Activation of complement by therapeutic liposomes and other lipid excipient-based therapeutic products: prediction and prevention

MicroRNAs in non-small cell lung cancer: Gene regulation, impact on cancer cellular processes, and therapeutic potential

Lung cancer remains the most lethal cancer among men and women in the United States and worldwide. The majority of lung cancer cases are classified as non-small cell lung cancer (NSCLC). Developing new therapeutics on the basis of better understanding of NSCLC biology is critical to improve the treatment of NSCLC. MicroRNAs (miRNAs or miRs) are a superfamily of genome-derived, small noncoding RNAs that govern posttranscriptional gene expression in cells. Functional miRNAs are commonly dysregulated in NSCLC, caused by genomic deletion, methylation, or altered processing, which may lead to the changes of many cancer-related pathways and processes, such as growth and death signaling, metabolism, angiogenesis, cell cycle, and epithelial to mesenchymal transition, as well as sensitivity to current therapies. With the understanding of miRNA biology in NSCLC, there are growing interests in developing new therapeutic strategies, namely restoration of tumor suppressive miRNAs and inhibition of tumor promotive miRNAs, to combat against NSCLC. In this article, we provide an overview on the molecular features of NSCLC and current treatment options with a focus on pharmacotherapy and personalized medicine. By illustrating the roles of miRNAs in the control of NSCLC tumorigenesis and progression, we highlight the latest efforts in assessing miRNA-based therapies in animal models and discuss some critical challenges in developing RNA therapeutics.

Lyophilized liposome-based parenteral drug development: Reviewing complex product design strategies and current regulatory environments

Given the successful entry of several liposomal drug products into market, and some with decades of clinical efficacy, liposomal drug delivery systems have proven capabilities to overcome certain limitations of traditional drug delivery, especially for toxic and biologic drugs. This experience has helped promote new liposomal approaches to emerging drug classes and current therapeutic challenges. All approved liposomal dosage forms are parenteral formulations, a pathway demonstrating greatest safety and efficacy to date. Due to the intrinsic instability of aqueous liposomal dispersions, lyophilization is commonly applied as an important solution to improve liposomal drug stability, and facilitate transportation, storage and improve product shelf-life. While lyophilization is a mature pharmaceutical technology, liposome-specific lyophilization platforms must be developed using particular lyophilization experience and strategies. This review provides an overview of liposome formulation-specific lyophilization approaches for parenteral use, excipients used exclusively in liposomal parenteral products, lyophilized liposome formulation design and process development, long-term storage, and current regulatory guidance for liposome drug products. Readers should capture a comprehensive understanding of formulation and process variables and strategies for developing parenterally administered liposomal drugs.

Subvisible Particles in IVIg Formulations Activate Complement in Human Serum

When administered intravenously, various particles and nanomedicines activate complement, potentially leading to infusion reactions and other adverse drug reactions. Particles form within formulations of therapeutic proteins due to stresses incurred during shipping, handling, and administration to patients. In this study, IVIg solutions were stored in multiple types of vials and prefilled syringes and exposed to agitation and freeze-thaw stresses to generate particles. The stressed samples were added to human serum to determine whether these particles activated complement. Subvisible IVIg particles ranging in size between 2 and 10 microns activated complement in a fashion that was linearly dependent on the number of particles dosed, whereas little correlation was found between doses of larger particles (>10 microns) and complement activation. Activation of complement by subvisible particles of IVIg followed the alternative pathway, as shown by the release of complement cascade factor Bb and the production of the anaphylatoxins C3a and C5a without generation of C4a. The number and the morphology of subvisible particles formed depended on the applied stress, formulation, and on the container material. But the capacity of the 2- to 10-micron-sized particles to activate complement in human serum appeared to depend only on particle concentration.

Grand challenges in nanomedicine

Nanotherapeutics and nanopharmaceuticals could achieve and facilitate earlier and more precise individual diagnosis, improve targeted therapies, reduce side effects, and enhance therapeutic monitoring. These advantages will improve quality of life, support a healthier and more independent aging population, and be instrumental in maximizing the cost-effectiveness of health care. However, the field of nanomedicine is at its early stage, most of the research still stays in the laboratory phase, and few success stories are translated into clinical trials and medical practice. This review will demonstrate the numerous challenges that are encountered during the development of commercial nanoparticle-based therapeutics and the possible solutions.

Formulation Strategies for Folate-Targeted Liposomes and Their Biomedical Applications

The folate receptor (FR) is a tumor-associated antigen that can bind with folic acid (FA) and its conjugates with high affinity and ingests the bound molecules inside the cell via the endocytic mechanism. A wide variety of payloads can be delivered to FR-overexpressed cells using folate as the ligand, ranging from small drug molecules to large DNA-containing macromolecules. A broad range of folate attached liposomes have been proven to be highly effective as the targeted delivery system. For the rational design of folate-targeted liposomes, an intense conceptual understanding combining chemical and biomedical points of view is necessary because of the interdisciplinary nature of the field. The fabrication of the folate-conjugated liposomes basically involves the attachment of FA with phospholipids, cholesterol or peptides before liposomal formulation. The present review aims to provide detailed information about the design and fabrication of folate-conjugated liposomes using FA attached uncleavable/cleavable phospholipids, cholesterol or peptides. Advances in the area of folate-targeted liposomes and their biomedical applications have also been discussed.

Red Blood Cells-Derived Vesicles for Delivery of Lipophilic Drug Camptothecin

Recently, cell membrane-derived nanoparticles, particularly of RBCs, have been explored for delivery of hydrophilic solutes of varied size and complexities. So far, these naturally derived nanoparticles show a significant overlap with liposomes in terms of stability, solute encapsulation, and release. Unlike hydrophilic molecules, which are loaded inside the aqueous core, hydrophobic moieties largely partition inside the lipophilic shell, hence fate of these nanocarriers may be different. Since vesicles have more complex membrane architecture (due to natural lipids and additional proteins and glycoproteins), ease of loading hydrophobic drug, its release pattern, and overall particle stability cannot be compared to those of synthetic lipid-based carriers. Therefore, we derived nanovesicles (NVEs) from RBC membrane, loaded with hydrophobic drug camptothecin (CPT) and labeled noncovalently with amphiphilic fluorophore (CM-DiI). Although both CPT and CM-DiI are known to partition inside the membrane, the overall stability of NVEs and composition of membrane proteins, particularly CD47, "marker of self", did not change. Additionally, the developed NVEs were found to be nonphagocytic even in the presence of serum and showed minimal stimulation of macrophages to release cytokines. Further, this system showed slow release but strong retention of CPT and CM-DiI, respectively, over 24 h, hence appropriate for theranostic applications. Also, NVEs were internalized by lung carcinoma cells and possessed slightly higher toxicity than free CPT. When injected intravenously in balb/c mice, these nanovesicles showed higher retention in blood over 48 h and insignificant accumulation in vital organs like heart and kidneys, thus suggesting its potential for in vivo application. We believe that this system has superior stealth and comparable physicochemical properties to synthetic lipid-based nanocarriers; hence, it can be further developed as personalized medicine.

