Self-assembled peptide/polymer hybrid nanoplatform for cancer immunostimulating therapies

Integrating peptide epitopes in self-assembling materials is a successful strategy to obtain nanovaccines with high antigen density and improved efficacy. In this study, self-assembling peptides containing MAGE-A3/PADRE epitopes were designed to generate functional therapeutic nanovaccines. To achieve higher stability, peptide/polymer hybrid nanoparticles were formulated by controlled self-assembly of the engineered peptides. The nanoparticles showed good biocompatibility to both human red blood- and dendritic cells. Incubation of the nanoparticles with immature dendritic cells triggered immune effects that ultimately activated CD8 + cells. The antigen-specific and IgG antibody responses of healthy C57BL/6 mice vaccinated with the nanoparticles were analyzed. The in vivo results indicate a specific response to the nanovaccines, mainly mediated through a cellular pathway. This research indicates that the immunogenicity of peptide epitope vaccines can be effectively enhanced by developing self-assembled peptide-polymer hybrid nanostructures.

Viral protein-based nanoparticles (part 2): Pharmaceutical applications

Viral protein nanoparticles (ViP NPs) such as virus-like particles and virosomes are structures halfway between viruses and synthetic nanoparticles. The biological nature of ViP NPs endows them with the biocompatibility, biodegradability, and functional properties that many synthetic nanoparticles lack. At the same time, the absence of a viral genome avoids the safety concerns of viruses. Such characteristics of ViP NPs offer a myriad of opportunities for theirapplication at several points across disease development: from prophylaxis to diagnosis and treatment. ViP NPs present remarkable immunostimulant properties, and thus the vaccination field has benefited the most from these platforms capable of overcoming the limitations of both traditional and subunit vaccines. This was reflected in the marketing authorization of several VLP- and virosome-based vaccines. Besides, ViP NPs inherit the ability of viruses to deliver their cargo to target cells. Because of that, ViP NPs are promising candidates as vectors for drug and gene delivery, and for diagnostic applications. In this review, we analyze the pharmaceutical applications of ViP NPs, describing the products that are commercially available or under clinical evaluation, but also the advances that scientists are making toward the implementation of ViP NPs in other areas of major pharmaceutical interest.

Viral protein nanoparticles (Part 1): Pharmaceutical characteristics

Viral protein nanoparticles fill the gap between viruses and synthetic nanoparticles. Combining advantageous properties of both systems, they have revolutionized pharmaceutical research. Virus-like particles are characterized by a structure identical to viruses but lacking genetic material. Another type of viral protein nanoparticles, virosomes, are similar to liposomes but include viral spike proteins. Both systems are effective and safe vaccine candidates capable of overcoming the disadvantages of both traditional and subunit vaccines. Besides, their particulate structure, biocompatibility, and biodegradability make them good candidates as vectors for drug and gene delivery, and for diagnostic applications. In this review, we analyze viral protein nanoparticles from a pharmaceutical perspective and examine current research focused on their development process, from production to administration. Advances in synthesis, modification and formulation of viral protein nanoparticles are critical so that large-scale production of viral protein nanoparticle products becomes viable and affordable, which ultimately will increase their market penetration in the future. We will discuss their expression systems, modification strategies, formulation, biopharmaceutical properties, and biocompatibility.

Purification of Hollow Sporopollenin Microcapsules from Sunflower and Chamomile Pollen Grains

Pollen grains are natural microcapsules comprised of the biopolymer sporopollenin. The uniformity and special tridimensional architecture of these sporopollenin structures confer them attractive properties such as high resistance and improved bioadhesion. However, natural pollen can be a source of allergens, hindering its biomedical applicability. Several methods have been developed to remove internal components and allergenic compounds, usually involving long and laborious processes, which often cannot be extended to other pollen types. In this work, we propose an abridged protocol to produce stable and pristine hollow pollen microcapsules, together with a complete physicochemical and morphological characterization of the intermediate and final products. The optimized procedure has been validated for different pollen samples, also producing sporopollenin microcapsules from Matricaria species for the first time. Pollen microcapsules obtained through this protocol presented low protein content (4.4%), preserved ornamented morphology with a nanoporous surface, and low product density (0.14 g/cm3). These features make them interesting candidates from a pharmaceutical perspective due to the versatility of this biomaterial as a drug delivery platform.

Delivery of transcription factors as modulators of cell differentiation

Fundamental studies performed during the last decades have shown that cell fate is much more plastic than previously considered, and technologies for its manipulation are a keystone for many new tissue regeneration therapies. Transcription factors (TFs) are DNA-binding proteins that control gene expression, and they have critical roles in the control of cell fate and other cellular behavior. TF-based therapies have much medical potential, but their use as drugs depends on the development of suitable delivery technologies that can help them reach their action site inside of the cells. TFs can be used either as proteins or encoded in polynucleotides. When used in protein form, many TFs require to be associated to a cell-penetrating peptide or another transduction domain. As polynucleotides, they can be delivered either by viral carriers or by non-viral systems such as polyplexes and lipoplexes. TF-based therapies have extensively shown their potential to solve many tissue-engineering problems, including bone, cartilage and cardiac regeneration. Yet, their use has expanded beyond regenerative medicine to other prominent disease areas such as cancer therapy and immunomodulation. This review summarizes some of the delivery options for effective TF-based therapies and their current main applications.

