Influence of polyethylene glycol density and surface lipid on pharmacokinetics and biodistribution of lipid-calcium-phosphate nanoparticles

Mannan-Decorated Lipid Calcium Phosphate Nanoparticle Vaccine Increased the Antitumor Immune Response by Modulating the Tumor Microenvironment

With the rapid development of tumor immunotherapy, nanoparticle vaccines have attracted much attention as potential therapeutic strategies. A systematic review and analysis must be carried out to investigate the effect of mannose modification on the immune response to nanoparticles in regulating the tumor microenvironment, as well as to explore its potential clinical application in tumor therapy. Despite the potential advantages of nanoparticle vaccines in immunotherapy, achieving an effective immune response in the tumor microenvironment remains a challenge. Tumor immune escape and the overexpression of immunosuppressive factors limit its clinical application. Therefore, our review explored how to intervene in the immunosuppressive mechanism in the tumor microenvironment through the use of mannan-decorated lipid calcium phosphate nanoparticle vaccines to improve the efficacy of immunotherapy in patients with tumors and to provide new ideas and strategies for the field of tumor therapy.

Emerging platinum(IV) prodrug nanotherapeutics: A new epoch for platinum-based cancer therapy

Owing to the unique DNA damaging cytotoxicity, platinum (Pt)-based chemotherapy has long been the first-line choice for clinical oncology. Unfortunately, Pt drugs are restricted by the severe dose-dependent toxicity and drug resistance. Correspondingly, Pt(IV) prodrugs are developed with the aim to improve the antitumor performance of Pt drugs. However, as "free" molecules, Pt(IV) prodrugs are still subject to unsatisfactory in vivo destiny and antitumor efficacy. Recently, Pt(IV) prodrug nanotherapeutics, inheriting both the merits of Pt(IV) prodrugs and nanotherapeutics, have emerged and demonstrated the promise to address the underexploited dilemma of Pt-based cancer therapy. Herein, we summarize the latest fronts of emerging Pt(IV) prodrug nanotherapeutics. First, the basic outlines of Pt(IV) prodrug nanotherapeutics are overviewed. Afterwards, how versatile Pt(IV) prodrug nanotherapeutics overcome the multiple biological barriers of antitumor drug delivery is introduced in detail. Moreover, advanced combination therapies based on multimodal Pt(IV) prodrug nanotherapeutics are discussed with special emphasis on the synergistic mechanisms. Finally, prospects and challenges of Pt(IV) prodrug nanotherapeutics for future clinical translation are spotlighted.

SPIONs Conjugate Supported Anticancer Drug Doxorubicin's Delivery: Current Status, Challenges, and Prospects

Considerable efforts have been directed towards development of nano-structured carriers to overcome the limitations of anticancer drug, doxorubicin's, delivery to various cancer sites. The drug's severe toxicity to cardio and hepatic systems, low therapeutic outcomes, inappropriate dose-demands, metastatic and general resistance, together with non-selectivity of the drug have led to the development of superparamagnetic iron oxide nanoparticles (SPIONs)-based drug delivery modules. Nano-scale polymeric co-encapsulation of the drug, doxorubicin, with SPIONs, the SPIONs surface end-groups' cappings with small molecular entities, as well as structural modifications of the SPIONs' surface-located functional end-groups, to attach the doxorubicin, have been achieved through chemical bonding by conjugation and cross-linking of natural and synthetic polymers, attachments of SPIONs made directly to the non-polymeric entities, and attachments made through mediation of molecular-spacer as well as non-spacer mediated attachments of several types of chemical entities, together with the physico-chemical bondings of the moieties, e.g., peptides, proteins, antibodies, antigens, aptamers, glycoproteins, and enzymes, etc. to the SPIONs which are capable of targeting multiple kinds of cancerous sites, have provided stable and functional SPIONs-based nano-carriers suitable for the systemic, and in vitro deliveries, together with being suitable for other biomedical/biotechnical applications. Together with the SPIONs inherent properties, and ability to respond to magnetic resonance, fluorescence-directed, dual-module, and molecular-level tumor imaging; as well as multi-modular cancer cell targeting; magnetic-field-inducible drug-elution capacity, and the SPIONs' magnetometry-led feasibility to reach cancer action sites have made sensing, imaging, and drug and other payloads deliveries to cancerous sites for cancer treatment a viable option. Innovations in the preparation of SPIONs-based delivery modules, as biocompatible carriers; development of delivery route modalities; approaches to enhancing their drug delivery-cum-bioavailability have explicitly established the SPIONs' versatility for oncological theranostics and imaging. The current review outlines the development of various SPIONs-based nano-carriers for targeted doxorubicin delivery to different cancer sites through multiple methods, modalities, and materials, wherein high-potential nano-structured platforms have been conceptualized, developed, and tested for, both, in vivo and in vitro conditions. The current state of the knowledge in this arena have provided definite dose-control, site-specificity, stability, transport feasibility, and effective onsite drug de-loading, however, with certain limitations, and these shortcomings have opened the field for further advancements by identifying the bottlenecks, suggestive and plausible remediation, as well as more clear directions for future development.

Immunomodulation, Toxicity, and Therapeutic Potential of Nanoparticles

Altered immune responses associated with human disease conditions, such as inflammatory and infectious diseases, cancers, and autoimmune diseases, are among the primary causes of morbidity across the world. A wealth of studies has demonstrated the efficiency of nanoparticles (NPs)-based immunotherapy strategies in different laboratory model systems. Nanoscale dimensions (<100 nm) enable NPs to have increased surface area to volume ratio, surface charge, and reactivity. Physicochemical properties along with the shapes, sizes, and elasticity influence the immunomodulatory response induced by NPs. In recent years, NPs-based immunotherapy strategies have attained significant focus in the context of cancers and autoimmune diseases. This rapidly growing field of nanomedicine has already introduced ~50 nanotherapeutics in clinical practices. Parallel to wide industrial applications of NPs, studies have raised concerns about their potential threat to the environment and human health. In past decades, a wealth of in vivo and in vitro studies has demonstrated the immunotoxicity potential of various NPs. Given that the number of engineered/designed NPs in biomedical applications is continuing to increase, it is pertinent to establish the toxicity profile for their safe and intelligent use in biomedical applications. The review is intended to summarize the NPs-induced immunomodulation pertaining to toxicity and therapeutic development in human health.

Modulating Macrophage Clearance of Nanoparticles: Comparison of Small-Molecule and Biologic Drugs as Pharmacokinetic Modifiers of Soft Nanomaterials

Nanomedicines show benefits in overcoming the limitations of conventional drug delivery systems by reducing side effects, toxicity, and exhibiting enhanced pharmacokinetic (PK) profiles to improve the therapeutic window of small-molecule drugs. However, upon administration, many nanoparticles (NPs) prompt induction of host innate immune responses, which in combination with other clearance pathways such as renal and hepatic, eliminate up to 99% of the administered dose. Here, we explore a drug predosing strategy to transiently suppress the mononuclear phagocyte system (MPS), subsequently improving the PK profile and biological behaviors exhibited by a model NP system [hyperbranched polymers (HBPs)] in an immunocompetent mouse model. In vitro assays allowed the identification of five drug candidates that attenuated cellular association. Predosing of lead compounds chloroquine (CQ) and zoledronic acid (ZA) further showed increased HBP retention within the circulatory system of mice, as shown by both fluorescence imaging and positron emission tomography-computed tomography. Flow cytometric evaluation of spleen and liver tissue cells following intravenous administration further demonstrated that CQ and ZA significantly reduced HBP association with myeloid cells by 23 and 16%, respectively. The results of this study support the use of CQ to pharmacologically suppress the MPS to improve NP PKs.