DEHP Nanodroplets Leached From Polyvinyl Chloride IV Bags Promote Aggregation of IVIG and Activate Complement in Human Serum

Concerns regarding the impact of subvisible particulate impurities on the safety and efficacy of therapeutic protein products have led manufacturers to implement strategies to minimize protein aggregation and particle formation during manufacturing, storage, and shipping. However, once these products are released, manufacturers have limited control over product handling. In this work, we investigated the effect of di(2-ethylhexyl) phthalate (DEHP) nanodroplets generated in polyvinyl chloride (PVC) bags of intravenous (IV) saline on the stability and immunogenicity of IV immunoglobulin (IVIG) formulations. We showed that PVC IV bags containing saline can release DEHP droplets into the solution when agitated or transported using a pneumatic tube transportation system in a clinical setting. We next investigated the effects of emulsified DEHP nanodroplets on IVIG stability and immunogenicity. IVIG adsorbed strongly to DEHP nanodroplets, forming a monolayer. In addition, DEHP nanodroplets accelerated IVIG aggregation in agitated samples. The immunogenicity of DEHP nanodroplets and IVIG aggregates generated in these formulations were evaluated using an in vitro assay of complement activation in human serum. The results suggested DEHP nanodroplets shed from PVC IV bags could reduce protein stability and induce activation of the complement system, potentially contributing to adverse immune responses during the administration of therapeutic proteins.

CAL02, a novel antitoxin liposomal agent, in severe pneumococcal pneumonia: a first-in-human, double-blind, placebo-controlled, randomised trial

BACKGROUND

Severe community-acquired pneumonia caused by Streptococcus pneumoniae is associated with high morbidity and mortality rates. CAL02, a novel antitoxin agent with an unprecedented mode of action, consists of liposomes that capture bacterial toxins known to dysregulate inflammation, cause organ damage, and impede immune defence. We aimed to assess the safety of CAL02 as an add-on therapy to antibiotics.

METHODS

This randomised, double-blind, multicentre, placebo-controlled trial was done in ten intensive care units (ICUs) in France and Belgium (but only six units enrolled patients), in patients with severe community-acquired pneumococcal pneumonia who required ICU admission and had been identified as being infected with S pneumoniae. We randomly assigned participants in two stages-the first stage randomly assigned six patients (1:1) to either low-dose CAL02 or placebo, and the second stage randomly assigned 18 patients (14:4) to either high-dose CAL02 or placebo, and stratified in four blocks (4:1, 4:1, 3:1, and 3:1), in addition to standard of care. Block randomisation was done with a computer-generated random number list. Participants, investigators, other site study personnel, the sponsor, and the sponsor's designees involved in study management and monitoring were masked to the randomisation list and treatment assignment. Patients were treated with low-dose (4 mg/kg) or high-dose (16 mg/kg) CAL02 or placebo (saline), in addition to standard antibiotic therapy. Two intravenous doses of study treatment were infused, with a 24 h interval, at a concentration of 10 mg/mL, stepwise, over a maximum of 2 h on days 1 and 2. The primary objective of the study was to assess the safety and tolerability of low-dose and high-dose CAL02 in patients with severe community-acquired pneumonia treated with standard antibiotic therapy, and the primary analysis was done on the safety population (all patients who received at least one dose of the study treatment). Efficacy was a secondary outcome. This trial is registered with ClinicalTrials.gov, number NCT02583373.

FINDINGS

Between March 21, 2016, and Jan 13, 2018, we screened 280 patients with community-acquired pneumonia. 19 patients were enrolled and randomly assigned, resulting in 13 patients in the CAL02 groups (three assigned to low-dose CAL02 and ten assigned to high-dose CAL02) and six in the placebo group. One patient randomly assigned to placebo was allocated to the wrong treatment group and received high-dose CAL02 instead of placebo. Thus, 14 patients received CAL02 (three received low-dose CAL02 and 11 received high-dose CAL02) and five patients received placebo, constituting the safety population. At baseline, the mean APACHE II score for the total study population was 21·5 (SD 4·9; 95% CI 19·3-23·7) and 11 (58%) of 19 patients had septic shock. Adverse events occurred in 12 (86%) of 14 patients in the CAL02 treatment groups combined and all five (100%) patients in the placebo group. Serious adverse events occurred in four (29%) of 14 patients in the CAL02 treatment groups combined and two (40%) of five patients in the placebo group. One non-serious adverse event (mild increase in triglycerides) in a patient in the high-dose CAL02 group was reported as related to study drug. However, analysis of the changes in triglyceride levels in the CAL02 groups compared with the placebo group revealed no correlation with administration of CAL02. No adverse events were linked to local tolerability events. All patients, apart from one who died in the low CAL02 group (death not related to the study drug) achieved clinical cure at the test of cure visit between days 15 and 22. The sequential organ failure assessment score decreased by mean 65·0% (95% CI 50·7-79·4) in the combined CAL02 groups compared with 29·2% (12·8-45·5) in the placebo group between baseline and day 8.

INTERPRETATION

The nature of adverse events was consistent with the profile of the study population and CAL02 showed a promising safety profile and tolerability. However, the difference between high-dose and low-dose CAL02 could not be assessed in this study. Efficacy was in line with the expected benefits of neutralising toxins. The results of this study support further clinical development of CAL02 and provide a solid basis for a larger clinical study.

FUNDING

Combioxin.