Extracellular matrix mechanics regulate transfection and SOX9-directed differentiation of mesenchymal stem cells

Gene delivery within hydrogel matrices can potentially direct mesenchymal stem cells (MSCs) towards a chondrogenic fate to promote regeneration of cartilage. Here, we investigated whether the mechanical properties of the hydrogel containing the gene delivery systems could enhance transfection and chondrogenic programming of primary human bone marrow-derived MSCs. We developed collagen-I-alginate interpenetrating polymer network hydrogels with tunable stiffness and adhesion properties. The hydrogels were activated with nanocomplexed SOX9 polynucleotides to direct chondrogenic differentiation of MSCs. MSCs transfected within the hydrogels showed higher expression of chondrogenic markers compared to MSCs transfected in 2D prior to encapsulation. The nanocomplex uptake and resulting expression of transfected SOX9 were jointly enhanced by increased stiffness and cell-adhesion ligand density in the hydrogels. Further, transfection of SOX9 effectively induced MSCs chondrogenesis and reduced markers of hypertrophy compared to control matrices. These findings highlight the importance of matrix stiffness and adhesion as design parameters in gene-activated matrices for regenerative medicine. STATEMENT OF SIGNIFICANCE: Gene-activated matrices (GAMs) are biodegradable polymer networks integrating gene therapies, and they are promising technologies for supporting tissue regeneration. Despite this interest, there is still limited information on how to rationally design these systems. Here, we provide a systematic study of the effect of matrix stiffness and cell adhesion ligands on gene transfer efficiency. We show that high stiffness and the presence of cell-binding sites promote transfection efficiency and that this result is related to more efficient internalization and trafficking of the gene therapies. GAMs with optimized mechanical properties can induce cartilage formation and result in tissues with better characteristics for articular cartilage tissue engineering as compared to previously described standard methods.

Preparation and characterization of lamotrigine containing nanocapsules for nasal administration

Nanocapsules (NCs) have become one of the most researched nanostructured drug delivery systems due to their advantageous properties and versatility. NCs can enhance the bioavailabiliy of hydrophobic drugs by impoving their solubility and permeability. Also, they can protect these active pharmaceutical agents (APIs) from the physiological environment with preventing e.g. the enzymatic degradation. NCs can be used for many administration routes: e.g. oral, dermal, nasal and ocular formulations are exisiting in liquid and solid forms. The nose is one of the most interesting alternative drug administration route, because local, systemic and direct central nervous system (CNS) delivery can be achived; this could be utilized in the therapy of CNS diseases. Therefore, the goal of this study was to design, prepare and investigate a novel, lamotrigin containing NC formulation for nasal administration. The determination of micrometric parameters (particle size, polydispersity index, surface charge), in vitro (drug loading capacity, release and permeability investigations) and in vivo characterization of the formulations were performed in the study. The results indicate that the formulation could be a promising alternative of lamotrigine (LAM) as the NCs were around 305 nm size with high encapsulation efficiency (58.44%). Moreover, the LAM showed rapid and high release from the NCs in vitro and considerable penetration to the brain tissues was observed during the in vivo study.

mRNA-activated matrices encoding transcription factors as primers of cell differentiation in tissue engineering

Gene-activated matrices (GAMs) encoding pivotal transcription factors (TFs) represent a powerful tool to direct stem cell specification for tissue engineering applications. However, current TF-based GAMs activated with pDNA, are challenged by their low transfection efficiency and delayed transgene expression. Here, we report a GAM technology activated with mRNAs encoding TFs SOX9 (cartilage) and MYOD (muscle). We find that these mRNA-GAMs induce a higher and faster TF expression compared to pDNA-GAMs, especially in the case of RNase resistant mRNA sequences. This potent TF expression was translated into a high synthesis of cartilage- and muscle-specific markers, and ultimately, into successful tissue specification in vitro. Additionally, we show that the expression of tissue-specific markers can be further modulated by altering the properties of the mRNA-GAM environment. These results highlight the value of this GAM technology for priming cell lineage specification, a key centerpiece for future tissue engineering devices.

Self-assembled hyaluronan nanocapsules for the intracellular delivery of anticancer drugs

Preparation of sophisticated delivery systems for nanomedicine applications generally involve multi-step procedures using organic solvents. In this study, we have developed a simple self-assembling process to prepare docetaxel-loaded hyaluronic acid (HA) nanocapsules by using a self-emulsification process without the need of organic solvents, heat or high shear forces. These nanocapsules, which comprise an oily core and a shell consisting of an assembly of surfactants and hydrophobically modified HA, have a mean size of 130 nm, a zeta potential of -20 mV, and exhibit high docetaxel encapsulation efficiency. The nanocapsules exhibited an adequate stability in plasma. Furthermore, in vitro studies performed using A549 lung cancer cells, showed effective intracellular delivery of docetaxel. On the other hand, blank nanocapsules showed very low cytotoxicity. Overall, these results highlight the potential of self-emulsifying HA nanocapsules for intracellular drug delivery.