Zwitterionic Amino Acid Polymer-Grafted Core-Crosslinked Particle toward Tumor Delivery

Zwitterionic amino acid polymers (ZAPs) exhibit biocompatibility and recognition capability for amino acid transporters (AATs) overexpressed on cancer cells. They are potential cancer-targeting ligands in nanoparticle-based nanomedicines utilized in cancer chemotherapy. Here, a poly(glutamine methacrylate) (pGlnMA)-grafted core-crosslinked particle (pGlnMA-CCP) is prepared through the formation of nanoemulsions stabilized using amphiphilic block copolymers comprising pGlnMA as the hydrophilic block. The chain conformation of the grafted polymer and the particle structure of pGlnMA-CCP are precisely elucidated by dynamic light scattering, X-ray scattering, and transmission electron microscopy. pGlnMA-CCP demonstrates active cellular uptake and deep penetration behaviors for cancer cells and spheroids, respectively, via an AAT-mediated mechanism. The in vivo pharmacokinetics of pGlnMA-CCP is practically comparable to those of a CCP covered with poly(polyethylene glycol methacrylate) (pPEGMA), which inhibits protein adsorption and prolongs blood retention, implying that the biocompatible properties of pGlnMA are similar to those of pPEGMA. Furthermore, pGlnMA-CCP accumulates in cancer tissues at a higher level than that of pPEGMA systems. The results demonstrate that the properties of cancer targetability, tumor permeability, efficient tumor accumulation, and biocompatibility can be obtained by grafting pGlnMA onto nanoparticles, suggesting a high potential of pGlnMA as a ligand for cancer-targeting nanomedicines.

ICAM-1 targeted thermal-sensitive micelles loaded with tofacitinib for enhanced treatment of rheumatoid arthritis via microwave assistance

Rheumatoid arthritis (RA) is an immune-mediated inflammatory disease without effective treatment. Tofacitinib (TOF) is a JAK inhibitor that can be used for RA therapy, but it still faces the problems of nonspecific distribution and relatively low therapeutic effect. Herein, ICAM-1-modified TOF-loaded P(AN-co-AAm)-PEG micelles (AI-TM) were developed, which can result in an enhanced RA therapy when combining with microwave hyperthermia (MH). It was found that AI-TM could rapidly release the encapsulated TOF under a thermal condition of >43 °C, which was due to the fact that the polymeric micelles has an upper critical solution temperature (UCST) of 43 °C. AI-TM could specifically distribute into the inflamed joints of RA mice, which is associated with the high affinity between anti-ICAM-1 and overexpressed ICAM-1 receptors. Moreover, the combination of AI-TM and MH could result in a remarkably enhanced anti-rheumatic activity, which was related to the RA-targeted ability of AI-TM, the rapid TOF release under MH, and the combined effect between TOF and MH treatment. Our study definitely provides a novel strategy for effective treatment of RA.

Nanoparticles for Coronavirus Control

More than 2 years have passed since the SARS-CoV-2 outbreak began, and many challenges that existed at the beginning of this pandemic have been solved. Some countries have been able to overcome this global challenge by relying on vaccines against the virus, and vaccination has begun in many countries. Many of the proposed vaccines have nanoparticles as carriers, and there are different nano-based diagnostic approaches for rapid detection of the virus. In this review article, we briefly examine the biology of SARS-CoV-2, including the structure of the virus and what makes it pathogenic, as well as describe biotechnological methods of vaccine production, and types of the available and published nano-based ideas for overcoming the virus pandemic. Among these issues, various physical and chemical properties of nanoparticles are discussed to evaluate the optimal conditions for the production of the nano-mediated vaccines. At the end, challenges facing the international community and biotechnological answers for future viral attacks are reviewed.

Nanoparticle based medicines: approaches for evading and manipulating the mononuclear phagocyte system and potential for clinical translation

For decades, nanomedicines have been reported as a potential means to overcome the limitations of conventional drug delivery systems by reducing side effects, toxicity and the non-ideal pharmacokinetic behaviour typically exhibited by small molecule drugs. However, upon administration many nanoparticles prompt induction of host inflammatory responses due to recognition and uptake by macrophages, eliminating up to 95% of the administered dose. While significant advances in nanoparticle engineering and consequent therapeutic efficacy have been made, it is becoming clear that nanoparticle recognition by the mononuclear phagocyte system (MPS) poses an impassable junction in the current framework of nanoparticle development. Hence, this has negative consequences on the clinical translation of nanotechnology with respect to therapeutic efficacy, systemic toxicity and economic benefit. In order to improve the translation of nanomedicines from bench-to-bedside, there is a requirement to either modify nanomedicines in terms of how they interact with intrinsic processes in the body, or modulate the body to be more accommodating for nanomedicine treatments. Here we provide an overview of the current standard for design elements of nanoparticles, as well as factors to consider when producing nanomedicines that have minimal MPS-nanoparticle interactions; we explore this landscape across the cellular to tissue and organ levels. Further, rather than designing materials to suit the body, a growing research niche involves modulating biological responses to administered nanomaterials. We here discuss how developing strategic methods of MPS 'pre-conditioning' with small molecule or biological drugs, as well as implementing strategic dosing regimens, such as 'decoy' nanoparticles, is essential to increasing nanoparticle therapeutic efficacy. By adopting such a perspective, we hope to highlight the increasing trends in research dedicated to improving nanomedicine translation, and subsequently making a positive clinical impact.

Optimizing the Polymer Cloak for Upconverting Nanoparticles: An Evaluation of Bioactivity and Optical Performance

The ability of upconversion nanoparticles (UCNPs) to convert low-energy near-infrared (NIR) light into high-energy visible-ultraviolet light has resulted in their development as novel contrast agents for biomedical imaging. However, UCNPs often succumb to poor colloidal stability in aqueous media, which can be conquered by decorating the nanoparticle surface with polymers. The polymer cloak, therefore, plays an instrumental role in ensuring good stability in biological media. This study aims to understand the relationship between the length and grafting density of the polymer shell on the physicochemical and biological properties of these core-shell UCNPs. Poly(ethylene glycol) methyl ether methacrylate block ethylene glycol methacrylate phosphate (PPEGMEMA_n-b-PEGMP₃) with different numbers of PEGMEMA repeating units (26, 38, and 80) was prepared and attached to the UCNPs via the phosphate ligand of the poly(ethylene glycol methacrylate phosphate) (PEGMP) block at different polymer densities. The in vitro and in vivo protein corona, cellular uptake in two-dimensional (2D) monolayer and three-dimensional (3D) multicellular tumor spheroid (MCTS) models, and in vivo biodistribution in mice were evaluated. Furthermore, the photoluminescence of single-polymer-coated UCNPs was compared in solid state and cancer cells using laser scanning confocal microscopy (LSCM). Our results showed that the bioactivity and luminescence properties are chain length and grafting density dependent. The UCNPs coated with the longest PPEGMEMA chain, grafted at low brush density, were able to reduce the formation of the protein corona in vitro and in vivo, while these UCNPs also showed the brightest upconversion luminescence in the solid state. Moreover, these particular polymer-coated UCNPs showed enhanced cellular uptake, extended in vivo blood circulation time, and more accumulation in the liver, brain, and heart.

