3D printing of gellan-dextran methacrylate IPNs in glycerol and their bioadhesion by RGD derivatives

The ever-growing need for new tissue and organ replacement approaches paved the way for tissue engineering. Successful tissue regeneration requires an appropriate scaffold, which allows cell adhesion and provides mechanical support during tissue repair. In this light, an interpenetrating polymer network (IPN) system based on biocompatible polysaccharides, dextran (Dex) and gellan (Ge), was designed and proposed as a surface that facilitates cell adhesion in tissue engineering applications. The new matrix was developed in glycerol, an unconventional solvent, before the chemical functionalization of the polymer backbone, which provides the system with enhanced properties, such as increased stiffness and bioadhesiveness. Dex was modified introducing methacrylic groups, which are known to be sensitive to UV light. At the same time, Ge was functionalized with RGD moieties, known as promoters for cell adhesion. The printability of the systems was evaluated by exploiting the ability of glycerol to act as a co-initiator in the process, speeding up the kinetics of crosslinking. Following semi-IPNs formation, the solvent was removed by extensive solvent exchange with HEPES and CaCl2, leading to conversion into IPNs due to the ionic gelation of Ge chains. Mechanical properties were investigated and IPNs ability to promote osteoblasts adhesion was evaluated on thin-layer, 3D-printed disk films. Our results show a significant increase in adhesion on hydrogels decorated with RGD moieties, where osteoblasts adopted the spindle-shaped morphology typical of adherent mesenchymal cells. Our findings support the use of RGD-decorated Ge/Dex IPNs as new matrices able to support and facilitate cell adhesion in the perspective of bone tissue regeneration.

The European Polysaccharide Network of Excellence (EPNOE) research roadmap 2040: Advanced strategies for exploiting the vast potential of polysaccharides as renewable bioresources

Polysaccharides are among the most abundant bioresources on earth and consequently need to play a pivotal role when addressing existential scientific challenges like climate change and the shift from fossil-based to sustainable biobased materials. The Research Roadmap 2040 of the European Polysaccharide Network of Excellence (EPNOE) provides an expert's view on how future research and development strategies need to evolve to fully exploit the vast potential of polysaccharides as renewable bioresources. It is addressed to academic researchers, companies, as well as policymakers and covers five strategic areas that are of great importance in the context of polysaccharide related research: (I) Materials & Engineering, (II) Food & Nutrition, (III) Biomedical Applications, (IV) Chemistry, Biology & Physics, and (V) Skills & Education. Each section summarizes the state of research, identifies challenges that are currently faced, project achievements and developments that are expected in the upcoming 20 years, and finally provides outlines on how future research activities need to evolve.

Polysaccharide-Based Nanogels to Overcome Mucus, Skin, Cornea, and Blood-Brain Barriers: A Review

Nanocarriers have been extensively developed in the biomedical field to enhance the treatment of various diseases. However, to effectively deliver therapeutic agents to desired target tissues and enhance their pharmacological activity, these nanocarriers must overcome biological barriers, such as mucus gel, skin, cornea, and blood-brain barriers. Polysaccharides possess qualities such as excellent biocompatibility, biodegradability, unique biological properties, and good accessibility, making them ideal materials for constructing drug delivery carriers. Nanogels, as a novel drug delivery platform, consist of three-dimensional polymer networks at the nanoscale, offering a promising strategy for encapsulating different pharmaceutical agents, prolonging retention time, and enhancing penetration. These attractive properties offer great potential for the utilization of polysaccharide-based nanogels as drug delivery systems to overcome biological barriers. Hence, this review discusses the properties of various barriers and the associated constraints, followed by summarizing the most recent development of polysaccharide-based nanogels in drug delivery to overcome biological barriers. It is expected to provide inspiration and motivation for better design and development of polysaccharide-based drug delivery systems to enhance bioavailability and efficacy while minimizing side effects.

Polyacrylate-Cholesterol Amphiphilic Derivative: Formulation Development and Scale-up for Health Care Applications

The novel amphiphilic polyacrylate grafted with cholesterol moieties, PAAbCH, previously synthesized, was deeply characterized and investigated in the lab and on a pre-industrial scale. Solid-state NMR analysis confirmed the polymer structure, and several water-based pharmaceutical and cosmetic products were developed. In particular, stable oil/water emulsions with vegetable oils, squalene, and ceramides were prepared, as well as hydrophilic medicated films loaded with diclofenac, providing a prolonged drug release. PAAbCH also formed polyelectrolyte hydrogel complexes with chitosan, both at the macro- and nano-scale. The results demonstrate that this polymer has promising potential as an innovative excipient, acting as a solubility enhancer, viscosity enhancer, and emulsifying agent with an easy scale-up transfer process.

Hyaluronan-estradiol nanogels as potential drug carriers to target ER+ breast cancer cell line

An innovative hyaluronan-based nano-delivery system is proposed for the active targeting towards ER+ breast cancer. Hyaluronic acid (HA), an endogenous and bioactive anionic polysaccharide, is functionalized with estradiol (ES), a sexual hormone involved in the development of some hormone-dependent tumors, to give an amphiphilic derivative (HA-ES) able to spontaneously self-assemble in water to form soft nanoparticles or nanogels (NHs). The synthetic strategy used to obtain the polymer derivatives and the physico-chemical properties of the obtained nanogels (ES-NHs) are reported. ES-NHs ability to entrap hydrophobic molecules has also been investigated, by loading curcumin (CUR) and docetaxel (DTX), both able to inhibit the growth of ER+ breast cancer. The formulations are studied for their capability to inhibit the growth of the MCF-7 cell line, thus evaluating their efficacy and potential as a selective drug delivery systems. Our results demonstrate that ES-NHs have not toxic effects on the cell line, and that both ES-NHs/CUR and ES-NHs/DTX treatments inhibit MCF-7 cell growth, with ES-NHs/DTX effect higher than that of free DTX. Our findings support the use of ES-NHs to deliver drugs to ER+ breast cancer cells, assuming a receptor-dependent targeting.