Co-delivery of RNAi and chemokine by polyarginine nanocapsules enables the modulation of myeloid-derived suppressor cells

Myeloid-Derived Suppressor Cells (MDSCs), immunosuppressive cells that promote tumor growth, represent an attractive target in cancer immunotherapy. However, the clinical success of this strategy is limited by the lack of efficient drug delivery vehicles targeting this cell compartment. The objective of this work was to develop a delivery carrier, multilayer polymer nanocapsules, with the capacity to co-encapsulate two types of immunomodulatory drugs, a chemokine and an RNAi sequence, aimed at reverting MDSC-mediated immunosuppression. The chemokine CCL2, intended to attract monocyte-macrophage MDSCs, was encapsulated within the L2 inverse micellar aqueous domains of the lipid core of these nanocapsules. On the other hand, two different RNAi sequences that modulate the CCAAT/enhancer-binding protein beta (C/EBPβ) pathway, shC/EBPβ and miR 142-3p, were successfully associated to their polymer shell. These RNAi sequences were covered by subsequent layers of polyarginine and hyaluronic acid, thereby creating multi-layered assemblies that protected them and facilitated their targeted delivery. The in vitro studies performed in primary MDSCs cultures showed the capacity of miR 142-3p-loaded nanocapsules to reduce the highly immunosuppressive monocyte-macrophage subset. Additionally, the encapsulation of CCL2 within the nanocapsules induced a potent monocyte-macrophage chemoattraction that could be used to direct the therapy to these cell subsets. Finally, in vitro and in vivo studies showed the capacity of shC/EBPβ-loaded nanocapsules to downregulate C/EBPβ levels in MDSCs and to reduce monocyte differentiation into tumor-associated macrophages in an MCA-203 fibrosarcoma mice model. In conclusion, the multilayer polymer nanocapsules described here are efficient vehicles for the co-delivery of proteins and RNA, and are potential candidates as nanomedicines for the modulation of MDSCs.

New scaffolds encapsulating TGF-β3/BMP-7 combinations driving strong chondrogenic differentiation

The regeneration of articular cartilage remains an unresolved question despite the current access to a variety of tissue scaffolds activated with growth factors relevant to this application. Further advances might result from combining more than one of these factors; here, we propose a scaffold composition optimized for the dual delivery of BMP-7 and TGF-β3, two proteins with described chondrogenic activity. First, we tested in a mesenchymal stem cell micromass culture with TGF-β3 whether the exposure to microspheres loaded with BMP-7 would improve cartilage formation. Histology and qRT-PCR data confirmed that the sustained release of BMP-7 cooperates with TGF-β3 towards chondrogenic differentiation. Then, we optimized a scaffold prototype for tissue culture and dual encapsulation of BMP-7 and TGF-β3. The scaffolds were prepared from poly(lactic-co-glycolic acid), and BMP-7/TGF-β3 were loaded as nanocomplexes with heparin and Tetronic 1107. The scaffolds showed the sustained release of both proteins over four weeks, with minimal burst effect. We finally cultured human mesenchymal stem cells on these scaffolds, in the absence of exogenous chondrogenic factor supplementation. The cells cultured on the scaffolds loaded with BMP-7 and TGF-β3 showed clear signs of cartilage formation macroscopically and histologically. RT-PCR studies confirmed a clear upregulation of cartilage markers SOX9 and Aggrecan. In summary, scaffolds encapsulating BMP-7 and TGF-β3 can efficiently deliver a cooperative growth factor combination that drives efficient cartilage formation in human mesenchymal stem cell cultures. These results open attractive perspectives towards in vivo translation of this technology in cartilage regeneration experiments.

Biomaterials to suppress cancer stem cells and disrupt their tumoral niche

Lack of improvement in the treatment options of several types of cancer can largely be attributed to the presence of a subpopulation of cancer cells with stem cell signatures and to the tumoral niche that supports and protects these cells. This review analyses the main strategies that specifically modulate or suppress cancer stem cells (CSCs) and the tumoral niche (TN), focusing on the role of biomaterials (i.e. implants, nanomedicines, etc.) in these therapies. In the case of CSCs, we discuss differentiation therapies and the disruption of critical cellular signaling networks. For the TN, we analyze diverse strategies to modulate tumor hypervascularization and hypoxia, tumor extracellular matrix, and the inflammatory and tumor immunosuppressive environment. Due to their capacity to control drug disposition and integrate diverse functionalities, biomaterial-based therapies can provide important benefits in these strategies. We illustrate this by providing case studies where biomaterial-based therapies either show CSC suppression and TN disruption or improved delivery of major modulators of these features. Finally, we discuss the future of these technologies in the framework of these emerging therapeutic concepts.

Pore size is a critical parameter for obtaining sustained protein release from electrochemically synthesized mesoporous silicon microparticles

Mesoporous silicon has become a material of high interest for drug delivery due to its outstanding internal surface area and inherent biodegradability. We have previously reported the preparation of mesoporous silicon microparticles (MS-MPs) synthesized by an advantageous electrochemical method, and showed that due to their inner structure they can adsorb proteins in amounts exceeding the mass of the carrier itself. Protein release from these MS-MPs showed low burst effect and fast delivery kinetics with complete release in a few hours. In this work, we explored if tailoring the size of the inner pores of the particles would retard the protein release process. To address this hypothesis, three new MS-MPs prototypes were prepared by electrochemical synthesis, and the resulting carriers were characterized for morphology, particle size, and pore structure. All MS-MP prototypes had 90 µm mean particle size, but depending on the current density applied for synthesis, pore size changed between 5 and 13 nm. The model protein α-chymotrypsinogen was loaded into MS-MPs by adsorption and solvent evaporation. In the subsequent release experiments, no burst release of the protein was detected for any prototype. However, prototypes with larger pores (>10 nm) reached 100% release in 24-48 h, whereas prototypes with small mesopores (<6 nm) still retained most of their cargo after 96 h. MS-MPs with ∼6 nm pores were loaded with the osteogenic factor BMP7, and sustained release of this protein for up to two weeks was achieved. In conclusion, our results confirm that tailoring pore size can modify protein release from MS-MPs, and that prototypes with potential therapeutic utility for regional delivery of osteogenic factors can be prepared by convenient techniques.

