Hepatitis B virus preS1-derived lipopeptide functionalized liposomes for targeting of hepatic cells

A nano-platform combats the "attack" and "defense" of cytoskeleton to block cascading tumor metastasis

The cytoskeleton facilitates tumor cells invasion into the bloodstream via vasculogenic mimicry (VM) for "attack", and protects cells against external threats through cytoskeletal remodeling and tunneling nanotubes (TNTs) for "defense". However, the existing strategies involving cytoskeleton are not sufficient to eliminate tumor metastasis due to mitochondrial energy supply, both within tumor cells and from outside microenvironment. Here, considering the close relationship between cytoskeleton and mitochondria both in location and function, we construct a nano-platform that combats the "attack" and "defense" of cytoskeleton in the cascading metastasis. The nano-platform is composed of KFCsk@LIP and KTMito@LIP for the cytoskeletal collapse and mitochondrial dysfunction. KFCsk@LIP prevents the initiation and circulation of cascading tumor metastasis, but arouses limited suppression in tumor cell proliferation. KTMito@LIP impairs mitochondria to trigger apoptosis and impede energy supply both from inside and outside, leading to an amplified effect for metastasis suppression. Further mechanisms studies reveal that the formation of VM and TNTs are seriously obstructed. Both in situ and circulating tumor cells are disabled. Subsequently, the broken metastasis cascade results in a remarkable anti-metastasis effect. Collectively, based on the nano-platform, the cytoskeletal collapse with synchronous mitochondrial dysfunction provides a potential therapeutic strategy for cascading tumor metastasis suppression.

Novel therapeutic approaches for the management of hepatitis infections

Hepatitis B virus (HBV) & hepatitis C virus (HCV) infection is a substantial reason for morbidity and mortality around the world. Chronic hepatitis B (CHB) infection is connected with an enhanced risk of liver cirrhosis, liver decompensation and hepatocellular carcinoma (HCC). Conventional therapy do face certain challenges, for example, poor tolerability and the growth of active resistance. Thus, novel treatment procedures are essential to accomplish the initiation of strong and stable antiviral immune reactions of the individuals. This review explores the current nanotechnology-based carriers for drug and vaccine delivery to treat HBV and HCV.

CREKA-modified liposomes target activated hepatic stellate cells to alleviate liver fibrosis by inhibiting collagen synthesis and angiogenesis

Activated hepatic stellate cells (HSCs) are considered the key driver of excessive extracellular matrix and abnormal angiogenesis, which are the main pathological manifestations of hepatic fibrosis. However, the absence of specific targeting moieties has rendered the development of HSC-targeted drug delivery systems a significant obstacle in the treatment of liver fibrosis. Here we have identified a notable increase in fibronectin expression on HSCs, which positively correlates with the progression of hepatic fibrosis. Thus, we decorated PEGylated liposomes with CREKA, a peptide with high affinity for fibronectin, to facilitate the targeted delivery of sorafenib to activated HSCs. The CREKA-coupled liposomes exhibited enhanced cellular uptake in the human hepatic stellate cell line LX2 and selective accumulation in CCl4-induced fibrotic liver through the recognition of fibronectin. When loaded with sorafenib, the CREKA-modified liposomes effectively suppressed HSC activation and collagen accumulation in vitro. Furthermore. in vivo results demonstrated that the administration of sorafenib-loaded CREKA-liposomes at a low dose significantly mitigated CCl4-induced hepatic fibrosis, prevented inflammatory infiltration and reduced angiogenesis in mice. These findings suggest that CREKA-coupled liposomes have promising potential as a targeted delivery system for therapeutic agents to activated HSCs, thereby providing an efficient treatment option for hepatic fibrosis. STATEMENT OF SIGNIFICANCE: In liver fibrosis, activated hepatic stellate cells (aHSCs) are the key driver of extracellular matrix and abnormal angiogenesis. Our investigation has revealed a significant elevation in fibronectin expression on aHSCs, which is positively associated with the progression of hepatic fibrosis. Thus, we developed PEGylated liposomes decorated with CREKA, a molecule with a high affinity for fibronectin, to facilitate the targeted delivery of sorafenib to aHSCs. The CREKA-coupled liposomes can specifically target aHSCs both in vitro and in vivo. Loading sorafenib into CREKA-Lip significantly alleviated CCl4-induced liver fibrosis, angiogenesis and inflammation at low doses. These findings suggest that our drug delivery system holds promise as a viable therapeutic option for liver fibrosis with minimal risk of adverse effects.

Comparison of two methods for tumour-targeting peptide modification of liposomes

Liposomes decorated with tumour-targeting cell-penetrating peptides can enhance specific drug delivery at the tumour site. The TR peptide, c(RGDfK)-AGYLLGHINLHHLAHL(Aib)HHIL, is pH-sensitive and actively targets tumour cells that overexpress integrin receptor αvβ3, such as B16F10 melanoma cells. Liposomes can be modified with the TR peptide by two different methods: utilization of the cysteine residue on TR to link DSPE-PEG2000-Mal contained in the liposome formula (LIPTR) or decoration of TR with a C18 stearyl chain (C18-TR) for direct insertion into the liposomal phospholipid bilayer through electrostatic and hydrophobic interactions (LIPC18-TR). We found that both TR and C18-TR effectively reversed the surface charge of the liposomes when the systems encountered the low pH of the tumour microenvironment, but LIPC18-TR exhibited a greater increase in the charge, which led to higher cellular uptake efficiency. Correspondingly, the IC50 values of PTX-LIPTR and PTX-LIPC18-TR in B16F10 cells in vitro were 2.1-fold and 2.5-fold lower than that of the unmodified PTX-loaded liposomes (PTX-LIP), respectively, in an acidic microenvironment (pH 6.3). In B16F10 tumour-bearing mice, intravenous administration of PTX-LIPTR and PTX-LIPC18-TR (8 mg/kg PTX every other day for a total of 4 injections) caused tumour reduction ratios of 39.4% and 56.1%, respectively, compared to 20.8% after PTX-LIP administration. Thus, we demonstrated that TR peptide modification could improve the antitumour efficiency of liposomal delivery systems, with C18-TR presenting significantly better results. After investigating different modification methods, our data show that selecting an adequate method is vital even when the same molecule is used for decoration.