Overview of the blood compatibility of nanomedicines: A trend analysis of in vitro and in vivo studies

As nanomedicines have the potential to address many currently unmet medical needs, the early identification of regulatory requirements that could hamper a smooth translation of nanomedicines from the laboratory environment to clinical applications is of utmost importance. The blood system is especially relevant as many nanomedicinal products that are currently under development are designed for intravenous administration and cells of the blood system will be among the first biological systems exposed to the injected nanomedicine. This review collects and summarizes the current knowledge related to the blood compatibility of nanomedicines and nanomaterials with a potential use in biomedical applications. Different types of nanomedicines were analyzed for their toxicity to the blood system, and the role of their physicochemical properties was further elucidated. Trends were identified related to: (a) the nature of the most frequently occurring blood incompatibilities such as thrombogenicity and complement activation, (b) the contribution of physicochemical properties to these blood incompatibilities, and (c) the similarities between data retrieved from in vivo and in vitro studies. Finally, we provide an overview of available standards that allow evaluating the compatibility of a material with the blood system. This article is categorized under: Toxicology and Regulatory Issues in Nanomedicine > Toxicology of Nanomaterials Therapeutic Approaches and Drug Discovery > Emerging Technologies Toxicology and Regulatory Issues in Nanomedicine > Regulatory and Policy Issues in Nanomedicine.

Nanoparticle physicochemical properties determine the activation of intracellular complement

The complement system plays an essential role in both innate and adaptive immunity. The traditional understanding of this system comes from studies investigating complement proteins produced by the liver and present in plasma to "complement" the immune cell-mediated response to invading pathogens. Recently, it has been reported that immune cells including, but not limited to, T-cells and monocytes, express complement proteins. This complement is referred to as intracellular (IC) and implicated in the regulation of T-cell activation. The mechanisms and the structure-activity relationship between nanomaterials and IC, however, are currently unknown. Herein, we describe a structure-activity relationship study demonstrating that under in vitro conditions, only polymeric materials with cationic surfaces activate IC in T-cells. The effect also depends on particle size and occurs through a mechanism involving membrane damage, thereby IC on the cell surface serves as a self-opsonization marker in response to the nanoparticle-triggered danger affecting the cell integrity.

Mapping Molecular Structure of Protein Locating on Nanoparticles with Limited Proteolysis

The molecular structure of a protein could be altered when it is attached to nanoparticles (NPs), affecting the performance of NPs present in biological systems. Limited proteolysis coupled with LC-MS/MS could reveal the changes in protein structure when it binds to a variety of entities, including macro-molecules and small drugs, but it has not yet been applied to study protein-NP interaction. Herein, adsorption of proteins, transferrin, and catalase on the polystyrene (PS) or iron oxide (IO) NPs was analyzed with this method. Both increased and decreased proteolytic efficiency in certain regions on the proteins were observed. Identification of the peptides affected by protein-NP interaction led to proper prediction of alterations to protein function as well as to colloidal stability of NPs. Overall, the present work has demonstrated the utility of limited proteolysis in helping to elucidate the potential biological outcomes of the protein-NP conjugate, obtaining knowledge to guide improvement of the rational design of the protein-conjugated NPs for biomedical applications and to understand the biological behaviors of the engineered NPs.

Nanoparticle-based CT visualization of pulmonary vasculature for minimally-invasive thoracic surgery planning

Purpose

To evaluate CF800, a novel lipid-based liposomal nanoparticle that co-encapsulates indocyanine green (ICG) and iohexol, for CT imaging of pulmonary vasculature in minimally-invasive thoracic surgery planning.

Methods

CF800 was intravenously administered to 7 healthy rabbits. In vivo CT imaging was performed 15 min post-injection, with a subset of animals imaged at 24h, 48h, and 72h post injection. Signal-to-background ratios (SBR) were calculated at the inferior vena cava and compared across time-points. A similar protocol was applied to 2 healthy pigs to evaluate the feasibility and efficacy in a large animal model. To evaluate the feasibility of clinical application, a survey was completed by 7 surgical trainees to assess pre- and post-injection CT images of rabbits and pigs. Responses on the discernibility of pulmonary vasculature sub-branches and comfort level to use the images for pre-operative planning were collected and analyzed.

Results

CF800 injection improved visualization of pulmonary vessels in both rabbit and pig models. The SBR of rabbit pulmonary vasculature was significantly higher after CF800 injection (range 3.7–4.4) compared to pre-injection (range 3.3–3.8, n = 7; p<0.05). SBR remained significantly different up to 24 hours after injection (range 3.7–4.3, n = 4; p<0.05). Trainees’ evaluation found the post-injection CT images had significantly higher discernibility at the second vessel branch generation in both rabbit and pig models. Trainees identified smaller vasculature branch generations in the post-injection images compared to the pre-treatment images in both rabbit (mean 6.7±1.8 vs 5.4±2.1; p<0.05) and pig (mean 6.7±1.8 vs 5.4±2.1; p<0.05). Trainees were significantly more comfortable using post-injection images for surgical planning compared to the pre-injection images (rabbit: 8.1±1.1 vs. 4.7±2.1; pig: 7.6±2.1 vs. 4.9±2.2; p<0.05).

Conclusion

CF800 provides SBR and contrast enhancement of pulmonary vasculature which may assist in pre-surgical CT planning of minimally invasive thoracic surgery.

Exhausting tumor associated macrophages with sialic acid-polyethyleneimine-cholesterol modified liposomal doxorubicin for enhancing sarcoma chemotherapy

To overstep the dilemma of chemical drug degradation within powerful lysosomes of tumor associated macrophages (TAMs), a sialic acid-polyethylenimine-cholesterol (SA-PEI-CH) modified liposomal doxorubicin (DOX-SPCL) was designed with both TAMs targeting and smart lysosomal trafficking. The modified liposome DOX-SPCL performed particle size as 103.2 ± 3.1 nm and zeta potential as -4.5 ± 0.9 mV with encapsulation efficiency as 95.8 ± 0.5%. In in vitro cell experiments, compared with conventional liposomal doxorubicin (DOX-CL) and PEGylated liposomal doxorubicin (DOX-PL), DOX-SPCL showed a selective binding on TAMs and a mere lysosomal concentration. In pharmacokinetic study, DOX-SPCL effectively impeded/delayed the disposition of mononuclear phagocyte system (MPS) with a value of AUC_0-t as 796.03 ± 66.93 mg L^-1 h. In S180 sarcomas bearing mice, DOX-SPCL showed the greatest tumor inhibition rate (92.7% ± 3.6%) compared with DOX-CL (46.4% ± 2.0%) or DOX-PL (58.8% ± 7.6%). The <0.5% positive region of TAMs in tumor section indicated a super TAMs exhaustion for DOX-SPCL treatment. Conclusively, DOX-SPCL was supposed as a safe and effective liposomal preparation for clinical sarcoma treatment via TAMs targeting/deletion delivery strategy.

