In vitro activity of novel apramycin-dextran nanoparticles and free apramycin against selected Dutch and Pakistani Klebsiella pneumonia isolates

Klebsiella pneumoniae are bacteria associated with respiratory tract infections and are increasingly becoming resistant to antibiotics, including carbapenems. Apramycin is a veterinary antibiotic that may have the potential to be re-purposed for use in human health, for example, for the treatment of respiratory tract infections after coupling to inhalable nanoparticles. In the present study, the antibiotic apramycin was formulated with single chain polymeric nanoparticles and tested in free and formulated forms against a set of 13 Klebsiella pneumoniae isolates (from the Netherlands and Pakistan) expressing different aminoglycoside resistance phenotypes. Minimum Inhibitory Concentration, Time Kill Kinetics and biofilm experiments were performed providing evidence for the potential efficacy of apramycin and apramycin-based nanomedicines for the treatment of human Klebsiella pneumonia infections.

Self-Assembled Oleic Acid-Modified Polyallylamines for Improved siRNA Transfection Efficiency and Lower Cytotoxicity

Small interference RNA (siRNA) is a tool for gene modulation, which can silence any gene involved in genetic disorders. The potential of this therapeutic tool is hampered by RNA instability in the blood stream and difficulties to reach the cytosol. Polyamine-based nanoparticles play an important role in gene delivery. Polyallylamine hydrochloride (PAH) is a polycation displaying primary amines that can be easily chemically modified to match the balance between cell viability and siRNA transfection. In this work, PAH has been covalently functionalized with oleic acid at different molar ratios by carbodiimide chemistry. The substituted polymers form polyplexes that keep positive surface charge and fully encapsulate siRNA. Oleic acid substitution improves cell viability in the pulmonary cell line A549. Moreover, 6 and 14% of oleic acid substitution show an improvement in siRNA transfection efficiency. CD47 is a ubiquitous protein which acts as "don't eat me signal." SIRPα protein of macrophages recognizes CD47, leading to tumor cell phagocytosis by macrophages. By knocking down CD47 with siRNA, cancer cells become vulnerable to be eliminated by the immune system. PAH-oleic acid substitutes show high efficacy in silencing the CD47 protein, making them a potential candidate for immunotherapy.

3D Printable Dynamic Hydrogel: As Simple as it Gets!

3D Printing technology offers a vast range of applications for tissue engineering applications. Over the past decade a vast range of new equipment has been developed; while, 3D printable biomaterials, especially hydrogels, are investigated to fit the printability requirements. The current candidates for bioprinting often requires post-printing cross-linking to maintain their shape. On the other hand, dynamic hydrogels are considered as the most promising candidate for this application with their extrudability and self-healing properties. However, it proves to be very difficult to match the required rheological in a simple material. Here, we present for the first time the simplest formulation of a dynamic hydrogel based on thiol-functionalized hyaluronic acid formulated with gold ions that fulfill all the requirements to be printed without the use of external stimuli, as judged by the rheological studies. The printability was also demonstrated with a 3D printer allowing to print the dynamic hydrogel as it is, achieving 3D construct with a relatively good precision and up to 24 layers, corresponding to 10 mm high. This material is the simplest 3D printable hydrogel and its mixture with cells and biological compounds is expected to open a new era in 3D bioprinting. This article is protected by copyright. All rights reserved.