Rhinitis associated with asthma is distinct from rhinitis alone: The ARIA-MeDALL hypothesis

Asthma, rhinitis and atopic dermatitis (AD) are interrelated clinical phenotypes that partly overlap in the human interactome. The concept of "one-airway-one-disease", coined over 20 years ago, is a simplistic approach of the links between upper- and lower-airway allergic diseases. With new data, it is time to reassess the concept. This article reviews (i) the clinical observations that led to Allergic Rhinitis and its Impact on Asthma (ARIA), (ii) new insights into polysensitisation and multimorbidity, (iii) advances in mHealth for novel phenotype definition, (iv) confirmation in canonical epidemiologic studies, (v) genomic findings, (vi) treatment approaches and (vii) novel concepts on the onset of rhinitis and multimorbidity. One recent concept, bringing together upper- and lower-airway allergic diseases with skin, gut and neuropsychiatric multimorbidities, is the "Epithelial Barrier Hypothesis". This review determined that the "one-airway-one-disease" concept does not always hold true and that several phenotypes of disease can be defined. These phenotypes include an extreme "allergic" (asthma) phenotype combining asthma, rhinitis and conjunctivitis. Rhinitis alone and rhinitis and asthma multimorbidity represent two distinct diseases with the following differences: (i) genomic and transcriptomic background (Toll-Like Receptors and IL-17 for rhinitis alone as a local disease; IL-33 and IL-5 for allergic and non-allergic multimorbidity as a systemic disease), (ii) allergen sensitisation patterns (mono- or pauci-sensitisation versus polysensitisation), (iii) severity of symptoms and (iv) treatment response. In conclusion, rhinitis alone (local disease) and rhinitis with asthma multimorbidity (systemic disease) should be considered as two distinct diseases, possibly modulated by the microbiome, and may be a model for understanding the epidemics of chronic and auto-immune diseases.

Dual Nanostructured Lipid Carriers/Hydrogel System for Delivery of Curcumin for Topical Skin Applications

This work focuses on the development and evaluation of a dual nanostructured lipid carrier (NLC)/Carbopol®-based hydrogel system as a potential transporter for the topical delivery of curcumin to the skin. Two populations of different sized negatively charged NLCs (P1, 70–90 nm and P2, 300–350 nm) were prepared and characterized by means of dynamic light scattering. NLCs presented an ovoid platelet shape confirmed by transmission electron microscopy techniques. Curcumin NLC entrapment efficiency and release profiles were assessed by HPLC (high pressure liquid chromatography) and spectrophotometric methods. Preservation and enhancement of curcumin (CUR) antioxidant activity in NLCs (up to 7-fold) was established and cell viability assays on fibroblasts and keratinocytes indicated that CUR-NLCs are non-cytotoxic for concentrations up to 10 μM and exhibited a moderate anti-migration/proliferation effect (20% gap reduction). CUR-NLCs were then embedded in a Carbopol®-based hydrogel without disturbing the mechanical properties of the gel. Penetration studies on Franz diffusion cells over 24 h in CUR-NLCs and CUR-NLCs/gels demonstrated an accumulation of CUR in Strat-M® membranes of 22% and 5%, respectively. All presented data support the use of this new dual CUR-NLC/hydrogel system as a promising candidate for adjuvant treatment in topical dermal applications.

Therapeutic effects of dexamethasone-loaded hyaluronan nanogels in the experimental cholestasis

A major function of the intrahepatic biliary epithelium is bicarbonate excretion in bile. Recent reports indicate that budesonide, a corticosteroid with high receptor affinity and hepatic first pass clearance, increases the efficacy of ursodeoxycholic acid, a choleretic agent, in primary biliary cholangitis patients. We have previously reported that bile ducts isolated from rats treated with dexamethasone or budesonide showed an enhanced activity of the Na⁺/H⁺ exchanger isoform 1 (NHE1) and Cl^-/HCO₃^- exchanger protein 2 (AE2) . Increasing the delivery of steroids to the liver may result in three beneficial effects: increase in the choleresis, treatment of the autoimmune or inflammatory liver injury and reduction of steroids' systemic harmful effects. In this study, the steroid dexamethasone was loaded into nanohydrogels (or nanogels, NHs), in order to investigate corticosteroid-induced increased activities of transport processes driving bicarbonate excretion in the biliary epithelium (NHE-1 isoform) and to evaluate the effects of dexamethasone-loaded NHs (NHs/dex) on liver injury induced by experimental cholestatis. Our results showed that NHs and NHs/dex do not reduce cell viability in vitro in human cholangiocyte cell lines. Primary and immortalized human cholangiocytes treated with NHs/dex show an increase in the functional marker expression of NHE1 cholangiocytes compared to control groups. A mouse model of cholangiopathy treated with NHs/dex shows a reduction in markers of hepatocellular injury compared to control groups (NHs, dex, or sham group). In conclusion, we believe that the NHs/dex formulation is a suitable candidate to be investigated in preclinical models of cholangiopathies.