PEGylated liposomes: immunological responses

A commonly held view is that nanocarriers conjugated to polyethylene glycol (PEG) are non-immunogenic. However, many studies have reported that unexpected immune responses have occurred against PEG-conjugated nanocarriers. One unanticipated response is the rapid clearance of PEGylated nanocarriers upon repeat administration, called the accelerated blood clearance (ABC) phenomenon. ABC involves the production of antibodies toward nanocarrier components, including PEG, which reduces the safety and effectiveness of encapsulated therapeutic agents. Another immune response is the hypersensitivity or infusion reaction referred to as complement (C) activation-related pseudoallergy (CARPA). Such immunogenicity and adverse reactivities of PEGylated nanocarriers may be of potential concern for the clinical use of PEGylated therapeutics. Accordingly, screening of the immunogenicity and CARPA reactogenicity of nanocarrier-based therapeutics should be a prerequisite before they can proceed into clinical studies. This review presents PEGylated liposomes, immunogenicity of PEG, the ABC phenomenon, C activation and lipid-induced CARPA from a toxicological point of view, and also addresses the factors that influence these adverse interactions with the immune system.

Roadmap and strategy for overcoming infusion reactions to nanomedicines

Infusion reactions (IRs) are complex, immune-mediated side effects that mainly occur within minutes to hours of receiving a therapeutic dose of intravenously administered pharmaceutical products. These products are diverse and include both traditional pharmaceuticals (for example biological agents and small molecules) and new ones (for example nanotechnology-based products). Although IRs are not unique to nanomedicines, they represent a hurdle for the translation of nanotechnology-based drug products. This Perspective offers a big picture of the pharmaceutical field and examines current understanding of mechanisms responsible for IRs to nanomedicines. We outline outstanding questions, review currently available experimental evidence to provide some answers and highlight the gaps. We review advantages and limitations of the in vitro tests and animal models used for studying IRs to nanomedicines. Finally, we propose a roadmap to improve current understanding, and we recommend a strategy for overcoming the problem.

Efficacy of the perfluorocarbon dodecafluoropentane as an adjunct to pre-hospital resuscitation

BACKGROUND

Hemorrhage is the most common cause of preventable death in the pre-hospital phase in trauma, with a critical capability gap optimizing pre-hospital resuscitation in austere environments. One promising avenue is the concept of a multi-functional resuscitation fluid (MRF) that contains a blood product backbone with agents that promote clotting and enhance oxygen delivery. Oxygen therapeutics, such as hemoglobin based oxygen carriers(HBOCs) and perfluorocarbons(PFCs), may be a critical MRF component. Our purpose was to assess the efficacy of resuscitation with a PFC, dodecafluoropentane(DDFPe), compared to fresh whole blood(FWB).

METHODS AND FINDINGS

Forty-five swine(78±5kg) underwent splenectomy and controlled hemorrhage via femoral arterial catheter until shock physiology(lactate = 7.0) was achieved prior to randomization into the following groups: 1) Control-no intervention, 2)Hextend-500mL, 3)FFP-500mL, 4)FFP+DDFPe-500mL, 5)FWB-500mL. Animals were observed for an additional 180 minutes following randomization.

RESULTS

Baseline physiologic values did not statistically differ. At T = 60min, FWB had significantly decreased lactate(p = 0.001) and DDFPe was not statistically different from control. There was no statistical significance in tissue oxygenation(StO2) between groups at T = 60min. Survival was highest in the FWB and Hextend groups(30% at 180min). Kaplan-Meier analysis showed decreased survival of DDFPe+FFP in comparison to FWB(p<0.05) and was not significantly different from control or FFP. Four animals who received DDFPe died within 10 minutes of administration. This study was limited by a group receiving DDFPe alone, however this would not be feasible in this lethal swine model as DDFPe given its small volume.

CONCLUSION

DDFPe administration with FFP does not improve survival or enhance tissue oxygenation. However, given similar survival rates of Hextend and FWB, there is evidence that an ideal MRF should contain an element of volume expansion to enhance oxygen delivery.

Lipid-Based Oral Formulation Strategies for Lipophilic Drugs

Partition coefficient (log P) is a key physicochemical characteristic of lipophilic drugs which plays a significant role in formulation development for oral administration. Lipid-based formulation strategies can increase lymphatic transport of these drugs and can enhance bioavailability many folds. The number of lipophilic drugs in pharmacopoeias and under discovery are continuously increasing and making the job of the formulation scientist difficult to develop suitable formulation of these drugs due to potent nature and water insolubility of these drugs. Recently, many natural and synthetic lipids are appearing in the market which are helpful in the development of lipid-based formulations of these types of drugs having enhanced solubility and bioavailability. One such reason for this enhanced bioavailability is the accessibility of the lymphatic transport as well as avoidance of first-pass effect. This review discusses the impact of lipophilicity in enhancing the intestinal lymphatic drug transport thereby reducing first-pass metabolism. The most appropriate strategy for developing a lipid-based formulation depending upon the degree of lipophilicity has been critically discussed and provides information on how to develop optimum formulation. Various formulation strategies are discussed in-depth by classifying lipid-based oral drug delivery systems with case studies of few marketed formulations with challenges and opportunities for the future of the formulations.