Preparation and Characterization of siRNA-Loaded Liposomes

The major challenge for RNAi-based therapy is the fabrication of the delivery system that meet the requirement of clinical applicability. Liposome-derived nanoparticles (NPs) are one of the best investigated systems for in vivo siRNA delivery. In the recent years, we have successfully redesigned the conventional cationic liposomes into Liposome/Protamine/hyaluronic acid (LPH) NPs and Lipid-Calcium-Phosphate (LCP) NPs in order to increase the in vivo gene silencing effect and reduce the toxicity. Here we describe the preparation of LPH and LCP NPs loaded with siRNA, and characterization analysis including size distribution, trapping efficiency, and in vivo activity. This protocol could be used for in vivo delivery of siRNA to target genes in cancer cells.

Applications of Nanobiomaterials in the Therapy and Imaging of Acute Liver Failure

This review focuses on the therapeutic mechanisms, targeting strategies of various nanomaterials in acute liver failure, and recent advances of diverse nanomaterials for acute liver failure therapy, diagnosis, and imaging. This review provides an outlook on the applications of nanomaterials, especially on the new horizons in acute liver failure therapy, and inspires broader interests across various disciplines. Acute liver failure (ALF), a fatal clinical disease featured with overwhelming hepatocyte necrosis, is a grand challenge in global health. However, a satisfactory therapeutic option for curing ALF is still absent, other than liver transplantation. Nanobiomaterials are currently being developed for the diagnosis and treatment of ALF. The liver can sequester most of nanoparticles from blood circulation, which becomes an intrinsic superiority for nanobiomaterials targeting hepatic diseases. Nanobiomaterials can enhance the bioavailability of free drugs, thereby significantly improving the therapeutic effects in ALF. Nanobiomaterials can also increase the liver accumulation of therapeutic agents and enable more effective targeting of the liver or specific liver cells. In addition, stimuli-responsive, optical, or magnetic nanomaterials exhibit great potential in the therapeutical, diagnostic, and imaging applications in ALF. Therefore, therapeutic agents in combination with nanobiomaterials increase the specificity of ALF therapy, diminish adverse systemic effects, and offer a multifunctional theranostic platform. Nanobiomaterial holds excellent significance and prospects in ALF theranostics. In this review, we summarize the therapeutic mechanisms and targeting strategies of various nanobiomaterials in ALF. We highlight recent developments of diverse nanomedicines for ALF therapy, diagnosis, and imaging. Furthermore, the challenges and future perspectives in the theranostics of ALF are also discussed.

Long-Circulating Thermosensitive Liposomes for the Targeted Drug Delivery of Oxaliplatin

Introduction

Oxaliplatin (L-OHP) is a well-known third-generation platinum anticancer drug with severe systemic- and neuro-toxicity. The main objective of the current research was to develop a targeted long-circulating thermosensitive smart-release liposome (LCTL) system for better therapeutic efficacy and less toxicity.

Methods

The reverse-phase evaporation method (REV) was used to prepare L-OHP loaded LCTL (L-OHP/LCTL). The physical characteristics were evaluated including encapsulation efficiency (EE), size, zeta potential and stability. The release behavior, cytotoxicity and in vivo evaluation were also carried out.

Results

EE of LCTL was around 25% with a uniform size distribution, and LCTL achieved almost complete release at 42°C while it was only 10% at 37°C. Moreover, the LCTL showed significantly higher cytotoxicity at 42°C than that at 37°C. The in vivo results indicated LCTL could target tumors and enhance retention for more than 24 h, thereby enhancing anti-tumor efficacy on 4T1-bearing mice.

Discussion

These results indicated that LCTL not only possessed a prolonged circulation time but it also enhanced accumulation and achieved selective release at the tumor sites. Conclusively, LCTL could serve as a promising carrier for oxaliplatin delivery to treat solid tumors.

Anticancer activities of phytoconstituents and their liposomal targeting strategies against tumor cells and the microenvironment

Various bioactive ingredients have been extracted from Chinese herbal medicines (CHMs) that affect tumor progression and metastasis. To further understand the mechanisms of CHMs in cancer therapy, this article summarizes the effects of five categories of CHMs and their active ingredients on tumor cells and the tumor microenvironment. Despite their treatment potential, the undesirable physicochemical properties (poor permeability, instability, high hydrophilicity or hydrophobicity, toxicity) and unwanted pharmacokinetic profiles (short half-life in blood and low bioavailability) restrict clinical studies of CHMs. Therefore, development of liposomes through relevant surface modifying techniques to achieve targeted CHM delivery for cancer cells, i.e., extracellular and intracellular targets and targets in tumor microenvironment or vasculature, have been reviewed. Current challenges of liposomal targeting of these phytoconstituents and future perspective of CHM applications are discussed to provide an informative reference for interested readers.

ɑvβ3-targeted liposomal drug delivery system with attenuated immunogenicity enabled by linear pentapeptide for glioma therapy

Owing to the binding capacity to ɑ_vβ₃ integrin overexpressed on glioma, vasculogenic mimicry and neovasculature, the peptide c(RGDyK) has been exploited pervasively to functionalize nanocarriers for targeted delivery of bioactives. The former study in our group substantiated the immunotoxicity of c(RGDyK)-modified liposome, and this unfavorable immunogenicity is known to compromise blood circulation, targeting efficacy and therapeutic outcome. Therefore, we need to find a superior alternative ligand in order to evade the exquisite immuno-sensitization. We developed mn by structure-guided peptide design and retro-inverso isomerization technique, which was experimentally substantiated to have exceptional binding affinity to ɑ_vβ₃ integrin. Besides mn does not have affinity toward normal liver cells and kidney cells, which c(RGDyK) possesses in a certain degree. Warranting that mn and c(RGDyK) anchored ɑ_vβ₃, we formulated peptide-tethered liposomes and investigated in vivo bio-fate. Compared with c(RGDyK)-modified liposome, mn-modified liposome presented longer blood circulation and reduced ingestion by Kupffer cells with decreased retention in liver accordingly, benefitting from attenuated anti-liposome IgG and IgM response elicited by multiple sequential doses. Those merits strengthened the anti-glioma efficacy of ɑ_vβ₃-targeted doxorubicin-loaded liposomes, proving the importance of immunocompatibility in process of targeted drug delivery.

The Application of Nanotechnology in the Codelivery of Active Constituents of Plants and Chemotherapeutics for Overcoming Physiological Barriers during Antitumor Treatment

Antitumor therapy using a combination of drugs has shown increased clinical efficacy. Active constituents derived from plants can offer several advantages, such as high efficiacy, low toxicity, extensive effects, and multiple targets. At present, the combination of plants' active constituents and chemotherapeutic drugs has attracted increased attention. Nanodrug delivery systems (NDDSs) have been widely used in tumor-targeted therapy because of their efficacy of delivering antitumor drugs. The in vivo process of tumor-targeted NDDSs has several steps. They include blood circulation, tumor accumulation and penetration, target cell internalization and uptake, and drug release and drug response. In each step, NDDSs encounter multiple barriers that prevent their effective delivery to target sites. Studies have been performed to find alternative strategies to overcome these barriers. We reviewed the recent progress of codelivery of active constituents of plants and chemotherapeutics using NDDSs. Progress into transversing the physiological barriers for more effective in vivo antitumor delivery will be discussed in this review.