Hyaluronan-Cholesterol Nanogels for the Enhancement of the Ocular Delivery of Therapeutics

The anatomy and physiology of the eye strongly limit the bioavailability of locally administered drugs. The entrapment of therapeutics into nanocarriers represents an effective strategy for the topical treatment of several ocular disorders, as they may protect the embedded molecules, enabling drug residence on the ocular surface and/or its penetration into different ocular compartments. The present work shows the activity of hyaluronan-cholesterol nanogels (NHs) as ocular permeation enhancers. Thanks to their bioadhesive properties, NHs firmly interact with the superficial corneal epithelium, without penetrating the stroma, thus modifying the transcorneal penetration of loaded therapeutics. Ex vivo transcorneal permeation experiments show that the permeation of hydrophilic drugs (i.e., tobramycin and diclofenac sodium salt), loaded in NHs, is significantly enhanced when compared to the free drug solutions. On the other side, the permeation of hydrophobic drugs (i.e., dexamethasone and piroxicam) is strongly dependent on the water solubility of the entrapped molecules. The obtained results suggest that NHs formulations can improve the ocular bioavailability of the instilled drugs by increasing their preocular retention time (hydrophobic drugs) or facilitating their permeation (hydrophilic drugs), thus opening the route for the application of HA-based NHs in the treatment of both anterior and posterior eye segment diseases.

Volume fraction determination of microgel composed of interpenetrating polymer networks of PNIPAM and polyacrylic acid

Interpenetrated polymer network microgels, composed of crosslinked networks of poly(N-isopropylacrylamide) and polyacrylic acid (PAAc), have been investigated through rheological measurements at four different amounts of PAAc. Both PAAc content and crosslinking degree modify particle dimensions, mass and softness, thereby strongly affecting the volume fraction and the system viscosity. Here the volume fraction is derived from the flow curves at low concentrations by fitting the zero-shear viscosity with the Einstein-Batchelor equation which provides a parameterkto shift weight concentration to volume fraction. We find that particles with higher PAAc content and crosslinker are characterized by a greater value ofkand therefore by larger volume fractions when compared to softer particles. The packing fractions obtained from rheological measurements are compared with those from static light scattering for two PAAc contents revealing a good agreement. Moreover, the behaviour of the viscosity as a function of packing fraction, at room temperature, has highlighted an Arrhenius dependence for microgels synthesized with low PAAc content and a Vogel-Fulcher-Tammann dependence for the highest investigated PAAc concentration. A comparison with the hard spheres behaviour indicates a steepest increase of the viscosity with decreasing particles softness. Finally, the volume fraction dependence of the viscosity at a fixed PAAc and at two different temperatures, below and above the volume phase transition, shows a quantitative agreement with the structural relaxation time measured through dynamic light scattering indicating that interpenetrated polymer network microgels softness can be tuned with PAAc and temperature and that, depending on particle softness, two different routes are followed.

Biodistribution and intracellular localization of hyaluronan and its nanogels. A strategy to target intracellular S. aureus in persistent skin infections

Intracellular pathogens are a critical challenge for antimicrobial therapies. Staphylococcus aureus (S. aureus) causes approximately 85% of all skin and soft tissue infections in humans worldwide and more than 30% of patients develop chronic or recurrent infections within three months, even after appropriate antibacterial therapies. S. aureus is also one of the most common bacteria found in chronic wounds. Recent evidences suggest that S. aureus is able to persist within phagolysosomes of skin cells (i.e. keratinocytes, phagocytic cells), being protected from both the immune system and a number of antimicrobials. To overcome these limits, nano-formulations that enable targeted therapies against intracellular S. aureus might be developed. Herein, the biodistribution and intracellular localisation of hyaluronan (HA) and HA-based nanoparticles (nanogels, NHs) are investigated, both after intravenous (i.v.) injections (in mice) and topical administrations (in ex vivo human skin). Results indicate HA and NHs accumulate especially in skin and liver of mice after i.v. injection. After topical application on human skin explants, no penetration of both HA and NHs was detected in skin with intact stratum corneum. By contrast, in barrier-disrupted human skin (with partial removal and loosening of stratum corneum), HA and NHs penetrate to the viable epidermis and are taken up by keratinocytes. In mechanically produced wounds (skin without epidermis) they accumulate in wound tissue and are taken up by dermis cells, e.g. fibroblasts and phagocytic cells. Interestingly, in all cases, the cellular uptake is CD44-mediated. In vitro studies confirmed that after CD44-mediated uptake, both HA and NHs accumulate in lysosomes of dermal fibroblasts and macrophages, as previously reported for keratinocytes. Finally, the colocalisation between intracellular S. aureus and HA or NHs is demonstrated, in macrophages. Altogether, for the first time, these results strongly suggest that HA and HA-based NHs can provide a targeted therapy to intracellular S. aureus, in persistent skin or wound infections.

Nano-hydrogel embedded with quercetin and oleic acid as a new formulation in the treatment of diabetic foot ulcer: A pilot study

Wound healing, especially diabetic ones, is a relevant clinical problem, so it is not surprising that surgical procedures are often needed. To overcome invasive procedures, several strategies with drugs or natural compound are used. Recently, in an experimental study, we described an increase in keratinocyte proliferation after their exposition to quercetin plus oleic acid. In the present clinical study, we evaluated both the clinical efficacy and the safety of nano-hydrogel embedded with quercetin and oleic acid in the treatment of lower limb skin wound in patients with diabetes mellitus (DM). Fifty-six DM patients (28 men and 28 women, mean age 61.7 ± 9.2 years) unsuccessfully treated with mechanical compression were enrolled and randomised to receive an add on treatment with hyaluronic acid (0.2%) or nano-hydrogel embedded with quercetin and oleic acid. The treatment with nano-hydrogel embedded with quercetin and oleic acid significantly (P < .01) reduced the wound healing time, in comparison to hyaluronic acid (0.2%) without developing of adverse drug reactions, suggesting that this formulation could be used in the management of wound healing even if other clinical trials must be performed in order to validate this observation.