Hyaluronic acid/Chitosan nanoparticles as delivery vehicles for VEGF and PDGF-BB

The development of a vascular network in tissue-engineered constructs is a fundamental bottleneck of bioregenerative medicine, particularly when the size of the implant exceeds a certain limit given by diffusion lengths and/or if the host tissue shows a very active metabolism. One of the approaches to achieve the vascularization of tissue constructs is generating a sustained release of proangiogenic factors from the ischemic site. This work describes the formation and characterization of hyaluronic acid-chitosan (HA/CS) nanoparticles for the delivery of two pro-angiogenic growth factors: vascular endothelial growth factor (VEGF) and platelet derived growth factor (PDGF-BB). These nanoparticles were prepared by an ionic gelification technique, and different formulations were developed by encapsulating the growth factors in association with two stabilizing agents: bovine serum albumin or heparin sodium salt. These carriers were characterized with regard to their physicochemical properties, their stability in biological media, and their cytotoxicity in the C3a hepatoma cell line. The results show that nanoparticles around 200 nm can be prepared by this method. HA/CS nanoparticles were stable when incubated in EMEM cell culture medium or in water at 37°C for 24 h. Cell culture tests confirmed that HA/CS nanoparticles are not cytotoxic within the concentration range used for growth factor delivery. Moreover, HA/CS nanoparticles were able to entrap efficiently both growth factors, reaching association values of 94% and 54% for VEGF and PDGF, respectively. In vitro release studies confirm that PDGF-BB is released from HA/CS nanoparticles in a sustained manner over approximately 1 week. On the other hand, VEGF is completely released within the first 24 h.

A comparative study of chitosan and chitosan/cyclodextrin nanoparticles as potential carriers for the oral delivery of small peptides

The aim of this study was to characterize new nanoparticles (NPs) containing chitosan (CS), or CS/cyclodextrin (CDs), and evaluate their potential for the oral delivery of the peptide glutathione (GSH). More precisely, NP formulations composed of CS, CS/alpha-CD and CS/sulphobutyl ether-beta-cyclodextrin (SBE(7m)-beta-CD) were investigated for this application. CS/CD NPs showed particle sizes ranging from 200 to 500nm. GSH was loaded more efficiently in CS/SBE(7m)-beta-CD NPs by forming a complex between the tripeptide and the CD. X-ray Photoelectron Spectroscopy (XPS) analysis suggested that GSH is located in the core of CS/SBE(7m)-beta-CD NPs and that it is almost absent from the NP surface. Release studies performed in vitro at pH 1.2 and pH 6.8 showed that NP release properties can be modulated by selecting an appropriate CD. Transport studies performed in the frog intestine model confirmed that both CS and CS/CD nanoparticles could induce permeabilization of the intestinal epithelia. However, CS/SBE(7m)-beta-CD NPs provided absorption-enhancing properties in all segments of the duodenum, whereas CS NPs effect was restricted to the first segment of the duodenum. From the data obtained, we believe that CS/CD nanoparticles might represent an interesting technological platform for the oral administration of small peptides.

Silk fibroin/hyaluronan scaffolds for human mesenchymal stem cell culture in tissue engineering

The design of new bioactive scaffolds mimicking the physiologic environment present during tissue formation is an important frontier in biomaterials research. Herein, we evaluated scaffolds prepared from blends of two biopolymers: silk fibroin and hyaluronan. Our rationale was that such blends would allow the combination of silk fibroin's superior mechanical properties with the biological characteristics of hyaluronan. We prepared scaffolds with porous microstructures by freeze-drying aqueous solutions of silk fibroin and hyaluronan and subsequent incubation in methanol to induce water insolubility of silk fibroin. Hyaluronan acted as an efficient porogenic excipient for the silk fibroin scaffolding process, allowing the formation of microporous structures within the scaffolds under mild processing conditions. Mesenchymal stem cells were seeded on silk fibroin/hyaluronan scaffolds and cultured for three weeks. Histology of the constructs after cell culture showed enhanced cellular ingrowth into silk fibroin/hyaluronan scaffolds as compared to plain silk fibroin scaffolds. In the presence of tissue-inductive stimuli, in vitro stem cell culture on silk fibroin/hyaluronan scaffolds resulted in more efficient tissue formation when measured by glycosaminoglycan and type-I and type-III collagen gene expression, as compared to plain silk fibroin scaffolds. In conclusion, our data encourages further exploration of silk fibroin/hyaluronan scaffolds as biomimetic platform for mesenchymal stem cells in tissue engineering.

