation of autophagosomes in Ihara cells. Notably, FA-M-β-CyD suppressed melanoma growth in BALB/c nude recombinase-activating gene-2 (Rag-2)/Janus kinase 3 (Jak3) double deficient mice bearing Ihara cells. Therefore, these results suggest that FA-M-β-CyD could be utilized as a potent anticancer agent for melanoma chemotherapy by regulating autophagy.

2-Hydroxypropyl-β-Cyclodextrin Acts as a Novel Anticancer Agent

2-Hydroxypropyl-β-cyclodextrin (HP-β-CyD) is a cyclic oligosaccharide that is widely used as an enabling excipient in pharmaceutical formulations, but also as a cholesterol modifier. HP-β-CyD has recently been approved for the treatment of Niemann-Pick Type C disease, a lysosomal lipid storage disorder, and is used in clinical practice. Since cholesterol accumulation and/or dysregulated cholesterol metabolism has been described in various malignancies, including leukemia, we hypothesized that HP-β-CyD itself might have anticancer effects. This study provides evidence that HP-β-CyD inhibits leukemic cell proliferation at physiologically available doses. First, we identified the potency of HP-β-CyD in vitro against various leukemic cell lines derived from acute myeloid leukemia (AML), acute lymphoblastic leukemia and chronic myeloid leukemia (CML). HP-β-CyD treatment reduced intracellular cholesterol resulting in significant leukemic cell growth inhibition through G₂/M cell-cycle arrest and apoptosis. Intraperitoneal injection of HP-β-CyD significantly improved survival in leukemia mouse models. Importantly, HP-β-CyD also showed anticancer effects against CML cells expressing a T315I BCR-ABL mutation (that confers resistance to most ABL tyrosine kinase inhibitors), and hypoxia-adapted CML cells that have characteristics of leukemic stem cells. In addition, colony forming ability of human primary AML and CML cells was inhibited by HP-β-CyD. Systemic administration of HP-β-CyD to mice had no significant adverse effects. These data suggest that HP-β-CyD is a promising anticancer agent regardless of disease or cellular characteristics.

Effect of cyclodextrins on the structure and functions of blood components in vitro

Cyclodextrins have been extensively used in various biomedical and pharmaceutical applications. In these applications, cyclodextrins administered in vivo would inevitably enter blood stream. However, there is not enough information on the hemocompatibility of cyclodextrins until now. In this study, we investigated the influences of cyclodextrins (α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin) on human blood components and functions in vitro, that is, morphology and lysis of red blood cells, structure and conformation of fibrinogen, complement activation, and blood coagulation. It was found that 10 mg/mL of α- or β-cyclodextrins caused abnormal red blood cell morphology and serious hemolysis, while γ-cyclodextrin at 10 mg/mL did not impair red blood cell membrane morphology and integrity. The three cyclodextrins at up to 10 mg/mL affected the local microstructure but did not change the conformation of fibrinogen. The three cyclodextrins from 0.01 to 1 mg/mL all significantly activated the complement system in a concentration-dependent way. The three cyclodextrins at up to 5 mg/mL in blood plasma did not cause significantly different coagulation times compared with the negative control. In addition, the three cyclodextrins at up to 5 mg/mL in whole blood did not cause abnormal coagulation parameters. These results provide significant information on blood safety of the three cyclodextrins for their biomedical and pharmaceutical applications.