Construction of redox-sensitive liposomes modified by glycyrrhetinic acid and evaluation of anti-hepatocellular carcinoma activity

The aim of this study was to construct a bifunctional liposome with hepatic-targeting capacity by modifying with a targeting ligand and an intracellular tumor reduction response functional group to deliver drugs precisely to focal liver tissues and release them in large quantities in hepatocellular carcinoma cells. This could improve drug efficacy and reduce toxic side effects at the same time. First, the bifunctional ligand for liposome was successfully obtained by chemically synthesizing it from the hepatic-targeting glycyrrhetinic acid (GA) molecule, cystamine, and the membrane component cholesterol. Then the ligand was used to modify the liposomes. The particle size, PDI and zeta potential of the liposomes were determined with a nanoparticle sizer, and the morphology was observed by transmission electron microscopy. The encapsulation efficiency and drug release behavior were also determined. Further, the stability in vitro of the liposomes and the changes in the simulated reducing environment were determined. Finally, the antitumor activity in vitro and cellular uptake efficiency of the drug-loaded liposomes were investigated by performing cellular assays. The results showed that the prepared liposomes had a uniform particle size of 143.6 ± 2.86 nm with good stability and an encapsulation rate of 84.3 ± 2.1 %. Moreover, the particle size of the liposomes significantly increased and the structure was destroyed in a DTT reducing environment. Cellular experiments showed that the modified liposoes had better cytotoxic effects on hepatocarcinoma cells than both normal liposomes and free drugs. This study has great potential for tumor therapy and provides novel ideas for the clinical use of oncology drugs in dosage forms.

Functionalized lipid-based drug delivery nanosystems for the treatment of human infectious diseases

Infectious diseases are still public health problems. Microorganisms such as fungi, bacteria, viruses, and parasites are the main causing agents related to these diseases. In this context, the search for new effective strategies in prevention and/or treatment is considered essential, since current drugs often have side effects or end up, causing microbial resistance, making it a serious health problem. As an alternative to these limitations, nanotechnology has been widely used. The use of lipid-based drug delivery nanosystems (DDNs) has some advantages, such as biocompatibility, low toxicity, controlled release, the ability to carry both hydrophilic and lipophilic drugs, in addition to be easel scalable. Besides, as an improvement, studies involving the conjugation of signalling molecules on the surfaces of these nanocarriers can allow the target of certain tissues or cells. Thus, this review summarizes the performance of functionalized lipid-based DDNs for the treatment of infectious diseases caused by viruses, including SARS-CoV-2, bacteria, fungi, and parasites.

Regulation of protein corona on liposomes using albumin-binding peptide for targeted tumor therapy

Nanocarriers entering the body are usually coated by plasma protein, leading to a protein "corona" easily recognized by tissues and cells. Adjusting the composition of protein coronas may be an efficient way to change the properties and behavior of nanoparticles in vivo. In this study, we modified doxorubicin-loaded liposomes (Lip/DOX) with an albumin-binding domain (ABD) to prepare nanoparticles (ABD-Lip/DOX) that can specifically bind to albumin and form albumin-based protein coronas in vivo for targeted tumor therapy. The prepared liposomes were spherical with a particle size of about 100 nm. After incubating the liposomes with rat serum, the albumin content was eight times higher on ABD-Lip than on control liposomes. ABD-Lip significantly inhibited adsorption of IgG and complement activation in rat serum in vitro, while corona-coated ABD-Lip was internalized to a significantly greater extent than corona-coated control liposomes. In addition, ABD-Lip showed longer blood circulation time, higher tumor accumulation and greater antitumor efficacy than control liposomes in mice bearing 4 T1 tumors, while both liposome formulations showed similar biocompatibility. These results confirm that adjusting the component of protein coronas around nanoparticles can improve their therapeutic efficacy.

Hepatocyte-targeting and tumor microenvironment-responsive liposomes for enhanced anti-hepatocarcinoma efficacy

To increase the antitumor drug concentration in the liver tumor site and improve the therapeutic effects, a functionalized liposome (PPP-LIP) with tumor targetability and enhanced internalization after matrix metalloproteinase-2 (MMP2)-triggered cell-penetrating peptide (TATp) exposure was modified with myrcludex B (a synthetic HBV preS-derived lipopeptide endowed with compelling liver tropism) for liver tumor-specific delivery. After intravenous administration, PPP-LIP was mediated by myrcludex B to reach the hepatocyte surface. The MMP2-overexpressing tumor microenvironment deprotected PEG, exposing it to TATp, facilitating tumor penetration and subsequent efficient destruction of tumor cells. In live imaging of small animals and cellular uptake, PPP-LIP was taken up much more than typical unmodified liposomes in the ICR mouse liver and liver tumor cells. Hydroxycamptothecin (HCPT)-loaded PPP-LIP showed a better antitumor effect than commercially available HCPT injections among MTT, three-dimensional (3 D) tumor ball, and tumor-bearing nude mouse experiments. Our findings indicated that PPP-LIP nanocarriers could be a promising tumor-targeted medication delivery strategy for treating liver cancers with elevated MMP2 expression.

Specific Binding and Endocytosis of Liposomes to HEK293T Cells via Myrisoylated Pre-S1 Peptide Bound to Sodium Taurocholate Cotransporting Polypeptide

(1) Background: Sodium taurocholate cotransporting polypeptide (NTCP) functions as a key receptor for the hepatitis B virus (HBV) infection. Analyzing HBV and NTCP interaction is an important issue not only for basic research but also for the development of anti-HBV therapeutics. We developed here a novel model system to analyze the interaction of NTCP with liposomes instead of HBV. (2) Methods: Liposomal binding and endocytosis through NTCP in HEK293T cells were achieved by serial treatments of HEL293T cells transiently expressing NTCP-green fluorescence protein (GFP) fusion protein with a synthetic biotinylated pre-S1 peptide (Myr47-Bio) and streptavidin (SA) complex (i.e., Myr47-Bio+SA) followed by biotinylated liposomes. By this procedure, binding of [biotinylated liposomes]-[Myr47-Bio+SA]-[NTCP-GFP] was formed. (3) Results: Using this model system, we found that liposomal binding to NTCP on the cell surface via Myr47-Bio+SA was far more efficient than that to scavenger receptor class B type 1 (SR-B1). Furthermore, liposomes bound to cell surface NTCP via Myr47-Bio+SA were endocytosed into cells after cells were cultured at 37 °C. However, this endocytosis was suppressed by 4 °C or cytochalasin B treatment. (4) Conclusions: This model system will be useful for not only analyzing HBV entry mechanisms but also screening substances to prevent HBV infection.