Optimization strategies for electrospun silk fibroin tissue engineering scaffolds

As a contribution to the functionality of scaffolds in tissue engineering, here we report on advanced scaffold design through introduction and evaluation of topographical, mechanical and chemical cues. For scaffolding, we used silk fibroin (SF), a well-established biomaterial. Biomimetic alignment of fibers was achieved as a function of the rotational speed of the cylindrical target during electrospinning of a SF solution blended with polyethylene oxide. Seeding fibrous SF scaffolds with human mesenchymal stem cells (hMSCs) demonstrated that fiber alignment could guide hMSC morphology and orientation demonstrating the impact of scaffold topography on the engineering of oriented tissues. Beyond currently established methodologies to measure bulk properties, we assessed the mechanical properties of the fibers by conducting extension at breakage experiments on the level of single fibers. Chemical modification of the scaffolds was tested using donor/acceptor fluorophore labeled fibronectin. Fluorescence resonance energy transfer imaging allowed to assess the conformation of fibronectin when adsorbed on the SF scaffolds, and demonstrated an intermediate extension level of its subunits. Biological assays based on hMSCs showed enhanced cellular adhesion and spreading as a result of fibronectin adsorbed on the scaffolds. Our studies demonstrate the versatility of SF as a biomaterial to engineer modified fibrous scaffolds and underscore the use of biofunctionally relevant analytical assays to optimize fibrous biomaterial scaffolds.

Nanoparticles for nasal vaccination

The great interest in mucosal vaccine delivery arises from the fact that mucosal surfaces represent the major site of entry for many pathogens. Among other mucosal sites, nasal delivery is especially attractive for immunization, as the nasal epithelium is characterized by relatively high permeability, low enzymatic activity and by the presence of an important number of immunocompetent cells. In addition to these advantageous characteristics, the nasal route could offer simplified and more cost-effective protocols for vaccination with improved patient compliance. The use of nanocarriers provides a suitable way for the nasal delivery of antigenic molecules. Besides improved protection and facilitated transport of the antigen, nanoparticulate delivery systems could also provide more effective antigen recognition by immune cells. These represent key factors in the optimal processing and presentation of the antigen, and therefore in the subsequent development of a suitable immune response. In this sense, the design of optimized vaccine nanocarriers offers a promising way for nasal mucosal vaccination.

Nanoparticles as protein and gene carriers to mucosal surfaces

One of the most exciting and challenging applications of nanotechnology in medicine is the development of nanocarriers for the intraepithelial delivery of biomacromolecules through mucosal surfaces. These biomacromolecules represent an increasingly important segment of the therapeutic arsenal; however, their potential is still limited by their instability and inability to cross biological barriers. Nanoparticle carriers have emerged as one of the most promising technologies to overcome this limitation, owing mainly to their demonstrated capacity to interact with biological barriers. In this review, we summarize the current advances made on nanoparticles designed for transmucosal delivery. Supported by the examples of a variety of therapeutic macromolecules – peptides and proteins, gene medicines and vaccines – we review the lessons learned from the past and we offer a future perspective for this field.

Novel drug nanocarriers combining hydrophilic cyclodextrins and chitosan

The aim of this study was to explore the possibility of obtaining nanoparticles (NPs) containing high amounts of cyclodextrin (CD) derivatives such as carboxymethyl-β-CD and sulphobutyl ether-β-CD. The rationale used was to combine the drug solubilizing and stabilizing properties of cyclodextrins (CDs) with the mucoadhesive properties of chitosan (CS) in a unique nanoparticulate drug delivery system. The size of the resulting NPs was affected by the nature of the CDs, ranging between 275 and 550 nm, whereas the zeta potential of the NPs was always positive and close to +35 mV. The positive zeta values, together with the results from NMR studies, suggest that CS is the major compound on the surface of the NPs, while CD molecules are strongly associated with the NP matrix. The empirical composition of the NPs was quantified by elemental analysis and the results indicated that the amount of CD associated with the NPs was strictly dependent on its electrostatic charge. Finally, in vitro stability studies indicated that the presence of CDs in the NP structure can prevent the aggregation of this nanometric carrier system in simulated intestinal fluid. Overall, this new type of NP represents an attractive drug delivery platform of particular interest for the oral administration of drugs with low bioavailability.

Protection of the peptide glutathione by complex formation with α-cyclodextrin: NMR spectroscopic analysis and stability study

The main objective of this work was to investigate the complexation mechanism of the tripeptide glutathione with alpha-cyclodextrin (alpha-CyD). The final purpose was to explore the possibility of using this complexation approach for preserving the stability of this peptide in all biological environments relevant for oral drug delivery. The complexes between the peptide and alpha-CyD were formed in aqueous solution and the complexation mechanism was investigated using different (1)H NMR experimental approaches. The resulting complexes were also studied with respect to their ability to protect the peptide against proteolytic degradation by the exopeptidase, gamma-glutamyltranspeptidase. The NMR experiment, 1D-saturation transfer NOE difference (STD), evidenced the interaction between alpha-CyD and glutathione. The binding constants, calculated by a titration method, were in the range of 55-70 M(-1) at 25 degrees C and in the range 68-72 M(-1) at 37 degrees C. Moreover, from the 1D-pulse field gradient spin echo-transverse-rotating frame nuclear Overhauser (PFGSE-T ROESY) spectra it was concluded that alpha-CyD binds preferably to the l-glutamate (side chain) moiety of glutathione, leaving the glycine residue exposed to the external medium. This result was consistent with those of the in vitro stability study, which indicated that the degradation of glutathione was markedly reduced to the half in 2h upon inclusion in alpha-CyD. Overall, these results show the possibility of protecting specific peptide groups by their inclusion in CyDs as well as the utility of NMR experiments for the understanding of this stabilization strategy.

