Causative factors behind poloxamer 188 (Pluronic F68, Flocor™)-induced complement activation in human sera

Preclinical Efficacy of Cabazitaxel Loaded Poly(2-alkyl cyanoacrylate) Nanoparticle Variants

Background

Biodegradable poly(alkyl cyanoacrylate) (PACA) nanoparticles (NPs) are receiving increasing attention in anti-cancer nanomedicine development not only for targeted cancer chemotherapy, but also for modulation of the tumor microenvironment. We previously reported promising results with cabazitaxel (CBZ) loaded poly(2-ethylbutyl cyanoacrylate) NPs (PEBCA-CBZ NPs) in a patient derived xenograft (PDX) model of triple-negative breast cancer, and this was associated with a decrease in M2 macrophages. The present study aims at comparing two endotoxin-free PACA NP variants (PEBCA and poly(2-ethylhexyl cyanoacrylate); PEHCA), loaded with CBZ and test whether conjugation with folate would improve their effect.

Methods

Cytotoxicity assays and cellular uptake of NPs by flow cytometry were performed in different breast cancer cells. Biodistribution and efficacy studies were performed in PDX models of breast cancer. Tumor associated immune cells were analyzed by multiparametric flow cytometry.

Results

In vitro studies showed similar NP-induced cytotoxicity patterns despite difference in early NP internalization. On intravenous injection, the liver cleared the majority of NPs. Efficacy studies in the HBCx39 PDX model demonstrated an enhanced effect of drug-loaded PEBCA variants compared with free drug and PEHCA NPs. Furthermore, the folate conjugated PEBCA variant did not show any enhanced effects compared with the unconjugated counterpart which might be due to unfavorable orientation of folate on the NPs. Finally, analyses of the immune cell populations in tumors revealed that treatment with drug loaded PEBCA variants affected the myeloid cells, especially macrophages, contributing to an inflammatory, immune activated tumor microenvironment.

Conclusion

We report for the first time, comparative efficacy of PEBCA and PEHCA NP variants in triple negative breast cancer models and show that CBZ-loaded PEBCA NPs exhibit a combined effect on tumor cells and on the tumor associated myeloid compartment, which may boost the anti-tumor response.

Accelerated blood clearance of PEGylated nanoparticles induced by PEG-based pharmaceutical excipients

PEGylated nanomedicines have been extensively developed and applied to cancer therapy. However, the antitumor efficacy of these nanoparticles is hampered by the accelerated blood clearance (ABC) effect caused by anti-PEG antibodies in vivo. There is still limited understanding about the cause of pre-existing anti-PEG antibodies in the human body. Herein, we discovered that PEG-based pharmaceutical excipients, commonly used in clinical and daily settings, could induce anti-PEG antibodies in vivo and lead to considerable potential clinical impacts on pharmacokinetics and pharmacodynamics of PEGylated nanoparticles. Specifically, we investigated the ability of poloxamer 188 (F68) and poloxamer 407 (F127), the two most frequently used PEG-based pharmaceutical excipients, to elicit the production of anti-PEG antibodies and influence the pharmacokinetics of PEGylated nanoparticles, with PEGylated liposome nanoparticles (L-NPs) as a model. Anti-PEG IgG and IgM levels were significantly boosted 3.8- and 32.2-fold, respectively, after pre-injection with F68, leading to rapid clearance of subsequently injected L-NPs from circulation due to the capture by neutrophils and monocytes. However, pre-injection of F127 did not induce the production of anti-PEG IgG, although there was a 7.7-fold increase in IgM level, which resulted in minimal effect on circulation time of L-NPs. Furthermore, the potential clinical impacts of F68 and F127 were further inspected for PEGylated liposomal doxorubicin (PLD). It was found that administering F68 prior to treatment led to over a one-third decrease in the antitumor effectiveness of PLD, while F127 had a negligible impact. Our study elucidates the mechanism by which PEG-based pharmaceutical excipients influence the effectiveness of PEGylated nanomedicines. It also highlights the significance of considering the potential for an ABC effect induced by PEG-based pharmaceutical excipients in patients.

HRMAS-NMR and simulation study of the self-assembly of surfactants on carbon nanotubes

Polyethoxylated surfactants, such as those of the Tween and Pluronic series, are commonly used to disperse carbon nanotubes (CNTs) and other nanoparticles. However, the current understanding of the nature of interactions between these surfactants and CNTs is limited. The nature of the interactions between surfactants (Tween-80 [T80] and Pluronic F68 [PF68]) and CNTs was investigated using high-resolution magic angle spinning nuclear magnetic resonance (HRMAS-NMR) and coarse-grained molecular dynamics (MD) simulations. HRMAS-NMR revealed that T80 molecules interact with single-walled CNTs (SWCNTs) and multi-walled CNTs (MWCNTs) via the oleyl chain, whereas PF68 molecules interact with the surface of SWCNTs and MWCNTs via the polypropylene oxide residues. The polyethylene oxide chains were oriented towards the external aqueous environment. The HRMAS-NMR results were supported by MD simulations, and the latter provided further insights into the nature of the interactions.

Micelle Formation and Phase Separation of Poloxamer 188 and Preservative Molecules in Aqueous Solutions Studied by Small Angle X-ray Scattering

Multi-injection pharmaceutical products such as insulin must be formulated to prevent aggregation and microbial contamination. Small-molecule preservatives and nonionic surfactants such as poloxamer 188 (P188) are thus often employed in protein drug formulations. However, mixtures of preservatives and surfactants can induce aggregation and even phase separation over time, despite the fact that all components are well dissolvable when used alone in aqueous solution. A systematic study is conducted here to understand the phase behavior and morphological causes of aggregation of P188 in the presence of the preservatives phenol and benzyl alcohol, primarily using small-angle x-ray scattering (SAXS). Based on SAXS results, P188 remains as unimers in solution when below a certain phenol concentration. Upon increasing the phenol concentration, a regime of micelle formation is observed due to the interaction between P188 and phenol. Further increasing the phenol concentration causes mixtures to become turbid and phase-separate over time. The effect of benzyl alcohol on the phase behavior is also investigated.

