Liposome-induced hypersensitivity reactions: Risk reduction by design of safe infusion protocols in pigs

Comirnaty-induced cardiopulmonary distress and other symptoms of complement-mediated pseudo-anaphylaxis in a hyperimmune pig model: Causal role of anti-PEG antibodies

Background

Comirnaty, Pfizer-BioNTech's polyethylene-glycol (PEG)-containing Covid-19 vaccine, can cause hypersensitivity reactions (HSRs), or rarely, life-threatening anaphylaxis in a small fraction of immunized people. A causal role of anti-PEG antibodies (Abs) has been proposed, but causality has not yet proven in an animal model. The aim of this study was to provide such evidence using pigs immunized against PEG, which displayed very high levels of anti-PEG antibodies (Abs). We also aimed to find evidence for a role of complement activation and thromboxane A2 release in blood to explore the mechanism of anaphylaxis.

Methods

Pigs (n = 6) were immunized with 0.1 mg/kg PEGylated liposome (Doxebo) i.v., and the rise of anti-PEG IgG and IgM were measured in serial blood samples with ELISA. After ∼2-3 weeks the animals were injected i.v. with 1/3 human dose of the PEGylated mRNA vaccine, Comirnaty, and the hemodynamic (PAP, SAP) cardiopulmonary (HR, EtCO2,), hematological (WBC, granulocyte, lymphocyte and platelet counts) parameters and blood immune mediators (anti-PEG IgM and IgG antibodies, thromboxane B2, C3a) were measured as endpoints of HSRs (anaphylaxis).

Results

The level of anti-PEG IgM and IgG rose 5-10-thousand-fold in all of 6 pigs immunized with Doxebo by day 6, after which time all animals developed anaphylactic shock to i.v. injection of 1/3 human dose of Comirnaty. The reaction, starting within 1 min involved maximal pulmonary hypertension and decreased systemic pulse pressure amplitude, tachycardia, granulo- and thrombocytopenia, and skin reactions (flushing or rash). These physiological changes or their absence were paralleled by C3a and TXB2 rises in blood.

Conclusions

Consistent with previous studies, these data show a causal role of anti-PEG Abs in the anaphylaxis to Comirnaty, which involves complement activation, and, hence, it represents C activation-related pseudo-anaphylaxis. The setup provides the first large-animal model for mRNA-vaccine-induced anaphylaxis in humans.

siRNA-mediated reduction of a circulating protein in swine using lipid nanoparticles

Genetic manipulation of animal models is a fundamental research tool in biology and medicine but is challenging in large animals. In rodents, models can be readily developed by knocking out genes in embryonic stem cells or by knocking down genes through in vivo delivery of nucleic acids. Swine are a preferred animal model for studying the cardiovascular and immune systems, but there are limited strategies for genetic manipulation. Lipid nanoparticles (LNPs) efficiently deliver small interfering RNA (siRNA) to knock down circulating proteins, but swine are sensitive to LNP-induced complement activation-related pseudoallergy (CARPA). We hypothesized that appropriately administering optimized siRNA-LNPs could knock down circulating levels of plasminogen, a blood protein synthesized in the liver. siRNA-LNPs against plasminogen (siPLG) reduced plasma plasminogen protein and hepatic plasminogen mRNA levels to below 5% of baseline values. Functional assays showed that reducing plasminogen levels modulated systemic blood coagulation. Clinical signs of CARPA were not observed, and occasional mild and transient hepatotoxicity was present in siPLG-treated animals at 5 h post-infusion, which returned to baseline by 7 days. These findings advance siRNA-LNPs in swine models, enabling genetic engineering of blood and hepatic proteins, which can likely expand to proteins in other tissues in the future.

Rediscovery of mononuclear phagocyte system blockade for nanoparticle drug delivery

Rapid uptake of nanoparticles by mononuclear phagocyte system (MPS) significantly hampers their therapeutic efficacy. Temporal MPS blockade is one of the few ways to overcome this barrier - the approach rediscovered many times under different names but never extensively used in clinic. Using meta-analysis of the published data we prove the efficacy of this technique for enhancing particle circulation in blood and their delivery to tumours, describe a century of its evolution and potential combined mechanism behind it. Finally, we discuss future directions of the research focusing on the features essential for successful clinical translation of the method.

Free PEG Suppresses Anaphylaxis to PEGylated Nanomedicine in Swine

Covalent conjugation of poly(ethylene glycol) (PEG) is frequently employed to enhance the pharmacokinetics and biodistribution of various protein and nanoparticle therapeutics. Unfortunately, some PEGylated drugs can induce elevated levels of antibodies that can bind PEG, i.e., anti-PEG antibodies (APA), in some patients. APA in turn can reduce the efficacy and increase the risks of allergic reactions, including anaphylaxis. There is currently no intervention available in the clinic that specifically mitigates allergic reactions to PEGylated drugs without the use of broad immunosuppression. We previously showed that infusion of high molecular weight free PEG could safely and effectively suppress the induction of APA in mice and restore prolonged circulation of various PEGylated therapeutics. Here, we explored the effectiveness of free PEG as a prophylaxis against anaphylaxis induced by PEG-specific allergic reactions in swine. Injection of PEG-liposomes (PL) resulted in anaphylactoid shock (pseudoanaphylaxis) within 1-3 min in both naïve and PL-sensitized swine. In contrast, repeated injection of free PEG alone did not result in allergic reactions, and injection of free PEG effectively suppressed allergic reactions to PL, including in previously PL-sensitized swine. These results strongly support the further investigation of free PEG for reducing APA and allergic responses to PEGylated therapeutics.