Design and characterization of a new drug nanocarrier made from solid-liquid lipid mixtures

The classical lipid nanoparticles that have been proposed for drug delivery are composed of solid lipids. Due to their composition, these nanoparticles have a limited drug loading and controlled release capacity. The present work was aimed at modifying the inner structure of nanoparticles made of tripalmitin, lecithin, and poly(ethylene glycol) (PEG)-stearate with the incorporation of a liquid lipid (Miglyol 812 oil). The composition and structural organization of the components of the resulting nanoparticles were characterized by (1)H NMR spectroscopy. Any possible changes in the crystalline domains of individual components when in the form of the nanoparticles were investigated by differential scanning calorimetry (DSC) and X-ray diffraction spectroscopy. The results of the NMR analysis indicated a significant incorporation of the oil to the solid nanoparticle matrix. Furthermore, the relaxation time constants as well as the peak width of the (1)H NMR spectrum of the nanoparticles suggest the presence of the oil in the form of phase-separated liquid nanoreservoirs within the nanoparticles. This conclusion was supported by the observation of restricted diffusion dynamics for the oil molecules. Interestingly, the incorporation of the oil did not interfere with the crystallization of the solid lipids (tripalmitin and PEG-stearate). In conclusion, a new nanostructure consisting of solid lipids and oily nanodomains was developed. This structural modification of the solid lipid nanoparticles may have an effect on their encapsulation capacity and controlled release properties.

The performance of nanocarriers for transmucosal drug delivery

Most of the newly designed drug molecules are characterised by low solubility in aqueous medium, low permeability through biological membranes and/or an insufficient stability in the biological environment. Fundamental studies have provided proof-of-concept of the potential of particulate nanocarriers for overcoming these unsuitable properties. For example, it is known that polymeric nanosystems may enhance transmucosal transport of drugs with poor penetration capacities while preserving their biological activity. Moreover, in recent years it has become clear that through an appropriate selection of the nanosystem components it is possible to enhance its affinity for the mucosa and, hence, the residence time of the drug in contact with the absorptive epithelium. These properties, combined with a suitably tailored release profile can markedly increase the efficacy of pharmaceuticals. Overall, the properties that have been identified as critical for the performance of these delivery systems are particle size, surface charge and surface chemical composition. These properties are known to affect the physical and chemical stability of the nanoparticles in the biological environment as well as their ability to interact (unspecific bioadhesion, receptor-mediated interaction and so on) and, eventually, overcome biological barriers. The present article aims to critically review the latest advances in this area and to provide some insights into these complex issues. Thus, herein the most widely investigated transmucosal drug delivery nanosystems and their most promising applications are reported.

A new drug nanocarrier consisting of chitosan and hydoxypropylcyclodextrin

The objective of the present work was to develop a new drug nanocarrier consisting of nanoparticles made of chitosan and cyclodextrins. The rationale behind the design of this new nanosystem was to simultaneously implement the cyclodextrin drug complexation power and the inherent properties of chitosan nanoparticles, in a unique delivery system. The complexation with the cyclodextrin permits the solubilization as well as the protection for sensitive drugs, whereas the entrapment in the chitosan network is expected to facilitate their absorption. Chitosan nanoparticles including hydroxypropylcyclodextrins could be prepared by the ionic crosslinking of chitosan with sodium tripolyphosphate in the presence of cyclodextrins. Two hydrophobic drugs, triclosan and furosemide, were selected as models for complexation with the cyclodextrin and further entrapment in the chitosan nanocarrier. The resulting nanosystems were thoroughly characterized for their size and zeta potential and also for their ability to associate and deliver the complexed drugs. The results showed that the size of the nanoparticles was slightly affected by the incorporation of cyclodextrins, whereas the zeta potential did not suffer a significant modification. Moreover, the complexation of the drugs with the cyclodextrin facilitated their entrapment into the nanoparticles, increasing up to 4 and 10 times (for triclosan and furosemide, respectively) the final drug loading of the nanoparticles. These results led to the conclusion that the drug-cyclodextrin complex was efficiently retained in the nanoparticulate structure. Finally, the in vitro release profile observed for these nanoparticles was characterized by an initial fast release followed by a delayed release phase. In conclusion, this new nanosystem offers an interesting potential for the transmucosal delivery of hydrophobic compounds.

New surface-modified lipid nanoparticles as delivery vehicles for salmon calcitonin

The aim of the present work was to develop a new nanoparticulate system, consisting of lipid nanoparticles coated with chitosan (CS), intended for the oral administration of peptide drugs. These new nanoparticles were studied, and compared with the previously developed PEG-coated lipid nanoparticles, with regard to their ability to incorporate and deliver the model peptide salmon calcitonin (sCT). Moreover, the influence of the core composition, either a solid triglyceride (tripalmitin), or a mixture of a liquid and a solid triglyceride (Miglyol 812 and tripalmitin) on the encapsulation and release of sCT was investigated. The results showed that a CS coating could be formed around the tripalmitin nanoparticles by simple incubation of the lipid cores in a CS solution, due to the high affinity of CS for the lipid core. In addition, sCT could be efficiently associated, irrespective of the core composition, to the nanoparticles. This important association was attributed to the marked affinity of sCT for the lipid cores, as confirmed by the adsorption studies. However, the nature of the coating affected the surface association of the peptide, which was less important for the nanoparticles coated with CS, than for PEG-coated nanoparticles. This was attributed to the displacement of the sCT molecules located on the surface of the nanoparticles by the positively charged CS molecules. This reduced surface association led to a decrease in the burst release effect, which was more pronounced for the nanoparticles coated with PEG than for those coated with CS. Following the initial burst, the systems provided a continuous and slow release of the associated peptide, independently of the nature of the coating. This slow release was attributed to the affinity of the peptide for the lipids and to the absence of degradation of the lipid matrix under the in vitro release conditions.