Relaxin gene delivery mitigates liver metastasis and synergizes with check point therapy

Activated hepatic stellate cell (aHSC)-mediated liver fibrosis is essential to the development of liver metastasis. Here, we discover intra-hepatic scale-up of relaxin (RLN, an anti-fibrotic peptide) in response to fibrosis along with the upregulation of its primary receptor (RXFP1) on aHSCs. The elevated expression of RLN serves as a natural regulator to deactivate aHSCs and resolve liver fibrosis. Therefore, we hypothesize this endogenous liver fibrosis repair mechanism can be leveraged for liver metastasis treatment via enforced RLN expression. To validate the therapeutic potential, we utilize aminoethyl anisamide-conjugated lipid-calcium-phosphate nanoparticles to deliver plasmid DNA encoding RLN. The nanoparticles preferentially target metastatic tumor cells and aHSCs within the metastatic lesion and convert them as an in situ RLN depot. Expressed RLN reverses the stromal microenvironment, which makes it unfavorable for established liver metastasis to grow. In colorectal, pancreatic, and breast cancer liver metastasis models, we confirm the RLN gene therapy results in significant inhibition of metastatic progression and prolongs survival. In addition, enforced RLN expression reactivates intra-metastasis immune milieu. The combination of the RLN gene therapy with PD-L1 blockade immunotherapy further produces a synergistic anti-metastatic efficacy. Collectively, the targeted RLN gene therapy represents a highly efficient, safe, and versatile anti-metastatic modality, and is promising for clinical translation.

Biomolecule-assisted green synthesis of nanostructured calcium phosphates and their biomedical applications

Calcium phosphates (CaPs) are ubiquitous in nature and vertebrate bones and teeth, and have high biocompatibility and promising applications in various biomedical fields. Nanostructured calcium phosphates (NCaPs) are recognized as promising nanocarriers for drug/gene/protein delivery owing to their high specific surface area, pH-responsive degradability, high drug/gene/protein loading capacity and sustained release performance. In order to control the structure and surface properties of NCaPs, various biomolecules with high biocompatibility such as nucleic acids, proteins, peptides, liposomes and phosphorus-containing biomolecules are used in the synthesis of NCaPs. Moreover, biomolecules play important roles in the synthesis processes, resulting in the formation of various NCaPs with different sizes and morphologies. At room temperature, biomolecules can play the following roles: (1) acting as a biocompatible organic phase to form biomolecule/CaP hybrid nanostructured materials; (2) serving as a biotemplate for the biomimetic mineralization of NCaPs; (3) acting as a biocompatible modifier to coat the surface of NCaPs, preventing their aggregation and increasing their colloidal stability. Under heating conditions, biomolecules can (1) control the crystallization process of NCaPs by forming biomolecule/CaP nanocomposites before heating; (2) prevent the rapid and disordered growth of NCaPs by chelating with Ca2+ ions to form precursors; (3) provide the phosphorus source for the controlled synthesis of NCaPs by using phosphorus-containing biomolecules. This review focuses on the important roles of biomolecules in the synthesis of NCaPs, which are expected to guide the design and controlled synthesis of NCaPs. Moreover, we will also summarize the biomedical applications of NCaPs in nanomedicine and tissue engineering, and discuss their current research trends and future prospects.

Codelivery of GRP78 siRNA and docetaxel via RGD-PEG-DSPE/DOPA/CaP nanoparticles for the treatment of castration-resistant prostate cancer

Background: Castration-resistant prostate cancer (CRPC) accounts for the majority of prostate cancer deaths, and patients with CRPC are prone to developing drug resistance. Therefore, there is a need to develop effective therapeutics to treat CRPC, especially drug-resistant CRPC. Although various nanoparticles have been developed for drug or gene delivery and control release, approaches to reproducibly formulate the optimal treatment with nanoparticles that could effectively target CRPC and bone metastasis remain suboptimal. Recently, codelivery of a chemotherapeutic agent and a small interfering RNA (siRNA) has become a promising strategy for the treatment of drug-resistant prostate cancer.

Methods: In a previous study, we prepared a novel RGD-PEG-DSPE/CaP nanoparticle as an effective and biocompatible drug and gene delivery system. In this study, we further modify the nanoparticle to obtain the LCP-RGD nanoparticle, which contains a calcium phosphate (CaP) core, dioleoyl phosphatidic acid (DOPA) and RGD modified poly(ethylene glycol)-conjugated distearoyl phosphatidylethanolamine (RGD-PEG-DSPE). This drug delivery system was used for codelivery of GRP78 siRNA and docetaxel (DTXL) for the treatment of the PC-3 CRPC.

Results: The nanoparticles contain the CaP core, which can effectively compress the negatively charged siRNA, while the DOPA and RGD-PEG-DSPE component can effectively carry DTXL. The arginine-glycine-aspartic acid (RGD) segment can target the prostate cancer site, as the cancer site is neovascularized. This novel nanoparticle has good stability, excellent biocompatibility, high drug and siRNA loading capacity, and an in vitro sustainable release profile.

Conclusion: Codelivery of DTXL and GRP78 siRNA has enhanced in vitro and in vivo anti-prostate cancer effects which are much greater than using free DTXL and free GRP78 siRNA together. Our study also indicated that codelivery of DTXL and GRP78 siRNA have an in vitro and in vivo combinational anti-prostate cancer effect and also could effectively sensitize the cell-killing effect of DTXL; this method may be especially suitable for drug-resistant CRPC treatment.

Novel PEGylated Liposomes Enhance Immunostimulating Activity of isRNA

The performance of cationic liposomes for delivery of therapeutic nucleic acids in vivo can be improved and specifically tailored to certain types of cargo and target cells by incorporation of PEG-containing lipoconjugates in the cationic liposome's composition. Here, we report on the synthesis of novel PEG-containing lipoconjugates with molecular masses of PEG 800, 1500 and 2000 Da. PEG-containing lipoconjugates were used as one of the components in liposome preparation with the polycationic amphiphile 1,26-bis(cholest-5-en-3β-yloxycarbonylamino)-7,11,16,20-tetra-azahexacosan tetrahydrochloride (2X3) and the lipid-helper dioleoylphosphatidylethanolamine (DOPE). We demonstrate that increasing the length of the PEG chain reduces the transfection activity of liposomes in vitro, but improves the biodistribution, increases the circulation time in the bloodstream and enhances the interferon-inducing activity of immunostimulating RNA in vivo.