Approaches for reducing chemo/radiation-induced cardiotoxicity by nanoparticles

Nanoparticles are fascinating and encouraging carriers for cancer treatment due to their extraordinary properties and potential applications in targeted drug delivery, treatment, and diagnosis. Experimental studies including in vitro and in vivo examinations show that nanoparticles can cause a revolution in different aspects of cancer therapy. Normal tissue toxicity and early and late consequences are the major limitations of cancer therapy by radiotherapy and chemotherapy. However, the delivery of drugs into tumors or reducing the accumulation of drugs in normal tissues can permit a more satisfactory response of malignancies to therapy with more inferior side effects. Cardiac toxicity is one of the major problems for chemotherapy and radiotherapy. Therefore, several experimental studies have been performed to minimize the degenerative impacts of cancer treatment on the heart and also enhance the influences of radiotherapy and chemotherapy agents in cancers. This review article emphasizes the benefits of nanoparticle-based drug delivery techniques, including minimizing the exposure of the heart to anticancer drugs, enhancing the accumulation of drugs in cancers, and expanding the effectiveness of radiotherapy. The article also discusses the challenges and problems accompanied with nanoparticle-based drug delivery techniques such as toxicity, which need to be addressed through further research. Moreover, the article emphasizes the importance of developing safe and effective nanoparticle-based therapies that can be translated into clinical practice.

Advances in nanoprobes for molecular MRI of Alzheimer's disease

Alzheimer's disease is the most common cause of dementia and a leading cause of mortality in the elderly population. Diagnosis of Alzheimer's disease has traditionally relied on evaluation of clinical symptoms for cognitive impairment with a definitive diagnosis requiring post-mortem demonstration of neuropathology. However, advances in disease pathogenesis have revealed that patients exhibit Alzheimer's disease pathology several decades before the manifestation of clinical symptoms. Magnetic resonance imaging (MRI) plays an important role in the management of patients with Alzheimer's disease. The clinical availability of molecular MRI (mMRI) contrast agents can revolutionize the diagnosis of Alzheimer's disease. In this article, we review advances in nanoparticle contrast agents, also referred to as nanoprobes, for mMRI of Alzheimer's disease. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Therapeutic Approaches and Drug Discovery > Nanomedicine for Neurological Disease.

Recent advances and clinical translation of liposomal delivery systems in cancer therapy

The limitations of conventional cancer treatment are driving the emergence and development of nanomedicines. Research in liposomal nanomedicine for cancer therapy is rapidly increasing, opening up new horizons for cancer treatment. Liposomal nanomedicine, which focuses on targeted drug delivery to improve the therapeutic effect of cancer while reducing damage to normal tissues and cells, has great potential in the field of cancer therapy. This review aims to clarify the advantages of liposomal delivery systems in cancer therapy. We describe the recent understanding of spatiotemporal fate of liposomes in the organism after different routes of drug administration. Meanwhile, various types of liposome-based drug delivery systems that exert their respective advantages in cancer therapy while reducing side effects were discussed. Moreover, the combination of liposomal agents with other therapies (such as photodynamic therapy and photothermal therapy) has demonstrated enhanced tumor-targeting efficiency and therapeutic efficacy. Finally, the opportunities and challenges faced by the field of liposome nanoformulations for entering the clinical treatment of cancer are highlighted.

Evaluation of the Acute Anaphylactoid Reactogenicity of Nanoparticle-Containing Medicines and Vaccines Using the Porcine CARPA Model

A small fraction, up to 10%, of people treated intravenously with state-of-the-art nanoparticulate drugs or diagnostic agents develop an acute infusion reaction which can be severe or even lethal. Activation of the complement (C) system can play a causal, or contributing role in these atypical, "pseudoallergic" reactions, hence their name, C activation-related pseudoallergy (CARPA). Intravenous (i.v.) administration of the human reaction-triggering (very small) dose of a test sample in pigs triggers a symptom tetrad (characteristic hemodynamic, hematological, skin, and laboratory changes) that correspond to the major human symptoms. Quantitating these changes provides a highly sensitive and reproducible method for assessing the risk of CARPA, enabling the implementation of appropriate preventive measures. Accordingly, the porcine CARPA model has been increasingly used for the safety evaluation of therapeutic and diagnostic nanomedicines and, recently, mRNA-lipid nanoparticle vaccines. This chapter provides details of the experimental procedure followed upon using the model.

Targeting cancer with mRNA-lipid nanoparticles: key considerations and future prospects

Harnessing mRNA-lipid nanoparticles (LNPs) to treat patients with cancer has been an ongoing research area that started before these versatile nanoparticles were successfully used as COVID-19 vaccines. Currently, efforts are underway to harness this platform for oncology therapeutics, mainly focusing on cancer vaccines targeting multiple neoantigens or direct intratumoural injections of mRNA-LNPs encoding pro-inflammatory cytokines. In this Review, we describe the opportunities of using mRNA-LNPs in oncology applications and discuss the challenges for successfully translating the findings of preclinical studies of these nanoparticles into the clinic. We critically appraise the potential of various mRNA-LNP targeting and delivery strategies, considering physiological, technological and manufacturing challenges. We explore these approaches in the context of the potential clinical applications best suited to each approach and highlight the obstacles that currently need to be addressed to achieve these applications. Finally, we provide insights from preclinical and clinical studies that are leading to this powerful platform being considered the next frontier in oncology treatment.