Preclinical validation of silibinin/albumin nanoparticles as an applicable system against acute liver injury

BACKGROUND

Silibinin (SIL) has been extensively studied for its therapeutic effects on various liver diseases. However, its effect on acute liver injury was limited for poor solubility and low bioavailability. Thus, we prepared SIL and bovine serum albumin (SIL/BSA) nanoparticles and further evaluated their therapeutic efficacy against acute liver injury in mouse models.

METHODS

SIL/BSA nanoparticles were prepared via a nanoprecipitation method. Both in vitro cell culture model and in vivo mouse models of acetaminophen (APAP) and lipopolysaccharide (LPS)/D-galactosamine (D-GalN)-induced acute liver injury were used to evaluate the therapeutic effect of SIL/BSA nanoparticles and potential mechanisms.

RESULTS

The SIL/BSA nanoparticles with hydrophilic diameters of 90 ± 29 nm were stably suspended. SIL/BSA nanoparticles presented better biocompatibility and more liver distribution in vivo than SIL microparticles. SIL/BSA nanoparticles significantly alleviated APAP and LPS/D-GalN induced acute liver injury in mice. Similarly, SIL/BSA nanoparticles remarkably enhanced the viability of hepatocytes in vitro against both APAP and LPS/D-GalN induced hepatocyte damage. Moreover, SIL/BSA nanoparticles exhibited antioxidant effects against intracellular oxidative stress via upregulating the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant responsive element (ARE) pathway, decreasing ROS and regulating antioxidant enzyme reactivity. And the downstream of mitochondria damage and caspase 9/3 related apoptosis pathway was also inhibited CONCLUSION: SIL/BSA nanoparticles were successfully prepared to enhance the liver availability of SIL. Both in vivo and in vitro, SIL/BSA nanoparticles exerted ideal hepatoprotective and antioxidant efficacy against acute liver injury, suggesting the promising future in clinical transfer.

STATEMENT OF SIGNIFICANCE

In our study, we prepared small-size, stable and well-dispersed silibinin/bovine serum albumin (SIL/BSA) nanoparticles via using simple and cost-effective nanoprecipitation techniques. Their physicochemical and pharmacokinetic characteristics were analyzed. We systematically studied the hepatoprotective and antioxidant efficacy of SIL/BSA both in vivo and in vitro, using two acute liver injury models. These findings revealed that SIL/BSA nanoparticles exerted ideal hepatoprotective and antioxidant efficacy against acute liver injury, suggesting the promising future in clinical transfer.

Advances in Nanoliposomes for the Diagnosis and Treatment of Liver Cancer

The mortality rate of liver cancer is gradually increasing worldwide due to the increasing risk factors such as fatty liver, diabetes, and alcoholic cirrhosis. The diagnostic methods of liver cancer include ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI), among others. The treatment of liver cancer includes surgical resection, transplantation, ablation, and chemoembolization; however, treatment still faces multiple challenges due to its insidious development, high rate of recurrence after surgical resection, and high failure rate of transplantation. The emergence of liposomes has provided new insights into the treatment of liver cancer. Due to their excellent carrier properties and maneuverability, liposomes can be used to perform a variety of functions such as aiding in imaging diagnoses, combinatorial therapies, and integrating disease diagnosis and treatment. In this paper, we further discuss such advantages.

Integrin α2β1 Targeting DGEA-Modified Liposomal Doxorubicin Enhances Antitumor Efficacy against Breast Cancer

Breast cancer was the leading cause of newly diagnosed cases of tumors in 2020, ranking as the second highest cause of female death. Chemotherapy remains the conventional treatment of choice for breast tumors in most clinical cases. However, it is often accompanied by a poor prognosis and severe side effects, resulting from an insufficient accumulation of the drug at tumor sites and an unsystematic distribution of the drug across the body. Inspired by the fact that breast tumor cells overexpress integrin α2β1 on the surface, we designed and constructed an integrin α2β1 targeting DGEA-modified liposomal doxorubicin (DGEA-Lipo-DOX) platform for application in breast cancer therapy. The DGEA-Lipo-DOX was stable with a uniform particle size of 121.1 ± 3.8 nm and satisfactory drug encapsulation. Demonstrated in vitro and in vivo, the constructed platform exhibited improved antitumor ability. The DGEA-Lipo-DOX showed 4-fold enhanced blood circulation and 6-fold increased accumulation of DOX at the tumor sites compared to those of free DOX, resulting in a significantly enhanced antitumor efficacy in tumor-bearing mice. A preliminary safety evaluation suggested that the systemic toxicity of DOX was relieved by DGEA-Lipo delivery. Collectively, binding integrin α2β1 by DGEA may represent an alternative therapeutic strategy for potentially safer breast cancer treatment.