Intracellular Delivery of Natural Antioxidants via Hyaluronan Nanohydrogels

Natural antioxidants, such as astaxanthin (AX), resveratrol (RV) and curcumin (CU), are bioactive molecules that show a number of therapeutic effects. However, their applications are remarkably limited by their poor water solubility, physico-chemical instability and low bioavailability. In the present work, it is shown that self-assembled hyaluronan (HA)-based nanohydrogels (NHs) are taken up by endothelial cells (Human Umbilical Vein Endothelial Cells, HUVECs), preferentially accumulating in the perinuclear area of oxidatively stressed HUVECs, as evidenced by flow cytometry and confocal microscopy analyses. Furthermore, NHs are able to physically entrap and to significantly enhance the apparent water solubility of AX, RV and CU in aqueous media. AX/NHs, RV/NHs and CU/NHs systems showed good hydrodynamic diameters (287, 214 and 267 nm, respectively), suitable ζ-potential values (-45, -43 and -37 mV, respectively) and the capability to neutralise reactive oxygen species (ROS) in tube. AX/NHs system was also able to neutralise ROS in vitro and did not show any toxicity against HUVECs. This research suggests that HA-based NHs can represent a kind of nano-carrier suitable for the intracellular delivery of antioxidant agents, for the treatment of oxidative stress in endothelial cells.

Halting hyaluronidase activity with hyaluronan-based nanohydrogels: development of versatile injectable formulations

Hyaluronan (HA) is among the most used biopolymers for viscosupplementation and dermocosmetics. However, the current injectable HA-based formulations present relevant limitations: I) unmodified HA is quickly degraded by endogenous hyaluronidases (HAase), resulting in short lasting properties; II) cross-linked HA, although shows enhanced stability against HAase, often contains toxic chemical cross-linkers. As such, herein, we present biocompatible self-assembled hyaluronan-cholesterol nanohydrogels (HA-CH NHs) able to bind to HAase and inhibit the enzyme activity in vitro, more efficiently than currently marketed HA-based cross-linked formulations (e.g. Jonexa™). HA-CH NHs inhibit HAase through a mixed mechanism, by which NHs bind to HAase with an affinity constant 7-fold higher than that of native HA. Similar NHs, based on gellan-CH, evidenced no binding to HAase, neither inhibition of the enzyme activity, suggesting this effect might be due to the specific binding of HA-CH to the active site of the enzyme. Therefore, HA-CH NHs were engineered into injectable hybrid HA mixtures or physical hydrogels, able to halt the enzymatic degradation of HA.

Uptake and intracellular fate of biocompatible nanocarriers in cycling and noncycling cells

AIM

To elucidate whether different cytokinetic features (i.e., presence or absence of mitotic activity) may influence cell uptake and distribution of nanocarriers, in vitro tests on liposomes, mesoporous silica nanoparticles, poly(lactide-co-glycolide) nanoparticles and nanohydrogels were carried out on C2C12 murine muscle cells either able to proliferate as myoblasts (cycling cells) or terminally differentiate into myotubes (noncycling cells).

MATERIALS & METHODS

Cell uptake and intracellular fate of liposomes, mesoporous silica nanoparticles, poly(lactide-co-glycolide) nanoparticles and nanohydrogels were investigated by confocal fluorescence microscopy and transmission electron microscopy.

RESULTS

Nanocarrier internalization and distribution were similar in myoblasts and myotubes; however, myotubes demonstrated a lower uptake capability.

CONCLUSION

All nanocarriers proved to be suitably biocompatible for both myoblasts and myotubes. The lower uptake capability of myotubes is probably due to different plasma membrane composition related to the differentiation process.

Advances in Drug Delivery and Biomaterials: Facts and Vision

Drug delivery and biomaterials are different fields of science but, at the same time, are tightly related and intertwined. The 2018 CRS Italy Chapter Annual Workshop aims to explore recent advances in design and development in these areas. Many colleagues from Europe participated to the Workshop, stimulating the discussion. To foster the discussion on recent research and networking opportunities, especially among younger attendees, all poster-presenting authors were asked to provide a short talk. The very friendly and stimulating atmosphere allowed the attendees to explore new frontiers and tackle new horizons.

Long-Circulating Hyaluronan-Based Nanohydrogels as Carriers of Hydrophobic Drugs

Nanohydrogels based on natural polymers, such as polysaccharides, are gaining interest as vehicles for therapeutic agents, as they can modify the pharmacokinetics and pharmacodynamics of the carried drugs. In this work, hyaluronan-riboflavin nanohydrogels were tested in vivo in healthy rats highlighting their lack of toxicity, even at high doses, and their different biodistribution with respect to that of native hyaluronan. They were also exploited as carriers of a hydrophobic model drug, the anti-inflammatory piroxicam, that was physically embedded within the nanohydrogels by an autoclave treatment. The nanoformulation was tested by intravenous administration showing an improvement of the pharmacokinetic parameters of the molecule. The obtained results indicate that hyaluronan-based self-assembled nanohydrogels are suitable systems for low-soluble drug administration, by increasing the dose as well as the circulation time of poorly available therapeutic agents.

