Uptake of phosphatidylserine-containing liposomes by liver sinusoidal endothelial cells in the serum-free perfused rat liver

Advanced therapeutics avenues in hepatocellular carcinoma: a novel paradigm

Hepatocellular carcinoma (HCC) is the most frequent type of primary liver cancer, and it poses a significant risk to patients health and longevity due to its high morbidity and fatality rates. Surgical ablation, radiotherapy, chemotherapy, and, most recently, immunotherapy have all been investigated for HCC, but none have yielded the desired outcomes. Several unique nanocarrier drug delivery techniques have been studied for their potential therapeutic implications in the treatment of HCC. Nanoparticle-based imaging could be effective for more accurate HCC diagnosis. Since its inception, nanomedicine has significantly transformed the approach to both the treatment and diagnostics of liver cancer. Nanoparticles (NPs) are being studied as a potential treatment for liver cancer because of their ability to carry small substances, such as treatment with chemotherapy, microRNA, and therapeutic genes. The primary focus of this study is on the most current discoveries and practical uses of nanomedicine-based diagnostic and therapeutic techniques for liver cancer. In this section, we had gone over what we know about metabolic dysfunction in HCC and the treatment options that attempt to fix it by targeting metabolic pathways. Furthermore, we propose a multi-target metabolic strategy as a viable HCC treatment option. Based on the findings given here, the scientists believe that smart nanomaterials have great promise for improving cancer theranostics and opening up new avenues for tumor diagnosis and treatment.

pH-Sensitive Liposomes for Enhanced Cellular Uptake and Cytotoxicity of Daunorubicin in Melanoma (B16-BL6) Cell Lines

Daunorubicin (DNR) was delivered using a pH-sensitive liposomal system in B16-BL6 melanoma cell lines for enhanced cytotoxic effects. DNR was encapsulated within liposomes and CL as a component of the lipid bilayer. PEGylated pH-sensitive liposomes, containing CL, were prepared in the molar ratio of 40:30:5:17:8 for DOPE/cholesterol/DSPE-mPEG (2000)/CL/SA using the lipid film hydration method and loaded with DNR (drug: lipid ratio of 1:5). The CL liposomes exhibited high drug encapsulation efficiency (>90%), a small size (~94 nm), narrow size distribution (polydispersity index ~0.16), and a rapid release profile at acidic pH (within 1 h). Furthermore, the CL liposomes exhibited 12.5- and 2.5-fold higher cytotoxicity compared to DNR or liposomes similar to DaunoXome®. This study provides a basis for developing DNR pH-sensitive liposomes for melanoma treatment.

Extracellular vesicles as a drug delivery system: A systematic review of preclinical studies

During the past decades, extracellular vesicles (EVs) have emerged as an attractive drug delivery system. Here, we assess their pre-clinical applications, in the form of a systematic review. For each study published in the past decade, disease models, animal species, EV donor cell types, active pharmaceutical ingredients (APIs), EV surface modifications, API loading methods, EV size and charge, estimation of EV purity, presence of biodistribution studies and administration routes were quantitatively analyzed in a defined and reproducible way. We have interpreted the trends we observe over the past decade, to define the niches where to apply EVs for drug delivery in the future and to provide a basis for regulatory guidelines.

The Dual Role of the Liver in Nanomedicine as an Actor in the Elimination of Nanostructures or a Therapeutic Target

The development of nanostructures for therapeutic purpose is rapidly growing, following the results obtained in vivo in animal models and in the clinical trials. Unfortunately, the potential therapeutic efficacy is not completely exploited, yet. This is mainly due to the fast clearance of the nanostructures in the body. Nanoparticles and the liver have a unique interaction because the liver represents one of the major barriers for drug delivery. This interaction becomes even more relevant and complex when the drug delivery strategies employing nanostructures are proposed for the therapy of liver diseases, such as hepatocellular carcinoma (HCC). In this case, the selective delivery of therapeutic nanoparticles to the tumor microenvironment collides with the tendency of nanostructures to be quickly eliminated by the organ. The design of a new therapeutic approach based on nanoparticles to treat HCC has to particularly take into consideration passive and active mechanisms to avoid or delay liver elimination and to specifically address cancer cells or the cancer microenvironment. This review will analyze the different aspects concerning the dual role of the liver, both as an organ carrying out a clearance activity for the nanostructures and as target for therapeutic strategies for HCC treatment.

