Biotinylated disulfide containing PEI/avidin bioconjugate shows specific enhanced transfection efficiency in HepG2 cells

A Comprehensive Review on Liver Targeting: Emphasis on Nanotechnology- based Molecular Targets and Receptors Mediated Approaches

BACKGROUND

The pathogenesis of hepatic diseases involves several cells, which complicates the delivery of pharmaceutical agents. Many severe liver diseases affecting the worldwide population cannot be effectively treated. Major hindrances or challenges are natural physiological barriers and non-specific targeting of drugs administered, leading to inefficient treatment. Hence, there is an earnest need to look for novel therapeutic strategies to overcome these hindrances. A kind of literature has reported that drug safety and efficacy are incredibly raised when a drug is incorporated inside or attached to a polymeric material of either hydrophilic or lipophilic nature. This has driven the dynamic investigation for developing novel biodegradable materials, drug delivery carriers, target-specific drug delivery systems, and many other novel approaches.

OBJECTIVE

Present review is devoted to summarizing receptor-based liver cell targeting using different modified novel synthetic drug delivery carriers. It also highlights recent progress in drug targeting to diseased liver mediated by various receptors, including asialoglycoprotein, mannose and galactose receptor, Fc receptor, low-density lipoprotein, glycyrrhetinic, and bile acid receptor. The essential consideration is given to treating liver cancer targeting using nanoparticulate systems, proteins, viral and non-viral vectors, homing peptides and gene delivery.

CONCLUSION

Receptors based targeting approach is one such approach that was explored by researchers to develop novel formulations which can ensure site-specific drug delivery. Several receptors are on the surfaces of liver cells, which are highly overexpressed in various disease conditions. They all are helpful for the treatment of liver cancer.

Biotinylated photoactive Pt(iv) anticancer complexes

Novel biotinylated diazido-Pt(iv) complexes exhibit high visible light photocytotoxicity while being stable in the dark. Photocytotoxicity and cellular accumulation of all-trans-[Pt(py)₂(N₃)₂(biotin)(OH)] (2a) were enhanced significantly when bound to avidin; irradiation induced dramatic cellular morphological changes in human ovarian cancer cells treated with 2a.

A Versatile Nanowire Platform for Highly Efficient Isolation and Direct PCR-free Colorimetric Detection of Human Papillomavirus DNA from Unprocessed Urine

Purpose: As human papillomavirus (HPV) is primarily responsible for the development of cervical cancer, significant efforts have been devoted to develop novel strategies for detecting and identifying HPV DNA in urine. The analysis of target DNA sequences in urine offers a potential alternative to conventional methods as a non-invasive clinical screening and diagnostic assessment tool for the detection of HPV. However, the lack of efficient approaches to isolate and directly detect HPV DNA in urine has restricted its potential clinical use. In this study, we demonstrated a novel approach of using polyethylenimine-conjugated magnetic polypyrrole nanowires (PEI-mPpy NWs) for the extraction, identification, and PCR-free colorimetric detection of high-risk strains of HPV DNA sequences, particularly HPV-16 and HPV-18, in urine specimens of cervical cancer patients. Materials and Methods: We fabricated and characterized polyethylenimine-conjugated magnetic nanowires (PEI/mPpy NWs). PEI/mPpy NWs-based HPV DNA isolation and detection strategy appears to be a cost-effective and practical technology with greater sensitivity and accuracy than other urine-based methods. Results: The analytical and clinical performance of PEI-mPpy NWs was evaluated and compared with those of cervical swabs, demonstrating a superior type-specific concordance rate of 100% between urine and cervical swabs, even when using a small volume of urine (300 µL). Conclusion: We envision that PEI-mPpy NWs provide substantive evidence for clinical diagnosis and management of HPV-associated disease with their excellent performance in the recovery and detection of HPV DNA from minimal amounts of urine samples.

Degradable polyesters via ring-opening polymerization of functional valerolactones for efficient gene delivery

Degradable polymers as gene and drug carriers are emerging as one of the most promising types of materials in the biomedical and pharmaceutical areas.