Liposomal formulation of hypoxia activated prodrug for the treatment of ovarian cancer

In this work, a new sphingomyelin-cholesterol liposomal formulation (CPD100Li) for the delivery of a hypoxia activated prodrug of vinblastine, mon-N-oxide (CPD100), is developed. The optimized liposomal formulation uses an ionophore (A23187) mediated pH-gradient method. Optimized CPD100Li is characterized for size, drug loading, and stability. The in vitro toxicity of CPD100Li is assessed on different aspects of cell proliferation and apoptosis of ES2 ovarian cancer under normoxic and hypoxic conditions. The pharmacokinetics of CPD100Li in mice as well as the influence of A23187 on the retention of CPD100 are assessed. The dose limiting toxicity (DLT) and maximum tolerated dose (MTD) for CPD100Li are evaluated in nude mice. CPD100 is loaded in the liposome at 5.5 mg/mL. The sizes of CPD100Li using DLS, qNano and cryo-TEM techniques are 155.4 ± 4.2 nm, 132 nm, and 112.6 ± 19.8 nm, respectively. There is no difference between the in vitro characterization of CPD100Li with and without ionophore. Freshly prepared CPD100Li with ionophore are stable for 48 h at 4 °C, while the freeze-dried formulation is stable for 3 months under argon at 4 °C. The hypoxic cytotoxicity ratios (HCR) of CPD100 and CPD100Li are 0.16 and 0.11, respectively. CPD100Li under hypoxic conditions has a 9.2-fold lower IC₅₀ value as compared to CPD100Li under normoxic conditions, confirming the hypoxia dependent activation of CPD100. CPD100Li treated ES2 cells show a time dependent enhanced cell death, along with caspase production and an increase in the number of cells in G₀/G₁ and higher cell arrest. The blood concentration profile of CPD100Li in mice without A23187 has a 12.6-fold lower area under the curve (AUC) and 1.6-fold lower circulation time compared to the CPD100Li with A23187. The DLT for both CPD100 and CPD100Li is 45 mg/kg and the MTD is 40 mg/kg in nude mice. Based on the preliminary data obtained, we clearly show that the presence of ionophore affects the in vivo stability of CPD100. CPD100Li presents a unique opportunity to develop a first-in-kind chemotherapy product based on achieving selective drug activation through the hypoxic physiologic microenvironment of solid tumors.

Involvement of complement activation in the pulmonary vasoactivity of polystyrene nanoparticles in pigs: unique surface properties underlying alternative pathway activation and instant opsonization

Background

It has been proposed that many hypersensitivity reactions to nanopharmaceuticals represent complement (C)-activation-related pseudoallergy (CARPA), and that pigs provide a sensitive animal model to study the phenomenon. However, a recent study suggested that pulmonary hypertension, the pivotal symptom of porcine CARPA, is not mediated by C in cases of polystyrene nanoparticle (PS-NP)-induced reactions.

Goals

To characterize PS-NPs and reexamine the contribution of CARPA to their pulmonary reactivity in pigs.

Study design

C activation by 200, 500, and 750 nm (diameter) PS-NPs and their opsonization were measured in human and pig sera, respectively, and correlated with hemodynamic effects of the same NPs in pigs in vivo.

Methods

Physicochemical characterization of PS-NPs included size, ζ-potential, cryo-transmission electron microscopy, and hydrophobicity analyses. C activation in human serum was measured by ELISA and opsonization of PS-NPs in pig serum by Western blot and flow cytometry. Pulmonary vasoactivity of PS-NPs was quantified in the porcine CARPA model.

Results

PS-NPs are monodisperse, highly hydrophobic spheres with strong negative surface charge. In human serum, they caused size-dependent, significant rises in C3a, Bb, and sC5b-9, but not C4d. Exposure to pig serum led within minutes to deposition of C5b-9 and opsonic iC3b on the NPs, and opsonic iC3b fragments (C3dg, C3d) also appeared in serum. PS-NPs caused major hemodynamic changes in pigs, primarily pulmonary hypertension, on the same time scale (minutes) as iC3b fragmentation and opsonization proceeded. There was significant correlation between C activation by different PS-NPs in human serum and pulmonary hypertension in pigs.

Conclusion

PS-NPs have extreme surface properties with no relevance to clinically used nanomedicines. They can activate C via the alternative pathway, entailing instantaneous opsonization of NPs in pig serum. Therefore, rather than being solely C-independent reactivity, the mechanism of PS-NP-induced hypersensitivity in pigs may involve C activation. These data are consistent with the “double-hit” concept of nanoparticle-induced hypersensitivity reactions involving both CARPA and C-independent pseudoallergy.

Nanoformulations of doxorubicin: how far have we come and where do we go from here?

Nanotechnology, focused on discovery and development of new pharmaceutical products is known as nanopharmacology, and one research area this branch is engaged in are nanopharmaceuticals. The importance of being nano has been particularly emphasized in scientific areas dealing with nanomedicine and nanopharmaceuticals. Nanopharmaceuticals, their routes of administration, obstacles and solutions concerning their improved application and enhanced efficacy have been briefly yet comprehensively described. Cancer is one of the leading causes of death worldwide and evergrowing number of scientific research on the topic only confirms that the needs have not been completed yet and that there is a wide platform for improvement. This is undoubtedly true for nanoformulations of an anticancer drug doxorubicin, where various nanocarrriers were given an important role to reduce the drug toxicity, while the efficacy of the drug was supposed to be retained or preferably enhanced. Therefore, we present an interdisciplinary comprehensive overview of interdisciplinary nature on nanopharmaceuticals based on doxorubicin and its nanoformulations with valuable information concerning trends, obstacles and prospective of nanopharmaceuticals development, mode of activity of sole drug doxorubicin and its nanoformulations based on different nanocarriers, their brief descriptions of biological activity through assessing in vitro and in vivo behavior.

Dexamethasone prodrugs as potent suppressors of the immunostimulatory effects of lipid nanoparticle formulations of nucleic acids

Lipid nanoparticles (LNPs) are playing a leading role in enabling clinical applications of gene therapies based on DNA or RNA polymers. One factor impeding clinical acceptance of LNP therapeutics is that LNP formulations of nucleic acid polymers can be immunostimulatory, necessitating co-administration of potent corticosteroid immunosuppressive agents. Here, we describe the development of hydrophobic prodrugs of a potent corticosteroid, dexamethasone, that can be readily incorporated into LNP systems. We show that the presence of the dexamethasone prodrug LD003 effectively suppresses production of cytokines such as KC-GRO, TNFα, IL-1β and IL-6 following intravenous administration of LNP loaded with immune stimulatory oligodeoxynucleotides containing cytosine-guanine dinucleotide motifs. Remarkably, LD003 dose levels corresponding to 0.5 mg/kg dexamethasone achieve a greater immunosuppressive effect than doses of 20 mg/kg of free dexamethasone. Similar immunosuppressive effects are observed for subcutaneously administered LNP-siRNA. Further, the incorporation of low levels of LD003 in LNP containing unmodified mRNA or plasmid DNA significantly reduced pro-inflammatory cytokine levels following intravenous administration. Our results suggest that incorporation of hydrophobic prodrugs such as LD003 into LNP systems could provide a convenient method for avoiding the immunostimulatory consequences of systemic administration of genetic drug formulations.