Hyaluronan-Based Nanohydrogels for Targeting Intracellular S. Aureus in Human Keratinocytes

Staphylococcus aureus is one of the most significant human pathogens that is frequently isolated in a wide range of superficial and systemic infections. The ability of S. aureus to invade and survive within host cells such as keratinocytes and host immune cells has been increasingly recognized as a potential factor in persistent infections and treatment failures. The incorporation of antibiotics into hyaluronan-cholesterol nanohydrogels represents a novel paradigm in the delivery of therapeutic agents against intracellular bacteria. The work presented herein shows that NHs quickly enter human keratinocytes and accumulate into lysosomes. When used for targeting intracellular S. aureus the antimicrobial activity of loaded levofloxacin is enhanced, possibly changing the antibiotic intracellular fate from cytosol to lysosome. Indeed, gentamicin, an antibiotic that predominantly accumulates in lysosomes, shows significant and equal antibacterial activity when entrapped into NHs. These results strongly suggest that lysosomal formulations may display preferential activity toward intracellular S. aureus, opening new avenues for the use of HA-based NHs for treatment of such skin infections.

Pursuing Intracellular Pathogens with Hyaluronan. From a 'Pro-Infection' Polymer to a Biomaterial for 'Trojan Horse' Systems

Hyaluronan (HA) is among the most important bioactive polymers in mammals, playing a key role in a number of biological functions. In the last decades, it has been increasingly studied as a biomaterial for drug delivery systems, thanks to its physico-chemical features and ability to target and enter certain cells. The most important receptor of HA is ‘Cluster of Differentiation 44’ (CD44), a cell surface glycoprotein over-expressed by a number of cancers and heavily involved in HA endocytosis. Moreover, CD44 is highly expressed by keratinocytes, activated macrophages and fibroblasts, all of which can act as ‘reservoirs’ for intracellular pathogens. Interestingly, both CD44 and HA appear to play a key role for the invasion and persistence of such microorganisms within the cells. As such, HA is increasingly recognised as a potential target for nano-carriers development, to pursuit and target intracellular pathogens, acting as a ‘Trojan Horse’. This review describes the biological relationship between HA, CD44 and the entry and survival of a number of pathogens within the cells and the subsequent development of HA-based nano-carriers for enhancing the intracellular activity of antimicrobials.

Preparation of gellan-cholesterol nanohydrogels embedding baicalin and evaluation of their wound healing activity

In the present work, the preparation, characterization and therapeutic potential of baicalin-loaded nanohydrogels are reported. The nanohydrogels were prepared by sonicating (S nanohydrogel) or autoclaving (A nanohydrogel) a dispersion of cholesterol-derivatized gellan in phosphate buffer. The nanohydrogel obtained by autoclave treatment showed the most promising results: smaller particles (∼362 nm vs. ∼530 nm), higher homogeneity (polydispersity index = ∼0.24 vs. ∼0.47), and lower viscosity than those obtained by sonication. In vitro studies demonstrated the ability of the nanohydrogels to favour the deposition of baicalin in the epidermis. A high biocompatibility was found for baicalin-loaded nanohydrogels, along with a great ability to counteract the toxic effect induced by hydrogen peroxide in cells, as the nanohydrogels re-established the normal conditions (∼100% viability). Further, the potential of baicalin-loaded nanohydrogels in skin wound healing was demonstrated in vivo in mice by complete skin restoration and inhibition of specific inflammatory markers (i.e., myeloperoxidase, tumor necrosis factor-α, and oedema).

PVA/Dextran hydrogel patches as delivery system of antioxidant astaxanthin: a cardiovascular approach

After myocardial infarction, the heart's mechanical properties and its intrinsic capability to recover are compromised. To improve this recovery, several groups have developed cardiac patches based on different biomaterials strategies. Here, we developed polyvinylalcohol/dextran (PVA/Dex) elastic hydrogel patches, obtained through the freeze thawing (FT) process, with the aim to deliver locally a potent natural antioxidant molecule, astaxanthin, and to assist the heart's response against the generated myofibril stress. Extensive rheological and dynamo-mechanical characterization of the effect of the PVA molecular weight, number of freeze-thawing cycles and Dex addition on the mechanical properties of the resulting hydrogels, were carried out. Hydrogel systems based on PVA 145 kDa and PVA 47 kDa blended with Dex 40 kDa, were chosen as the most promising candidates for this application. In order to improve astaxanthin solubility, an inclusion system using hydroxypropyl-β-cyclodextrin was prepared. This system was posteriorly loaded within the PVA/Dex hydrogels. PVA145/Dex 1FT and PVA47/Dex 3FT showed the best rheological and mechanical properties when compared to the other studied systems; environmental scanning electron microscope and confocal imaging evidenced a porous structure of the hydrogels allowing astaxanthin release. In vitro cellular behavior was analyzed after 24 h of contact with astaxanthin-loaded hydrogels. In vivo subcutaneous biocompatibility was performed in rats using PVA145/Dex 1FT, as the best compromise between mechanical support and astaxanthin delivery. Finally, ex vivo and in vivo experiments showed good mechanical and compatibility properties of this hydrogel. The obtained results showed that the studied materials have a potential to be used as myocardial patches to assist infarcted heart mechanical function and to reduce oxidative stress by the in situ release of astaxanthin.