CCRK is a novel signalling hub exploitable in cancer immunotherapy

Cyclin-dependent kinase 20 (CDK20), or more commonly referred to as cell cycle-related kinase (CCRK), is the latest member of CDK family with strong linkage to human cancers. Accumulating studies have reported the consistent overexpression of CCRK in cancers arising from brain, colon, liver, lung and ovary. Such aberrant up-regulation of CCRK is clinically significant as it correlates with tumor staging, shorter patient survival and poor prognosis. Intriguingly, the signalling molecules perturbed by CCRK are divergent and cancer-specific, including the cell cycle regulators CDK2, cyclin D1, cyclin E and RB in glioblastoma, ovarian carcinoma and colorectal cancer, and KEAP1-NRF2 cytoprotective pathway in lung cancer. In hepatocellular carcinoma (HCC), CCRK mediates virus-host interaction to promote hepatitis B virus-associated tumorigenesis. Further mechanistic analyses reveal that CCRK orchestrates a self-reinforcing circuitry comprising of AR, GSK3β, β-catenin, AKT, EZH2, and NF-κB signalling for transcriptional and epigenetic regulation of oncogenes and tumor suppressor genes. Notably, EZH2 and NF-κB in this circuit have been recently shown to induce IL-6 production to facilitate tumor immune evasion. Concordantly, in a hepatoma preclinical model, ablation of Ccrk disrupts the immunosuppressive tumor microenvironment and enhances the therapeutic efficacy of immune checkpoint blockade via potentiation of anti-tumor T cell responses. In this review, we summarized the multifaceted tumor-intrinsic and -extrinsic functions of CCRK, which represents a novel signalling hub exploitable in cancer immunotherapy.

Disulfiram-loaded mixed nanoparticles with high drug-loading and plasma stability by reducing the core crystallinity for intravenous delivery

To develop an injectable formulation and improve the stability of disulfiram (DSF), DSF was encapsulated into mixed nanoparticles (DSF-NPs) through a high-pressure homogenization method. The Flory-Huggins interaction parameters (χ_FH) were calculated to predict the miscibility between DSF and the hydrophobic core, resulting in PCL₅₀₀₀ selected as the hydrophobic block to encapsulate the DSF, as PCL₅₀₀₀ had a lower χ_FH 3.39 and the drug loading of the nanoparticles prepared by mPEG₅₀₀₀-PCL₅₀₀₀ was relatively higher. mPEG₅₀₀₀-PCL₅₀₀₀ and PCL₅₀₀₀ were blended to reduce the leakage of DSF during preparation, as well as increase the stability of the nanoparticles. The cargo-loading capacity of the nanoparticles was improved from 3.35% to 5.50% by reducing the crystallinity of the PCL nanoparticle core, and the crystallinity decreased from 51.13% to 25.15% after adding medium chain triglyceride (MCT). The DSF-NPs prepared by the above method had a small particle size of 98.1 ± 10.54 nm, with a polydispersity index (PDI) of 0.036, as well as drug loading of 5.50%. Furthermore, DSF-NPs containing MCT showed higher stability than DSF-NPs without MCT and DSF-sol (DSF dissolved in Cremophor EL and ethanol) in water and 90% plasma-containing PBS. The pharmacokinetics proved that DSF-NPs containing MCT enhanced the DSF concentration in the blood. Finally, DSF-NPs effectively inhibited H22 xenograft tumor growth in vivo.

Nanoparticle-Mediated Therapeutic Agent Delivery for Treating Metastatic Breast Cancer-Challenges and Opportunities

Breast cancer (BC) is the second leading cause of cancer-related death in American women and more than 90% of BC-related death is caused by metastatic BC (MBC). This review stresses the limited success of traditional therapies as well as the use of nanomedicine for treating MBC. Understanding the biological barriers of MBC that nanoparticle in vivo trafficking must overcome could provide valuable new insights for translating nanomedicine from the bench side to the bedside. A view about nanomedicine applied in BC therapy has been summarized with their present status, which is gaining attention in the clinically-applied landscape. The progressions of drug/gene delivery systems, especially the status of their preclinical or clinical trials, are also discussed. Here we highlight that the treatment of metastasis, in addition to the extensively described inhibition of primary tumor growth, is an indispensable requirement for nanomedicine. Along with more innovations in material chemistry and more progressions in biology, nanomedicine will constantly supply more exciting new approaches for targeted drug/gene delivery against MBC.

Biodistribution Analysis of NIR-Labeled Nanogels Using in Vivo FMT Imaging in Triple Negative Human Mammary Carcinoma Models

The purpose of this study is to evaluate the biodistribution properties of random-copolymer-based core-cross-linked nanogels of various sizes and surface poly(ethylene glycol) composition. Systematic variations of near-IR labeled nanogels, comprising varying particle sizes (28-135 nm), PEG corona quantity (0-50 mol %), and PEG length (PEG M_n 1000, 2000, and 5000), were prepared and injected in mice that had been subcutaneously implanted with MDA-MB-231-luc-D3H2LN human mammary carcinoma. In vivo biodistribution was obtained using fluorescence molecular tomography imaging at 0, 6, 24, 48, and 72 h postinjection. Retention of total body probe and percentages of total injected dose in the tumor, liver, spleen, lungs, heart, intestines, and kidneys were obtained. Smaller nanogels (∼30-40 nm) with a high PEG conjugation (∼43-46 mol %) of M_n 2000 on their coronas achieved the highest tumor specificity with peak maximum 27% ID/g, a statistically significant propensity toward accumulation with 16.5% ID/g increase from 0 to 72 h of imaging, which constitutes a 1.5-fold increase. Nanogels with greater tumor localization also had greater retention of total body probe over 72 h. Nanogels without extensive PEGylation were rapidly excreted, even at similar sizes to PEGylated nanogels exhibiting whole body retention. Of all tissues, the liver had the highest % ID, however, like other tissues, it displayed a monotonic decrease over time, suggesting nanogel clearance by hepatic metabolism. Ex vivo quantification of individual tissues from gross necropsy at 72 h postinjection generally correlated with the FMT analysis, providing confidence in tissue signal segmentation in vivo. The parameters determined to most significantly direct a nanogel to the desired tumor target can lead to improve effectiveness for nanogels as therapeutic delivery vehicles.

Effect of Synthetic High Density Lipoproteins Modification with Polyethylene Glycol on Pharmacokinetics and Pharmacodynamics

Synthetic high density lipoprotein nanoparticles (sHDLs) capable of mobilizing excess cholesterol from atherosclerotic arteries and delivering it to the liver for elimination have been shown to reduce plaque burden in patients. Unfortunately, sHDLs have a narrow therapeutic index and relative to the endogenous HDL shorter circulation half-life. Surface modification with polyethylene glycol (PEG) was investigated for its potential to extend sHDL circulation in vivo. Various amounts (2.5, 5, and 10%) and different chain lengths (2 and 5 kDa) of PEG-modified lipids were incorporated in sHDL's lipid membrane. Incorporating PEG did not reduce the ability of sHDL to facilitate cholesterol efflux, nor did it inhibit cholesterol uptake by the liver cells. By either adding more PEG or using PEG of longer chain lengths, the circulation half-life was extended. Addition of PEG also increased the area under the curve for the phospholipid component of sHDL (p < 0.05), but not for the apolipoprotein A-I peptide component of sHDL, suggesting sHDL is remodeled by endogenous lipoproteins in vivo. The extended phospholipid circulation led to a higher mobilization of plasma free cholesterol, a biomarker for facilitation of reverse cholesterol transport. The area under the cholesterol mobilization increased about 2-4-fold (p < 0.05), with greater increases observed for longer PEG chains and higher molar percentages of incorporated PEGylated lipids. Mobilized cholesterol was associated primarily with the HDL fraction, led to a transient increase in VLDL cholesterol, and returned to baseline 24 h postdose. Overall, PEGylation of sHDL led to beneficial changes in sHDL particle pharmacokinetic and pharmacodynamic behaviors.