Using fluorescently-labeled magnetic nanocomposites as a dual contrast agent for optical and magnetic resonance imaging

The intravenous administration of atta@Fe₃O₄@Ru nanocomposites to a rabbit model resulted in a marked and negatively enhanced T₂-weighted MRI.

Reducible cationic PAA-g-PEI polymeric micelle/DNA complexes for enhanced gene delivery

The design of unique vectors to overcome the cytotoxicity and increase the efficiency of gene transfection has enormous challenges. Polyethylenimine (PEI) is one of the most effective polymer-based gene carriers. However, the transfection efficiency and toxicity of PEI correlate strongly to its molecular weight (MW). In this study, novel reduction-sensitive amphiphilic poly[phenethylamido- N,N-bis(acryloyl) cystine]- g-polyethylenimine (PAA- g-PEI) copolymers were synthesized by grafting low-MW PEIs onto reducible poly[phenethylamido-N,N-bis(acryloyl) cystine] (PAA).

These copolymers self-assembled in aqueous solution into micelles with sizes <70 nm, as determined by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The PAA- g-PEI2000 micelles effectively condense with the plasmid DNA to form complex nanoparticles with diameters of ~100 nm at an N/P ratio of 4/1. The PAA- g-PEI2000 micelle/DNA complexes protected the DNA from degrading by nuclease and released DNA under reductive conditions by the cleavage of the disulfide bonds and the subsequent disassembly of the micelles. As determined by gene transfection experiments, the transfection efficiency of the PAA- g-PEI2000 micelle/DNA complexes was significantly greater than that of the PEI25K/DNA complexes, while the cytotoxicity of the copolymers was much lower than that for PEI25K.

Rational design of magnetic nanorattles as contrast agents for ultrasound/magnetic resonance dual-modality imaging

Nanorattles, as promising functional hollow nanomaterials, show considerable advantages in a variety of applications for drug delivery, biosensors, and biomedical imaging because of their tailored ability in both the movable core and shell. In this study, we formulate a facile controllable route to synthesize a monodisperse magnetic nanorattle with an Fe3O4 superparticle as the core and poly(vinylsilane) (PVS) as the outer shell (Fe3O4@air@PVS) using the polymer-backbone-transition strategy. In the process of synthesis, besides acting as the precursor for the PVS shells of nanorattles, organosilica (o-SiO2) plays the role of template for the middle cavities. The structures of nanorattles can be easily formed via etching treatment of NaOH solution. Through encapsulating sensitive perfluorohexane (PFH) in the cavities of Fe3O4@air@PVS, the biocompatible magnetic nanosystem shows a relatively stable ultrasound signal intensity and a high r2 value of 62.19 mM(-1) s(-1) for magnetic resonance imaging (MRI). After intravenous administration of nanorattles to a healthy rat, dramatically positively enhanced ultrasound imaging and negatively enhanced T2-weighted MRI are detected in the liver. Furthermore, when the Fe3O4@PFH@PVS nanorattles are administered to tumor-bearing mice, a significant passive accumulation in the tumor via an electron paramagnetic resonance effect is detected by both ultrasound imaging and MRI. In vivo experiments indicate that the obtained Fe3O4@PFH@PVS nanorattles can be used as dual-modality contrast agents for simultaneous ultrasound and MRI detection.

Stimuli-responsive biodegradable poly(methacrylic acid) based nanocapsules for ultrasound traced and triggered drug delivery system

Ultrasound contrast agents (UCAs) have been investigated for echogenic intravenous drug delivery system. Due to the traditional UCAs with overlarge size (micro-scale), their reluctant accumulation in target organs and the instability have presented severe obstacles to the accurate response to the ultrasound and severely limited their further clinical application. Furthermore, elimination of drug carriers from the biologic system after their carrying out the diagnostic or therapeutic functions is one important aspect to be considered. The drug carriers with large sizes, avoiding renal filtration, will lead to increasing toxicity. In this present paper, we design and develop a new type of triple-stimuli responsive (ultrasound/pH/GSH) biodegradable nanocapsules, in which fill up with perfluorohexane, and the DOX-loaded PMAA with disulfide crosslinking forms the wall. These soft nanocapsules with uniform size of 300 nm can easily enter the tumor tissues via EPR effects. The PMAA shell has high DOX-loading content (36 wt%) and great drug loading efficiency (93.5%), the PFH filled can effectively enhance US imaging signal through acoustic droplet vaporization (ADV), ensuring diagnostic and image-guided therapeutic applications. What is more, the disulfide-crosslinked PMAA shell is biodegradable and thus safe for normal organisms. These merits enabled us optimize the balance of diagnostic, therapeutic and biodegradable functionalities in a multifunctional theranostic nanoplatform.