Nanodesign of new self-assembling core-shell gellan-transfersomes loading baicalin and in vivo evaluation of repair response in skin

Gellan nanohydrogel and phospholipid vesicles were combined to incorporate baicalin in new self-assembling core-shell gellan-transfersomes obtained by an easy, scalable method. The vesicles were small in size (~107 nm) and monodispersed (P.I. ≤ 0.24), forming a viscous system (~24 mPa/s) as compared to transfersomes (~1.6 mPa/s), as confirmed by rheological studies. Gellan was anchored to the bilayer domains through cholesterol, and the polymer chains were distributed onto the outer surface of the bilayer, thus forming a core-shell structure, as suggested by SAXS analyses. The optimal carrier ability of core-shell gellan-transfersomes was established by the high deposition of baicalin in the skin (~11% in the whole skin), especially in the deeper tissue (~8% in the dermis). Moreover, their ability to improve baicalin efficacy in anti-inflammatory and skin repair tests was confirmed in vivo in mice, providing the complete skin restoration and inhibiting all the studied inflammatory markers.

Glycerosomes: Investigation of role of 1,2-dimyristoyl-sn-glycero-3-phosphatidycholine (DMPC) on the assembling and skin delivery performances

Glycerosomes were formulated using 1,2-dimyristoyl-sn-glycero-3-phosphatidycholine (DMPC), diclofenac sodium salt and 10, 20 or 30% glycerol in the water phase, while corresponding liposomes were prepared with the same amount of DMPC and diclofenac, without glycerol. The aim of the present work was to evaluate the effect of the used phospholipid on vesicle features and ability to favour diclofenac skin deposition by comparing these results with those found in previous works performed using hydrogenated soy phosphatidylcholine (P90H) and dipalmitoylphosphatidylcholine (DPPC). Liposomes and glycerosomes were multilamellar, liposomes being smaller (72±6nm). Interactions among glycerol, phospholipids and drug led to the formation of a non-rigid bilayer structure and a variation of the main transition temperature, which shifted to lower temperature. The addition of glycerol led to the formation of more viscous systems (from ∼2.5mPa/s for basic liposomes to ∼5mPa/s for glycerosomes), which improved spread ability of the formulations on the skin.Results obtained in vitro were promising using glycerosomes, irrespective of the amount of glycerol used: the amount of drug, which accumulated into and permeated through the different skin strata, was high and comparable with that obtained using P90H, suggesting that glycerosomes may represent an efficient carrier for both local effect or systemic absorption.

"Click" hyaluronan based nanohydrogels as multifunctionalizable carriers for hydrophobic drugs

Highly hydrophilic and biocompatible nanocarriers based on polysaccharide hydrogels (nanohydrogels, NHs) were shown to be promising systems for drug delivery applications. Following the idea of these emerging drug carriers, the aim of the present work was to develop self-assembled hydrogel nanoparticles based on amphiphilic derivatives of hyaluronic acid (HA) and riboflavin (Rfv), synthesized by "click" Copper(I)-catalyzed Azide-Alkyne Cycloaddition (CuAAC) reaction. The obtained amphiphilic product (HA-c-Rfv) was able to form nanohydrogels in aqueous environments, in particular by applying an innovative autoclave-based method. HA of different molecular weights (M_w) and degrees of substitution (DS) were prepared and the effect of these parameters on the NHs formation was assessed. The derivative HA²²⁰-c-Rfv 40/40 was chosen as the most interesting system, capable to form NHs in the range of 150-200nm and with a negative ζ-potential. NHs were very stable in water solutions and, by adding dextrose as cryoprotectant, it was also possible to freeze-dry the NHs formulation. The developed system is proposed for the delivery of hydrophobic drugs; for this purpose, dexamethasone, piroxicam and paclitaxel were used as model drugs; these molecules were loaded into NHs with high efficiency by film-hydration technique. Furthermore, a HA-c-Rfv derivative bearing an excess of propargylic portions was capable to react with other N₃-derivatized molecules, opening the route to a wide spectrum of functionalization opportunities: in this direction, PEG-N₃ has been tested as a model molecule for the preparation of PEGylated NHs.

Design of Hybrid Gels Based on Gellan-Cholesterol Derivative and P90G Liposomes for Drug Depot Applications

Gels are extensively studied in the drug delivery field because of their potential benefits in therapeutics. Depot gel systems fall in this area, and the interest in their development has been focused on long-lasting, biocompatible, and resorbable delivery devices. The present work describes a new class of hybrid gels that stem from the interaction between liposomes based on P90G phospholipid and the cholesterol derivative of the polysaccharide gellan. The mechanical properties of these gels and the delivery profiles of the anti-inflammatory model drug diclofenac embedded in such systems confirmed the suitability of these hybrid gels as a good candidate for drug depot applications.

Glycerosomes: Use of hydrogenated soy phosphatidylcholine mixture and its effect on vesicle features and diclofenac skin penetration

In this work, diclofenac was encapsulated, as sodium salt, in glycerosomes containing 10, 20 or 30% of glycerol in the water phase with the aim to ameliorate its topical efficacy. Taking into account previous findings, glycerosome formulation was modified, in terms of economic suitability, using a cheap and commercially available mixture of hydrogenated soy phosphatidylcholine (P90H). P90H glycerosomes were spherical and multilamellar; photon correlation spectroscopy showed that obtained vesicles were ∼131nm, slightly larger and more polydispersed than those made with dipalmitoylphosphatidylcholine (DPPC) but, surprisingly, they were able to ameliorate the local delivery of diclofenac, which was improved with respect to previous findings, in particular using glycerosomes containing high amount of glycerol (20 and 30%). Finally, this drug delivery system showed a high in vitro biocompatibility toward human keratinocytes.