Concentration-Dependent Viscoelasticity of Poloxamer-Shelled Microbubbles

The oscillation of shelled microbubbles during exposure to ultrasound is influenced by the mechanical properties of the shell components. The oscillation behavior of bubbles coated with various phospholipids and other amphiphiles has been studied. However, there have been few investigations of how the adsorption conditions of the shell molecules relate to the viscoelastic properties of the shell and influence the oscillation behavior of the bubbles. In the present study, we investigated the oscillation characteristics of microbubbles coated with a poloxamer surfactant, that is, Pluronic F-68, at several concentrations after the adsorption kinetics of the surfactant at the gas-water interface had reached equilibrium. The dilatational viscoelasticity of the shell during exposure to ultrasound was analyzed in the frequency domain from the attenuation characteristics of the acoustic pulses propagated in the bubble suspension. At Pluronic F-68 concentrations lower than 2.0 × 10^-2 mol L^-1, the attenuation characteristics typically exhibited a sharp peak. At concentrations higher than 2.0 × 10^-2 mol L^-1, the peak flattened. The dilatational elasticity and viscosity of the shell were estimated by fitting the theoretical model to the experimental values, which revealed that both the elasticity and viscosity increased markedly at approximately 2.0 × 10^-2 mol L^-1. This suggests that the adsorption properties of Pluronic F-68 strongly affect the oscillation characteristics of microbubbles of a size suitable for medical ultrasound diagnostics.

The Relevance of Physico-Chemical Properties and Protein Corona for Evaluation of Nanoparticles Immunotoxicity-In Vitro Correlation Analysis on THP-1 Macrophages

Alongside physiochemical properties (PCP), it has been suggested that the protein corona of nanoparticles (NPs) plays a crucial role in the response of immune cells to NPs. However, due to the great variety of NPs, target cells, and exposure protocols, there is still no clear relationship between PCP, protein corona composition, and the immunotoxicity of NPs. In this study, we correlated PCP and the protein corona composition of NPs to the THP-1 macrophage response, focusing on selected toxicological endpoints: cell viability, reactive oxygen species (ROS), and cytokine secretion. We analyzed seven commonly used engineered NPs (SiO2, silver, and TiO2) and magnetic NPs. We show that with the exception of silver NPs, all of the tested TiO2 types and SiO2 exhibited moderate toxicities and a transient inflammatory response that was observed as an increase in ROS, IL-8, and/or IL-1β cytokine secretion. We observed a strong correlation between the size of the NPs in media and IL-1β secretion. The induction of IL-1β secretion was completely blunted in NLR family pyrin domain containing 3 (NLRP3) knockout THP-1 cells, indicating activation of the inflammasome. The correlations analysis also implicated the association of specific NP corona proteins with the induction of cytokine secretion. This study provides new insights toward a better understanding of the relationships between PCP, protein corona, and the inflammatory response of macrophages for different engineered NPs, to which we are exposed on a daily basis.

Effects of Surfactants on Zein Cast Films for Simultaneous Delivery of Two Hydrophilic Active Components

In order to prepare edible films with outstanding antimicrobials and antioxidants utilized in applications of food and pharmaceutics, in this study, effects of surfactants on zein cast films for simultaneous delivery of lysozyme (LY) and ascorbic acid (AA) were investigated, where sodium alginate (SA), soy lecithin (SL), and Pluronic f-68 (PF-68) were selected as surfactants. FT-IR tests indicated that SL or PF-68 dramatically changed secondary structure of zein composite films, which heightened the irregularity of the composite film and inhibited LY crystallization. Mechanical tests showed that highly flexible films exhibiting elongations between 129% and 157% were obtained when adding PF-68. Compared with the film without emulsifier, zein film containing SL and PF-68 showed approximately 7.51 and 0.55 times lower initial release rates for LY and AA respectively, which significantly improved the controlled release and heightened the anti-microbial and anti-oxidant activities of the film. Finally, emulsified mechanisms of the surfactants in zein films were proposed.

Emerging Challenges and Innovations in Surfactant-mediated Stabilization of Biologic Formulations

Biologics may be subjected to various destabilizing conditions during manufacturing, transportation, storage, and use. Therefore, biologics must be appropriately formulated to meet their desired quality target product profiles. In the formulations of protein-based biologics, one critical component is surfactant. Polysorbate 80 and Polysorbate 20 remain the most commonly used surfactants. Surfactants can stabilize proteins through different mechanisms and help the proteins withstand destabilization stresses. However, the challenges associated with surfactants, for instance, impurities, degradation, and potential triggering of adverse immune responses, have been encountered. Therefore, there are continued efforts to develop novel surfactants to overcome these challenges associated with traditional surfactants. Meanwhile, surfactants have also found their use in formulations of newer and novel modalities, namely, antibody-drug conjugates, bispecific antibodies, and adeno-associated viruses (AAV). This review provides an updated in-depth discussion of surfactants in the above-mentioned areas, namely mechanism of action of surfactants, a critical review of challenges with surfactants and current mitigation approaches, and emerging technologies to develop novel surfactants. In addition, gaps, current mitigations, and future directions have been presented to trigger further discussion and research to facilitate the use and development of novel surfactants.