Surface-grafted polyethylene glycol conformation impacts the transport of PEG-functionalized liposomes through a tumour extracellular matrix model

The effect of surface PEGylation on nanoparticle transport through an extracellular matrix (ECM) is an important determinant for tumor targeting success. Fluorescent stealth liposomes (base lipid DOPC) were prepared incorporating different proportions of PEG-grafted lipids (2.5, 5 and 10% of the total lipid content) for a series of PEG molecular weights (1000, 2000 and 5000 Da). The ECM was modelled using a collagen matrix. The kinetics of PEGylated liposome adhesion to and transport in collagen matrices were tracked using fluorescence correlation spectroscopy (FCS) and confocal microscopy, respectively. Generalized least square regressions were used to determine the temporal correlations between PEG molecular weight, surface density and conformation, and the liposome transport in a collagen hydrogel over 15 hours. PEG conformation determined the interaction of liposomes with the collagen hydrogel and their transport behaviour. Interestingly, liposomes with mushroom PEG conformation accumulated on the interface of the collagen hydrogel, creating a dense liposomal front with short diffusion distances into the hydrogels. On the other hand, liposomes with dense brush PEG conformation interacted to a lesser extent with the collagen hydrogel and diffused to longer distances. In conclusion, a better understanding of PEG surface coating as a modifier of transport in a model ECM matrix has resulted. This knowledge will improve design of future liposomal drug carrier systems.

The effect of surface PEGylation on nanoparticle transport through an extracellular matrix (ECM) is an important determinant for tumor targeting success.

Calcium-based biomaterials for diagnosis, treatment, and theranostics

Calcium-based biomaterials with good biosafety and bio-absorbability are promising for biomedical applications such as diagnosis, treatment, and theranostics.

Lipid-coated calcium phosphate nanoparticle and beyond: a versatile platform for drug delivery

In recent years, lipid-coated calcium-phosphate (LCP) nanoparticle has been developed as a versatile platform for delivery of various therapeutics including gene, protein/peptide, chemotherapeutics and theranostic agents. The high endosomal escape, coupled with the ability to efficiently encapsulate phosphorylated drugs or prodrugs, make LCP become attractive vehicle for drug delivery. Additionally, the principle behind LCP formulation has also allowed rational design of LCP-derived nanoparticles (NPs) with other solid core or lipid membrane to overcome the various drug delivery barriers. Here, we briefly review the history of the development of LCP NPs, highlight the optimisations and modulations in the development process, and summarise the major applications of LCP NPs and LCP-derived NPs in drug delivery.

Compact Vesicles Self-Assembled from Binary Graft Copolymers with High Hydrophilic Fraction for Potential Drug/Protein Delivery

Hollow vesicles self-assembled from amphiphilic copolymers are of great interest in biomedicine field as drug and protein carriers. Efficient preparation of polymeric vesicles with high stability in vivo is highly desirable. Herein, a novel cooperative self-assembly of two graft copolymers (GCPs) with reversed hydrophilic-hydrophobic segments is investigated to achieve morphology control for biomedical application. Interestingly, nanosized vesicles are obtained for the binary system with relatively high hydrophilic fraction (f_hydrophilic, ∼60%), contrary to what is found in its single-component counterpart. The cooperative self-assembly endowed the hybrid vesicles with excellent resistance to protein adsorption, prolonged blood circulation time, as well as low leakage of hydrophilic drugs/proteins. Furthermore, the biological activity of the protein is well preserved inside the cooperative vesicles, making it a promising candidate as the protein carrier.

Hydrophobic Effect from Conjugated Chemicals or Drugs on In Vivo Biodistribution of RNA Nanoparticles

Liver or other organ accumulation of drugs is one of the major problems that leads to toxicity and side effects in therapy using chemicals or other macromolecules. It has been shown that specially designed RNA nanoparticles can specifically target cancer cells, silence oncogenic genes, and stop cancer growth with little or no accumulation in the liver or other vital organs. It is well known that physical properties of nanoparticles such as size, shape, and surface chemistry affect biodistribution and pharmacokinetic profiles in vivo. This study examined how the hydrophobicity of chemicals conjugated to RNA nanoparticles affect in vivo biodistribution. Weaker organ accumulation was observed for hydrophobic chemicals after they were conjugated to RNA nanoparticles, revealing RNA's ability to solubilize hydrophobic chemicals. It was found that different chemicals conjugated to RNA nanoparticles resulted in the alteration of RNA hydrophobicity. Stronger hydrophobicity induced by chemical conjugates resulted in higher accumulation of RNA nanoparticles in vital organs in mice. This study provides new insights for handling drug insolubility, therapeutic toxicity, and organ clearance in drug development.

The interaction of clozapine loaded nanocapsules with the hCMEC/D3 cells - In vitro model of blood brain barrier

Despite progress in the development of novel pharmacological compounds, their efficacy in the treatment of neuropathologies is not satisfactory. One strategy to achieve safe and efficient brain targeting therapy is to design nanocarriers capable of transporting antipsychotic drugs through the BBB (without affecting the normal functions of the barrier) in a defined part of the brain. Here we investigate the interaction of clozapine-loaded polymeric Nano capsules (CLO-NCs) with hCMEC/D3 (human cerebral microvascular endothelial cells, D3 clone) cells that constitutes an in vitro model of the blood brain barrier (BBB). CLO-NCs (average size of 100nm) were constructed by the technique of sequential adsorption of polyelectrolytes (LbL), using biocompatible polyanion PGA (Poly-l-glutamic acid sodium salt) and polycation PLL (poly L-lysine) on clozapine-loaded nano-emulsion cores. Pegylated external layers were prepared using PGA-g(39)-PEG (PGA grafted by PEG poly(ethylene glycol)). The influence of the physicochemical properties of the CLO-NCs (charge, size, surface modification) on cell viability was determined. Advanced studies of CLO-NCs internalization (including endocytosis and transcytosis experiments) using confocal microscopy, flow cytometry and fluorescence spectroscopy are presented. Our results indicate that among the studied NCs, the pegylated clozapine-loaded NCs were the most protected from their uptake by macrophages, and they were the least toxic to hCMEC/D3 cells. They were also the most efficient in the transcytosis experiment, which serves as an indicator of their ability to cross a model BBB.

Leveraging Colloidal Aggregation for Drug-Rich Nanoparticle Formulations

While limited drug loading continues to be problematic for chemotherapeutics formulated in nanoparticles, we found that we could take advantage of colloidal drug aggregation to achieve high loading when combined with polymeric excipients. We demonstrate this approach with two drugs, fulvestrant and pentyl-PABC doxazolidine (PPD; a prodrug of doxazolidine, which is a DNA cross-linking anthracycline), and two polymers, polysorbate 80 (UP80) and poly(d,l-lactide-co-2-methyl-2-carboxytrimethylene carbonate)-graft-poly(ethylene glycol) (PLAC-PEG; a custom-synthesized, self-assembling amphiphilic polymer). In both systems, drug-loaded nanoparticles had diameters < 200 nm and were stable for up to two days in buffered saline solution and for up to 24 h in serum-containing media at 37 °C. While colloidal drug aggregates alone are typically unstable in saline and serum-containing media, we attribute the colloid stability observed herein to the polymeric excipients and consequent decreased protein adsorption. We expect this strategy of polymer-stabilized colloidal drug aggregates to be broadly applicable in delivery formulations.