Understanding the Role of Anti-PEG Antibodies in the Complement Activation by Doxil in Vitro

Infusion reactions (IRs) are common immune-mediated side effects in patients treated with a variety of drug products, including, but not limited to, nanotechnology formulations. The mechanism of IRs is not fully understood. One of the best studied mechanisms of IRs to nanomedicines is the complement activation. However, it is largely unknown why some patients develop reactions to nanomedicines while others do not, and why some nanoparticles are more reactogenic than others. One of the theories is that the pre-existing anti-polyethylene glycol (PEG) antibodies initiate the complement activation and IRs in patients. In this study, we investigated this hypothesis in the case of PEGylated liposomal doxorubicin (Doxil), which, when used in a clinical setting, is known to induce IRs; referred to as complement activation-related pseudoallergy (CARPA) in sensitive individuals. We conducted the study in vitro using plasma derived from C57BL/6 mice and twenty human donor volunteers. We used mouse plasma to test a library of well-characterized mouse monoclonal antibodies with different specificity and affinity to PEG as it relates to the complement activation by Doxil. We determined the levels of pre-existing polyclonal antibodies that bind to PEG, methoxy-PEG, and PEGylated liposomes in human plasma, and we also assessed complement activation by Doxil and concentrations of complement inhibitory factors H and I in these human plasma specimens. The affinity, specificity, and other characteristics of the human polyclonal antibodies are not known at this time. Our data demonstrate that under in vitro conditions, some anti-PEG antibodies contribute to the complement activation by Doxil. Such contribution, however, needs to be considered in the context of other factors, including, but not limited to, antibody class, type, clonality, epitope specificity, affinity, and titer. In addition, our data contribute to the knowledge base used to understand and improve nanomedicine safety.

Human Biomolecular Corona of Liposomal Doxorubicin: The Overlooked Factor in Anticancer Drug Delivery

More than 20 years after its approval by the Food and Drug Administration (FDA), liposomal doxorubicin (DOX) is still the drug of choice for the treatment of breast cancer and other conditions such as ovarian cancer and multiple myeloma. Yet, despite the efforts, liposomal DOX did not satisfy expectations at the clinical level. When liposomal drugs enter a physiological environment, their surface gets coated by a dynamic biomolecular corona (BC). The BC changes liposome's synthetic identity, providing it with a new one, referred to as "biological identity" (size, aggregation state, and BC composition). Today, the concept is emerging that specific BCs may determine either success (e.g., stealth effect and accumulation at the target site) or failure (e.g., rapid blood clearance and off-target interactions) of liposomal drugs. To get a comprehensive investigation of liposome synthetic identity, biological identity, and cellular response as a function of human plasma (HP) concentration, here we used a straightforward combination of quantitative analytical and imaging tools, including dynamic light scattering, microelectrophoresis, synchrotron small-angle X-ray scattering, transmission electron microscopy (TEM), fluorescence lifetime imaging microscopy (FLIM), nano-liquid chromatography tandem mass spectrometry/mass spectrometry (nano-LC-MS/MS), confocal microscopy, flow cytometry, and cell viability assays. Doxoves was selected as a reference. Following exposure to HP, Doxoves was surrounded by a complex BC that changed liposome's synthetic identity. Observations made with nano-LC-MS/MS revealed that the BC of Doxoves did not evolve as a function of HP concentration and was poorly enriched of typical "opsonins" (complement proteins, immunoglobulins, etc.). This provides a possible explanation for the prolonged blood circulation of liposomal DOX. On the other hand, flow cytometry showed that protein binding reduced the internalization of DOX in MCF7 and MDA-MB-435S human breast carcinoma. Combining FLIM and TEM experiments, we clarified that reduction in DOX intracellular content was likely due to the frequent rupture of the liposome membrane and consequent leakage of the cargo. In light of reported results, we are prompted to speculate that a detailed understanding of BC formation, composition, and effects on liposome stability and uptake is an indispensable task of future research in the field, especially along the way to clinical translation of liposomal drugs.

Engineering Intravenously Administered Nanoparticles to Reduce Infusion Reaction and Stop Bleeding in a Large Animal Model of Trauma

Bleeding from traumatic injury is the leading cause of death for young people across the world, but interventions are lacking. While many agents have shown promise in small animal models, translating the work to large animal models has been exceptionally difficult in great part because of infusion-associated complement activation to nanomaterials that leads to cardiopulmonary complications. Unfortunately, this reaction is seen in at least 10% of the population. We developed intravenously infusible hemostatic nanoparticles that were effective in stopping bleeding and improving survival in rodent models of trauma. To translate this work, we developed a porcine liver injury model. Infusion of the first generation of hemostatic nanoparticles and controls 5 min after injury led to massive vasodilation and exsanguination even at extremely low doses. In naïve animals, the physiological changes were consistent with a complement-associated infusion reaction. By tailoring the zeta potential, we were able to engineer a second generation of hemostatic nanoparticles and controls that did not exhibit the complement response at low and moderate doses but did at the highest doses. These second-generation nanoparticles led to cessation of bleeding within 10 min of administration even though some signs of vasodilation were still seen. While the complement response is still a challenge, this work is extremely encouraging in that it demonstrates that when the infusion-associated complement response is managed, hemostatic nanoparticles are capable of rapidly stopping bleeding in a large animal model of trauma.

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.

Drug metabolism and pharmacokinetic strategies for oligonucleotide- and mRNA-based drug development

Oligonucleotide and modified mRNA therapeutics have great potential to treat diseases that are currently challenging to cure and are expanding into global and chronic disease areas such as cancer and various cardiovascular diseases. Advanced drug delivery systems or ligand-drug conjugates are utilized to achieve 'the right dose to the right target' to benefit efficacy and safety in patients. Chemistry and ADME characteristics distinguish these therapeutics from small molecules. Understanding the scalability and translatability between species and compound properties is crucial for robust nonclinical PKPD predictions to support clinical study design. Although the field has been developing for three decades, there is still room for innovation but also a need for nonclinical regulatory guidance to address these new modalities.