Artificial Cornea: Past, Current, and Future Directions

Corneal diseases are a leading cause of blindness with an estimated 10 million patients diagnosed with bilateral corneal blindness worldwide. Corneal transplantation is highly successful in low-risk patients with corneal blindness but often fails those with high-risk indications such as recurrent or chronic inflammatory disorders, history of glaucoma and herpetic infections, and those with neovascularisation of the host bed. Moreover, the need for donor corneas greatly exceeds the supply, especially in disadvantaged countries. Therefore, artificial and bio-mimetic corneas have been investigated for patients with indications that result in keratoplasty failure. Two long-lasting keratoprostheses with different indications, the Boston type-1 keratoprostheses and osteo-odonto-keratoprostheses have been adapted to minimise complications that have arisen over time. However, both utilise either autologous tissue or an allograft cornea to increase biointegration. To step away from the need for donor material, synthetic keratoprostheses with soft skirts have been introduced to increase biointegration between the device and native tissue. The AlphaCor™, a synthetic polymer (PHEMA) hydrogel, addressed certain complications of the previous versions of keratoprostheses but resulted in stromal melting and optic deposition. Efforts are being made towards creating synthetic keratoprostheses that emulate native corneas by the inclusion of biomolecules that support enhanced biointegration of the implant while reducing stromal melting and optic deposition. The field continues to shift towards more advanced bioengineering approaches to form replacement corneas. Certain biomolecules such as collagen are being investigated to create corneal substitutes, which can be used as the basis for bio-inks in 3D corneal bioprinting. Alternatively, decellularised corneas from mammalian sources have shown potential in replicating both the corneal composition and fibril architecture. This review will discuss the limitations of keratoplasty, milestones in the history of artificial corneal development, advancements in current artificial corneas, and future possibilities in this field.

Technological challenges in the preclinical development of an HIV nanovaccine candidate

Despite a very active research in the field of nanomedicine, only a few nano-based drug delivery systems have reached the market. The "death valley" between research and commercialization has been partially attributed to the limited characterization and reproducibility of the nanoformulations. Our group has previously reported the potential of a peptide-based nanovaccine candidate for the prevention of SIV infection in macaques. This vaccine candidate is composed of chitosan/dextran sulfate nanoparticles containing twelve SIV peptide antigens. The aim of this work was to rigorously characterize one of these nanoformulations containing a specific peptide, following a quality-by-design approach. The evaluation of the different quality attributes was performed by several complementary techniques, such as dynamic light scattering, nanoparticle tracking analysis, and electron microscopy for particle size characterization. The inter-batch reproducibility was validated by three independent laboratories. Finally, the long-term stability and scalability of the manufacturing technique were assessed. Overall, these data, together with the in vivo efficacy results obtained in macaques, underline the promise this new vaccine holds with regard to its translation to clinical trials. Graphical abstract.

Interfacial activity of modified dextran polysaccharide to produce enzyme-responsive oil-in-water nanoemulsions

Herein, we report the evaluation of dextran (DXT) derivatives bearing hydrophobic or hydrophilic functional groups as stabilisers of oil-in-water (O/W) emulsions. All investigated modifications conferred interfacial activity to produce stable O/W emulsions, methacrylate(MA)-functionalised DXT being the most promising stabiliser. A minimum amount of MA was required to obtain stable O/W nanoemulsions, which could be degraded in the presence of lipases.

A high molecular weight hyaluronic acid biphasic dispersion as potential therapeutics for interstitial cystitis

Interstitial cystitis (IC) is a progressive bladder disease characterized by increased urothelial permeability, inflammation of the bladder with abdominal pain. While there is no consensus on the etiology of the disease, it was believed that restoring the barrier between urinary solutes and (GAG) urothelium would interrupt the progression of this disease. Currently, several treatment options include intravesical delivery of hyaluronic acid (HA) and/or chondroitin sulfate solutions, through a catheter to restore the urothelial barrier, but have shown limited success in preclinical, clinical trials. Herein we report for the first time successful engineering and characterization of biphasic system developed by combining cross‐linked hyaluronic acid and naïve HA solution to decrease inflammation and permeability in an in vitro model of interstitial cystitis. The cross‐linking of HA was performed by 4‐arm‐polyethyeleneamine chemistry. The HA formulations were tested for their viscoelastic properties and the effects on cell metabolism, inflammatory markers, and permeability. Our study demonstrates the therapeutic effects of different ratios of the biphasic system and reports their ability to increase the barrier effect by decreasing the permeability and alteration of cell metabolism with respect to relative controls. Restoring the barrier by using biphasic system of HA therapy may be a promising approach to IC.