A comparative study of the potential of solid triglyceride nanostructures coated with chitosan or poly(ethylene glycol) as carriers for oral calcitonin delivery

We have previously reported the formation and characterization of poly(ethylene glycol) (PEG)-coated and chitosan (CS)-coated lipid nanoparticles. In the present work our goal was to study the interaction of these surface-modified lipid nanoparticles with Caco-2 cells and to evaluate the potential of these nanostructures as oral delivery systems for salmon calcitonin (sCT). The interaction of rhodamine-loaded nanoparticles with the Caco-2 cell monolayers was evaluated quantitatively and qualitatively by confocal laser scanning microscopy and fluorimetry, respectively. The ability of these nanoparticles to reversibly enhance the transport of hydrophilic macromolecules through the monolayers was investigated by measuring the transepithelial electric resistance and the permeability to Texas Red-dextran. Finally, in vivo studies of the response to sCT-loaded nanoparticles were performed in rats. The results showed that the association of rhodamine-loaded nanoparticles to the Caco-2 cell monolayer was independent of the surface coating of the nanoparticles (CS-coated versus PEG-coated nanoparticles). However, while PEG-coated nanoparticles did not affect the permeability of Caco-2 monolayers, CS-coated nanoparticles produced a dose-dependent reduction in the transepithelial electric resistance, simultaneously to an enhanced dextran transport. The results obtained following oral administration of sCT-loaded CS-coated nanoparticles to rats showed a significant and prolonged reduction in the serum calcium levels as compared to those obtained for control (sCT solution). In contrast, the hypocalcemic response of sCT-loaded PEG-coated nanoparticles was not significantly different of that provided by the control (sCT solution). Therefore, these results indicate that the surface composition of the particles is a key factor in the improvement of the efficiency of oral sCT formulations. Moreover, the encouraging results obtained for CS-coated nanoparticles underline their potential as carriers for peptide delivery.

Application of NMR spectroscopy to the characterization of PEG-stabilized lipid nanoparticles

The main purpose of the present work was to apply NMR techniques to characterize the nanostructural organization of a new drug nanocarrier composed of tripalmitin, lecithin, and poly(ethylene glycol) (PEG)-stearate. These nanocarriers were prepared by an emulsification-solvent evaporation technique and were characterized for their composition and nanostructural architecture. The results showed that tripalmitin, present in the core of the nanoparticles, is the main component of these systems, whereas PEG-stearate is firmly attached to the surface of the nanoparticles, forming a hydrated polymeric layer. Furthermore, the results indicate that, by selecting appropriately the composition of the lipid mixtures used for nanoparticle preparation, it was possible to modulate the PEG-coating density. This rigorous characterization by NMR provided very useful information about the architectural organization of this new colloidal drug carrier and showed the potential of modern NMR techniques for the characterization of core-coated nanostructures intended for drug delivery.

Variables affecting BMI evolution at 2 and 5 years after vertical banded gastroplasty

BACKGROUND

Vertical banded gastroplasty (VBG) has been found to result in significant reduction in body mass index (BMI) during the first postoperative year. We investigated the impact of some intrinsic and extrinsic factors on long-term BMI evolution in morbidly obese patients who underwent VBG, with the aim of establishing a long-term weight-loss prognosis.

METHODS

67 consecutive morbidly obese patients who underwent VBG were followed for 2 years; of these, 34 were followed 3 more years, for a total follow-up of 5 years. BMI was monitored and correlated with demographic (preoperative BMI, obese relatives, age and gender) and lifestyle variables (physical activity, habitual dietary transgression and occupational status).

RESULTS

Global BMI fell from 47.5 at the time of the intervention to 32.1 when patients were examined 12 months after surgery. From the second year, an upward trend was observed, and at 5 years, mean BMI was above 35, considered in the high-risk range. Modifiable variables affecting lifestyle have shown significantly favorable effects on BMI evolution. Among intrinsic variables, BMI before surgery and obese parents also affect long-term evolution.

CONCLUSION

Different variables should be considered in order to establish a long-term weight-loss prognosis for each patient, thus making it possible to act more specifically on modifiable variables.

Polymorphism of the platelet glycoprotein IIIa gene in patients with coronary stenosis

Based on genetic variability, structural differences in the glycoprotein IIb/IIIa platelet receptor for adhesive proteins result in individual differences in the thrombogenicity of platelets. Recent studies suggest a controversial association between a genetic polymorphism of the glycoprotein IIIa gene (PlA2) and the risk of coronary artery disease. In our study, the prevalence of the PlA2 allele in a group of patients undergoing percutaneous coronary revascularization was 37%, a value significantly higher than in controls [13%, odds ratio (OR) = 3.93, 95% CI, 1.84 to 8.53] suggesting a significant association between this polymorphism and documented coronary stenosis, which is strongest among <60 years old patients (OR = 12.30, 95% CI, 2.98 to 70.93). This polymorphism represents an inherited risk factor for severe cardiovascular disease due to coronary occlusion.