Lipid-based nanoparticle technologies for liver targeting

Liver diseases such as hepatitis, cirrhosis, and hepatocellular carcinoma are global health problems accounting for approximately 800 million cases and over 2 million deaths per year worldwide. Major drawbacks of standard pharmacological therapies are the inability to deliver a sufficient concentration of a therapeutic agent to the diseased liver, and nonspecific drug delivery leading to undesirable systemic side effects. Additionally, depending on the specific liver disease, drug delivery to a subset of liver cells is required. In recent years, lipid nanoparticles have been developed to passively and actively target drugs to the liver. The success of this approach has been highlighted by the FDA-approval of the first liver-targeting lipid nanoparticle, ONPATTRO, in 2018 and many other promising candidate technologies are expected to follow. This review summarizes recent developments of various lipid-based liver-targeting technologies, namely solid-lipid nanoparticles, liposomes, niosomes and micelles, and discusses the challenges and future perspectives in this field.

Optimization-by-design of hepatotropic lipid nanoparticles targeting the sodium-taurocholate cotransporting polypeptide

Active targeting and specific drug delivery to parenchymal liver cells is a promising strategy to treat various liver disorders. Here, we modified synthetic lipid-based nanoparticles with targeting peptides derived from the hepatitis B virus large envelope protein (HBVpreS) to specifically target the sodium-taurocholate cotransporting polypeptide (NTCP; SLC10A1) on the sinusoidal membrane of hepatocytes. Physicochemical properties of targeted nanoparticles were optimized and NTCP-specific, ligand-dependent binding and internalization was confirmed in vitro. The pharmacokinetics and targeting capacity of selected lead formulations was investigated in vivo using the emerging zebrafish screening model. Liposomal nanoparticles modified with 0.25 mol% of a short myristoylated HBV derived peptide, that is Myr-HBVpreS2-31, showed an optimal balance between systemic circulation, avoidance of blood clearance, and targeting capacity. Pronounced liver enrichment, active NTCP-mediated targeting of hepatocytes and efficient cellular internalization were confirmed in mice by ¹¹¹In gamma scintigraphy and fluorescence microscopy demonstrating the potential use of our hepatotropic, ligand-modified nanoparticles.

Design concepts of polyplex micelles for in vivo therapeutic delivery of plasmid DNA and messenger RNA

Nonviral delivery of plasmid (p)DNA or messenger (m)RNA is a safe and promising therapeutic option to continuously supply therapeutic proteins into diseased tissues. In most cases of in vivo pDNA and mRNA delivery, these nucleic acids are loaded into carriers based on cationic polymers and/or lipids to prevent nuclease-mediated degradation before reaching target cells. The carriers should also evade host clearance mechanisms, including uptake by scavenger cells and filtration in the spleen. Installation of ligands onto the carriers can facilitate their rapid uptake into target cells. Meanwhile, carrier toxicity should be minimized not only for preventing undesirable adverse responses in patients, but also for preserving the function of transfected cells to exert therapeutic effects. Long-term progressive improvement of platform technologies has helped overcome most of these issues, though some still remain hindering the widespread clinical application of nonviral pDNA and mRNA delivery. This review discusses design concepts of nonviral carriers for in vivo delivery and the issues to be overcome, focusing especially on our own efforts using polyplex micelles. © 2019 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 107A: 978-990, 2019.

Directing Nanoparticle Biodistribution through Evasion and Exploitation of Stab2-Dependent Nanoparticle Uptake

Up to 99% of systemically administered nanoparticles are cleared through the liver. Within the liver, most nanoparticles are thought to be sequestered by macrophages (Kupffer cells), although significant nanoparticle interactions with other hepatic cells have also been observed. To achieve effective cell-specific targeting of drugs through nanoparticle encapsulation, improved mechanistic understanding of nanoparticle-liver interactions is required. Here, we show the caudal vein of the embryonic zebrafish ( Danio rerio) can be used as a model for assessing nanoparticle interactions with mammalian liver sinusoidal (or scavenger) endothelial cells (SECs) and macrophages. We observe that anionic nanoparticles are primarily taken up by SECs and identify an essential requirement for the scavenger receptor, stabilin-2 ( stab2) in this process. Importantly, nanoparticle-SEC interactions can be blocked by dextran sulfate, a competitive inhibitor of stab2 and other scavenger receptors. Finally, we exploit nanoparticle-SEC interactions to demonstrate targeted intracellular drug delivery resulting in the selective deletion of a single blood vessel in the zebrafish embryo. Together, we propose stab2 inhibition or targeting as a general approach for modifying nanoparticle-liver interactions of a wide range of nanomedicines.