COSAN-stabilised omega-3 oil-in-water nanoemulsions to prolong lung residence time for poorly water soluble drugs

Herein, we report on the capacity of the amphiphilic inorganic anion cobalt bis(dicarbollide) to stabilise oil-in-water nanoemulsions (NEs). The resulting NEs show long term stability in water and high drug-loading capacity, and can prolong the residence time of hydrophobic drugs in the lungs as determined by in vivo positron emission tomography imaging.

Evaluation of Nisin and LL-37 Antimicrobial Peptides as Tool to Preserve Articular Cartilage Healing in a Septic Environment

Cartilage repair still represents a challenge for clinicians and only few effective therapies are nowadays available. In fact, surgery is limited by the tissue poor self-healing capacity while the autologous transplantation is often forsaken due to the poor in vitro expansion capacity of chondrocytes. Biomaterials science offers a unique alternative based on the replacement of the injured tissue with an artificial tissue-mimicking scaffold. However, the implantation surgical practices and the scaffold itself can be a source of bacterial infection that currently represents the first reason of implants failure due to the increasing antibiotics resistance of pathogens. So, alternative antibacterial tools to prevent infections and consequent device removal are urgently required. In this work, the role of Nisin and LL-37 peptides has been investigated as alternative to antibiotics to their antimicrobial performances for direct application at the surgical site or as doping chemicals for devices aimed at articular cartilage repair. First, peptides cytocompatibility was investigated toward human mesenchymal stem cells to determine safe concentrations; then, the broad-range antibacterial activity was verified toward the Gram-positive Staphylococcus aureus and Staphylococcus epidermidis as well as the Gram-negative Escherichia coli and Aggregatibacter actinomycetemcomitans pathogens. The peptides selective antibacterial activity was verified by a cells-bacteria co-culture assay, while chondrogenesis was assayed to exclude any interference within the differentiation route to simulate the tissue repair. In the next phase, the experiments were repeated by moving from the cell monolayer model to 3D cartilage-like spheroids to revisit the peptides activity in a more physiologically relevant environment model. Finally, the spheroid model was applied in a perfusion bioreactor to simulate an infection in the presence of circulating peptides within a physiological environment. Results suggested that 75 μg/ml Nisin can be considered as a very promising candidate since it was shown to be more cytocompatible and potent against the investigated bacteria than LL-37 in all the tested models.

Antimicrobial Peptide-Loaded Nanoparticles as Inhalation Therapy for Pseudomonas aeruginosa Infections

INTRODUCTION

Antibiotic-resistant bacteria kill 25,000 people every year in the EU. Patients subject to recurrent lung infections are the most vulnerable to severe or even lethal infections. For these patients, pulmonary delivery of antibiotics would be advantageous, since inhalation can achieve higher concentration in the lungs than iv administration and can provide a faster onset of action. This would allow for the delivery of higher doses and hence reduce the number of treatments required. We report here about a new nanosystem (M33-NS) obtained by capturing SET-M33 peptide on single-chain dextran nanoparticles. SET-M33 is a non-natural antimicrobial peptide synthesized in branched form. This form gives the peptide resistance to degradation in biological fluids. SET-M33 has previously shown efficacy in vitro against about one hundred of Gram-negative multidrug and extensively drug-resistant clinical isolates and was also active in preclinical infection models of pneumonia, sepsis and skin infections.

METHODS

The new nanosystem was evaluated for its efficacy in bacteria cells and in a mouse model of pneumonia. Toxicity and genotoxicity were also tested in vitro. Biodistribution and pharmacokinetic studies in healthy rats were carried out using a radiolabeled derivative of the nanosystem.

RESULTS

The M33-nanosystem, studied here, showed to be effective against Pseudomonas aeruginosa in time-kill kinetic experiments. Cytotoxicity towards different animal cell lines was acceptable. Lung residence time of the antimicrobial peptide, administered via aerosol in healthy rats, was markedly improved by capturing SET-M33 on dextran nanoparticles. M33-NS was also efficient in eradicating pulmonary infection in a BALB/c mouse model of pneumonia caused by P. aeruginosa.