Clinical Translation of Extracellular Vesicles

Extracellular vesicles (EVs) occur in a variety of bodily fluids and have gained recent attraction as natural materials due to their bioactive surfaces, internal cargo, and role in intercellular communication. EVs contain various biomolecules, including surface and cytoplasmic proteins; and nucleic acids that are often representative of the originating cells. EVs can transfer content to other cells, a process that is thought to be important for several biological processes, including immune responses, oncogenesis, and angiogenesis. An increased understanding of the underlying mechanisms of EV biogenesis, composition, and function has led to an exponential increase in preclinical and clinical assessment of EVs for biomedical applications, such as diagnostics and drug delivery. Bacterium-derived EV vaccines have been in clinical use for decades and a few EV-based diagnostic assays regulated under Clinical Laboratory Improvement Amendments have been approved for use in single laboratories. Though, EV-based products are yet to receive widespread clinical approval from national regulatory agencies such as the United States Food and Drug Administration (USFDA) and European Medicine Agency (EMA), many are in late-stage clinical trials. This perspective sheds light on the unique characteristics of EVs, highlighting current clinical trends, emerging applications, challenges and future perspectives of EVs in clinical use.

Nature vs. Manmade: Comparing Exosomes and Liposomes for Traumatic Brain Injury

Traumatic brain injury (TBI) of all severities is a significant public health burden, causing a range of effects that can lead to death or a diminished quality of life. Liposomes and mesenchymal stem cell-derived exosomes are two drug delivery agents with potential to be leveraged in the treatment of TBI by increasing the efficacy of drug therapies as well as having additional therapeutic effects. They exhibit several physical similarities, but key differences affect their performances as nanocarriers. Liposomes can be produced commercially at scale, and liposomes achieve higher encapsulation efficiency. Meanwhile, the intrinsic cargo and targeting moieties of exosomes, which liposomes lack, give exosomes a greater ability to facilitate neural regeneration, and exosomes do not trigger the infusion reactions that liposomes can. However, there are concerns about both exosomes and liposomes regarding interactions with tumors. The same routes of administration can be used for both exosomes and liposomes, resulting in somewhat different distribution throughout the body. While the effect of the nanocarrier type on accumulation in the brain is not concrete, targeting leads to increased accumulation of both exosomes and liposomes in the brain, upon which on-demand release can be used for both drug deliverers. Although neither have been applied to TBI in humans, preclinical trials have shown their immense potential, as have clinical trials pertaining to other brain injuries and conditions. While questions remain, research thus far shows that the various differences make exosomes a better choice of nanocarrier for TBI.

Zymosan Particle-Induced Hemodynamic, Cytokine and Blood Cell Changes in Pigs: An Innate Immune Stimulation Model with Relevance to Cytokine Storm Syndrome and Severe COVID-19

Hemodynamic disturbance, a rise in neutrophil-to-lymphocyte ratio (NLR) and release of inflammatory cytokines into blood, is a bad prognostic indicator in severe COVID-19 and other diseases involving cytokine storm syndrome (CSS). The purpose of this study was to explore if zymosan, a known stimulator of the innate immune system, could reproduce these changes in pigs. Pigs were instrumented for hemodynamic analysis and, after i.v. administration of zymosan, serial blood samples were taken to measure blood cell changes, cytokine gene transcription in PBMC and blood levels of inflammatory cytokines, using qPCR and ELISA. Zymosan bolus (0.1 mg/kg) elicited transient hemodynamic disturbance within minutes without detectable cytokine or blood cell changes. In contrast, infusion of 1 mg/kg zymosan triggered maximal pulmonary hypertension with tachycardia, lasting for 30 min. This was followed by a transient granulopenia and then, up to 6 h, major granulocytosis, resulting in a 3-4-fold increase in NLR. These changes were paralleled by massive transcription and/or rise in IL-6, TNF-alpha, CCL-2, CXCL-10, and IL-1RA in blood. There was significant correlation between lymphopenia and IL-6 gene expression. We conclude that the presented model may enable mechanistic studies on late-stage COVID-19 and CSS, as well as streamlined drug testing against these conditions.

Lipid Nanoparticles for Nucleic Acid Delivery to Endothelial Cells

Endothelial cells play critical roles in circulatory homeostasis and are also the gateway to the major organs of the body. Dysfunction, injury, and gene expression profiles of these cells can cause, or are caused by, prevalent chronic diseases such as diabetes, cardiovascular disease, and cancer. Modulation of gene expression within endothelial cells could therefore be therapeutically strategic in treating longstanding disease challenges. Lipid nanoparticles (LNP) have emerged as potent, scalable, and tunable carrier systems for delivering nucleic acids, making them attractive vehicles for gene delivery to endothelial cells. Here, we discuss the functions of endothelial cells and highlight some receptors that are upregulated during health and disease. Examples and applications of DNA, mRNA, circRNA, saRNA, siRNA, shRNA, miRNA, and ASO delivery to endothelial cells and their targets are reviewed, as well as LNP composition and morphology, formulation strategies, target proteins, and biomechanical factors that modulate endothelial cell targeting. Finally, we discuss FDA-approved LNPs as well as LNPs that have been tested in clinical trials and their challenges, and provide some perspectives as to how to surmount those challenges.