Bioactive hydrogel scaffolds - advances in cartilage regeneration through controlled drug delivery

The importance of growth factor delivery in cartilage tissue engineering is nowadays widely recognized. However, when growth factors are administered by a bolus injection, they undergo rapid clearance before they could stimulate the cells of interest at promoting cartilage repair. Their short half-lives make growth factors ineffective, unless administered at supraphysiological doses, with potentially harmful consequences on patient safety. Recently, new tissue engineering strategies relying on the combination of biodegradable scaffolds and specific biological cues, such as growth or adhesive factors or genetic material, have demonstrated that controlled release is the key factor for achieving effective cartilage repair at lower drug doses. Among all biomaterials, hydrogels have emerged as promising cartilage tissue engineering scaffolds for simultaneous cell growth and drug delivery. In fact, hydrogels can be easily loaded with cells and drugs, that are subsequently released in a controlled fashion. The success of hydrogels in controlled drug delivery for tissue engineering originates from their biocompatibility and capacity to integrate well with the host tissue. This review overviews the hydrogels technologies now available for the regeneration of cartilage that base their efficacy on the controlled release of bioactive substances able to modulate cellular behavior and to eventually lead to successful tissue repair.

Effects of ethanol and diclofenac on the organization of hydrogenated phosphatidylcholine bilayer vesicles and their ability as skin carriers

In this study, the effects of ethanol and/or diclofenac on vesicle bilayer structure have been studied. Liposomes with hydrogenated soy phosphatidylcholine, cholesterol and two different concentrations of diclofenac sodium (5 and 10 mg/ml) were obtained. In addition, ethanol was mixed in the water phase at different concentrations (5, 10 and 20 % v/v) to obtain ethosomes. To characterize vesicles, rehological analysis were carried out to investigate the intervesicle interactions, while bilayer structure was evaluated by small- and wide-angle X-ray scattering. Finally, the ethanol and/or diclofenac concentration-dependent ability to improve diclofenac skin delivery was evaluated in vitro. The addition of 20 % ethanol and/or diclofenac led to solid-like ethosome dispersion due to the formation of a new intervesicle structure, as previously found in transcutol containing vesicle dispersions. However, when using 5-10 % of ethanol the induction to form vesicle interconnections was less evident but the simultaneous presence of the drug at the highest concentration facilitated this phenomenon. Ethosomes containing the highest amount of both, drug (10 mg/ml) and ethanol (20 % v/v), improved the drug deposition in the skin strata and in the receptor fluid up to 1.5-fold, relative to liposomes. Moreover this solid-like formulation can easily overcome drawbacks of traditional liquid liposome formulations which undergo a substantial loss at the application site.

One-step formation and sterilization of gellan and hyaluronan nanohydrogels using autoclave

The sterilization of nanoparticles for biomedical applications is one of the challenges that must be faced in the development of nanoparticulate systems. Usually, autoclave sterilization cannot be applied because of stability concerns when polymeric nanoparticles are involved. This paper describes an innovative method which allows to obtain, using a single step autoclave procedure, the preparation and, at the same time, the sterilization of self-assembling nanohydrogels (NHs) obtained with cholesterol-derivatized gellan and hyaluronic acid. Moreover, by using this approach, NHs, while formed in the autoclave, can be easily loaded with drugs. The obtained NHs dispersion can be lyophilized in the presence of a cryoprotectant, leading to the original NHs after re-dispersion in water.

Gel-embedded niosomes: preparation, characterization and release studies of a new system for topical drug delivery

In the present paper physical gels, prepared with two polysaccharides, Xanthan and Locust Bean Gum, and loaded with non-ionic surfactant vesicles, are described. The vesicles, composed by Tween20 and cholesterol or by Tween85 and Span20, were loaded with Monoammonium glycyrrhizinate for release experiments. Size and zeta (ζ)-potential of the vesicles were evaluated and the new systems were characterized by rheological and dynamo-mechanical measurements. For an appropriate comparison, a Carbopol gel and a commercial gel for topical applications were also tested. The new formulations showed mechanical properties comparable with those of the commercial product indicating their suitability for topical applications. In vitro release experiments showed that the polysaccharide network protects the integrity of the vesicles and leads to their slow release without disruption of the aggregated structures. Furthermore, being the vesicles composed of molecules possessing enhancing properties, the permeation of the loaded drugs topically delivered can be improved. Thus, the new systems combine the advantages of matrices for a modified release (polymeric component) and those of an easier permeability across the skin (vesicle components). Finally, shelf live experiments indicated that the tested gel/vesicle formulations were stable over 1 year with no need of preservatives.

Polyaspartamide-doxorubicin conjugate as potential prodrug for anticancer therapy

PURPOSE

To synthesize a new polymeric prodrug based on α,β-poly(N-2-hydroxyethyl)(2-aminoethylcarbamate)-d,l-aspartamide copolymer bearing amine groups in the side chain (PHEA-EDA), covalently linked to the anticancer drug doxorubicin and to test its potential application in anticancer therapy.

METHODS

The drug was previously derivatized with a biocompatible and hydrophilic linker, leading to a doxorubicin derivative highly reactive with amino groups of PHEA-EDA. The PHEA-EDA-DOXO prodrug was characterized in terms of chemical stability. The pharmacokinetics, biodistribution and cytotoxicity of the product was investigated in vitro and in vivo on human breast cancer MCF-7 and T47D cell lines and NOD-SCID mice bearing a MCF-7 human breast carcinoma xenograft. Data collected were compared to those obtained using free doxorubicin.