DISCUSSION

This study revealed that the encapsulation of the antimicrobial peptide in dextran nanoparticles markedly improved lung residence time of the peptide administered via aerosol. The result has to be considered among the aims of the development of a new therapeutic option for patients suffering recurrent infections, that will benefit from high local doses of persistent antimicrobials.

Biocompatible single-chain polymer nanoparticles loaded with an antigen mimetic as potential anticancer vaccine

The "pancarcinoma" Tn antigen (αGalNAc-O-Ser/Thr) is a tumor-associated carbohydrate antigen (TACA) overexpressed on the surface of cancer cells and suitable target for anticancer vaccines. However, TACAs commonly show weak immunogenicity, low in vivo stability, and poor bioavailability. To address these issues, the development of physiologically stable TACA synthetic mimetics and novel nanocarriers for multivalent display are object of intense research. Nanomaterials represent suitable scaffolds to multimerize antigens, but absence of toxicity, easy functionalization and capability to incorporate biomolecules are compulsory characteristics for vaccine nanocarriers. Here, we report on the conjugation of a synthetic Tn-antigen mimetic to biocompatible and water-dispersible dextran-based single-chain nanoparticles (DXT-SCPNs). In vitro stimulation of PBMCs and analysis of interleukins production indicated a specific innate immune modulation mediated by the multivalent presentation of the Tn mimetic at the nanoparticle surface. These preliminary results pave the way for the development of Tn-mimetic clusters on biocompatible DXT-SCPN for TACA-based vaccines.

Abstract P3-13-23: Predicting residual disease in breast conservative surgery after neoadjuvant treatments in breast cancer patients using the margin index tool

Background. The appropriate surgical margin after neoadjuvant treatment (NAT) is controversial. Margin index, a relationship of the margin obtained to the size of the tumor, is a reliable method for the prediction of residual disease after breast conservative surgery (BCS) in the adjuvant setting. Our aim was to apply the margin index to patients with BCS after NAT to predict residual disease.

Material and Methods. From a prospectively maintained database, patients with stage I - III with NAT who underwent BCS between July 2008 and December 2012 were included. Margin index was calculated as for the adjuvant setting: margin index = closest margin (mm)/tumor size (mm) × 100 considering the tumor size of the lumpectomy specimen. A receiver operating curve was created using the derived margin index and the presence or absence of residual disease in the re-excision specimen. Patients with pathologic complete response (pCR) (no invasive tumor) were excluded.

Results. Of the 206 patients, 63 (30.5%) had a pCR and were excluded. Of the 143 patients, 76 (53%) had an intraoperative re-excision depending on the surgeon or the intraoperative pathology report. Of the 76 patients, 23 (32%) had residual tumor in the intraoperative re-excision specimen. There were no statistically significant differences in residual disease regardless of who indicates intraoperative re-excision. (p= 0.56) Twenty-three patients (16%) underwent a second surgery for positive or close margins ( < 2mm). Residual disease, whether infiltrating or in situ or both, was found in 10 (43%) patients. The overall c index for the receiver operating curve was 0.76. A margin index > 5 had a sensitivity of 80% and a specificity of 63%.

Conclusion. Rates of re-excision after NAT in BCS patients are similar to the adjuvant setting. Margin index may be a valuable tool for determine residual disease after NAT in patients undergoing BCS. Further validation of this index is warranted in a larger cohort of patients after NAT to confirm these results.

Citation Format: Rubio IT, Loinaz I, Esgueva-Colmenarejo AJ. Predicting residual disease in breast conservative surgery after neoadjuvant treatments in breast cancer patients using the margin index tool [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P3-13-23.

Synthesis and functionalization of dextran-based single-chain nanoparticles in aqueous media

Water-dispersible dextran-based single-chain polymer nanoparticles (SCPNs) were prepared in aqueous media and under mild conditions.