Cyclodextrins, blood-brain barrier, and treatment of neurological diseases

Biological barriers are the main defense systems of the homeostasis of the organism and protected organs. The blood-brain barrier (BBB), formed by the endothelial cells of brain capillaries, not only provides nutrients and protection to the central nervous system but also restricts the entry of drugs, emphasizing its importance in the treatment of neurological diseases. Cyclodextrins are increasingly used in human pharmacotherapy. Due to their favorable profile to form hydrophilic inclusion complexes with poorly soluble active pharmaceutical ingredients, they are present as excipients in many marketed drugs. Application of cyclodextrins is widespread in formulations for oral, parenteral, nasal, pulmonary, and skin delivery of drugs. Experimental and clinical data suggest that cyclodextrins can be used not only as excipients for centrally acting marketed drugs like antiepileptics, but also as active pharmaceutical ingredients to treat neurological diseases. Hydroxypropyl-β-cyclodextrin received orphan drug designation for the treatment of Niemann-Pick type C disease. In addition to this rare lysosomal storage disease with neurological symptoms, experimental research revealed the potential therapeutic use of cyclodextrins and cyclodextrin nanoparticles in neurodegenerative diseases, stroke, neuroinfections and brain tumors. In this context, the biological effects of cyclodextrins, their interaction with plasma membranes and extraction of different lipids are highly relevant at the level of the BBB.

Cytotoxicity of purified listeriolysin O on mouse and human leukocytes and leukaemia cells

Background

Listeriolysin O (LLO) is the main virulence factor of Listeria monocytogenes and facilitates the intracellular survival of the pathogen. Some of its characteristics endorse the growing popularity of LLO for use in biotechnology, particularly in the development of novel vaccines. Here, we evaluate the use of LLO to eradicate leukaemia cells.

Results

A purified LLO preparation was obtained by affinity chromatography. The LLO preparation procedure was optimized and purified LLO was tested for optimal conditions of storage including temperature, application of proteinase inhibitors and serum components. We demonstrated the possibility of regulating LLO activity by adjusting cell membrane cholesterol content. The LLO preparation had haemolytic activity and had a cytotoxic effect on the human T-leukaemia Jurkat cell line as well as mouse and human peripheral blood mononuclear cells.

Conclusions

LLO has a very potent cytotoxic activity towards human leukocytes. Importantly, the cytotoxic activity was easily regulated in vitro and could be restricted to areas containing malignant cells, raising the possibility of future clinical application of LLO for leukaemia treatment.

Involvement of autophagy in antitumor activity of folate-appended methyl-β-cyclodextrin

Autophagy, the major lysosomal pathway for recycling intracellular components including organelles, is emerging as a key process regulating tumorigenesis and cancer therapy. Most recently, we newly synthesized folate-appended methyl-β-cyclodextrin (FA-M-β-CyD), and demonstrated the potential of FA-M-β-CyD as a new antitumor drug. In this study, we investigated whether anticancer activity of FA-M-β-CyD in folate receptor-α (FR-α)-positive tumor cells is involved in autophagy. In contrast to methyl-β-cyclodextrin (M-β-CyD), FA-M-β-CyD entered KB cells (FR-α (+)) through CLIC/GEEC endocytosis. No significant depression in the DNA content was observed in KB cells after treatment with FA-M-β-CyD. Additionally, the transmembrane potential of mitochondria after treatment with FA-M-β-CyD was drastically elevated. Meanwhile, FA-M-β-CyD induced the formation of autophagic vacuoles, which were partially colocalized with mitochondria, in KB cells. Taken together, these results suggest that FR-α-expressing cell-selective cytotoxic activity of FA-M-β-CyD could be mediated by the regulation of autophagy, rather than the induction of apoptosis.

High-efficiency localization of Na(+)-K(+) ATPases on the cytoplasmic side by direct stochastic optical reconstruction microscopy

We describe a concise and effective strategy towards precisely mapping Na(+)-K(+) ATPases on the cytoplasmic side of cell membranes by direct stochastic optical reconstruction microscopy (dSTORM). We found that most Na(+)-K(+) ATPases are localized in different sizes of clusters on human red blood cell (hRBC) membranes, revealed by Ripley's K-function analysis. Further evidence that cholesterol depletion causes the dispersion of Na(+)-K(+) ATPase clusters indicates that such clusters could be localized in cholesterol-enriched domains. Our results suggest that Na(+)-K(+) ATPases might aggregate within the lipid rafts to fulfill their functions.