Optimization of pegylated iron oxide nanoplatforms for antibody coupling and bio-targeting

PEGylation has been established as a valuable strategy to minimize nanoparticle clearance by the reticulo-endothelial system due to hydrophilicity and steric repulsion of PEG chains. In this study we functionalized superparamagnetic iron oxide nanoparticle surface with two PEG differing in their length (n = 23 and 44) and terminal functionality, COOH and CH₃. By varying the ratio of the two different PEG, we optimized the molecular architecture of the nanoplatform to obtain maximum stability and low toxicity under physiological conditions. The best nanoplatform was evaluated as MRI contrast for mouse brain vascularization imaging at 7 T. The carboxylic acid functions of the nanoplatform were used to covalently bind an antibody, Ab. This antibody, labeled with a fluorophore, targets the ET_A receptor, a G-protein-coupled receptor involved in the endothelin axis and overexpressed in various solid tumours, including ovarian, prostate, colon, breast, bladder and lung cancers. In vitro studies, performed by flow cytometry and magnetic quantification, showed the targeting efficiency of the Ab-nanoplatforms. Clearly, an imaging tracer for cancer diagnosis from a bimodal contrast agent (fluorescence and MRI) was thus obtained.

Assessing the Benefits of Drug Delivery by Nanocarriers: A Partico/Pharmacokinetic Framework

OBJECTIVE

An in vivo kinetic framework is introduced to analyze and predict the quantitative advantage of using nanocarriers to deliver drugs, especially anticancer agents, compared to administering the same drugs in their free form.

METHODS

This framework recognizes three levels of kinetics. First is the particokinetics associated with deposition of nanocarriers into tissues associated with drug effect and toxicity, their residence inside those tissues, and elimination of the nanocarriers from the body. Second is the release pattern in time of free drug from the nanocarriers. Third is the pharmacokinetics of free drug, as it relates to deposition and elimination processes in the target and toxicity associated tissues, and total body clearance. A figure of merit, the drug targeting index (DTI), is used to quantitate the benefit of nanocarrier-based drug delivery by considering the effects of preferential deposition of nanoparticles into target tissues and relative avoidance of tissues associated with drug toxicity, compared to drug that is administered in its free form.

RESULTS

General methods are derived for calculating DTI when appropriate particokinetic, pharmacokinetic, and drug release rate information is available, and it is shown that relatively simple algebraic forms result when some common assumptions are made.

CONCLUSION

This approach may find use in developing and selecting nanocarrier formulations, either for populations or for individuals.

The Binding Site Barrier Elicited by Tumor-Associated Fibroblasts Interferes Disposition of Nanoparticles in Stroma-Vessel Type Tumors

The binding site barrier (BSB) was originally proposed to describe the binding behavior of antibodies to cells peripheral to blood vessels, preventing their further penetration into the tumors. Yet, it is revisited herein to describe the intratumoral cellular disposition of nanoparticles (NPs). Specifically, the BSB limits NP diffusion and results in unintended internalization of NPs by stroma cells localized near blood vessels. This not only limits the therapeutic outcome but also promotes adverse off-target effects. In the current study, it was shown that tumor-associated fibroblast cells (TAFs) are the major component of the BSB, particularly in tumors with a stroma-vessel architecture where the location of TAFs aligns with blood vessels. Specifically, TAF distance to blood vessels, expression of receptor proteins, and binding affinity affect the intensity of the BSB. The physical barrier elicited by extracellular matrix also prolongs the retention of NPs in the stroma, potentially contributing to the BSB. The influence of particle size on the BSB was also investigated. The strongest BSB effect was found with small (∼18 nm) NPs targeted with the anisamide ligand. The uptake of these NPs by TAFs was about 7-fold higher than that of the other cells 16 h post-intravenous injection. This was because TAFs also expressed the sigma receptor under the influence of TGF-β secreted by the tumor cells. Overall, the current study underscores the importance of BSBs in the delivery of nanotherapeutics and provides a rationale for exploiting BSBs to target TAFs.

A vertical-flow bioreactor array compacts hepatocytes for enhanced polarity and functions

Although hepatocytes in vivo experience intra-abdominal pressure (IAP), pressure is typically not incorporated in hepatocyte culture systems. The cuboidal cell shape and extent of intercellular contact between cultured hepatocytes are critical parameters that influence the differentiated hepatic phenotype. Using a microfluidic device, the application of pressure to artificially compact cells and forge cell-cell interactions was previously demonstrated to be effective in accelerating hepatic repolarization. In seeking to implement this approach to higher throughput culture platforms for potential drug screening applications, we specifically designed a vertical-flow compaction bioreactor array (VCBA) that compacts hepatocytes within the range of IAP and portal pressure in vivo in a multi-well setup. As a result of vertical perfusion-generated forces, hepatocytes not only exhibited accelerated repolarization, an in vivo-like cuboidal morphology, but also better maintained hepatic functions in long-term culture as compared to the same cells cultured under static conditions. As a novel engineering tool to modulate cell compaction and intercellular interactions, this platform is a promising approach to confer tight control over hepatocyte repolarization for in vitro culture.

Maximizing the Supported Bilayer Phenomenon: Liposomes Comprised Exclusively of PEGylated Phospholipids for Enhanced Systemic and Lymphatic Delivery

Traditional liposomes degrade into lower-order micelles when PEGylated to even minor degrees (6-7 mol %) and therefore can offer only limited steric exclusion against opsonization during in vivo delivery. In this work, we present for the first time a liposome coated exclusively by PEGylated phospholipids, utilizing lipid-coated calcium phosphate (CaP) cores of diverse sizes (10-15 nm, 30-40 nm) as well as varying polyethylene glycol (PEG) chain lengths (350-5000 Da). Such fully-PEGylated liposome calcium phosphate (LCP) particles exhibit a PEG chain length-dependent circulation longevity and robust immune evasion, while facilitating both strong accumulation within solid tumors upon intravenous injection and a more rapid and extensive lymphatic drainage upon subcutaneous administration. Further, these fully-PEGylated liposomes remain amenable to active targeting strategies which facilitate improved degrees of focused distribution and nanoparticle uptake, represent a lipid packing density commensurate with the formation of a lipid bilayer, and avoid use of scale-limited physical resuspension methods. We expect such improved delivery properties to translate into improved therapeutic safety and efficacy for a variety of systemic and lymphatic diseases.

Enhanced detection with spectral imaging fluorescence microscopy reveals tissue- and cell-type-specific compartmentalization of surface-modified polystyrene nanoparticles

BACKGROUND

Precisely targeted nanoparticle delivery is critically important for therapeutic applications. However, our knowledge on how the distinct physical and chemical properties of nanoparticles determine tissue penetration through physiological barriers, accumulation in specific cells and tissues, and clearance from selected organs has remained rather limited. In the recent study, spectral imaging fluorescence microscopy was exploited for precise and rapid monitoring of tissue- and cell-type-specific distribution of fluorescent polystyrene nanoparticles with chemically distinct surface compositions.

METHODS

Fluorescent polystyrene nanoparticles with 50-90 nm diameter and with carboxylated- or polyethylene glycol-modified (PEGylated) surfaces were delivered into adult male and pregnant female mice with a single intravenous injection. The precise anatomical distribution of the particles was investigated by confocal microscopy after a short-term (5 min) or long-term (4 days) distribution period. In order to distinguish particle-fluorescence from tissue autofluorescence and to enhance the detection-efficiency, fluorescence spectral detection was applied during image acquisition and a post hoc full spectrum analysis was performed on the final images.