Functional Single-Chain Polymer Nanoparticles: Targeting and Imaging Pancreatic Tumors in Vivo

The development of tools for the early diagnosis of pancreatic adenocarcinoma is an urgent need in order to increase treatment success rate and reduce patient mortality. Here, we present a modular nanosystem platform integrating soft nanoparticles with a targeting peptide and an active imaging agent for diagnostics. Biocompatible single-chain polymer nanoparticles (SCPNs) based on poly(methacrylic acid) were prepared and functionalized with the somatostatin analogue PTR86 as the targeting moiety, since somatostatin receptors are overexpressed in pancreatic cancer. The gamma emitter 67Ga was incorporated by chelation and allowed in vivo investigation of the pharmacokinetic properties of the nanoparticles using single photon emission computerized tomography (SPECT). The resulting engineered nanosystem was tested in a xenograph mouse model of human pancreatic adenocarcinoma. Imaging results demonstrate that accumulation of targeted SCPNs in the tumor is higher than that observed for nontargeted nanoparticles due to improved retention in this tissue.

Injectable and self-healing dynamic hydrogel containing bioactive glass nanoparticles as a potential biomaterial for bone regeneration

Combination of Au-based dynamic hydrogel with 100 nm bioactive glass nanoparticles resulted in the formation of an injectable, self-healing and biocompatible hydrogel nanocomposites with osteoinductive properties and potential for bone regeneration.

Injectable and Self-Healing Dynamic Hydrogels Based on Metal(I)-Thiolate/Disulfide Exchange as Biomaterials with Tunable Mechanical Properties

Despite numerous strategies involving dynamic covalent bonds to produce self-healing hydrogels with similar frequency-dependent stiffness to native tissues, it remains challenging to use biologically relevant thiol/disulfide exchange to confer such properties to polymeric networks. Herein, we report a new method based on Metal(I) [Au(I) or Ag(I)] capping to protect thiolates from aerial oxidation without preventing thiolate/disulfide exchange. Dynamic hydrogels were readily prepared by injecting simultaneously aqueous solutions of commercially available HAuCl4 and 4-arm thiol-terminated polyethylene glycol [(PEGSH)4], resulting in a network containing a mixture of Au(I)-thiolate (Au-S) and disulfide bonds (SS). While the dynamic properties of the hydrogel were closely dependent on the pH, the mechanical properties could be easily tuned by adjusting (PEGSH)4 concentration and amount of Au-S, as judged by dynamic rheology studies. Permanent Au-S/SS exchange at physiological pH conferred self-healing behavior and frequency-dependent stiffness to the hydrogel. In addition, in vitro studies confirmed that Au-based dynamic material was not cytotoxic to human dermal fibroblasts, demonstrating its potential use as a medical device. Dynamic hydrogels obtained using Ag(I) ions demonstrated that the exchange reaction was not affected by the nature of the Metal(I) capping. Finally, this efficient thiolate capping strategy offers a simple way to produce injectable and self-healing dynamic hydrogels from virtually any thiol-containing polymers.

Intradermal air pouch leukocytosis as an in vivo test for nanoparticles

The need for test systems for nanoparticle biocompatibility, toxicity, and inflammatory or adaptive immunological responses is paramount. Nanoparticles should be free of microbiological and chemical contaminants, and devoid of toxicity. Nevertheless, in the absence of contamination, these particles may still induce undesired immunological effects in vivo, such as enhanced autoimmunity, hypersensitivity reactions, and fibrosis. Here we show that artificial particles of specific sizes affect immune cell recruitment as tested in a dermal air pouch model in mice. In addition, we demonstrate that the composition of nanoparticles may influence immune cell recruitment in vivo. Aside from biophysical characterizations in terms of hydrodynamic diameter, zeta potential, concentration, and atomic concentration of metals, we show that – after first-line in vitro assays – characterization of cellular and molecular effects by dermal air pouch analysis is straightforward and should be included in the quality control of nanoparticles. We demonstrate this for innate immunological effects such as neutrophil recruitment and the production of immune-modulating matrix metalloproteases such as MMP-9; we propose the use of air pouch leukocytosis analysis as a future standard assay.