Pharmacodynamics and Biodistribution of Single-Dose Liposomal Amphotericin B at Different Stages of Experimental Visceral Leishmaniasis

Visceral leishmaniasis is a neglected tropical disease that causes significant morbidity and mortality worldwide. Characterization of the pharmacokinetics and pharmacodynamics of antileishmanial drugs in preclinical models is important for drug development and use. Here we investigated the pharmacodynamics and drug distribution of liposomal amphotericin B (AmBisome) in Leishmania donovani-infected BALB/c mice at three different dose levels and two different time points after infection. We additionally compared drug levels in plasma, liver, and spleen in infected and uninfected BALB/c mice over time. At the highest administered dose of 10 mg/kg AmBisome, >90% parasite inhibition was observed within 2 days after drug administration, consistent with drug distribution from blood to tissue within 24 h and a fast rate of kill. Decreased drug potency was observed in the spleen when AmBisome was administered on day 35 after infection, compared to day 14 after infection. Amphotericin B concentrations and total drug amounts per organ were lower in liver and spleen when AmBisome was administered at the advanced stage of infection and compared to those in uninfected BALB/c mice. However, the magnitude of difference was lower when total drug amounts per organ were estimated. Differences were also noted in drug distribution to L. donovani-infected livers and spleens. Taken together, our data suggest that organ enlargement and other pathophysiological factors cause infection- and organ-specific drug distribution and elimination after administration of single-dose AmBisome to L. donovani-infected mice. Plasma drug levels were not reflective of changes in drug levels in tissues.

Copper-64 labeled liposomes for imaging bone marrow

INTRODUCTION

Bone marrow is the soft tissue compartment inside the bones made up of hematopoietic cells, adipocytes, stromal cells, phagocytic cells, stem cells, and sinusoids. While [¹⁸F]-FLT has been utilized to image proliferative marrow, to date, there are no reports of particle based positron emission tomography (PET) imaging agents for imaging bone marrow. We have developed copper-64 labeled liposomal formulation that selectively targets bone marrow and therefore serves as an efficient PET probe for imaging bone marrow.

METHODS

Optimized liposomal formulations were prepared with succinyl PE, DSPC, cholesterol, and mPEG-DSPE (69:39:1:10:0.1) with diameters of 90 and 140nm, and were doped with DOTA-Bn-DSPE for stable ⁶⁴Cu incorporation into liposomes.

RESULTS

PET imaging and biodistribution studies with ⁶⁴Cu-labeled liposomes indicate that accumulation in bone marrow was as high as 15.18±3.69%ID/g for 90nm liposomes and 7.01±0.92%ID/g for 140nm liposomes at 24h post-administration. In vivo biodistribution studies in tumor-bearing mice indicate that the uptake of 90nm particles is approximately 0.89±0.48%ID/g in tumor and 14.22±8.07%ID/g in bone marrow, but respective values for Doxil® like liposomes are 0.83±0.49%ID/g and 2.23±1.00%ID/g.

CONCLUSION

Our results indicate that our novel PET labeled liposomes target bone marrow with very high efficiency and therefore can function as efficient bone marrow imaging agents.

Influence of cationic lipid composition on gene silencing properties of lipid nanoparticle formulations of siRNA in antigen-presenting cells

Lipid nanoparticles (LNPs) are currently the most effective in vivo delivery systems for silencing target genes in hepatocytes employing small interfering RNA. Antigen-presenting cells (APCs) are also potential targets for LNP siRNA. We examined the uptake, intracellular trafficking, and gene silencing potency in primary bone marrow macrophages (bmMΦ) and dendritic cells of siRNA formulated in LNPs containing four different ionizable cationic lipids namely DLinDAP, DLinDMA, DLinK-DMA, and DLinKC2-DMA. LNPs containing DLinKC2-DMA were the most potent formulations as determined by their ability to inhibit the production of GAPDH target protein. Also, LNPs containing DLinKC2-DMA were the most potent intracellular delivery agents as indicated by confocal studies of endosomal versus cytoplamic siRNA location using fluorescently labeled siRNA. DLinK-DMA and DLinKC2-DMA formulations exhibited improved gene silencing potencies relative to DLinDMA but were less toxic. In vivo results showed that LNP siRNA systems containing DLinKC2-DMA are effective agents for silencing GAPDH in APCs in the spleen and peritoneal cavity following systemic administration. Gene silencing in APCs was RNAi mediated and the use of larger LNPs resulted in substantially reduced hepatocyte silencing, while similar efficacy was maintained in APCs. These results are discussed with regard to the potential of LNP siRNA formulations to treat immunologically mediated diseases.