Virus-Derived Peptides for Hepatic Enzyme Delivery

Recently, a lipopeptide derived from the hepatitis B virus (HBV) large surface protein has been developed as an HBV entry inhibitor. This lipopeptide, called MyrcludexB (MyrB), selectively binds to the sodium taurocholate cotransporting polypeptide (NTCP) on the basolateral membrane of hepatocytes. Here, the feasibility of coupling therapeutic enzymes to MyrB was investigated for the development of enzyme delivery strategies. Hepatotropic targeting shall enable enzyme prodrug therapies and detoxification procedures. Here, horseradish peroxidase (HRP) was conjugated to MyrB via maleimide chemistry, and coupling was validated by SDS-PAGE and reversed-phase HPLC. The specificity of the target recognition of HRP-MyrB could be shown in an NTCP-overexpressing liver parenchymal cell line, as demonstrated by competitive inhibition with an excess of free MyrB and displayed a strong linear dependency on the applied HRP-MyrB concentration. In vivo studies in zebrafish embryos revealed a dominating interaction of HRP-MyrB with scavenger endothelial cells vs xenografted NTCP expressing mammalian cells. In mice, radiolabeled ¹²⁵I-HRP-MyrBy, as well as the non-NTCP targeted control HRP-peptide-construct (¹²⁵I-HRP-alaMyrBy) demonstrated a strong liver accumulation confirming the nonspecific interaction with scavenger cells. Still, MyrB conjugation to HRP resulted in an increased and NTCP-mediated hepatotropism, as revealed by competitive inhibition. In conclusion, the model enzyme HRP was successfully conjugated to MyrB to achieve NTCP-specific targeting in vitro with the potential for ex vivo diagnostic applications. In vivo, target specificity was reduced by non-NTCP-mediated interactions. Nonetheless, tissue distribution experiments in zebrafish embryos provide mechanistic insight into underlying scavenging processes indicating partial involvement of stabilin receptors.

Chondroitin Sulfate-Modified Liposomes for Targeted Co-Delivery of Doxorubicin and Retinoic Acid to Suppress Breast Cancer Lung Metastasis

Breast cancer treatment remains challenging due to high levels of cell metastasis. Chemotherapy drug combinations can inhibit both tumor growth in situ and metastasis to distant organs. Therefore, here, we developed chondroitin sulfate liposomes (CSLs) as a carrier for the co-delivery of retinoic acid (RA) and doxorubicin (DOX) and examined their efficiency in suppressing lung metastasis of breast cancer. CSLs were prepared using CS-deoxycholic acid conjugates and found to encapsulate both RA and DOX via hydrophobic and hydrophilic interactions. The resulting DOX+RA-CSLs were uniformly spherical and showed good serum stability and encapsulation efficiency of 98.7% ± 1.3% for RA and 90.8% ± 2.9% for DOX. Pharmacodynamic experiments in vitro and in vivo also revealed that DOX+RA-CSLs had better anticancer and anti-metastatic activity than CS-free liposomes, single drug-loaded liposomes, and free drug solutions at the same dose (2 mg/kg DOX or RA). Our results suggest that this liposomal delivery system can effectively suppress lung metastasis of breast cancer.

Biomedical nanoparticle design: What we can learn from viruses

Viruses are nanomaterials with a number of properties that surpass those of many synthetic nanoparticles (NPs) for biomedical applications. They possess a rigorously ordered structure, come in a variety of shapes, and present unique surface elements, such as spikes. These attributes facilitate propitious biodistribution, the crossing of complex biological barriers and a minutely coordinated interaction with cells. Due to the orchestrated sequence of interactions of their stringently arranged particle corona with cellular surface receptors they effectively identify and infect their host cells with utmost specificity, while evading the immune system at the same time. Furthermore, their efficacy is enhanced by their response to stimuli and the ability to spread from cell to cell. Over the years, great efforts have been made to mimic distinct viral traits to improve biomedical nanomaterial performance. However, a closer look at the literature reveals that no comprehensive evaluation of the benefit of virus-mimetic material design on the targeting efficiency of nanomaterials exists. In this review we, therefore, elucidate the impact that viral properties had on fundamental advances in outfitting nanomaterials with the ability to interact specifically with their target cells. We give a comprehensive overview of the diverse design strategies and identify critical steps on the way to reducing them to practice. More so, we discuss the advantages and future perspectives of a virus-mimetic nanomaterial design and try to elucidate if viral mimicry holds the key for better NP targeting.

Hepatitis B virus pre-S region: Clinical implications and applications

Hepatitis B virus (HBV) infection is a major threat to global public health, which can result in many acute and chronic liver diseases. HBV, a member of the family Hepadnaviridae, is a small enveloped DNA virus containing a circular genome of 3.2 kb. Located upstream of the S-open-reading frame of the HBV genome is the pre-S region, which is vital to the viral life cycle. The pre-S region has high variability and many mutations in the pre-S region are associated with several liver diseases, such as fulminant hepatitis (FH), liver cirrhosis (LC), and hepatocellular carcinoma (HCC). In addition, the pre-S region has been applied in the development of several pre-S-based materials and systems to prevent or treat HBV infection. In conclusion, the pre-S region plays an essential role in the occurrence, diagnosis, and treatment of HBV-related liver diseases, which may provide a novel perspective for the study of HBV infection and relevant diseases.

Improved melanoma suppression with target-delivered TRAIL and Paclitaxel by a multifunctional nanocarrier

Malignant melanoma, a highly dangerous type of skin cancer, is usually resistant to pro-apoptosis agents such as tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) due to low death receptor expression levels. After verifying combination of chemotherapy drug paclitaxel (PTX) and TRAIL could significantly enhance their anti-melanoma effects, we developed a liposomal melanoma target-delivery system with tumor microenvironment responsiveness (TRAIL-[Lip-PTX]^C18-TR) to co-deliver TRAIL and PTX. TRAIL is attached to negatively-charged liposome surface while PTX is encapsulated inside, with final surface modification of a stearyl chain (C18) fused pH-sensitive cell-penetrating peptide (TR). Here, C18-TR could specifically binds to melanoma-rich integrin receptors α_vβ₃ for melanoma targeting, help release TRAIL in low pH microenvironment by reversing the liposomal charge, and facilitate consequent liposome internalization. TRAIL-[Lip-PTX]^C18-TR displayed significantly better in vitro half-maximal inhibitory concentration (IC₅₀) than other formulations, and an in vivo tumor inhibition rate of 93.8%. Mechanistic study revealed that this synergistic effect is associated with the upregulation of death receptors DR4/5 by PTX. This co-delivery system significantly improved TRAIL-based therapy against melanoma, and provided a simple platform to co-deliver other drugs/agents for melanoma treatment.