L-diphenylalanine microtubes as a potential drug-delivery system: characterization, release kinetics, and cytotoxicity

Microtubes obtained from the self-assembly of L-diphenylalanine (FF-MTs) were evaluated as potential vehicles for drug delivery. The biological marker Rhodamine B (RhB) was chosen as a model drug and conjugated to the peptide arrays during self-organization in the liquid phase. Microscopy and X-ray studies were performed to provide morphological and structural information. The data revealed that the cargo was distributed either in small aggregates at the hydrophobic surface of the FF-MTs or homogeneously embedded in the structure, presumably anchored at polar sites in the matrix. Raman spectroscopy revealed notable shifts of the characteristic RhB resonance peaks, demonstrating the successful conjugation of the fluorophore and peptide assemblies. In vitro assays were conducted in erythrocytes and fibroblast cells. Interestingly, FF-MTs were found to modulate the release of the load. The release of RhB from the FF-MTs followed first-order kinetics with a steady-state profile, demonstrating the potential of these carriers to deliver drugs at constant rates in the body. Cytotoxicity investigations revealed high cell viability up to concentrations of 5 mg mL(-1), demonstrating the low toxicity of the FF-MTs.

Effects of β-cyclodextrin on the intestinal absorption of berberine hydrochloride, a P-glycoprotein substrate

The major objective of this work is to investigate the enhancing effect of β-cyclodextrin on the intestinal absorption of berberine hydrochloride, a P-glycoprotein (Pgp) substrate. The inclusion complexation behavior of BBH with β-CD was investigated by phase-solubility diagram, Fourier transform infrared spectroscopy, differential scanning calorimetry, X-ray powder diffractometry, NMR spectroscopy, and molecular modeling studies. Results indicated that the 1,3-benzodioxole of BBH was included into the cavity of β-CD to form an inclusion complex which exhibited higher dissolution rate than BBH in vitro. The intestinal absorption of the inclusion complex in rats was significantly higher than the free drug due to its solubilizing effect and Pgp modulatory activity. The mechanisms of β-CD on Pgp modulation were demonstrated by modifying the Pgp ATPase activity, the Pgp mRNA level and the Pgp expression.

Potential use of folate-appended methyl-β-cyclodextrin as an anticancer agent

To obtain a tumor cell-selectivity of methyl-β-cyclodextrin (M-β-CyD), we newly synthesized folate-appended M-β-CyD (FA-M-β-CyD), and evaluated the potential of FA-M-β-CyD as a novel anticancer agent in vitro and in vivo. Potent antitumor activity and cellular association of FA-M-β-CyD were higher than those of M-β-CyD in KB cells, folate receptor (FR)-positive cells. FA-M-β-CyD drastically inhibited the tumor growth after intratumoral or intravenous injection to FR-positive Colon-26 cells-bearing mice. The antitumor activity of FA-M-β-CyD was comparable and superior to that of doxorubicin after both intratumoral and intravenous administrations, respectively, at the same dose, in the tumor-bearing mice. All of the tumor-bearing mice after an intravenous injection of FA-M-β-CyD survived for at least more than 140 days. Importantly, an intravenous administration of FA-M-β-CyD to tumor-bearing mice did not show any significant change in blood chemistry values. These results strongly suggest that FA-M-β-CyD has the potential as a novel anticancer agent.

Improvement of the bitter taste of drugs by complexation with cyclodextrins: applications, evaluations and mechanisms

Drugs having bitter tastes cause low patient compliance. Many taste-masking techniques such as physical barrier coatings, chemical modification and sensory masking have been developed. Among chemical modification, the inclusion complexation of drugs with cyclodextrins (CyDs) can provide the effective bitter taste-masking effects without complicated formulation and/or delayed dissolution of drugs. Herein, we describe some quantitative methods to evaluate the taste-masking effects of CyD complexes with drugs in solution and the solid state. In addition, we introduce the recent applications of CyDs to excipients for taste masking against various bitter-taste drugs, as well as discuss the possible mechanisms for the taste-masking effect of CyD complexation.