RESULTS

Spectral imaging fluorescence microscopy allowed distinguishing particle-fluorescence from tissue-fluorescence in all examined organs (brain, kidney, liver, spleen and placenta) in NP-treated slice preparations. In short-time distribution following in vivo NP-administration, all organs contained carboxylated-nanoparticles, while PEGylated-nanoparticles were not detected in the brain and the placenta. Importantly, nanoparticles were not found in any embryonic tissues or in the barrier-protected brain parenchyma. Four days after the administration, particles were completely cleared from both the brain and the placenta, while PEGylated-, but not carboxylated-nanoparticles, were stuck in the kidney glomerular interstitium. In the spleen, macrophages accumulated large amount of carboxylated and PEGylated nanoparticles, with detectable redistribution from the marginal zone to the white pulp during the 4-day survival period.

CONCLUSIONS

Spectral imaging fluorescence microscopy allowed detecting the tissue- and cell-type-specific accumulation and barrier-penetration of polystyrene nanoparticles with equal size but chemically distinct surfaces. The data revealed that polystyrene nanoparticles are retained by the reticuloendothelial system regardless of surface functionalization. Taken together with the increasing production and use of nanoparticles, the results highlight the necessity of long-term distribution studies to estimate the potential health-risks implanted by tissue-specific nanoparticle accumulation and clearance.

Engineering nanoparticles to overcome barriers to immunotherapy

Advances in immunotherapy have led to the development of a variety of promising therapeutics, including small molecules, proteins and peptides, monoclonal antibodies, and cellular therapies. Despite this wealth of new therapeutics, the efficacy of immunotherapy has been limited by challenges in targeted delivery and controlled release, that is, spatial and temporal control on delivery. Particulate carriers, especially nanoparticles have been widely studied in drug delivery and vaccine research and are being increasingly investigated as vehicles to deliver immunotherapies. Nanoparticle-mediated drug delivery could provide several benefits, including control of biodistribution and transport kinetics, the potential for site-specific targeting, immunogenicity, tracking capability using medical imaging, and multitherapeutic loading. There are also a unique set of challenges, which include nonspecific uptake by phagocytic cells, off-target biodistribution, permeation through tissue (transport limitation), nonspecific immune-activation, and poor control over intracellular localization. This review highlights the importance of understanding the relationship between a nanoparticle's size, shape, charge, ligand density and elasticity to its vascular transport, biodistribution, cellular internalization, and immunogenicity. For the design of an effective immunotherapy, we highlight the importance of selecting a nanoparticle's physical characteristics (e.g., size, shape, elasticity) and its surface functionalization (e.g., chemical or polymer modifications, targeting or tissue-penetrating peptides) with consideration of its reactivity to the targeted microenvironment (e.g., targeted cell types, use of stimuli-sensitive biomaterials, immunogenicity). Applications of this rational nanoparticle design process in vaccine development and cancer immunotherapy are discussed.

Current and Future Theranostic Applications of the Lipid-Calcium-Phosphate Nanoparticle Platform

Over the last four years, the Lipid-Calcium-Phosphate (LCP) nanoparticle platform has shown success in a wide range of treatment strategies, recently including theranostics. The high specific drug loading of radiometals into LCP, coupled with its ability to efficiently encapsulate many types of cytotoxic agents, allows a broad range of theranostic applications, many of which are yet unexplored. In addition to providing an overview of current medical imaging modalities, this review highlights the current theranostic applications for LCP using SPECT and PET, and discusses potential future uses of the platform by comparing it with both systemically and locally delivered clinical radiotherapy options as well as introducing its applications as an MRI contrast agent. Strengths and weaknesses of LCP and of nanoparticles in general are discussed, as well as caveats regarding the use of fluorescence to determine the accumulation or biodistribution of a probe.

Nanoparticles combined with growth factors: recent progress and applications

Increasing attention has been focused on the applications of nanoparticles combined with growth factors (NPs/GFs) due to the substantial functions of GFs in regenerative medicine and disease treatments.

Effect of surface properties on liposomal siRNA delivery

Liposomes are one of the most widely investigated carriers for siRNA delivery. The surface properties of liposomal carriers, including the surface charge, PEGylation, and ligand modification can significantly affect the gene silencing efficiency. Three barriers of systemic siRNA delivery (long blood circulation, efficient tumor penetration and efficient cellular uptake/endosomal escape) are analyzed on liposomal carriers with different surface charges, PEGylations and ligand modifications. Cationic formulations dominate siRNA delivery and neutral formulations also have good performance while anionic formulations are generally not proper for siRNA delivery. The PEG dilemma (prolonged blood circulation vs. reduced cellular uptake/endosomal escape) and the side effect of repeated PEGylated formulation (accelerated blood clearance) were discussed. Effects of ligand modification on cationic and neutral formulations were analyzed. Finally, we summarized the achievements in liposomal siRNA delivery, outlined existing problems and provided some future perspectives.

Interactions of Apolipoproteins AI, AII, B and HDL, LDL, VLDL with Polyurethane and Polyurethane-PEO Surfaces

The lipoproteins (HDL, LDL, VLDL) are important components of blood present in high concentration. Surprisingly, their role in blood-biomaterial interactions has been largely ignored. In previous work apolipoprotein AI (the main protein component of HDL) was identified as a major constituent of protein layers adsorbed from plasma to biomaterials having a wide range of surface properties, and quantitative data on the adsorption of apo AI to a biomedical grade polyurethane were reported. In the present communication quantitative data on the adsorption of apo AI, apo AII and apoB (the latter being a constituent of LDL and VLDL), as well as the lipoprotein particles themselves (HDL, LDL, VLDL), to a biomedical segmented polyurethane (PU) with and without an additive containing poly(ethylene oxide) (material referred to as PEO) are reported. Using radiolabeled apo AI, apo AII, and apoB, adsorption levels on PU from buffer at a protein concentration of 50 μg/mL were found to be 0.34, 0.40, and 0.14 μg/cm(2) (12, 23, and 0.25 nmol/cm(2)) respectively. Adsorption to the PEO surface was <0.02 μg/cm(2) for all three apolipoproteins demonstrating the strong protein resistance of this material. In contrast to the apolipoproteins, significant amounts of the lipoproteins were found to adsorb to the PEO as well as to the PU surface. X-ray photoelectron spectra, following exposure of the surfaces to the lipoproteins, showed a strong phosphorus signal, confirming that adsorption had occurred. It therefore appears that a PEO-containing surface that is resistant to apolipoproteins may be less resistant to the corresponding lipoproteins.

Enhancing the pharmacokinetic/pharmacodynamic properties of therapeutic nucleotides using lipid nanoparticle systems

Although activity has been reported in vivo, free nucleic acid-based drugs are rapidly degraded and cleared following systemic administration. To address these challenges and improve the potency and bioavailability of genetic drugs, significant efforts have been made to develop effective delivery systems of which lipid nanoparticles (LNP) represent the most advanced technology currently available. In this review, we will describe and discuss the improvements to the pharmacokinetic and pharmacodynamic properties of nucleic acid-based drugs mediated by LNP delivery. It is envisioned that the significant improvements in potency and safety, largely driven by the development of LNP encapsulated siRNA drugs, will be translatable to other types of genetic drugs and enable the rapid development of potent molecular tools and drugs.