Targeted delivery of hyaluronic acid nanomicelles to hepatic stellate cells in hepatic fibrosis rats

Hepatic fibrosis is one kind of liver diseases with a high mortality rate and incidence. The activation and proliferation of hepatic stellate cells (HSCs) is the most fundamental reason of hepatic fibrosis. There are no specific and effective drug delivery carriers for the treatment of hepatic fibrosis at present. We found that when hepatic fibrosis occurs, the expression of CD44 receptors on the surface of HSCs is significantly increased. Based on this finding, we designed silibinin-loaded hyaluronic acid (SLB-HA) micelles to achieve the treatment of hepatic fibrosis. Meanwhile, we constructed liver fibrosis rat model using Sprague–Dawley rats. We demonstrated that HA micelles had specific uptake to HSCs in vitro while avoiding the distribution in normal liver cells and the phagocytosis of macrophages. Importantly, HA micelles showed a significant liver targeting effect in vivo, especially in fibrotic liver which highly expressed CD44 receptors. In addition, SLB-HA micelles could selectively kill activated HSCs, having an excellent anti-hepatic fibrosis effect in vivo and a significant sustained release effect, and also had a good biological safety and biocompatibility. Overall, HA micelles represented a novel nanomicelle system which showed great potentiality in anti-hepatic fibrosis drugs delivery.

A new tandem peptide modified liposomal doxorubicin for tumor "ecological therapy"

The tumor microenvironment (TME) acts as an ecosystem that includes not only tumor cells, but also stromal cells such as cancer-associated fibroblasts (CAFs) and tumor-associated macrophages (TAMs). In addition, the abnormal extracellular environment (ECM), of which the mechanical forces are regulated by fibronectin (Fn) and collagen I, orchestrates tumorigenesis and progression by directly promoting invasion and cellular transformation of the ecosystem. Herein, we develop a novel peptide-modified liposome incorporated into doxorubicin (FnBPA5-AAN-Dox) as an ecological therapy system, which targets not only the cellular compartment but also non-cellular components of breast cancer. FnBPA5 is a Fn-binding peptide showing high affinity with relaxed Fn and collagen I in the ECM as well as α-SMA-expressing CAFs. However, the fast clearance by Fn-excreting organs such as the liver and spleen limits the accumulation of FnBPA5-Dox in the TME. The AAN peptide, which targets legumain overexpressed in the TAMs, could extend the circulation time and improve the therapeutic response as well as modulate the tumor immune microenvironment (TMIE). Given twice at an equivalent dose of 5 mg kg^-1 intravenously, the multi-in-one 'ecological therapy' applied AAN-FnBPA5-Dox showed excellent antitumor efficacy in 4T1 breast cancer mice, and the tumor growth inhibition (TGI) is up to 98.20% compared with saline. Immunofluorescence, flow cytometry and reverse transcription polymerase chain reaction (RT-PCR) results revealed that the dramatic improvement in antitumor efficacy can be attributed to the multifunctional targets of the drug delivery system.

Targeted delivery of celastrol to renal interstitial myofibroblasts using fibronectin-binding liposomes attenuates renal fibrosis and reduces systemic toxicity

Renal fibrosis often occurs in chronic kidney disease, and effective treatment is needed. Celastrol (CEL) may attenuate renal fibrosis, but it distributes throughout the body, leading to severe systemic toxicities. Here we designed a system to deliver CEL specifically to interstitial myofibroblasts, which is a key driver of renal fibrogenesis. Fibronectin is highly expressed in fibrotic kidney. The pentapeptide CREKA, which specifically binds fibronectin, was conjugated to PEGylated liposomes (CREKA-Lip). CREKA-coupled liposomes significantly increased the uptake of unmodified liposomes by activated NRK-49F renal fibroblasts. Systemic administration of CREKA-Lip to mice led to their accumulation in fibrotic kidney, where they were specifically internalized by interstitial myofibroblasts. Loading CEL into CREKA-Lip effectively inhibited the activation and proliferation of NRK-49F cells in vitro, and they markedly alleviated renal fibrosis, injury and inflammation induced by unilateral ureteral obstruction in mice. Besides, CEL-loaded CREKA-Lip was associated with significantly lower toxicity to major organs than free CEL. These results suggest that encapsulating CEL in CREKA-Lip can increase its therapeutic efficacy and reduce its systemic toxicity as a potential treatment for renal fibrosis.

Chemical modification of enveloped viruses for biomedical applications

The unique characteristics of enveloped viruses including nanometer size, consistent morphology, narrow size distribution, versatile functionality and biocompatibility have attracted attention from scientists to develop enveloped viruses for biomedical applications. The biomedical applications of the viral-based nanoparticles include vaccine development, imaging and targeted drug delivery. The modification of the structural elements of enveloped viruses is necessary for the desired functions. Here, we review the chemical approaches that have been utilized to develop bionanomaterials based on enveloped viruses for biomedical applications. We first provide an overview of the structures of enveloped viruses which are composed of nucleic acids, structural and functional proteins, glycan residues and lipid envelope. The methods for modification, including direct conjugation, metabolic incorporation of functional groups and peptide tag insertion, are described based on the biomolecular types of viral components. Layer-by-layer technology is also included in this review to illustrate the non-covalent modification of enveloped viruses. Then, we further elaborate the applications of chemically-modified enveloped viruses, virus-like particles and viral subcomponents in biomedical research.

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.