Cell medium-dependent dynamic modulation of size and structural transformations of binary phospholipid/ω-3 fatty acid liquid crystalline nano-self-assemblies: Implications in interpretation of cell uptake studies

Lyotropic non-lamellar liquid crystalline (LLC) nanoparticles, with their tunable structural features and capability of loading a wide range of drugs and reporter probes, are emerging as versatile injectable nanopharmaceuticals. Secondary emulsifiers, such as Pluronic block copolymers, are commonly used for colloidal stabilization of LLC nanoparticles, but their inclusion often compromises the biological safety (e.g., poor hemocompatibility and enhanced cytotoxicity) of the formulation. Here, we introduce a library of colloidally stable, structurally tunable, and pH-responsive lamellar and non-lamellar liquid crystalline nanoparticles from binary mixtures of a phospholipid (phosphatidylglycerol) and three types of omega-3 fatty acids (ω-3 PUFAs), prepared in the absence of a secondary emulsifier and organic solvents. We study formulation size distribution, morphological heterogeneity, and the arrangement of their internal self-assembled architectures by nanoparticle tracking analysis, synchrotron small-angle X-ray scattering, and cryo-transmission electron microscopy. The results show the influence of type and concentration of ω-3 PUFAs in nanoparticle structural transitions spanning from a lamellar (L_α) phase to inverse discontinuous (micellar) cubic Fd3m and hexagonal phase (H₂) phases, respectively. We further report on cell-culture medium-dependent dynamic fluctuations in nanoparticle size, number and morphology, and simultaneously monitor uptake kinetics in two human cell lines. We discuss the role of these multiparametric biophysical transformations on nanoparticle-cell interaction kinetics and internalization mechanisms. Collectively, our findings contribute to the understanding of fundamental steps that are imperative for improved engineering of LLC nanoparticles with necessary attributes for pharmaceutical development.

A Critical Review of the Use of Surfactant-Coated Nanoparticles in Nanomedicine and Food Nanotechnology

Surfactants, whose existence has been recognized as early as 2800 BC, have had a long history with the development of human civilization. With the rapid development of nanotechnology in the latter half of the 20th century, breakthroughs in nanomedicine and food nanotechnology using nanoparticles have been remarkable, and new applications have been developed. The technology of surfactant-coated nanoparticles, which provides new functions to nanoparticles for use in the fields of nanomedicine and food nanotechnology, is attracting a lot of attention in the fields of basic research and industry. This review systematically describes these "surfactant-coated nanoparticles" through various sections in order: 1) surfactants, 2) surfactant-coated nanoparticles, application of surfactant-coated nanoparticles to 3) nanomedicine, and 4) food nanotechnology. Furthermore, current progress and problems of the technology using surfactant-coated nanoparticles through recent research reports have been discussed.

Preclinical autophagy modulatory nanomedicines: big challenges, slow advances

INTRODUCTION

Autophagy is a critical housekeeping pathway to remove toxic protein aggregates, damaged organelles, providing cells with bioenergetic substrates needed to survive under adverse conditions. Since altered autophagy is associated with diverse diseases, its pharmacological modulation is considered of therapeutic interest. Nanomedicines may reduce the toxicity and improve the activity of toxic autophagy modulatory drugs (amd).

AREAS COVERED

The status of the most relevant anti-tumor, anti-inflammatory, and anti-infectious treatments mediated by autophagy modulatory nanomedicines (amN) published in the last 5 years is discussed.

EXPERT OPINION

Antitumor and anti-inflammatory treatments may be improved by administering amN for selective, massive, and targeted delivery of amd to diseased tissues. The use of amN as antimicrobial agent remains almost underexploited. Assessing the effect of amN on the complex autophagy machinery operating under different basal diseases, however, is not a trivial task. Besides structural reproducibility, nanomedicines must grant higher efficiency, and lower adverse effects than conventional medication. Simplicity of design, carefully chosen (scalable) preparation techniques, and rigorous monitoring of preclinical efficacy and nanotoxicity will improve the chances of clinical success. Currently, available data are not sufficient to envisage a fast-succeeding translation. Application of quality by design criteria would help to reach such milestones.

Hypersensitivity reactions to paclitaxel: The Mexican experience of rapid desensitization

BACKGROUND

Taxanes adjuvant therapy is recommended in certain high risk or metastatic tumors, particularly in lung and breast cancer, but also in other types of cancer like ovarian. The incidence of severe adverse drug reactions to paclitaxel is of approximately 10%.

OBJECTIVES

Analyze type I hypersensitivity reactions to paclitaxel and their management in the Mexican population.

METHOD

It is a retrospective, observational and descriptive study that included type I hypersensitivity reactions to paclitaxel reported from our database. Symptoms of hypersensitivity reactions to paclitaxel were classified and skin testing was performed with a 6 mg/mL paclitaxel concentration. The desensitization procedure consisted of a 12-steps, 3-bags of 250 mL protocol with a 6-7-hour duration.

RESULTS

A total of 60 desensitization procedures were performed and were all completed successfully. All participants in our group were female, their median age was 44.5 years.All of our patients had hypersensitivity adverse drug reaction to paclitaxel during their first exposure and within the first 10 minutes of infusion. 63.6% of the patients had a moderate hypersensitivity reaction to paclitaxel and 36.4% had a severe reaction.

CONCLUSIONS

Paclitaxel continues to be a common use drug and has a high rate of adverse drug reactions. This is the first study of hypersensitivity to paclitaxel in a Mexican population.

Size shifting of solid lipid nanoparticle system triggered by alkaline phosphatase for site specific mucosal drug delivery

We aim to prepare a size-shifting nanocarrier for site-targeting mucosal drug delivery that can penetrate through mucus gel layer and remain close to the absorption membrane. As nanocarriers can be engineered to penetrate mucus but they can also back diffuse into outer mucus regions, a size shifting to micron range once they have reached the absorption membrane would prevent back-diffusion effect and extend drug release over a long period of time. For this purpose, we loaded solid lipid nanoparticles (SLN) with a phosphate ester surfactant and octadecylamine. Alkaline phosphatase (AP), a membrane bound enzyme was for the first time utilized as an in situ partner for triggering the size conversion at epithelial cell surface. Having the size of ~120 nm, SLN with hydrophilic and phosphate-decorated shells were shown to penetrate through mucus gel and form aggregates above cell layer surface. Aggregates of 5-8 µm were formed due to interparticle interactions induced by enzymatic phosphate removal after ~30 min in contact with isolated AP. The developed SLN system could be a potential tool for mucosal drug delivery to AP-expressing tissues like colon, lung, cervix, vagina and some mucus-secreting tumors.