RESULTS

The final polymeric product is water soluble and easily hydrolysable in vivo, due to the presence of ester and amide bonds along the spacer between the drug and the polymeric backbone. In vitro tests showed a retarded cytotoxic effect on tumor cells, whereas a significant improvement of the in vivo antitumor activity of PHEA-EDA-DOXO and a survival advantage of the treated NOD-SCID mice was evidenced, compared to that of free doxorubicin.

CONCLUSIONS

The features of the PHEA-EDA-DOXO provide a potential protection of the drug from the plasmatic enzymatic degradation and clearance, an improvement of the blood pharmacokinetic parameters and a suitable body biodistribution. The data collected support the promising rationale of the proposed macromolecular prodrug PHEA-EDA-DOXO for further potential development and application in the treatment of solid cancer diseases.

Highly versatile nanohydrogel platform based on riboflavin-polysaccharide derivatives useful in the development of intrinsically fluorescent and cytocompatible drug carriers

In this work we describe a new nanohydrogel platform, based on polysaccharides modified with the hydrophobic and fluorescent molecule riboflavin tetrabutyrate, which leads to innovative structures useful for drug delivery applications. Hyaluronic acid and pullulan were chosen as representative of anionic and neutral polysaccharides, respectively, and the bromohexyl derivative of riboflavin tetrabutyrate was chemically linked to these polymer chains. Because of such derivatization, polymer chains were able to self-assemble in aqueous environment thus forming nanohydrogels, with mean diameters of about 312 and 210 nm, for hyaluronan and pullulan, respectively. These new nanohydrogels showed low polydispersity index, and negative ζ-potential. Moreover, the nanohydrogels, which can be easily loaded with model drugs, showed long-term stability in water and physiological conditions and excellent cytocompatibility. All these properties allow to consider these intrinsically fluorescent nanohydrogels suitable for the formulation of innovative drug dosage forms.

The relation of airway obstruction to asthma, chronic rhinosinusitis and age: results from a population survey of adults

RATIONALE

There is conflicting evidence on whether patients with asthma experience an accelerated decline in lung function with age. We examined the association between postbronchodilator lung function, asthma, chronic rhinosinusitis (CRS), and atopy with age using a large European sample.

METHODS

In 17 centers in 11 European countries, case-control studies were nested within representative cross-sectional surveys of adults aged less than 75 years. Representative samples of participants with asthma, CRS or both and controls were assessed for postbronchodilator ventilatory function, smoking history, atopy, and treatment. Multiple regression was used to assess the interactive effects of age and diagnostic group on decline in postbronchodilator ventilatory function.

RESULTS

A total of 3337 participants provided adequate data (778 with asthma, 399 with CRS, 244 with both asthma and CRS and 1916 controls who had neither asthma nor CRS). Participants with asthma had lower FEV1 /FVC (-4.09% (95% CI: -5.02, -3.15, P < 0.001) and a steeper slope of FEV1 /FVC against age (-0.14%/annum [95%CI: -0.19, -0.08]) equivalent to smoking 1-2 packs of cigarettes per day. Those with atopy had a slope equivalent to controls.

CONCLUSIONS

People with asthma have a steeper decline in postbronchodilator lung function with age, but neither CRS nor atopy alone were associated with such decline.

Topical KGF treatment as a therapeutic strategy for vaginal atrophy in a model of ovariectomized mice

One of the most frequent complaints for post-menopausal women is vaginal atrophy, because of reduction in circulating oestrogens. Treatments based on local oestrogen administration have been questioned as topic oestrogens can reach the bloodstream, thus leading to consider their safety as controversial, especially for patients with a history of breast or endometrial cancers. Recently, growth factors have been shown to interact with the oestrogen pathway, but the mechanisms still need to be fully clarified. In this study, we investigated the effect of keratinocyte growth factor (KGF), a known mitogen for epithelial cells, on human vaginal mucosa cells, and its potential crosstalk with oestrogen pathways. We also tested the in vivo efficacy of KGF local administration on vaginal atrophy in a murine model. We demonstrated that KGF is able to induce proliferation of vaginal mucosa, and we gained insight on its mechanism of action by highlighting its contribution to switch ERα signalling towards non-genomic pathway. Moreover, we demonstrated that KGF restores vaginal trophism in vivo similarly to intravaginal oestrogenic preparations, without systemic effects. Therefore, we suggest a possible alternative therapy for vaginal atrophy devoid of the risks related to oestrogen-based treatments, and a patent (no. RM2012A000404) has been applied for this study.

Design and characterization of a chitosan physical gel promoting wound healing in mice

In this study, a sterile and biocompatible chitosan (CHI) gel for wound healing applications was formulated. CHI powder was treated in autoclave (ttCHI) to prepare sterile formulations. The heat treatment modified the CHI molecular weight, as evidenced by GPC analysis, and its physical-chemical features. Differential scanning calorimetry studies indicated that the macromolecules, before and after thermal treatment, differ in the strength of water-polymer interaction leading to different viscoelastic and flow properties. Thermally treated CHI exhibited the following effects: (i) increased the proliferation and migration of human foreskin foetal fibroblasts at 24 h; (ii) accelerated wound healing (measured as area of lesion) at 3 and 10 days in an in vivo model of pressure ulcers. These effects were linked to the increase of the hydroxyproline and haemoglobin content as well as Wnt protein expression. Moreover, we found a reduction of myeloperoxidase activity and TNF-α mRNA expression. These observations suggest the potential of this novel CHI gel in wound healing and other therapeutic applications.