Lessons learned from immunological characterization of nanomaterials at the Nanotechnology Characterization Laboratory

Nanotechnology carriers have become common in pharmaceutical products because of their benefits to drug delivery, including reduced toxicities and improved efficacy of active pharmaceutical ingredients due to targeted delivery, prolonged circulation time, and controlled payload release. While available examples of reduced drug toxicity through formulation using a nanocarrier are encouraging, current data also demonstrate that nanoparticles may change a drug’s biodistribution and alter its toxicity profile. Moreover, individual components of nanoparticles and excipients commonly used in formulations are often not immunologically inert and contribute to the overall immune responses to nanotechnology-formulated products. Said immune responses may be beneficial or adverse depending on the indication, dose, dose regimen, and route of administration. Therefore, comprehensive toxicology studies are of paramount importance even when previously known drugs, components, and excipients are used in nanoformulations. Recent data also suggest that, despite decades of research directed at hiding nanocarriers from the immune recognition, the immune system’s inherent property of clearing particulate materials can be leveraged to improve the therapeutic efficacy of drugs formulated using nanoparticles. Herein, I review current knowledge about nanoparticles’ interaction with the immune system and how these interactions contribute to nanotechnology-formulated drug products’ safety and efficacy through the lens of over a decade of nanoparticle characterization at the Nanotechnology Characterization Laboratory.

PEGylated Polyester Nanoparticles Trigger Adverse Events in a Large Animal Model of Trauma and in Naı̈ve Animals: Understanding Cytokine and Cellular Correlations with These Events

Intravenously infusible nanoparticles to control bleeding have shown promise in rodents, but translation into preclinical models has been challenging as many of these nanoparticle approaches have resulted in infusion responses and adverse outcomes in large animal trauma models. We developed a hemostatic nanoparticle technology that was screened to avoid one component of the infusion response: complement activation. We administered these hemostatic nanoparticles, control nanoparticles, or saline volume controls in a porcine polytrauma model. While the hemostatic nanoparticles promoted clotting as marked by a decrease in prothrombin time and both the hemostatic nanoparticles and controls did not active complement, in a subset of the animals, hard thrombi were found in uninjured tissues in both the hemostatic and control nanoparticle groups. Using data science methods that allow one to work across heterogeneous data sets, we found that the presence of these thrombi correlated with changes in IL-6, INF-alpha, lymphocytes, and neutrophils. While these findings might suggest that this formulation would not be a safe one for translation for trauma, they provide guidance for developing screening tools to make nanoparticle formulations in the complex milieux of trauma as well as for therapeutic interventions more broadly. This is important as we look to translate intravenously administered nanoparticle formulations for therapies, particularly considering the vascular changes seen in a subset of patients following COVID-19. We need to understand adverse events like thrombi more completely and screen for these events early to make nanomaterials as safe and effective as possible.

A naturally hypersensitive porcine model may help understand the mechanism of COVID-19 mRNA vaccine-induced rare (pseudo) allergic reactions: complement activation as a possible contributing factor

A tiny fraction of people immunized with lipid nanoparticle (LNP)-enclosed mRNA (LNP-mRNA) vaccines develop allergic symptoms following their first or subsequent vaccinations, including anaphylaxis. These reactions resemble complement (C) activation-related pseudoallergy (CARPA) to i.v. administered liposomes, for which pigs provide a naturally oversensitive model. Using this model, we injected i.v. the human vaccination dose (HVD) of BNT162b2 (Comirnaty, CMT) or its 2-fold (2x) or 5-fold (5x) amounts and measured the hemodynamic changes and other parameters of CARPA. We observed in 6 of 14 pigs transient pulmonary hypertension along with thromboxane A2 release into the blood and other hemodynamic and blood cell changes, including hypertension, granulocytosis, lymphopenia, and thrombocytopenia. One pig injected with 5x CMT developed an anaphylactic shock requiring resuscitation, while a repeat dose failed to induce the reaction, implying tachyphylaxis. These typical CARPA symptoms could not be linked to animal age, sex, prior immune stimulation with zymosan, immunization of animals with Comirnaty i.v., or i.m. 2 weeks before the vaccine challenge, and anti-PEG IgM levels in Comirnaty-immunized pigs. Nevertheless, IgM binding to the whole vaccine, used as antigen in an ELISA, was significantly higher in reactive animals compared to non-reactive ones. Incubation of Comirnaty with pig serum in vitro showed significant elevations of C3a anaphylatoxin and sC5b-9, the C-terminal complex. These data raise the possibility that C activation plays a causal or contributing role in the rare HSRs to Comirnaty and other vaccines with similar side effects. Further studies are needed to uncover the factors controlling these vaccine reactions in pigs and to understand their translational value to humans.