Linking In Vitro Intrinsic Dissolution Rate and Thermodynamic Solubility with Pharmacokinetic Profiles of Bedaquiline Long-Acting Aqueous Microsuspensions in Rats

Pharmacokinetic (PK) profiles of a range of bedaquiline (BDQ) long-acting injectable (LAI) microsuspensions in rats after parenteral (i.e., intramuscular and subcutaneous) administration were correlated with the in vitro intrinsic dissolution rate (IDR) and thermodynamic solubility of BDQ in media varying in surfactant type and concentration to better understand the impact of different nonionic surfactants on the in vivo performance of BDQ LAI microsuspensions. All LAI formulations had a similar particle size distribution. The investigated surfactants were d-α-tocopheryl polyethylene glycol 1000 succinate (TPGS), poloxamer 338, and poloxamer 188. Furthermore, the relevance of medium complexity by using a biorelevant setup to perform in vitro measurements was assessed by comparing IDR and thermodynamic solubility results obtained in biorelevant media and formulation vehicle containing different surfactants in varying concentrations. In the presence of a surfactant, both media could be applied to obtain in vivo representative dissolution and solubility data because the difference between the biorelevant medium and formulation vehicle was predominantly nonsignificant. Therefore, a more simplistic medium in the presence of a surfactant was preferred to obtain in vitro measurements to predict the in vivo PK performance of LAI aqueous suspensions. The type of surfactant influenced the PK profiles of BDQ microsuspensions in rats, which could be the result of a surfactant effect on the IDR and/or thermodynamic solubility of BDQ. Overall, two surfactant groups could be differentiated: TPGS and poloxamers. Most differences between the PK profiles (i.e., maximum concentration observed, time of maximum concentration observed, and area under the curve) were observed during the first 21 days postdose, the time period during which particles in the aqueous suspension are expected to dissolve.

A structurally diverse library of glycerol monooleate/oleic acid non-lamellar liquid crystalline nanodispersions stabilized with nonionic methoxypoly(ethylene glycol) (mPEG)-lipids showing variable complement activation properties

Pluronic F127-stabilized non-lamellar liquid crystalline aqueous nanodispersions are promising injectable platforms for drug and contrast agent delivery. These nanodispersions, however, trigger complement activation in the human blood, where the extent of complement activation and opsonization processes may compromise their biological performance and safety. Here, we introduce a broad family of nanodispersions from glycerol monooleate (GMO) and oleic acid (OA) in different weight ratios, and stabilized with a plethora of nonionic methoxypoly(ethylene glycol) (mPEG)-lipids of different PEG chain length and variable lipid moiety (monounsaturated or saturated diglycerides or D-α-tocopheryl succinate). Through an integrated biophysical approach involving dynamic light scattering, synchrotron small-angle scattering, and cryo-transmission electron microscopy, we examine the impact of nonionic mPEG-lipid stabilization on size, internal self-assembled architecture, and gross morphological characteristics of nanodispersions. The results show how the nonionic mPEG-lipid type and concentration, and dependent on GMO/OA weight ratio, can variably modulate the internal architectures of nanoparticles. Assessment of complement profiling from selected nanodispersions with diverse structural heterogeneity further suggests a variable modulatory role for the lipid type of the nonionic mPEG-lipid in the extent of complement activation, which span from no activation to moderate to high levels. We comment on plausible mechanisms driving the observed complement activation variability and discuss the potential utility of these nanodispersions for future development of injectable nanopharmaceuticals.

Impact of Surfactants on the Functionality of Prefilled Syringes

Previous studies revealed the impact of formulation factors (excipients and pH) on the functionality of prefilled syringes. Surfactant, a critical formulation component for therapeutic proteins and antibodies, aids in minimizing protein adsorption onto interfaces and reduces protein aggregation or particulate formation. This study evaluated the impact of different surfactants and protein concentration on the functionality of prefilled syringes. Syringes filled with solution formulations with different surfactants were stored at various temperatures and evaluated at selected time points. Upon thermal stress, polysorbate 80 and dodecyl-β-d-maltoside containing formulations showed significantly greater increase in glide force when compared with poloxamer 407 containing formulations. In contrast, syringes filled with poloxamer 188 containing formulations did not show any increase in glide force under the same conditions. Based on the results from this study, the increase in syringe glide force was inversely correlated with hydrophobic-lipophilic balance values and surface tension of different surfactants. The mechanism of increase in glide force was primarily the change of silicone oil coverage and lubricity in the barrel of syringes.

Main Chain Polysulfoxides as Active 'Stealth' Polymers with Additional Antioxidant and Anti-Inflammatory Behaviour

We present the evaluation of a sulfoxide-based polymer (poly(propylene sulfoxide), PPSO) as a potential 'stealth' macromolecule, and at the same time as a pharmacologically active (anti-inflammatory/anti-oxidant) material. The combination of these two concepts may at first seem peculiar since the gold standard polymer in biomaterials and drug delivery, poly(ethylene glycol) (PEG), is 'stealth' due to its chemical and biological inertness, which makes it hardly biologically active. Polysulfoxides, on the contrary, may couple a substantial inertness towards biomolecules under homeostatic conditions, with the possibility to scavenge reactive oxygen species (ROS) associated to inflammation. Polysulfoxides, therefore, are rather uniquely, 'active' 'stealth' polymers. Here, we describe the synthesis of PPSO through controlled oxidation of poly(propylene sulfide) (PPS), which on its turn was obtained via anionic ring-opening polymerization. In vitro, PPSO was characterized by a low toxicity (IC50 ~7 mg/mL at 24 h on human dermal fibroblasts) and a level of complement activation (in human plasma) and macrophage uptake slightly lower than PEG of a similar size. Importantly, and differently from PEG, on LPS-activated macrophages, PPSO showed a strong and dose-dependent ROS (hydrogen peroxide and hypochlorite)-scavenging activity, which resulted in a corresponding reduction of cytokine production.