Biodistribution and toxicological evaluation of micron- and nano-sized erythrocyte-derived optical particles in healthy Swiss Webster mice

Particle-based systems provide a capability for the delivery of imaging and/or therapeutic payloads. We have engineered constructs derived from erythrocytes, and doped with the FDA-approved near infrared dye, indocyanine green (ICG). We refer to these optical particles as NIR erythrocyte-mimicking transducers (NETs). A particular feature of NETs is that their diameters can be tuned from micron- to nano-scale. Herein, we investigated the effects of micron- (≈2.6 μm diameter), and nano- (≈145 nm diameter) sized NETs on their biodistribution, and evaluated their acute toxicity in healthy Swiss Webster mice. Following tail vein injection of free ICG and NETs, animals were euthanized at various time points up to 48 hours. Fluorescence analysis of blood showed that nearly 11% of the injected amount of nano-sized NETs (nNETs) remained in blood at 48 hours post-injection as compared to ≈5% for micron-sized NETs (μNETs). Similarly, at this time point, higher levels of nNETs were present in various organs including the lungs, liver, and spleen. Histological analyses of various organs, extracted at 24 hours post-injection of NETs, did not show pathological alterations. Serum biochemistry profiles, in general, did not show elevated levels of the various analyzed biomarkers associated with liver and kidney functions. Values of various hematological profiles remained within the normal ranges following the administration of μNETs and nNETs. Results of this study suggest that erythrocyte-derived particles can potentially provide a non-toxic platform for delivery of ICG.

An integrin-based nanoparticle that targets activated hepatic stellate cells and alleviates liver fibrosis

Activation of hepatic stellate cells (HSCs) contributes to the development of liver fibrosis. Because of a relatively small population of HSCs in the liver and the lack of specific membrane targeting proteins, HSC-targeted therapy remains a major clinical challenge. Here we first showed that a hallmark of activated HSC (aHSC) is their increased expression of integrin αvβ3. Thus we established sterically stable liposomes that contain the cyclic peptides (cRGDyK) with a high affinity to αvβ3 to achieve aHSC-specific delivery. Our results showed that the cRGDyK-guided liposomes were preferentially internalized by activated HSCs in vitro and in vivo, and the internalization was abolished by excess free cRGDyK or knockdown of αvβ3. In contrast, quiescent HSCs, hepatocytes, Kupffer cells, sinusoidal endothelial cells, or biliary cells showed minimal uptake of the cRGDyK-guided liposomes. When loaded with the hedgehog inhibitor vismodegib, the cRGDyK-guided liposomes inhibited hedgehog pathway signaling specifically in activated HSCs. Moreover, treatment of mice with vismodegib-loaded cRGDyK-liposomes markedly inhibited the fibrogenic phenotype in bile duct ligation- or thioacetamide-treated mice. We conclude that the cRGDyK-guided liposomes can specifically target the activated HSCs, but not quiescent HSCs. This nanoparticle system showed great promise to deliver therapeutic agents to aHSC to treat liver fibrosis.

A hepatitis B virus-derived human hepatic cell-specific heparin-binding peptide: identification and application to a drug delivery system

Viruses are naturally evolved nanocarriers that can evade host immune systems, attach specifically to the surfaces of target cells, enter the cells through endocytosis, escape from endosomes efficiently, and then transfer their genomes to host cells. Hepatitis B virus (HBV) is a ∼42 nm enveloped DNA virus that can specifically infect human hepatic cells. To utilize the HBV-derived early infection machinery in synthetic nanocarriers, the human hepatic cell-binding site (i.e., the sodium taurocholate co-transporting polypeptide (NTCP)-binding site, with myristoylated pre-S1(2-47)) and the low pH-dependent fusogenic domain (pre-S1(9-24)) are indispensable for targeting and endosomal escape, respectively. However, cell-surface NTCP has recently been shown not to be involved in the initial attachment of HBV. In this study, we identified a novel heparin-binding site (pre-S1(30-42)) in the N-terminal half of the pre-S1 region, which presumably interacts with cell-surface heparan sulfate proteoglycan (HSPG) and plays a pivotal role in the initial attachment of HBV to human hepatic cells. The evolutionarily conserved amino acid residues Asp-31, Trp-32, and Asp-33 are indispensable for the heparin-binding activity. Liposomes (LPs) displaying the peptide were endocytosed by human hepatic cells in a cell-surface heparin-dependent manner and delivered doxorubicin to human hepatic cells more efficiently than myristoylated pre-S1(2-47)-displaying LPs. These results demonstrated that the pre-S1(30-42) peptide is the most promising HBV-derived targeting peptide for synthetic nanocarriers, and that this peptide exhibits high specificity for human hepatic cells and efficiently induces endocytosis.

A novel α-enolase-targeted drug delivery system for high efficacy prostate cancer therapy

Prostate cancer, one of the leading causes of disease and death in men all over the world, is challenging to treat. α-Enolase, a multifunctional protein, is overexpressed on human prostate carcinoma cells, and thereby it is a potential target for treatment of prostate cancer. In the current study, the pHCT74 peptide was used to construct a kind of highly targeted liposome (pHCT74-lipo) loaded with doxorubicin (pHCT74-lipo-Dox), which specifically targeted α-enolase on prostate tumour cells. Compared with liposomes without pHCT74 modification, pHCT74-lipo-Dox displayed a superior intracellular internalization with enhanced tumour cytotoxicity. In the in vivo study, pHCT74-lipo showed much higher tumour accumulation. In addition, loaded into pHCT74-lipo, doxorubicin demonstrated significantly improved anti-tumour activity on prostate tumour-bearing mice. These results suggest that the pHCT74 peptide has potential to be used in the development of a novel drug delivery system for targeted therapy against prostate cancer.

Drug Delivery Strategies for Antivirals against Hepatitis B Virus

Chronic hepatitis B virus (HBV) infection poses a significant health challenge due to associated morbidity and mortality from cirrhosis and hepatocellular cancer that eventually results in the breakdown of liver functionality. Nanotechnology has the potential to play a pivotal role in reducing viral load levels and drug-resistant HBV through drug targeting, thus reducing the rate of evolution of the disease. Apart from tissue targeting, intracellular delivery of a wide range of drugs is necessary to exert a therapeutic action in the affected organelles. This review encompasses the strategies and techniques that have been utilized to target the HBV-infected nuclei in liver hepatocytes, with a significant look at the new insights and most recent advances in drug carriers and their role in anti-HBV therapy.