The Hitchhiker's Guide to Human Therapeutic Nanoparticle Development

Nanomedicine plays an essential role in developing new therapies through novel drug delivery systems, diagnostic and imaging systems, vaccine development, antibacterial tools, and high-throughput screening. One of the most promising drug delivery systems are nanoparticles, which can be designed with various compositions, sizes, shapes, and surface modifications. These nanosystems have improved therapeutic profiles, increased bioavailability, and reduced the toxicity of the product they carry. However, the clinical translation of nanomedicines requires a thorough understanding of their properties to avoid problems with the most questioned aspect of nanosystems: safety. The particular physicochemical properties of nano-drugs lead to the need for additional safety, quality, and efficacy testing. Consequently, challenges arise during the physicochemical characterization, the production process, in vitro characterization, in vivo characterization, and the clinical stages of development of these biopharmaceuticals. The lack of a specific regulatory framework for nanoformulations has caused significant gaps in the requirements needed to be successful during their approval, especially with tests that demonstrate their safety and efficacy. Researchers face many difficulties in establishing evidence to extrapolate results from one level of development to another, for example, from an in vitro demonstration phase to an in vivo demonstration phase. Additional guidance is required to cover the particularities of this type of product, as some challenges in the regulatory framework do not allow for an accurate assessment of NPs with sufficient evidence of clinical success. This work aims to identify current regulatory issues during the implementation of nanoparticle assays and describe the major challenges that researchers have faced when exposing a new formulation. We further reflect on the current regulatory standards required for the approval of these biopharmaceuticals and the requirements demanded by the regulatory agencies. Our work will provide helpful information to improve the success of nanomedicines by compiling the challenges described in the literature that support the development of this novel encapsulation system. We propose a step-by-step approach through the different stages of the development of nanoformulations, from their design to the clinical stage, exemplifying the different challenges and the measures taken by the regulatory agencies to respond to these challenges.

A porcine model of hemodialyzer reactions: roles of complement activation and rinsing back of extracorporeal blood

Hemodialysis reactions (HDRs) resemble complement-activation-related pseudoallergy (CARPA) to certain i.v. drugs, for which pigs provide a sensitive model. On this basis, to better understand the mechanism of human HDRs, we subjected pigs to hemodialysis using polysulfone (FX CorDiax 40, Fresenius) or cellulose triacetate (SureFlux-15UX, Nipro) dialyzers, or Dialysis exchange-set without membranes, as control. Experimental endpoints included typical biomarkers of porcine CARPA; pulmonary arterial pressure (PAP), blood cell counts, plasma sC5b-9 and thromboxane-B2 levels. Hemodialysis (60 min) was followed by reinfusion of extracorporeal blood into the circulation, and finally, an intravenous bolus injection of the complement activator zymosan. The data indicated low-extent steady rise of sC5b-9 along with transient leukopenia, secondary leukocytosis and thrombocytopenia in the two dialyzer groups, consistent with moderate complement activation. Surprisingly, small changes in baseline PAP and plasma thromboxane-B2 levels during hemodialysis switched into 30%-70% sharp rises in all three groups resulting in synchronous spikes within minutes after blood reinfusion. These observations suggest limited complement activation by dialyzer membranes, on which a membrane-independent second immune stimulus was superimposed, and caused pathophysiological changes also characteristic of HDRs. Thus, the porcine CARPA model raises the hypothesis that a second "hit" on anaphylatoxin-sensitized immune cells may be a key contributor to HDRs.

Nanomedicine at the crossroads - A quick guide for IVIVC

For many years, nanomedicine is pushing the boundaries of drug delivery. When applying these novel therapeutics, safety considerations are not only a key concern when entering clinical trials but also an important decision point in product development. Standing at the crossroads, nanomedicine may be able to escape the niche markets and achieve wider acceptance by the pharmaceutical industry. While there is a new generation of drug delivery systems, the extracellular vesicles, standing on the starting line, unresolved issues and new challenges emerge from their translation from bench to bedside. Some key features of injectable nanomedicines contribute to the predictability of the pharmacological and toxicological effects. So far, only a few of the physicochemical attributes of nanomedicines can be justified by a direct mathematical relationship between the in vitro and the in vivo responses. To further develop extracellular vesicles as drug carriers, we have to learn from more than 40 years of clinical experience in liposomal delivery and pass on this knowledge to the next generation. Our quick guide discusses relationships between physicochemical characteristics and the in vivo response, commonly referred to as in vitro-in vivo correlation. Further, we highlight the key role of computational methods, lay open current knowledge gaps, and question the established design strategies. Has the recent progress improved the predictability of targeted delivery or do we need another change in perspective?

Getting to the Core of It All: Nanocapsules to Mitigate Infusion Reactions Can Promote Hemostasis and Be a Platform for Intravenous Therapies

One of the significant challenges to translation of intravenously administered nanomaterials has been complement-mediated infusion reactions which can be lethal. Slow infusions can reduce infusion reactions, but slow infusions are not always possible in applications like controlling bleeding following trauma. Thus, avoiding complement activation and infusion responses is essential to manage bleeding. We identified nanocapsules based on polyurethane as candidates that did not activate C5a and explored their PEGylation and functionalization with the GRGDS peptide to create a new class of hemostatic nanomaterials. Using the clinically relevant rotational thromboelastography (ROTEM), we determined that nanocapsules promote faster clotting than controls and maintain the maximum clot firmness, which is critical for reducing bleeding. Excitingly, these polyurethane-based nanocapsules did not activate complement or the major pro-inflammatory cytokines. This work provides critical evidence for the role of modulating the core material in developing safer nanomedicines for intravenous applications.