Direct evidence of lipid rafts by in situ atomic force microscopy

Lipid rafts are membrane microdomains enriched with cholesterol, glycosphingolipids, and proteins. Although they are broadly presumed to play a pivotal role in various cellular functions, there are still fierce debates about the composition, functions, and even existence of lipid rafts. Here high-resolution and time-lapse in situ atomic force microscopy is used to directly confirm the existence of lipid rafts in native erythrocyte membranes. The results indicate some important aspects of lipid rafts: most of the lipid rafts are in the size range of 100-300 nm and have irregular shape; the detergent-resistant membranes consist of cholesterol microdomains and are not likely the same as the lipid rafts; cholesterol contributes significantly to the formation and stability of the protein domains; and Band III is an important protein of lipid rafts in the inner leaflet of erythrocyte membranes, indicating that lipid rafts are exactly the functional domains in plasma membrane. This work provides direct evidence of the presence, size, and main constitutive protein of lipid rafts at a resolution of a few nanometers, which will pave the way for studying their structure and functions in detail.

Preparation, characterization, and biological evaluation of 6(I),6(IV)-di-O-[α-l-fucopyranosyl-(1→6)-2-acetamido-2-deoxy-β-d-glucopyranosyl]-cyclomaltoheptaose and 6-O-[α-l-fucopyranosyl-(1→6)-2-acetamido-2-deoxy-β-d-glucopyranosyl]-cyclomaltoheptaose

6(I),6(IV)-Di-O-[α-l-fucopyranosyl-(1→6)-2-acetamido-2-deoxy-β-d-glucopyranosyl]-cyclomaltoheptaose (βCD) {6(I),6(IV)-di-O-[α-l-Fuc-(1→6)-β-d-GlcNAc]-βCD (5)} and 6-O-[α-l-fucopyranosyl-(1→6)-2-acetamido-2-deoxy-β-d-glucopyranosyl]-βCD {6-O-[α-l-Fuc-(1→6)-β-d-GlcNAc]-βCD (6)} were chemically synthesized using the corresponding authentic compounds, bis(2,3-di-O-acetyl)-pentakis(2,3,6-tri-O-acetyl)-βCD as the glycosyl acceptor and 2,3,4-tri-O-benzyl-α-l-fucopyranosyl-(1→6)-3,4-di-O-acetyl-2-deoxy-2-(2,2,2-trichloroethoxycarbonylamino)-d-glucopyranosyl trichloroacetimidate as the fuco-glucosaminyl donor. NMR confirmed that α-l-Fuc-(1→6)-d-GlcNAc was bonded by β-linking to the βCD ring. To evaluate biological efficiency, the biological activities of the new branched βCDs were examined. The cell detachment activity of 5 was lower than that of 6 in real-time cell sensing (RT-CES) assay, indicating that 5 has lower toxicity. In SPR analysis, 5 had a higher special binding with AAL, a fucose-recognizing lectin. These results suggest that 5 could be an efficient drug carrier directed at cells expressing fucose-binding proteins.

Effects of membrane cholesterol depletion and GPI-anchored protein reduction on osteoblastic mechanotransduction