Converting drugs into gelators: supramolecular hydrogels from N-acetyl-L-cysteine and coinage-metal salts

Here we present the concept of metallophilic hydrogels, supramolecular systems in which the gelator species are metal-thiolates that self-assemble through metallophilic attractions. The principle is applied for a small drug, the mucolytic agent N-acetyl-l-cysteine (NAC), which readily forms hydrogels in the presence of Au(iii), Ag(i) and Cu(ii) salts. The resulting transparent hydrogels present pH induced sol/gel transition. Scanning electron microscopy (SEM) measurements reveal a microporous structure in form of flakes for the three of them. The low pH at which these hydrogels are formed (pH < 4) limits their direct use as drug-delivery systems, but still this system constitutes a novel method for easy and fast conversion of small drugs into potent hydrogelators. Future developments will help to fully develop the idea in order to create a new class of supramolecular drug-delivery systems.

Electronic anabolic steroid recognition with carbon nanotube field-effect transistors

A proof of concept of the electronic detection of two anabolic steroids, stanozolol (Stz) and methylboldenone (MB), was carried out using two specific antibodies and arrays of carbon nanotube field-effect transistors (CNTFETs). Antibodies specific for Stz and MB were prepared and immobilized on the carbon nanotubes (CNTs) using two different approaches: direct noncovalent bonding of antibodies to the devices and bonding the antibodies covalently to a polymer previously attached to the CNTFETs. The results indicated that CNTFETs bonded to specific antibodies covalently or noncovalently are able to detect the presence of steroids. Statistically significant changes in the threshold voltage and drain current were registered in the transistors, allowing the steroids to be recognized. On the other hand, it was determined that the specific antibodies do not detect other steroids other than Stz and MB, such as nandrolone (ND) because, in this case, statistically significant changes in the transistors were not detected. The polymer prevents the aggregation of antibodies on the electrodes and decreases the transistor hysteresis. Nevertheless, it is not able to avoid the nonspecific adsorption of streptavidin, meaning that nonspecific adsorption on CNTs remains a problem and that this methodology is only useful for purified samples. Regarding the detection mechanism, in addition to charge transfer, Schottky barrier, SB, modification, and scattering potential reported by other authors, an electron/hole trapping mechanism leading to hysteresis modification has been determined. The presence of polymer seems to hinder the modulation of the electrode-CNT contact.

Label-free DNA biosensors based on functionalized carbon nanotube field effect transistors

A carbon nanotube transistor array was used to detect DNA hybridization. A new approach to ensure specific adsorption of DNA to the nanotubes was developed. The polymer poly (methylmethacrylate(0.6)-co-poly(ethyleneglycol)methacrylate(0.15)-co-N-succinimidyl methacrylate(0.25)) was synthesized and bonded noncovalently to the nanotube. Aminated single-strand DNA was then attached covalently to the polymer. After hybridization, statistically significant changes were observed in key transistor parameters. Hybridized DNA traps both electrons and holes, possibly caused by the charge-trapping nature of the base pairs.

Synthesis of Type II β-Turn Surrogate Dipeptides Based on syn-α-Amino-α,β-dialkyl-β-lactams

The achiral bis(trimethylsilyl)methyl group acts as an efficient stereochemical determinant of the alpha-alkylation reaction in beta-branched alpha-phenyloxazolidinyl- or alpha-diphenyloxazolidinyl-beta-lactams and provides the first stereocontrolled access to syn-alpha-amino-alpha,beta-dialkyl(aryl)-beta-lactams. These products are readily transformed into type II beta-turn mimetic surrogates 2B. [reaction: see text]

Scavenging of fluorinated N,N'-dialkylureas by hydrogen binding: a novel separation method for fluorous synthesis

[reaction: see text] A dramatic solubility increase in fluorous solvents is observed for N,N'-di(polyfluoroalkyl)ureas when hydrogen binding complexes are formed with commercially available perfluoroalkanoic acid scavengers. As a case example, analytically pure peptides and esters are obtained using this novel separation method.