A rapid cell-based assay for determining poloxamer quality in CHO suspension cell culture

Poloxamers are water-soluble polymers that are widely used in cell culture bioprocessing to protect cells against shearing forces. Use of poor-quality poloxamers may lead to a drastic reduction in cell growth, viabilities and productivities in cell culture-based manufacturing. In order to evaluate poloxamer quality and promote more consistent performance, a rapid cell membrane adhesion to hydrocarbon assay was developed based on the adhesive properties of cell membranes to selective hydrocarbons. The assay can identify a poor-performing poloxamer characterized by significant drop in viable cell density and percent viability. The assay was verified across multiple good and bad poloxamer lots, and the results were in agreement with established cell growth and high-performance liquid chromatography assays.

Inflammation level and renal function injury in antineutrophil cytoplasmic antibody-associated vasculitis: a correlation with low albumin and high-density lipoprotein

Aim: To explore the correlation of inflammation level and organ involvement in antineutrophil cytoplasmic antibody-associated vasculitis (AAV) patients with Alb and HDL. Materials & methods: Serum levels of Alb and HDL were measured, with AAV patients being grouped according to serum Alb and HDL levels, and indicators reflecting inflammation and renal injury were compared. Results: Serum levels of creatinine (Cr), uric acid and CRP and renal involvement rates were higher in lower Alb patients; Cr, CRP, renal and cardiovascular involvement rates in lower HDL patients were higher. Alb and HDL were negatively correlated with CRP and erythrocyte sedimentation rate. Conclusion: Serum Alb and HDL were good indictors for disease monitoring in AAV.

C1q-Mediated Complement Activation and C3 Opsonization Trigger Recognition of Stealth Poly(2-methyl-2-oxazoline)-Coated Silica Nanoparticles by Human Phagocytes

Poly(2-methyl-2-oxazoline) (PMOXA) is an alternative promising polymer to poly(ethylene glycol) (PEG) for design and engineering of macrophage-evading nanoparticles (NPs). Although PMOXA-engineered NPs have shown comparable pharmacokinetics and in vivo performance to PEGylated stealth NPs in the murine model, its interaction with elements of the human innate immune system has not been studied. From a translational angle, we studied the interaction of fully characterized PMOXA-coated vinyltriethoxysilane-derived organically modified silica NPs (PMOXA-coated NPs) of approximately 100 nm in diameter with human complement system, blood leukocytes, and macrophages and compared their performance with PEGylated and uncoated NP counterparts. Through detailed immunological and proteomic profiling, we show that PMOXA-coated NPs extensively trigger complement activation in human sera exclusively through the classical pathway. Complement activation is initiated by the sensing molecule C1q, where C1q binds with high affinity ( K_d = 11 ± 1 nM) to NP surfaces independent of immunoglobulin binding. C1q-mediated complement activation accelerates PMOXA opsonization with the third complement protein (C3) through the amplification loop of the alternative pathway. This promoted NP recognition by human blood leukocytes and monocyte-derived macrophages. The macrophage capture of PMOXA-coated NPs correlates with sera donor variability in complement activation and opsonization but not with other major corona proteins, including clusterin and a wide range of apolipoproteins. In contrast to these observations, PMOXA-coated NPs poorly activated the murine complement system and were marginally recognized by mouse macrophages. These studies provide important insights into compatibility of engineered NPs with elements of the human innate immune system for translational steps.

Efficient Shielding of Polyplexes Using Heterotelechelic Polysarcosines

Shielding agents are commonly used to shield polyelectrolyte complexes, e.g., polyplexes, from agglomeration and precipitation in complex media like blood, and thus enhance their in vivo circulation times. Since up to now primarily poly(ethylene glycol) (PEG) has been investigated to shield non-viral carriers for systemic delivery, we report on the use of polysarcosine (pSar) as a potential alternative for steric stabilization. A redox-sensitive, cationizable lipo-oligomer structure (containing two cholanic acids attached via a bioreducible disulfide linker to an oligoaminoamide backbone in T-shape configuration) was equipped with azide-functionality by solid phase supported synthesis. After mixing with small interfering RNA (siRNA), lipopolyplexes formed spontaneously and were further surface-functionalized with polysarcosines. Polysarcosine was synthesized by living controlled ring-opening polymerization using an azide-reactive dibenzo-aza-cyclooctyne-amine as an initiator. The shielding ability of the resulting formulations was investigated with biophysical assays and by near-infrared fluorescence bioimaging in mice. The modification of ~100 nm lipopolyplexes was only slightly increased upon functionalization. Cellular uptake into cells was strongly reduced by the pSar shielding. Moreover, polysarcosine-shielded polyplexes showed enhanced blood circulation times in bioimaging studies compared to unshielded polyplexes and similar to PEG-shielded polyplexes. Therefore, polysarcosine is a promising alternative for the shielding of non-viral, lipo-cationic polyplexes.

Polymer Therapeutics: Biomarkers and New Approaches for Personalized Cancer Treatment

Polymer therapeutics (PTs) provides a potentially exciting approach for the treatment of many diseases by enhancing aqueous solubility and altering drug pharmacokinetics at both the whole organism and subcellular level leading to improved therapeutic outcomes. However, the failure of many polymer-drug conjugates in clinical trials suggests that we may need to stratify patients in order to match each patient to the right PT. In this concise review, we hope to assess potential PT-specific biomarkers for cancer treatment, with a focus on new studies, detection methods, new models and the opportunities this knowledge will bring for the development of novel PT-based anti-cancer strategies. We discuss the various "hurdles" that a given PT faces on its passage from the syringe to the tumor (and beyond), including the passage through the bloodstream, tumor targeting, tumor uptake and the intracellular release of the active agent. However, we also discuss other relevant concepts and new considerations in the field, which we hope will provide new insight into the possible applications of PT-related biomarkers.