Engineering PEGylated Polyester Nanoparticles to Reduce Complement-Mediated Infusion Reaction

Translation of intravenously administered nanomaterials to the clinic is limited due to adverse infusion reactions. While these reactions are infrequent, with up to 10% prone to experiencing infusion reactions, the reactions can be severe and life-threatening. One of the innate immune pathways, the complement activation pathway, plays a significant role in mediating this response. Nanoparticle surface properties are a relevant design feature, as they control the blood proteins the nanoparticles interact with and allow the nanoparticles to evade the immune reaction. PEGylation of nanosurfaces is critical in improving the blood circulation of nanoparticles and reducing opsonization. Our goal was to understand whether modifying the surface architecture by varying the PEG density and architecture can impact the complement response in vitro. We utilized block copolymers of poly(lactic acid)-b-poly(ethylene glycol) prepared with poly(ethylene glycol) macroinitiators of molecular weights 3400 and 5000 Da. Tracking the complement biomarker C5a, we monitored the impact of changing PEGylation of the nanoparticles. We also investigated how the changing PEG length on the nanoparticle surface impacts further strengthening the stealth properties. Lastly, we determined which cytokines change upon blood incubation with nanoparticles in vitro to understand the extent to which inflammation may occur and the crosstalk between the complement and immune responses. Increasing PEGylation reduced the generation of complement-mediated anaphylatoxin C5a in vitro, with 5000 Da PEG more effectively reducing levels of C5a generated compared to 3400 Da PEG. The insights gathered regarding the impact of PEG density and PEG chain length would be critical in developing stealth nanoparticles that do not lead to infusion reactions upon intravenous administration.

Nanocarrier-based Drug Delivery System for Cancer Therapeutics: A Review of the Last Decade

In recent years, due to the shortcomings of conventional chemotherapy, such as poor bioavailability, low treatment index, and unclear side effects, the focus of cancer research has shifted to new nanocarriers of chemotherapeutic drugs. By using biodegradable materials, nanocarriers generally have the advantages of good biocompatibility, low side effects, targeting, controlled release profile, and improved efficacy. More to the point, nanocarrier based anti-cancer drug delivery systems clearly show the potential to overcome the problems associated with conventional chemotherapy. In order to promote the in-depth research and development in this field, we herein summarized and analyzed various nanocarrier based drug delivery systems for cancer therapy, including the concepts, types, characteristics, and preparation methods. The active and passive targeting mechanisms of cancer therapy were also included, along with a brief introduction of the research progress of nanocarriers used for anti-cancer drug delivery in the past decade.

Exploring interactions between extracellular vesicles and cells for innovative drug delivery system design

Extracellular vesicles (EVs) are submicron cell-secreted structures containing proteins, nucleic acids and lipids. EVs can functionally transfer these cargoes from one cell to another to modulate physiological and pathological processes. Due to their presumed biocompatibility and capacity to circumvent canonical delivery barriers encountered by synthetic drug delivery systems, EVs have attracted considerable interest as drug delivery vehicles. However, it is unclear which mechanisms and molecules orchestrate EV-mediated cargo delivery to recipient cells. Here, we review how EV properties have been exploited to improve the efficacy of small molecule drugs. Furthermore, we explore which EV surface molecules could be directly or indirectly involved in EV-mediated cargo transfer to recipient cells and discuss the cellular reporter systems with which such transfer can be studied. Finally, we elaborate on currently identified cellular processes involved in EV cargo delivery. Through these topics, we provide insights in critical effectors in the EV-cell interface which may be exploited in nature-inspired drug delivery strategies.

Highlighting the usage of polymeric nanoparticles for the treatment of traumatic brain injury: A review study

There are very limited options for treating traumatic brain injury (TBI). Nanoparticles offer the potential of targeting specific cell types, and, potentially, crossing the BBB under the right conditions making them an area of active research for treating TBI. This review focuses on polymeric nanoparticles and the impact of their chemistry, size, and surface groups on their interactions with the vasculature and cells of the brain following injury. The vast majority of the work in the field focuses on acute injury, and when the work is looked at closely, it suggests that nanoparticles rely on interactions with vascular and immune cells to alter the environment of the brain. Nonetheless, there are promising results from a number of approaches that lead to behavioral improvements coupled with neuroprotection that offer promise for therapeutic outcomes. The majority of approaches have been tested immediately following injury. It is not entirely clear what impact these approaches will have in chronic TBI, but being able to modulate inflammation specifically may have a role both during and after the acute phase of injury.