Clinical features and outcome of 95 patients with hypersensitivity vasculitis

PURPOSE

To evaluate the clinical features and outcome of patients with isolated hypersensitivity vasculitis (HV).

PATIENTS AND METHODS

Retrospective study of patients with cutaneous vasculitis followed up at a University Hospital from 1975 to 1994. Patients with vasculitis secondary to collagen vascular diseases, neoplasia, or major infections were excluded. Patients were classified as HV according to the differential criteria proposed by Michel et al (J Rheumatol. 1992;19:721-728).

RESULTS

Ninety-five patients were classified as HV. The mean age was 42.7 +/- 21.7 years, with similar disease frequency in both sexes. In 43 patients, the precipitating event was drug therapy, either alone or as a treatment for a coexistent infection, usually an upper respiratory tract infection. The most frequent clinical manifestation was palpable purpura followed by joint symptoms. Systemic involvement was infrequent: 7 patients had nephropathy, manifested almost exclusively by microhematuria, and 5 patients had gastrointestinal symptoms. In 54 subjects the vasculitis did not require treatment; 26 patients were treated with NSAIDs, and 14 required corticosteroids (associated to immunosuppressive agents in 2 of them). After a mean follow-up of 15.5 +/- 28.9 months (median 6), only 2 patients had slight renal impairment, whereas the remaining had a complete recovery.

CONCLUSION

Hypersensitivity vasculitis is usually a benign syndrome, often secondary to drugs or infections, or both. Its main clinical manifestations are skin and joint symptoms. The systemic involvement is scarce and its prognosis is excellent.

Increased IgA-producing cells in the blood of patients with active Henoch-Schönlein purpura

Peripheral blood lymphocytes (PBL) producing IgA, IgM, and IgG, both spontaneously and after pokeweed mitogen stimulation in cell culture, were determined by a protein A hemolytic plaque assay in 20 children with active Henoch-Schönlein purpura (HSP), 42 with inactive disease, 22 normal controls of the same ages, and 18 children with upper respiratory tract infections (URTI). The geometric mean of circulating IgA-producing cells in active HSP (1,016 X divided by 1.55 cells/10(6) PBL) was increased when compared with the group with inactive disease (P less than 0.001), normal controls (P less than 0.001), and children with URTI (542 X divided by 2.03 cells/10(6) PBL, P less than 0.05). The number of circulating IgM-producing cells was slightly increased in active HSP (260 X divided by 2.65 cells/10(6) PBL) and URTI (256 X divided by 3.16 cells/10(6) PBL). Both values were higher than those found in the group with inactive disease (113 X divided by 2.26 cells/10(6) PBL, P less than 0.01). There were no significant differences among the 4 groups in the number of circulating IgG-producing cells. The number of cells producing each type of immunoglobulin after in vitro stimulation with pokeweed mitogen was similar in patients with active HSP, normal controls, and the group with inactive disease. These data demonstrate a selective increase in the number of circulating IgA-producing cells only during disease activity, and add further support to a possible pathogenic role of this immunoglobulin in HSP.

Serum complement components in Henoch-Schönlein purpura

Serum levels of C1q, C4, C3, C5, factor B, and properdin were measured in patients with Henoch-Schönlein purpura (HSP). In the cases of acute HSP, 9 of 23 (39%) had a low CH50, and 5 of 17 (30%) a low properdin; C1q, C4, and C3 levels were not depressed. In 10 cases with chronic nephritis following HSP, complement components were normal except for 2 with reduced C4 and one with low properdin. These findings confirm that complement activation occurs in HSP; the low serum levels of properdin in the acute group indicate that there is activation of the alternative pathway in these patients.

Cryoglobulinaemia in Henoch-Schönlein purpura

Sera from patients with Henoch-Schönlein purpura were examined for cryoglobulinaemia. Thirty patients had acute Henoch-Schönlein purpura, with or without renal diseas; 14 had chronic nephritis after a previous episode of purpura; and 17 were well, without urinary abnormalities, after recovering from Henoch-Schönlen purpura. Raised concentrations of cryoglobulins were present in 14 (47%) of those with acute purpura, nine (64%) of those with chronic nephritis, but none of those who had recovered completely from Henoch-Schönlein purpura. This suggests that acute Henoch-Schönlein purpura and the chronic nephritis that sometimes follows it have an immune-complex pathogenesis. IgA and properdin were found in several cryoglobulins, which suggested that complement had been activated via the alternative pathway, but isolated cryoglobulins capable of splitting C3 in vitro did so via the classical pathway.

Distal renal tubular acidosis in infancy: a bicarbonate wasting state

Three unrelated infants with apparently distal RTA were investigated. Growth retardation, polyuria, nephrocalcinosis, inappropriately high urinary pH, and marked dependence of bicarbonate excretion on urinary flow were characteristic of the distal or classic form of RTA, but the urinary loss of bicarbonate at normal serum values exceeded that usually found in children or adults with this disorder. Renal tubular function was studied during hypotonic saline diuresis in the three patients and in seven healthy control infants of similar age. Fractional delivery of sodium to the distal nephron was significantly higher in the patients than in control subjects. Sodium transport at the diluting segment was not impaired. The results support the assumption that the bicarbonate wasting was the consequence of an increased delivery of this substance to an already impaired distal nephron and thus further inhibited the distal mechanisms of net acid excretion.