Needleless emulsion electrospinning for the regulated delivery of susceptible proteins

In the present work, we developed a novel needleless emulsion electrospinning technique that improves the production rate of the core/shell production process. The nanofibres are based on poly-ε-caprolactone (PCL) as a continuous phase combined with a droplet phase based on Pluronic F-68 (PF-68). The PCL-PF-68 nanofibres show a time-regulated release of active molecules. Needleless emulsion electrospinning was used to encapsulate a diverse set of compounds to the core phase [i.e. 5-(4,6-dichlorotriazinyl) aminofluorescein -PF-68, horseradish peroxidase, Tetramethylrhodamine-dextran, insulin growth factor-I, transforming growth factor-β and basic fibroblast growth factor]. In addition, the PF-68 facilitates the preservation of the bioactivity of delivered proteins. The system's potential was highlighted by an improvement in the metabolic activity and proliferation of mesenchymal stem cells. The developed system has the potential to deliver susceptible molecules in tissue-engineering applications.

Combinatorial drug delivery approaches for immunomodulation

Immunotherapy has been widely explored for applications to both augment and suppress intrinsic host immunity. Clinical achievements have seen a number of immunotherapeutic drugs displace established strategies like chemotherapy in treating immune-associated diseases. However, single drug approaches modulating an individual arm of the immune system are often incompletely effective. Imperfect mechanistic understanding and heterogeneity within disease pathology have seen monotherapies inadequately equipped to mediate complete disease remission. Recent success in applications of combinatorial immunotherapy has suggested that targeting multiple biological pathways simultaneously may be critical in treating complex immune pathologies. Drug delivery approaches through engineered biomaterials offer the potential to augment desired immune responses while mitigating toxic side-effects by localizing immunotherapy. This review discusses recent advances in immunotherapy and highlights newly explored combinatorial drug delivery approaches. Furthermore, prospective future directions for immunomodulatory drug delivery to exploit are provided.

Development of oral lyophilisates containing meloxicam nanocrystals using QbD approach

The aim of this study was to develop oral lyophilisates with improved meloxicam (MEL) dissolution, optimizing each step of the preparation by design of experiments. First, meloxicam nanosuspensions were prepared by high-pressure homogenization (HPH), using PVP, Poloxamer or PEG as stabilizers and were subjected to freeze-drying using mannitol as cryoprotectant. The effects of the stabilizers and cryoprotectant were assessed and an optimal formulation was generated within the Design Space where the particle sizes and the PDIs are at their lowest values. The optimal formulation was used at the preparation of oral lyophilisates. Sodium alginate (SA) and croscarmellose sodium (CCS) were tested as matrix forming agents and three different freezing regimes were applied. The formulation was optimized, choosing the polymer that yielded both high mechanical strength and fast MEL dissolution. Poloxamer led to particle size reduction down to 10.27% of the initial size, meaning 477.6±7.5nm, with a slight increase during freeze-drying process. PEG showed lower nanonizing capacity during HPH, but freeze-drying produced further diminution of the particle size. Since Poloxamer provided advanced size reduction while preserving MEL crystallinity, it was used for the optimized formulation containing 1% Poloxamer and 5% mannitol added before freeze-drying. SA showed good structural properties when compared to CCS and allowed fast MEL dissolution at low ratios. The optimal formulation contained 1.157% of SA was subjected to thermal treatment during freeze-drying. It disintegrated in 3.33s and released 77.14% of the MEL after 2min. The quality by design (QbD) approach for the development of pharmaceutical products ensured high quality of the dosage form and good understanding of the preparation process.

Influence of Defined Hydrophilic Blocks within Oligoaminoamide Copolymers: Compaction versus Shielding of pDNA Nanoparticles

Cationic polymers are promising components of the versatile platform of non-viral nucleic acid (NA) delivery agents. For a successful gene delivery system, these NA vehicles need to comprise several functionalities. This work focuses on the modification of oligoaminoamide carriers with hydrophilic oligomer blocks mediating nanoparticle shielding potential, which is necessary to prevent aggregation or dissociation of NA polyplexes in vitro, and hinder opsonization with blood components in vivo. Herein, the shielding agent polyethylene glycol (PEG) in three defined lengths (12, 24, or 48 oxyethylene repeats) is compared with two peptidic shielding blocks composed of four or eight repeats of sequential proline-alanine-serine (PAS). With both types of shielding agents, we found opposing effects of the length of hydrophilic segments on shielding and compaction of formed plasmid DNA (pDNA) nanoparticles. Two-arm oligoaminoamides with 37 cationizable nitrogens linked to 12 oxyethylene units or four PAS repeats resulted in very compact 40⁻50 nm pDNA nanoparticles, whereas longer shielding molecules destabilize the investigated polyplexes. Thus, the balance between sufficiently shielded but still compact and stable particles can be considered a critical optimization parameter for non-viral nucleic acid vehicles based on hydrophilic-cationic block oligomers.

The purified vepoloxamer prevents haemolysis in 42-day stored, DEHP/PVC-free red blood cell units

BACKGROUND

Use of the plasticiser di(2-ethylhexyl) phthalate (DEHP) in polyvinyl chloride (PVC) blood bags poses a potential dilemma. The presence of DEHP in blood bags has been shown to be beneficial to red blood cells during storage by diminishing haemolysis. However, DEHP use in PVC may be carcinogenic or estrogenising. Vepoloxamer is a poloxamer with rheological and cytoprotective rheological properties and a favourable toxicity profile in clinical trials. We hypothesised that vepoloxamer may be sufficient to replace the plasticiser DEHP to prevent elevated haemolysis while conserving the biochemical and redox potential++ in RBCs stored for up to 42 days.