Perspectives of nano-carrier drug delivery systems to overcome cancer drug resistance in the clinics

Advanced cancer is still considered an incurable disease because of its metastatic spread to distal organs and progressive gain of chemoresistance. Even though considerable treatment progress and more effective therapies have been achieved over the past years, recurrence in the long-term and undesired side effects are still the main drawbacks of current clinical protocols. Moreover, a majority of chemotherapeutic drugs are highly hydrophobic and need to be diluted in organic solvents, which cause high toxicity, in order to reach effective therapeutic dose. These limitations of conventional cancer therapies prompted the use of nanomedicine, the medical application of nanotechnology, to provide more effective and safer cancer treatment. Potential of nanomedicines to overcome resistance, ameliorate solubility, improve pharmacological profile, and reduce adverse effects of chemotherapeutical drugs is thus highly regarded. Their use in the clinical setting has increased over the last decade. Among the various existing nanosystems, nanoparticles have the ability to transform conventional medicine by reducing the adverse effects and providing a controlled release of therapeutic agents. Also, their small size facilitates the intracellular uptake. Here, we provide a closer review of clinical prospects and mechanisms of action of nanomedicines to overcome drug resistance. The significance of specific targeting towards cancer cells is debated as well.

Complement-mediated hypersensitivity reactions to an amphotericin B-containing lipid complex (Abelcet) in pediatric patients and anesthetized rats: Benefits of slow infusion

Intravenous administration of lipid-based nanodrugs can cause hypersensitivity, also known as infusion reactions (IRs), that can be attenuated by slow infusion in adult patients. We studied the role of infusion rate and complement (C) activation in IRs in pediatric patients treated with Abelcet, and also in anesthetized rats. IRs were observed in 6 out of 10 (60%) patients who received Abelcet infusion in 4 h or less, while no patients who received the infusion in 6 h showed C activation or IRs. The rat model indicated an inverse relationship between infusion speed and Abelcet-induced hypotension, taken as an experimental endpoint of IRs, while the rise of C3a in blood, an index of C activation, directly correlated with hypotension. The results suggest that pediatric patients are more prone to produce IRs, and that the optimal infusion time of Abelcet may be much longer than the presently recommended 2 h.

DPPG2-Based Thermosensitive Liposomes with Encapsulated Doxorubicin Combined with Hyperthermia Lead to Higher Doxorubicin Concentrations in the Bladder Compared to Conventional Application in Pigs: A Rationale for the Treatment of Muscle-Invasive Bladder Cancer

Purpose

Current treatment options for muscle-invasive bladder cancer (MIBC) are associated with substantial morbidity. Local release of doxorubicin (DOX) from phosphatidyldiglycerol-based thermosensitive liposomes (DPPG₂-TSL-DOX) potentiated by hyperthermia (HT) in the bladder wall may result in bladder sparing without toxicity of systemic chemotherapy. We investigated whether this approach, compared to conventional DOX application, increases DOX concentrations in the bladder wall while limiting DOX in essential organs.

Materials and Methods

Twenty-one pigs were anaesthetized, and a urinary catheter equipped with a radiofrequency-emitting antenna for HT (60 minutes) was placed. Experimental groups consisted of iv low or full dose (20 or 60 mg/m²) DPPG₂-TSL-DOX with/without HT, iv low dose (20 mg/m²) free DOX with HT, and full dose (50 mg/50 mL) intravesical DOX with/without HT. After the procedure, animals were immediately sacrificed. HPLC was used to measure DOX levels in the bladder, essential organs and serum, and fluorescence microscopy to evaluate DOX distribution in the bladder wall.

Results

Iv DPPG₂-TSL-DOX with HT resulted in a significantly higher bladder wall DOX concentration which was more homogeneous distributed, than iv and intravesical free DOX administration with HT. Specifically in the detrusor, DPPG₂-TSL-DOX with HT led to a >7- and 44-fold higher DOX concentration, compared to iv free DOX with HT and intravesical DOX, respectively. Organ DOX concentrations were significantly lower in heart and kidneys, and similar in liver, spleen and lungs, following iv DPPG₂-TSL-DOX with HT, compared to iv free DOX. Intravesical DOX led to the lowest organ DOX concentrations.

Conclusion

Iv DPPG₂-TSL-DOX combined with HT achieved higher DOX concentrations in the bladder wall including the detrusor, compared to conventional iv and intravesical DOX application. In combination with lower DOX accumulation in heart and kidneys, compared to iv free chemotherapy, DPPG₂-TSL-DOX with HT has great potential to attain a role as a bladder-sparing treatment for MIBC.

The Critical Choice of Animal Models in Nanomedicine Safety Assessment: A Lesson Learned From Hemoglobin-Based Oxygen Carriers

Intravenous injection of nanopharmaceuticals can induce severe hypersensitivity reactions (HSRs) resulting in anaphylactoid shock in a small percentage of patients, a phenomenon explicitly reproducible in pigs. However, there is a debate in the literature on whether the pig model of HSRs can be used as a safety test for the prediction of severe adverse reactions in humans. Given the importance of using appropriate animal models for toxicity/safety testing, the choice of the right species and model is a critical decision. In order to facilitate the decision process and to expand the relevant information regarding the pig or no pig dilemma, this review examines an ill-fated clinical development program conducted by Baxter Corporation in the United States 24 years ago, when HemeAssist, an αα (diaspirin) crosslinked hemoglobin-based O₂ carrier (HBOC) was tested in trauma patients. The study showed increased mortality in the treatment group relative to controls and had to be stopped. This disappointing result had far-reaching consequences and contributed to the setback in blood substitute research ever since. Importantly, the increased mortality of trauma patients was predicted in pig experiments conducted by US Army scientists, yet they were considered irrelevant to humans. Here we draw attention to that the underlying cause of hemoglobin-induced aggravation of hemorrhagic shock and severe HSRs have a common pathomechanism: cardiovascular distress due to vasoconstrictive effects of hemoglobin (Hb) and reactogenic nanomedicines, manifested, among others, in pulmonary hypertension. The main difference is that in the case of Hb this effect is due to NO-binding, while nanomedicines can trigger the release of proinflammatory mediators. Because of the higher sensitivity of cloven-hoof animals to this kind of cardiopulmonary distress compared to rodents, these reactions can be better reproduced in pigs than in murine or rat models. When deciding on the battery of tests and the appropriate models to identify the potential hazard for nanomedicine-induced severe HSR, the pros and cons of the various species must be considered carefully.