We previously demonstrated that oscillatory fluid flow activates MC3T3-E1 osteoblastic cell calcium signaling pathways via a mechanism involving ATP releases and P2Y(2) puringeric receptors. However, the molecular mechanisms by which fluid flow initiates cellular responses are still unclear. Accumulating evidence suggests that lipid rafts, one of the important membrane structural components, may play an important role in transducing extracellular fluid shear stress to intracellular responses. Due to the limitations of current techniques, there is no direct approach to study the role of lipid rafts in transmitting fluid shear stress. In this study, we targeted two important membrane components associated with lipid rafts, cholesterol, and glycosylphosphatidylinositol-anchored proteins (GPI-anchored proteins), to disrupt the integrity of cell membrane structures. We first demonstrated that membrane cholesterol depletion with the treatment of methyl-β-cyclodextrin inhibits oscillatory fluid flow induced intracellular calcium mobilization and ERK1/2 phosphorylation in MC3T3-E1 osteoblastic cells. Secondly, we used a novel approach to decrease the levels of GPI-anchored proteins on cell membranes by overexpressing glycosylphosphatidylinositol-specific phospholipase D in MC3T3-E1 osteoblastic cells. This resulted in significant inhibition of intracellular calcium mobilization and ERK1/2 phosphorylation in response to oscillatory fluid flow. Finally, we demonstrated that cholesterol depletion inhibited oscillatory fluid flow induced ATP releases, which were responsible for the activation of calcium signaling pathways in MC3T3-E1 osteoblastic cells. Our findings suggest that cholesterol and GPI-anchored proteins, two membrane structural components related to lipid rafts, may play an important role in osteoblastic cell mechanotransduction.

Some pharmaceutical and inclusion properties of 2-hydroxybutyl-β-cyclodextrin derivative

2-Hydroxybutyl-β-cyclodextrins (HB-β-CyDs) with different degrees of substitution (D.S.) were prepared and their physicochemical and biological properties and solubilizing abilities were studied and compared with those of 2-hydroxypropyl-β-cyclodextrin (HP-β-CyD). The surface activity of HB-β-CyD was higher than that of HP-β-CyD (D.S. 5.6) and increased with its concentration and D.S. The moisture sorption of HB-β-CyD (D.S. 5.5) was less than that of HP-β-CyD (D.S. 5.6), because of the introduction of hydrophobic hydroxybutyl groups in a molecule. The hemolytic activity (rabbit erythrocytes) decreased in the order of 2,6-di-O-methyl-β-cyclodextrin (DM-β-CyD)>methyl-β-cyclodextrin (M-β-CyD)>HB-β-CyD (D.S. 5.5)>β-CyD>HP-β-CyD (D.S. 5.6). The hemolytic activity of HB-β-CyD increased with D.S. and HB-β-CyD induced echinocyte (or crenation), as well as DM-β-CyD does. It was suggested from the solubility study of membrane components that HB-β-CyD interacted predominantly with cholesterol in erythrocytes, resulting in the hemolysis. The inclusion ability of HB-β-CyD was higher than that of HP-β-CyD (D.S. 5.6), especially for poorly water-soluble drugs with long linear structures such as biphenylylacetic acid and flurbiprofen (FP). For example, HB-β-CyD formed the inclusion complex with FP in a molar ratio of 1:1, by including the biphenyl moiety in the host cavity. The dissolution rate of FP/HB-β-CyD (D.S. 5.5) complex was faster than that of HP-β-CyD (D.S. 5.6) complex. The results suggested that HB-β-CyDs have considerable pharmaceutical potential and can work as a fast-dissolving carrier for poorly water-soluble drugs.

In Vitro Gene Delivery Mediated by Asialofetuin-Appended Cationic Liposomes Associated with γ-Cyclodextrin into Hepatocytes

The purpose of this study is to evaluate in vitro gene delivery mediated by asialofetuin-appended cationic liposomes (AF-liposomes) associating cyclodextrins (CyD/AF-liposomes) as a hepatocyte-selective nonviral vector. Of various CyDs, AF-liposomes associated with plasmid DNA (pDNA) and γ-cyclodextrin (γ-CyD) (pDNA/γ-CyD/AF-liposomes) showed the highest gene transfer activity in HepG2 cells without any significant cytotoxicity. In addition, γ-CyD enhanced the encapsulation ratio of pDNA with AF-liposomes, and also increased gene transfer activity as the entrapment ratio of pDNA into AF-liposomes was increased. γ-CyD stabilized the liposomal membrane of AF-liposomes and inhibited the release of calcein from AF-liposomes. The stabilizing effect of γ-CyD may be, at least in part, involved in the enhancing gene transfer activity of pDNA/γ-CyD/AF-liposomes. Therefore, these results suggest the potential use of γ-CyD for an enhancer of transfection efficiency of AF-liposomes.