MATERIALS AND METHODS

Paired analyses of aliquots from pooled RBC suspensions of ABO identical donors were aseptically split into test storage containers (DEHP/PVC or DEHP-free/ethylene vinyl acetate [EVA]) supplemented with or without vepoloxamer (at concentrations of 0.1, 1, 5 or 7.89 mg/mL) and cold stored for up to 42 days.

RESULTS

Vepoloxamer significantly prevented the increased haemolysis induced by the absence of DEHP in EVA bags in a dose-dependent manner by days 28 and 42 of storage (approx. 50% reduction of the maximum concentration of vepoloxamer; p<0.001). There was an inverse correlation between the concentration of vepoloxamer used and the haemolysis rate (r2=0.27, p<0.001) and a direct correlation between haemolysis and phosphatidylserine (PS) exposure (r2=0.42; p<0.01). Increased osmotic fragility and shear induced deformability of 42-day stored RBC in EVA bags was significantly corrected by the addition of vepoloxamer.

DISCUSSION

Vepoloxamer, in a concentration-dependent fashion, is able to partly rescue the increased haemolysis and PS exposure induced by the absence of the commonly used plasticiser DEHP. These results provide initial but strong evidence to support vepoloxamer use to replace DEHP in long-term storage of RBC.

Smart polymers in drug delivery: a biological perspective

Key to the widespread application of smart polymers in drug delivery is understanding the mechanistic interplay, as well as consequence, of the presence of these macromolecules within living systems.

Drug delivery's quest for polymers: Where are the frontiers?

Since the legendary 1964 article of Folkman and Long entitled "The use of silicone rubber as a carrier for prolonged drug therapy" the role of polymers in controlled drug delivery has come a long way. Today it is evident that polymers play a crucial if not the prime role in this field. The latest boost owes to the interest in drug delivery for the purpose of tissue engineering in regenerative medicine. The focus of this commentary is on a selection of general and personal observations that are characteristic for the current state of polymer therapeutics and carriers. It briefly highlights selected examples for the long march of synthetic polymer-drug conjugates from bench to bedside, comments on the ambivalence of selected polymers as inert excipients versus biological response modifiers, and on the yet unsolved dilemma of cationic polymers for the delivery of nucleic acid therapeutics. Further subjects are the complex design of multifunctional polymeric carriers including recent concepts towards functional supramolecular polymers, as well as observations on stimuli-sensitive polymers and the currently ongoing trend towards natural and naturally-derived biopolymers. The final topic is the discovery and early development of a novel type of biodegradable polyesters for parenteral use. Altogether, it is not the basic and applied research in polymer therapeutics and carriers, but the translational process that is the key hurdle to proceed towards an authoritative approval of new polymer therapeutics and carriers.

Synthesis and Characterization of Cleavable Core-Cross-Linked Micelles Based on Amphiphilic Block Copolypeptoids as Smart Drug Carriers

Amphiphilic block copolypeptoids consisting of a hydrophilic poly(N-ethyl glycine) segment and a hydrophobic poly[(N-propargyl glycine)-r-(N-decyl glycine)] random copolymer segment [PNEG-b-P(NPgG-r-NDG), EPgD] have been synthesized by sequential primary amine-initiated ring-opening polymerization (ROP) of the corresponding N-alkyl N-carboxyanhydride monomers. The block copolypeptoids form micelles in water and the micellar core can be cross-linked with a disulfide-containing diazide cross-linker by copper-mediated alkyne-azide cycloaddition (CuAAC) in aqueous solution. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis revealed the formation of spherical micelles with uniform size for both the core-cross-linked micelles (CCLMs) and non-cross-linked micelles (NCLMs) precursors for selective block copolypeptoid polymers. The CCLMs exhibited increased dimensional stability relative to the NCLMs in DMF, a nonselective solvent for the core and corona segments. Micellar dissociation of CCLMs can be induced upon addition of a reducing agent (e.g., dithiothreitol) in dilute aqueous solutions, as verified by a combination of fluorescence spectroscopy, size exclusion chromatography (SEC), and (1)H NMR spectroscopic measurement. Doxorubicin (DOX), an anticancer drug, can be loaded into the hydrophobic core of CCLMs with a maximal 23% drug loading capacity (DLC) and 37% drug loading efficiency (DLE). In vitro DOX release from the CCLMs can be triggered by DTT (10 mM), in contrast to significantly reduced DOX release in the absence of DTT, attesting to the reductively responsive characteristic of the CCLMs. While the CCLMs exhibited minimal cytotoxicity toward HepG2 cancer cells, DOX-loaded CCLMs inhibited the proliferation of the HepG2 cancer cells in a concentration and time dependent manner, suggesting the controlled release of DOX from the DOX-loaded CCLMS in the cellular environment.

Vehicle Systems and Excipients Used in Minipig Drug Development Studies

Minipigs have been used for dermal drug development studies for decades, and they are currently more frequently considered as the second nonrodent species for pivotal nonclinical studies, in lieu of the dog or nonhuman primate, for compounds delivered via standard systemic routes of administration. Little is known about the tolerability of different excipients in minipigs; sharing knowledge of excipient tolerability and compositions previously used in nonclinical studies may avoid testing of inadequate formulations, thereby contributing to reduced animal usage. This article reviews vehicles employed in the Göttingen® minipig based on the combined experience from a number of pharmaceutical companies and contract research organizations. The review includes vehicles tolerated for single or multiple dosing by the Göttingen minipig, some of which are not appropriate for administration to other common nonrodent species (e.g., dogs). By presenting these data for dermal, oral, subcutaneous, and intravenous routes of administration, studies to qualify these vehicles in minipigs can be minimized or avoided. Additionally, investigators may more frequently consider using the minipig in place of higher species if the tolerability of a vehicle in the minipig is known.