A porcine model of complement activation-related pseudoallergy to nano-pharmaceuticals: Pros and cons of translation to a preclinical safety test

Pigs provide a sensitive and quantitative animal model of non-IgE-mediated(pseudoallergic) hypersensitivity reactions (HSRs) caused by liposomes and many other nanoparticulate drugs or drug-carrier nanosystems (nanomedicines). The rapidly arising symptoms, including cardiopulmonary, hemodynamic, hematological, blood chemistry and skin changes, resemble the clinical picture in man undergoing infusion reactions toreactogenic nanoparticles. In addition to summarizing the basic features of the pig CARPA model, thereviewconsiderssome of the advantages and disadvantages of using the modelforpreclinical evaluation of nanomedicine safety.

nCVTs: a hybrid smart tumour targeting platform

A hybrid drug delivery platform involving the fusion of cell membranes from U937 monocytes and synthetic lipids to create nano-cell vesicle technology systems (nCVTs) is designed. nCVTs are engineered for a targeted approach towards tumour sites by preserving key surface proteins from U937 monocytes, while being amendable to functionalization and loading due to their liposomal components.

Progress and challenges towards targeted delivery of cancer therapeutics

Targeted delivery approaches for cancer therapeutics have shown a steep rise over the past few decades. However, compared to the plethora of successful pre-clinical studies, only 15 passively targeted nanocarriers (NCs) have been approved for clinical use and none of the actively targeted NCs have advanced past clinical trials. Herein, we review the principles behind targeted delivery approaches to determine potential reasons for their limited clinical translation and success. We propose criteria and considerations that must be taken into account for the development of novel actively targeted NCs. We also highlight the possible directions for the development of successful tumor targeting strategies.

Targeted delivery strategies based on nanocarriers have immense potential to change cancer care but current strategies have been shown only limited translation in the clinic. Here, the authors survey the challenge, progress and opportunities towards targeted delivery of cancer therapeutics.

Infusion Reactions Associated with the Medical Application of Monoclonal Antibodies: The Role of Complement Activation and Possibility of Inhibition by Factor H

Human application of monoclonal antibodies (mAbs), enzymes, as well as contrast media and many other particulate drugs and agents referred to as “nanomedicines”, can initiate pseudoallergic hypersensitivity reactions, also known as infusion reactions. These may in part be mediated by the activation of the complement system, a major humoral defense system of innate immunity. In this review, we provide a brief outline of complement activation-related pseudoallergy (CARPA) in general, and then focus on the reactions caused by mAb therapy. Because the alternative pathway of complement activation may amplify such adverse reactions, we highlight the potential use of complement factor H as an inhibitor of CARPA.

Glutathione-PEGylated liposomal methylprednisolone in comparison to free methylprednisolone: slow release characteristics and prolonged lymphocyte depression in a first-in-human study

AIMS

Intravenous high-dose free methylprednisolone (MP) hemisuccinate is the primary treatment for an acute relapse in relapsing-remitting multiple sclerosis. However, it is inconvenient and its side effects are undesirable. Both dose and dosing frequency can be reduced by incorporating free MP in glutathione-PEGylated liposomes, creating a slow-release formulation with reduced toxicity and prolonged peripheral efficacy. This first-in-human study was designed to assess the safety, pharmacokinetics and pharmacodynamics of glutathione-PEGylated liposomes containing MP (2B3-201).

METHODS

The first part was a double-blind, three-way cross over study in 18 healthy male subjects, receiving ascending doses of 2B3-201, active comparator (free MP) or placebo. Part 2 of the study was an open-label infusion of 2B3-201 (different doses), exploring pretreatment with antihistamines and different infusion schedules in another 18 healthy male subjects, and a cross-over study in six healthy female subjects. MP plasma concentrations, lymphocyte counts, adrenocorticotropic hormone, osteocalcin and fasting glucose were determined. Safety and tolerability profiles were assessed based on adverse events, safety measurements and central nervous system tests.

RESULTS

The most frequent recorded AE related to 2B3-201 was an infusion related reaction (89%). 2B3-201 was shown to have a plasma half-life between 24 and 37 h and caused a prolonged decrease in the lymphocyte count, adrenocorticotropic hormone and osteocalcin, and a rise in fasting glucose.

CONCLUSION

2B3-201 is considered safe, with no clinically relevant changes in central nervous system safety parameters and no serious adverse events. In addition, 2B3-201 shows a long plasma half-life and prolonged immunosuppressive effects.

Intravenous synthetic platelet (SynthoPlate) nanoconstructs reduce bleeding and improve 'golden hour' survival in a porcine model of traumatic arterial hemorrhage

Traumatic non-compressible hemorrhage is a leading cause of civilian and military mortality and its treatment requires massive transfusion of blood components, especially platelets. However, in austere civilian and battlefield locations, access to platelets is highly challenging due to limited supply and portability, high risk of bacterial contamination and short shelf-life. To resolve this, we have developed an I.V.-administrable 'synthetic platelet' nanoconstruct (SynthoPlate), that can mimic and amplify body's natural hemostatic mechanisms specifically at the bleeding site while maintaining systemic safety. Previously we have reported the detailed biochemical and hemostatic characterization of SynthoPlate in a non-trauma tail-bleeding model in mice. Building on this, here we sought to evaluate the hemostatic ability of SynthoPlate in emergency administration within the 'golden hour' following traumatic hemorrhagic injury in the femoral artery, in a pig model. We first characterized the storage stability and post-sterilization biofunctionality of SynthoPlate in vitro. The nanoconstructs were then I.V.-administered to pigs and their systemic safety and biodistribution were characterized. Subsequently we demonstrated that, following femoral artery injury, bolus administration of SynthoPlate could reduce blood loss, stabilize blood pressure and significantly improve survival. Our results indicate substantial promise of SynthoPlate as a viable platelet surrogate for emergency management of traumatic bleeding.

Immunotoxicology: A Brief History

Immunotoxicological research and testing have evolved from early studies of anaphylaxis to the robust and diverse field of immunotoxicology as we know it today. Early studies connecting immune dysfunction with exposure to exogenous agents focused on adverse reactions to immunogenic agents present in vaccines. Over time, work done by immunologists and pathologists leads to descriptions of characteristics of immunogenic agents as well as mechanisms by which anaphylaxis occurs and an understanding of the concept of immunosuppression. These myriad achievements greatly improved public health and led the field of immunotoxicology, which addresses all aspects of adverse immunological responses following exposure to exogenous agents as well as the development of testing paradigms to understand immunological responses of designed agents such as drugs and biologics.