Current Progress of Virus-mimicking Nanocarriers for Drug Delivery

Nanomedicines often involve the use of nanocarriers as a delivery system for drugs or genes for maximizing the therapeutic effect and/or minimizing the adverse effect. From drug administration to therapeutic activity, nanocarriers must evade the host's immune system, specifically and efficiently target and enter the cell, and release their payload into the cell cytoplasm by endosomal escape. These processes constitute the early infection stage of viruses. Viruses are a powerful natural nanomaterial for the efficient delivery of genetic information by sophisticated mechanisms. Over the past two decades, many virus-inspired nanocarriers have been generated to permit successful drug and gene delivery. In this review, we summarize the early infection machineries of viruses, of which the part has so far been utilized for delivery systems. Furthermore, we describe basics and applications of the bio-nanocapsule, which is a hepatitis B virus-mimicking nanoparticle harboring nearly all activities involved in the early infection machineries (i.e., stealth activity, targeting activity, cell entry activity, endosomal escaping activity).

Development of a multi-target peptide for potentiating chemotherapy by modulating tumor microenvironment

Finding effective cures against aggressive malignancy remains a major challenge in cancer chemotherapy. Here, we report a "tadpole"-like peptide by covalently conjugating the alanine-alanine-asparagine "tail" residual to the cyclic tumor homing peptide iRGD (CCRGDKGPDC) to afford nRGD, which significantly enhanced tumoricidal effects of doxorubicin, by either co-administered as a physical mixture or as a targeting ligand covalently conjugated to the liposomal carrier. Given twice at an equivalent dose of 5 mg/kg, doxorubicin loaded liposomes modified with nRGD (nRGD-Lipo-Dox) showed excellent antitumor efficacy in 4T1 breast cancer mice, of which 44.4% remained alive for over 90 days without recurrence during the period of investigation. The dramatic improvement in antitumor efficacy was attributed to nRGD-Lipo-Dox which appeared to specifically interact with tumor vascular endothelial cells to achieve efficient tumor penetration, and modulate tumor microenvironment with depletion of tumor associated macrophages.

Target delivery of small interfering RNAs with vitamin E-coupled nanoparticles for treating hepatitis C

RNA interference (RNAi) represents a promising strategy for the treatment of HCV infection. However, the development of an effective system for in vivo delivery of small interfering RNA (siRNA) to target organ remains a formidable challenge. Here, we develop a unique nanoparticle platform (VE-DC) composed of α-tocopherol (vitamin E) and cholesterol-based cationic liposomes (DOTAP-Chol) for systemic delivery of siRNAs to the liver. A HCV-replicable cell line, Huh7.5.1-HCV, and a transient HCV core expressing cell line, Huh7.5.1-Core, were constructed and used to assess the in vitro anti-HCV activity of VE-DC/siRNAs. A transient in vivo HCV model was also constructed by hydrodynamic injection of pCDNA3.1(+)-3FLAG-Core (pCore-3FLAG) plasmid expressing core protein or pGL3-5′UTR-luciferase (pGL3-5′UTR-luc) plasmid expressing luciferase driven by HCV 5′UTR. Nanoscale VE-DC/siRNA was intravenously injected to assess the liver-targeting property as well as antiviral activity. The nanoscale VE-DC effectively exerted an anti-HCV activity in the in vitro cell models. Post-administration of VE-DC/siRNAs also effectively delivered siRNAs to the liver, suppressing core protein production and firefly luciferase activity, without inducing an innate immunity response or off-target and toxicity effects. The VE-DC platform has high potential as a vehicle for delivery of siRNAs to the liver for gene therapy for targeting hepatitis C.

Nanoparticle-liver interactions: Cellular uptake and hepatobiliary elimination

30-99% of administered nanoparticles will accumulate and sequester in the liver after administration into the body. This results in reduced delivery to the targeted diseased tissue and potentially leads to increased toxicity at the hepatic cellular level. This review article focuses on the inter- and intra-cellular interaction between nanoparticles and hepatic cells, the elimination mechanism of nanoparticles through the hepatobiliary system, and current strategies to manipulate liver sequestration. The ability to solve the "nanoparticle-liver" interaction is critical to the clinical translation of nanotechnology for diagnosing and treating cancer, diabetes, cardiovascular disorders, and other diseases.

Development of a virus-mimicking nanocarrier for drug delivery systems: The bio-nanocapsule

As drug delivery systems, nanocarriers should be capable of executing the following functions: evasion of the host immune system, targeting to the diseased site, entering cells, escaping from endosomes, and releasing payloads into the cytoplasm. Since viruses perform some or all of these functions, they are considered naturally occurring nanocarriers. To achieve biomimicry of the hepatitis B virus (HBV), we generated the "bio-nanocapsule" (BNC)-which deploys the human hepatocyte-targeting domain, fusogenic domain, and polymerized-albumin receptor domain of HBV envelope L protein on its surface-by overexpressing the L protein in yeast cells. BNCs are capable of delivering various payloads to the cytoplasm of human hepatic cells specifically in vivo, which is achieved via formation of complexes with various materials (e.g., drugs, nucleic acids, and proteins) by electroporation, fusion with liposomes, or chemical modification. In this review, we describe BNC-related technology, discuss retargeting strategies for BNCs, and outline other virus-inspired nanocarriers.

A self-amplified transistor immunosensor under dual gate operation: highly sensitive detection of hepatitis B surface antigen

Ion-sensitive field-effect transistors (ISFETs), although they have attracted considerable attention as effective immunosensors, have still not been adopted for practical applications owing to several problems: (1) the poor sensitivity caused by the short Debye screening length in media with high ion concentration, (2) time-consuming preconditioning processes for achieving the highly-diluted media, and (3) the low durability caused by undesirable ions such as sodium chloride in the media. Here, we propose a highly sensitive immunosensor based on a self-amplified transistor under dual gate operation (immuno-DG ISFET) for the detection of hepatitis B surface antigen. To address the challenges in current ISFET-based immunosensors, we have enhanced the sensitivity of an immunosensor by precisely tailoring the nanostructure of the transistor. In the pH sensing test, the immuno-DG ISFET showed superior sensitivity (2085.53 mV per pH) to both standard ISFET under single gate operation (58.88 mV per pH) and DG ISFET with a non-tailored transistor (381.14 mV per pH). Moreover, concerning the detection of hepatitis B surface antigens (HBsAg) using the immuno-DG ISFET, we have successfully detected trace amounts of HBsAg (22.5 fg mL(-1)) in a non-diluted 1× PBS medium with a high sensitivity of 690 mV. Our results demonstrate that the proposed immuno-DG ISFET can be a biosensor platform for practical use in the diagnosis of various diseases.