Recent Findings Concerning PAMAM Dendrimer Conjugates with Cyclodextrins as Carriers of DNA and RNA

We have evaluated the potential use of various polyamidoamine (PAMAM) dendrimer [dendrimer, generation (G) 2-4] conjugates with cyclodextrins (CyDs) as novel DNA and RNA carriers. Among the various dendrimer conjugates with CyDs, the dendrimer (G3) conjugate with α-CyD having an average degree of substitution (DS) of 2.4 [α-CDE (G3, DS2)] displayed remarkable properties as DNA, shRNA and siRNA delivery carriers through the sensor function of α-CDEs toward nucleic acid drugs, cell surface and endosomal membranes. In an attempt to develop cell-specific gene transfer carriers, we prepared sugar-appended α-CDEs. Of the various sugar-appended α-CDEs prepared, galactose- or mannose-appended α-CDEs provided superior gene transfer activity to α-CDE in various cells, but not cell-specific gene delivery ability. However, lactose-appended α-CDE [Lac-α-CDE (G2)] was found to possess asialoglycoprotein receptor (AgpR)-mediated hepatocyte-selective gene transfer activity, both in vitro and in vivo. Most recently, we prepared folate-poly(ethylene glycol)-appended α-CDE [Fol-PαC (G3)] and revealed that Fol-PαC (G3) imparted folate receptor (FR)-mediated cancer cell-selective gene transfer activity. Consequently, α-CDEs bearing integrated, multifunctional molecules may possess the potential to be novel carriers for DNA, shRNA and siRNA.

Involvement of PI3K-Akt-Bad pathway in apoptosis induced by 2,6-di-O-methyl-beta-cyclodextrin, not 2,6-di-O-methyl-alpha-cyclodextrin, through cholesterol depletion from lipid rafts on plasma membranes in cells

Cyclodextrins (CyDs), which are widely used to increase the solubility of drug in pharmaceutical fields, are known to induce hemolysis and cytotoxicity at high concentrations. However, it is still not unclear whether cell death induced by CyDs is apoptosis or not. Therefore, in the present study, we investigated the effects of various kinds of CyDs on apoptosis in the cells such as NR8383 cells, A549 cells and Jurkat cells. Of various CyDs, methylated CyDs inducted cell death under the present experimental conditions, but hydroxypropylated CyDs or sulfobutyl ether-beta-CyD (SBE7-beta-CyD) did not. Of methylated CyDs, 2,6-di-O-methyl-beta-cyclodextrin (DM-beta-CyD) and 2,3,6-tri-O-methyl-beta-cyclodextrin (TM-beta-CyD) markedly caused apoptosis in NR8383 cells, A549 cells and Jurkat cells, through cholesterol depletion in cell membranes. In sharp contrast, 2,6-di-O-methyl-alpha-cyclodextrin (DM-alpha-CyD) and methyl-beta-cyclodextrin (M-beta-CyD) induced cell death in an anti-apoptotic mechanism. DM-beta-CyD induced apoptosis through the inhibition of the activation of PI3K-Akt-Bad pathway. Neither p38 MAP kinase nor p53 was contributed to the induction of apoptosis by DM-beta-CyD. Additionally, DM-beta-CyD significantly decreased mitochondrial transmembrane potential, and then caused the release of cytochrome c from mitochondria to cytosol in NR8383 cells. Furthermore, we confirmed that down-regulation of pro-caspase-3 and activation of caspase-3 after incubation with DM-beta-CyD. These results suggest that of methylated CyDs, DM-beta-CyD, not DM-alpha-CyD, induces apoptosis through the PI3K-Akt-Bad pathway, resulting from cholesterol depletion in lipid rafts of cell membranes.