In vitro assessments of nanomaterial toxicity

Nanotechnology has grown from a scientific interest to a major industry with both commodity and specialty nanomaterial exposure to global populations and ecosystems. Sub-micron materials are currently used in a wide variety of consumer products and in clinical trials as drug delivery carriers and imaging agents. Due to the expected growth in this field and the increasing public exposure to nanomaterials, both from intentional administration and inadvertent contact, improved characterization and reliable toxicity screening tools are required for new and existing nanomaterials. This review discusses current methodologies used to assess nanomaterial physicochemical properties and their in vitro effects. Current methods lack the desired sensitivity, reliability, correlation and sophistication to provide more than limited, often equivocal, pieces of the overall nanomaterial performance parameter space, particularly in realistic physiological or environmental models containing cells, proteins and solutes. Therefore, improved physicochemical nanomaterial assays are needed to provide accurate exposure risk assessments and genuine predictions of in vivo behavior and therapeutic value. Simpler model nanomaterial systems in buffer do not accurately duplicate this complexity or predict in vivo behavior. A diverse portfolio of complementary material characterization tools and bioassays are required to validate nanomaterial properties in physiology.

Delivery systems: a vaccine strategy for overcoming mucosal tolerance?

Antigens administered via the oral and, to a lesser extent, the nasal route are potentially able to invoke tolerance, resulting in a nonreactive immune response. This has been a hurdle for mucosal vaccine development and yet the desire to induce protective local and systemic responses, with pain-free and more convenient products, has been the impetus driving mucosal vaccine R&D. Nevertheless, few mucosal vaccines have reached the marketplace and products are still treated with caution, particularly where live organisms are utilized. In this review, we examine the use of delivery systems with adjuvant properties as key components in a vaccine strategy that does not require the use of live vectors to overcome tolerance and have exemplified their success in mucosal vaccines, concentrating on the nasal and oral routes of administration.

Clearance of adenovirus by Kupffer cells is mediated by scavenger receptors, natural antibodies, and complement

Kupffer cells (KCs) rapidly remove intravenously injected adenovirus (Ad) vectors from the circulation. A better understanding of the mechanisms involved could suggest strategies to improve Ad gene delivery by suppressing or evading KC uptake. We recently showed that clearance of Ad type 5 vectors by KCs does not involve the interaction of Ad with the well-established Ad receptors, namely, integrins or the coxsackievirus and Ad receptor (J. S. Smith, Z. Xu, J. Tian, S. C. Stevenson, and A. P. Byrnes, Hum. Gene Ther. 19:547-554, 2008). In the current study, we systematically quantified the contributions of various receptors and plasma proteins to the clearance of Ad by KCs. We found that scavenger receptors are a predominant mechanism for the clearance of Ad by KCs. In addition, we found that Ad is opsonized by natural immunoglobulin M antibodies and complement and that these opsonins play a contributory role in the clearance of Ad by KCs. We also examined additional mechanisms that have been postulated to be involved in the clearance of Ad, including the binding of Ad to platelets and vitamin K-dependent coagulation factors, but we found that neither of these were required for the clearance of Ad by KCs.

Actin-dependent regulation of connective tissue growth factor

Expression of connective tissue growth factor (CTGF) in endothelial cells is modulated by shear stress affecting the organization of the cytoskeleton. The molecular connection between alterations of actin and CTGF expression was investigated in human umbilical vein endothelial cells (HUVEC) and a microvascular endothelial cell line. Overexpression of nonpolymerizable monomeric actin R62D interfered with stress fiber formation in HUVEC and concomitantly reduced immunoreactive CTGF. In microvascular endothelial cells, flow-dependent upregulation of CTGF was prevented by this actin mutant. In contrast, overexpression of actin S14C strengthened filamentous actin and increased CTGF expression. These data indicated an inverse relationship between CTGF expression and monomeric actin. Coexpression of the mutant actins and different CTGF promoter constructs revealed an actin-sensitive site between 3 and 4.5 kb of the CTGF promoter. A CArG-like box at −3791 bp was responsible for actin-dependent CTGF induction as shown by mutagenesis. Overexpression of actin S14C activated the nonmutated promoter significantly more strongly than the mutated promoter. Actin polymerization is regulated by the small GTPase RhoA and activation of serum response factor (SRF). Overexpression of constitutively active RhoA or SRF significantly increased CTGF protein synthesis. The 4.5-kb promoter construct, but not the construct with a mutation in the CArG box, was activated by SRF or RhoA, providing evidence for a functional role of this site in CTGF induction. These findings provide novel evidence that monomeric actin is the connecting link between alterations in the cytoskeleton and CTGF gene expression and demonstrate the importance of SRF in regulating CTGF transcription.