Inhibition of Diethylnitrosamine-Induced Hepatocarcinogenesis in Mice by a High Dietary Protein Intake

Epidemiological and experimental evidence supports the key role of diet in the development of many types of cancer. Recent studies have suggested that dietary modifications may be beneficial for individuals at high risk for hepatocellular carcinoma (HCC). In this study, we investigated the effect of a high-protein (HP; 20% casein) dietondiethylnitrosamine (DEN)-induced hepatocarcinogenesis. Mice were given free access to water with 30 μg/ml DEN and fed a normal or HP diet for 22 wk. The results showed mice consuming HP diets had reduced mortality rates and body weights and lower hepatic enzyme activity compared to DEN-treated mice on a normal diet. HP consumption also promoted collagen accumulation in the liver, and reduced numbers of proliferating hepatocytes and infiltrating inflammatory cells, as well as decreased expression of inflammatory factor interleukin-1β, and nuclear factor κB activation. These data indicate that HP diets can inhibit DEN-induced hepatocarcinogenesis via suppression of the inflammatory response and provide a new evidence for the dietary management of clinical patients with hepatocellular carcinoma.

Applications of human hepatitis B virus preS domain in bio- and nanotechnology

Human hepatitis B virus (HBV) is a member of the family Hepadnaviridae, and causes acute and chronic infections of the liver. The hepatitis B surface antigen (HBsAg) contains the large (L), middle (M), and small (S) surface proteins. The L protein consists of the S protein, preS1, and preS2. In HBsAg, the preS domain (preS1 + preS2) plays a key role in the infection of hepatocytic cells by HBV and has several immunogenic epitopes. Based on these characteristics of preS, several preS-based diagnostic and therapeutic materials and systems have been developed. PreS1-specific monoclonal antibodies (e.g., MA18/7 and KR127) can be used to inhibit HBV infection. A myristoylated preS1 peptide (amino acids 2-48) also inhibits the attachment of HBV to HepaRG cells, primary human hepatocytes, and primary tupaia hepatocytes. Antibodies and antigens related to the components of HBsAg, preS (preS1 + preS2), or preS1 can be available as diagnostic markers of acute and chronic HBV infections. Hepatocyte-targeting delivery systems for therapeutic molecules (drugs, genes, or proteins) are very important for increasing the clinical efficacy of these molecules and in reducing their adverse effects on other organs. The selective delivery of diagnostic molecules to target hepatocytic cells can also improve the efficiency of diagnosis. In addition to the full-length HBV vector, preS (preS1 + preS2), preS1, and preS1-derived fragments can be useful in hepatocyte-specific targeting. In this review, we discuss the literature concerning the applications of the HBV preS domain in bio- and nanotechnology.

Tailoring the stealth properties of biocompatible polysaccharide nanocontainers

Fundamental development of a biocompatible and degradable nanocarrier platform based on hydroxyethyl starch (HES) is reported. HES is a derivative of starch and possesses both high biocompatibility and improved stability against enzymatic degradation; it is used to prepare nanocapsules via the polyaddition reaction at the interface of water nanodroplets dispersed in an organic miniemulsion. The synthesized hollow nanocapsules can be loaded with hydrophilic guests in its aqueous core, tuned in size, chemically functionalized in various pathways, and show high shelf life stability. The surface of the HES nanocapsules is further functionalized with poly(ethylene glycol) via different chemistries, which substantially enhanced blood half-life time. Importantly, methods for precise and reliable quantification of the degree of functionalization are also introduced, which enable the precise control of the chemistry on the capsules' surface. The stealth properties of these capsules is studied both in-vitro and in-vivo. The functionalized nanocapsules serve as a modular platform for specific cell targeting, as they show no unspecific up-taken by different cell types and show very long circulating time in blood (up to 72 h).

Carbohydrate nanocarriers in biomedical applications: functionalization and construction

Carbohydrates are used to functionalize or construct nanocarriers for biomedical applications – specific targeting, biocompatibility, stealth effect, biodegradability.

A safe and efficient hepatocyte-selective carrier system based on myristoylated preS1/21-47 domain of hepatitis B virus

A safe and efficient liver targeted PEGylated liposome (PEG-Lip) based on N-terminal myristoylated preS1/21-47 (preS1/21-47(myr)) of hepatitis B virus was successfully developed. The study aimed to elucidate the cellular uptake mechanism of preS1/21-47(myr) modified PEG-Lip (preS1/21-47(myr)-PEG-Lip) in hepatogenic cells and the distribution behavior of preS1/21-47(myr)-PEG-Lip in Vr:CD1 (ICR) mice. The cellular uptake results showed that preS1/21-47(myr)-PEG-Lip was effectively taken up by hepatogenic cells (including primary hepatocytes and liver tumor cells) through a receptor-mediated endocytosis pathway compared with non-hepatogenic cells. After systemic administration to H22 hepatoma-bearing mice, preS1/21-47(myr)-PEG-Lip showed significant liver-specific delivery and an increase in the distribution of preS1/21-47(myr)-PEG-Lip in hepatic tumor. Furthermore, the antitumor effect of preS1/21-47(myr)-PEG-Lip loaded with paclitaxel (PTX) was remarkably stronger than that of PTX injection and PTX loaded liposomes (including common liposomes and PEG-Lip). In safety evaluation, no acute systemic toxicity and immunotoxicity were observed after intravenous injection of preS1/21-47(myr)-PEG-Lip. No liver toxicity was observed despite the dramatic increase of preS1/21-47(myr)-PEG-Lip in liver. Taken together, preS1/21-47(myr)-PEG-Lip represents a promising carrier system for targeted liver disease therapy and imaging.