Complement Activation: A Potential Threat on the Safety of Poly(ethylene glycol)-Coated Nanomedicines

In this issue of ACS Nano, Chen et al. provide in vitro and in vivo evidence for monoclonal anti-poly(ethylene glycol) (anti-PEG) antibody-triggered, complement terminal complex-mediated damage to PEGylated liposomal doxorubicin, entailing the release of the encapsulated drug from the vesicles. These results reveal a new dimension of the potential damage of anti-PEG antibody-mediated complement activation on PEGylated nanomedicines in addition to previous observations on infusion hypersensitivity reactions and the accelerated blood clearance effect. The possibility of a destructive attack of the complement system on the liposome drug carrier may have safety implications in patients displaying high levels of preformed anti-PEG antibodies. In this Perspective, we summarize the experimental and clinical data highlighting the relationships among the above adverse immune phenomena and the options available for reducing the risk of immune damage caused by PEGylated nanomedicines.

Complement activation by drug carriers and particulate pharmaceuticals: Principles, challenges and opportunities

Considering the multifaceted protective and homeostatic roles of the complement system, many consequences arise when drug carriers, and particulate pharmaceutical formulations clash with complement proteins, and trigger complement cascade. Complement activation may induce formulation destabilization, promote opsonization, and affect biological and therapeutic performance of pharmaceutical nano- and micro-particles. In some cases, complement activation is beneficial, where complement may play a role in prophylactic protection, whereas uncontrolled complement activation is deleterious, and contributes to disease progression. Accordingly, design initiatives with particulate medicines should consider complement activation properties of the end formulation within the context of administration route, dosing, systems biology, and therapeutic perspective. Here we examine current progress in mechanistic processes underlying complement activation by pre-clinical and clinical particles, identify opportunities and challenges ahead, and suggest future directions in nanomedicine-complement interface research.

Human Clinical Relevance of the Porcine Model of Pseudoallergic Infusion Reactions

Pigs provide a highly sensitive animal model for pseudoallergic infusion reactions, which are mild-to-severe hypersensitivity reactions (HSRs) that arise following intravenous administration of certain nanoparticulate drugs (nanomedicines) and other macromolecular structures. This model has been used in research for three decades and was also proposed by regulatory bodies for preclinical assessment of the risk of HSRs in the clinical stages of nano-drug development. However, there are views challenging the human relevance of the model and its utility in preclinical safety evaluation of nanomedicines. The argument challenging the model refers to the “global response” of pulmonary intravascular macrophages (PIM cells) in the lung of pigs, preventing the distinction of reactogenic from non-reactogenic particles, therefore overestimating the risk of HSRs relative to its occurrence in the normal human population. The goal of this review is to present the large body of experimental and clinical evidence negating the “global response” claim, while also showing the concordance of symptoms caused by different reactogenic nanoparticles in pigs and hypersensitive man. Contrary to the model’s demotion, we propose that the above features, together with the high reproducibility of quantifiable physiological endpoints, validate the porcine “complement activation-related pseudoallergy” (CARPA) model for safety evaluations. However, it needs to be kept in mind that the model is a disease model in the context of hypersensitivity to certain nanomedicines. Rather than toxicity screening, its main purpose is specific identification of HSR hazard, also enabling studies on the mechanism and mitigation of potentially serious HSRs.

Immunological and Toxicological Considerations for the Design of Liposomes

Liposomes hold great potential as gene and drug delivery vehicles due to their biocompatibility and modular properties, coupled with the major advantage of attenuating the risk of systemic toxicity from the encapsulated therapeutic agent. Decades of research have been dedicated to studying and optimizing liposomal formulations for a variety of medical applications, ranging from cancer therapeutics to analgesics. Some effort has also been made to elucidate the toxicities and immune responses that these drug formulations may elicit. Notably, intravenously injected liposomes can interact with plasma proteins, leading to opsonization, thereby altering the healthy cells they come into contact with during circulation and removal. Additionally, due to the pharmacokinetics of liposomes in circulation, drugs can end up sequestered in organs of the mononuclear phagocyte system, affecting liver and spleen function. Importantly, liposomal agents can also stimulate or suppress the immune system depending on their physiochemical properties, such as size, lipid composition, pegylation, and surface charge. Despite the surge in the clinical use of liposomal agents since 1995, there are still several drawbacks that limit their range of applications. This review presents a focused analysis of these limitations, with an emphasis on toxicity to healthy tissues and unfavorable immune responses, to shed light on key considerations that should be factored into the design and clinical use of liposomal formulations.