Analysis of Complement Activation by Nanoparticles

The complement system is a group of proteins, which function in plasma to assist the innate immunity in rapid clearance of pathogens. The complement system also contributes to coordination of the adaptive immune response. Complement Activation Related Pseudo Allergy or CARPA is a life-threatening condition commonly reported with certain types of drugs and nanotechnology-based combination products. While CARPA symptoms are similar to that of anaphylaxis, the mechanism behind this pathology does not involve IgE and is mediated by the complement system. In vitro assays using serum or plasma derived from healthy donor volunteers correlate with the in vivo complement-mediated reactions, and therefore are helpful in understanding the propensity of a given drug formulation to cause CARPA in patients. In the first edition of this book, we have described an in vitro method for qualitative assessment of the complement activation by nanomaterials using western blotting. Herein, we present a similar method utilizing enzyme-linked immunoassay for quantitative analysis of the complement activation, and we compare the performance of this approach to that of the qualitative western blotting technique. The revised chapter also includes new details about nanoparticle sample preparation.

Evaluating Nanomedicines: Obstacles and Advancements

Continued advancements in nanotechnology are expanding the boundaries of medical research, most notably as drug delivery agents for treatment against cancer. Drug delivery with nanotechnology can offer greater control over the biodistribution of therapeutic agents to improve the therapeutic index. In the last 20 years, a number of nanomedicines have transitioned into the clinic. As nanomedicines evolve, techniques to properly evaluate their safety and efficacy must also evolve. Characterization methods for nano-based materials must be adapted to the demands of nanomedicine developers and regulators. This second edition book provides updated characterization protocols designed to address the clinical potential of nanomedicines during their preclinical development. In this chapter, the characterization challenges of nanoparticles intended for drug delivery will be discussed, along with examples of advancements and improvements in nanomedicine characterization.

Liposome-induced immunosuppression and tumor growth is mediated by macrophages and mitigated by liposome-encapsulated alendronate

Liposomal nanoparticles are the most commonly used drug nano-delivery platforms. However, recent reports show that certain pegylated liposomal nanoparticles (PLNs) and polymeric nanoparticles have the potential to enhance tumor growth and inhibit antitumor immunity in murine cancer models. We sought herein to identify the mechanisms and determine whether PLN-associated immunosuppression and tumor growth can be reversed using alendronate, an immune modulatory drug. By conducting in vivo and ex vivo experiments with the immunocompetent TC-1 murine tumor model, we found that macrophages were the primary cells that internalized PLN in the tumor microenvironment and that PLN-induced tumor growth was dependent on macrophages. Treatment with PLN increased immunosuppression as evidenced by increased expression of arginase-1 in CD11b⁺Gr1⁺ cells, diminished M1 functionality in macrophages, and globally suppressed T-cell cytokine production. Encapsulating alendronate in PLN reversed these effects on myeloid cells and shifted the profile of multi-cytokine producing T-cells towards an IFNγ⁺ perforin⁺ response, suggesting increased cytotoxic functionality. Importantly, we also found that PLN-encapsulated alendronate (PLN-alen), but not free alendronate, abrogated PLN-induced tumor growth and increased progression-free survival. In summary, we have identified a novel mechanism of PLN-induced tumor growth through macrophage polarization and immunosuppression that can be targeted and inactivated to improve the anticancer efficacy of PLN-delivered drugs. Importantly, we also determined that PLN-alen not only reversed protumoral effects of the PLN carrier, but also had moderate antitumor activity. Our findings strongly support the inclusion of immune-responsive tumor models and in-depth immune functional studies in the preclinical drug development paradigm for cancer nanomedicines, and the further development of chemo-immunotherapy strategies to co-deliver alendronate and chemotherapy for the treatment of cancer.

Anticoagulants Influence the Performance of In Vitro Assays Intended for Characterization of Nanotechnology-Based Formulations

The preclinical safety assessment of novel nanotechnology-based drug products frequently relies on in vitro assays, especially during the early stages of product development, due to the limited quantities of nanomaterials available for such studies. The majority of immunological tests require donor blood. To enable such tests one has to prevent the blood from coagulating, which is usually achieved by the addition of an anticoagulant into blood collection tubes. Heparin, ethylene diamine tetraacetic acid (EDTA), and citrate are the most commonly used anticoagulants. Novel anticoagulants such as hirudin are also available but are not broadly used. Despite the notion that certain anticoagulants may influence assay performance, a systematic comparison between traditional and novel anticoagulants in the in vitro assays intended for immunological characterization of nanotechnology-based formulations is currently not available. We compared hirudin-anticoagulated blood with its traditional counterparts in the standardized immunological assay cascade, and found that the type of anticoagulant did not influence the performance of the hemolysis assay. However, hirudin was more optimal for the complement activation and leukocyte proliferation assays, while traditional anticoagulants citrate and heparin were more appropriate for the coagulation and cytokine secretion assays. The results also suggest that traditional immunological controls such as lipopolysaccharide (LPS ) are not reliable for understanding the role of anticoagulant in the assay performance. We observed differences in the test results between hirudin and traditional anticoagulant-prepared blood for nanomaterials at the time when no such effects were seen with traditional controls. It is, therefore, important to recognize the advantages and limitations of each anticoagulant and consider individual nanoparticles on a case-by-case basis.

Immune responses to engineered nanomaterials: current understanding and challenges

Engineered nanomaterials (ENM) are utilized in many applications due to their unique physicochemical properties. The increasing use of ENMs in consumer products raises concerns of potential adverse effects in humans and the environment. A common outcome of exposure (intentional, environmental or occupational) to ENMs is altered immune responses including inflammation, hypersensitivity, and immunosuppression. ENMs have been shown to interact with the immune system through key effector cells (i.e. mast cells and antigen presenting cells) or via complement activation leading to consequences to both innate and adaptive immunity. Further, upon introduction into a biological system, ENMs are rapidly coated with proteins, lipids and other macromolecules forming a biocorona which impacts immune cell and complement responses. In this current opinion, we highlight key studies and challenges in understanding cellular mechanisms of ENM-mediated immunomodulation and toxicity.