IR 820 dye encapsulated in polycaprolactone glycol chitosan: Poloxamer blend nanoparticles for photo immunotherapy for breast cancer

In the present study, we have fabricated biocompatible and biodegradable monodisperse IR 820 encapsulated polycaprolactone (PCL) glycol chitosan (GC): Poloxamer blend nanoparticles (PP-IR NPs) for imaging and effective photo-immunotherapy. IR 820 has been used as an imaging and photothermal agent whereas glycol chitosan (GC) as an immunostimulatory agent. The combination of IR 820, poloxamer, and GC can be used effectively for photoimmunotherapy for cancer, drug-resistant and TNF-α resistant estrogen positive breast cancer. PP-IR NPs are stable in aqueous solution. The uniform size of 100-220 nm with a high zeta value of +38 ± 2 mV led them to accumulate in cancer cells. Laser treatment did not affect the morphology of PP-IR NPs as observed under the transmission electron microscope (TEM). In vitro cytotoxicity studies on MCF-7 cells showed enhanced toxicity upon laser treatment. Further, we validated the cell death by reactive oxygen species (ROS) production. Our studies thus showed that PP-IR NPs are effective in suppressing metastatic cancer as the combinational therapy leads to the formation of apoptotic bodies in MCF-7 cells.

Delivery of drugs bound to erythrocytes: new avenues for an old intravascular carrier

For several decades, researchers have used erythrocytes for drug delivery of a wide variety of therapeutics in order to improve their pharmacokinetics, biodistribution, controlled release and pharmacodynamics. Approaches include encapsulation of drugs within erythrocytes, as well as coupling of drugs onto the red cell surface. This review focuses on the latter approach, and examines the delivery of red blood cell (RBC)-surface-bound anti-inflammatory, anti-thrombotic and anti-microbial agents, as well as RBC carriage of nanoparticles. Herein, we discuss the progress that has been made in surface loading approaches, and address in depth the issues relevant to surface loading of RBC, including intrinsic features of erythrocyte membranes, immune considerations, potential surface targets and techniques for the production of affinity ligands.

Poly(2-oxazoline)s as materials for biomedical applications

The conjunction of polymers and medicine enables the development of new materials that display novel features, opening new ways to administrate drugs, design implants and biosensors, to deliver pharmaceuticals impacting cancer treatment, regenerative medicine or gene therapy. Poly(2-oxazoline)s (POx) constitute a polymer class with exceptional properties for their use in a plethora of different biomedical applications and are proposed as a versatile platform for the development of new medicine. Herein, a global vision of POx as a platform for novel biomaterials is offered, by highlighting the recent advances and breakthroughs in this fascinating field.

Cancer nanomedicine and the complement system activation paradigm: anaphylaxis and tumour growth

A wide variety of nanocarriers and particularly cancer nanomedicines activate the complement system, which is the first line of the innate immune defence mechanism. Complement activation may induce inflammatory responses, but such responses arising from uncontrolled complement activation could be life threatening. Accordingly, the role of complement in initiation of adverse reactions to particulate and polymer therapeutics is receiving increasing attention. Furthermore, the involvement of complement-activation products in promoting tumour growth has also been indicated. This could be of serious concern for development of cancer nanomedicines and cancer nanotechnology initiatives. These concepts are reviewed with preliminary evidence that intra-tumoural accumulation of model long circulating nanoparticles could promote tumour growth.

Cardiomyopathy of Duchenne muscular dystrophy: pathogenesis and prospect of membrane sealants as a new therapeutic approach

Duchenne muscular dystrophy (DMD) is a devastating progressive disease of striated muscle deterioration. This fatal X-linked disorder results from the loss of the protein dystrophin, which in turn causes striated muscle membrane instability. Cardiac dysfunction is a growing problem in patients with DMD, but relatively little is known about the pathophysiology of the dystrophic heart. At present, there is no effective treatment for DMD and the current clinical approaches are primarily supportive in nature. This review will discuss the pathogenesis of DMD in the heart and discuss how these pathogenic processes have led to a new class of agents directed specifically at restoring membrane integrity to dystrophic myocardium. The tri-block poloxamers, specifically poloxamer 188 (P188), are able to stabilize the membranes of dystrophic myocardium in animal models and may offer a new therapeutic approach for cardiac disease in DMD.

TUNABLE COMPLEMENT ACTIVATION BY PARTICLES WITH VARIABLE SIZE AND Fc DENSITY

The complement system is an integral innate immune component that is made up of a cascade of enzymatic proteins that, once activated, results in lysis of invading pathogens, opsonization or recruitment of other innate and/or acquired immune responders, or some combination of the three. Due to the importance of the signal amplification and control points present in the cascade, complement is highly sensitive to subtle variations in initiation conditions, including nanoscale changes to molecular spacing. Using Fc-functionalized microparticles and nanoparticles, we find that activation requires a minimum threshold surface concentration of Fc of at least 20% surface coverage. This result indicates that a high surface density Fc is necessary for micro/nanoparticle complement activation through the classical pathway. In addition, the magnitude of the response was dependent on the size of the particle, with larger particles causing decreased activation. We hypothesize that a high density of Fc is needed to efficiently bind and closely appose molecular initiators of the complement cascade, from initiation to terminal complement complex formation. These fundamental studies of the interaction of microparticles and nanoparticles with the immune system suggest design rules for particle size and molecular density that impact immunostimulation through the complement system. Providing a therapeutic agent to modulate the complement response could aid a variety of treatment strategies. Engineered nanoparticles with controlled gaps between molecular activators could lead to new types of immunomodulatory agents.

Human serum lipoproteins influence protein deposition patterns on nanoparticle surfaces

We report the concentration-dependent adsorption of serum lipoproteins onto silica nanoparticles, wherein elevated lipid levels deter complement activation. Two clinically relevant serum lipid levels - corresponding to low and borderline high levels in normal, healthy adults - were used to examine the influence of lipoprotein concentration on nanoparticle complement activation. Human serum albumin was used to study protein adsorption in the presence of lipoproteins. Preferential adsorption of high affinity lipoproteins led to greater lipid fractions in the protein corona, shielding particles from complement activation. These findings have significant implications for the design of intravenously administered carriers with biocompatible surface chemistries.