Efficient hepatic delivery of drugs: novel strategies and their significance

Liver is a vital organ responsible for plethora of functions including detoxification, protein synthesis, and the production of biochemicals necessary for the sustenance of life. Therefore, patients with chronic liver diseases such as viral hepatitis, liver cirrhosis, and hepatocellular carcinoma need immediate attention to sustain life and as a result are often exposed to the prolonged treatment with drugs/herbal medications. Lack of site-specific delivery of these medications to the hepatocytes/nonparenchymal cells and adverse effects associated with their off-target interactions limit their continuous use. This calls for the development and fabrication of targeted delivery systems which can deliver the drug payload at the desired site of action for defined period of time. The primary aim of drug targeting is to manipulate the whole body distribution of drugs, that is, to prevent distribution to non-target cells and concomitantly increase the drug concentration at the targeted site. Carrier molecules are designed for their selective cellular uptake, taking advantage of specific receptors or binding sites present on the surface membrane of the target cell. In this review, various aspects of liver targeting of drug molecules and herbal medications have been discussed which elucidate the importance of delivering the drugs/herbal medications at their desired site of action.

Development of streptavidin-based nanocomplex for siRNA delivery

In our previous study, we have identified a PCBP2 siRNA that exhibits antifibrotic activity in rat hepatic stellate cells (HSCs) by inhibition of αCP2, a protein responsible for stabilization of the collagen α1 (I) mRNA in alcoholic liver fibrosis. This study aims to develop a streptavidin-based nanocomplex that can efficiently deliver the PCBP2 siRNA to HSCs. Biotin-siRNA and biotin-cholesterol were mixed with streptavidin to form the streptavidin-biotin complex, which was further condensed electrostatically with positively charged protamine to form the final multicomponent siRNA nanocomplex in the size range of 150-250 nm. The siRNA nanocomplex does not induce cytotoxicity in rat HSCs as compared to commercially available transfection agents. The cellular uptake efficiency of the siRNA nanocomplex is higher in rat HSCs than other cell lines, such as Caco-2 and PC-3, indicating that receptor-mediated endocytosis mainly contributes to the cellular uptake of the siRNA nanocomplex. The siRNA nanocomplex exhibits more than 85% silencing effect on the PCBP2 mRNA in HSCs. Stability study indicates that the nanocomplex can efficiently protect siRNA from degradation in the serum. The streptavidin-based multicomponent siRNA nanocomplex provides a promising strategy to deliver the PCBP2 siRNA to HSCs. Moreover, the nanocomplex can be used as a platform for other diseases by changing the siRNA sequence and targeting ligand.

An oligopeptide ligand-mediated therapeutic gene nanocomplex for liver cancer-targeted therapy

The epidermal growth factor receptor (EGFR) is over-expressed in a wide variety of epithelial-derived cancer cells. In this study, EGFR-targeted gene carriers were designed to complex the therapeutic acetylcholinesterase gene (AChE gene), which suppresses cell proliferation via inactivating mitogen-activated protein kinase and PI3K/Akt pathways in cells, for treatment of EGFR-positive liver cancers. Different amounts of target ligand YC21 (an oligopeptide composed of 21 amino acid units) were coupled with the PEI(600)-CD (PC) vectors composed of β-cyclodextrin (β-CD) and low-molecular-weight polyethylenimine (PEI, Mw 600) to form the EGFR-targeted gene vectors (termed as YPCs). The YPC vectors possessed the highly efficient gene delivery ability to the EGFR-positive liver cancer cells. YPCs could effectively promote AChE gene expression. The YPC/AChE complexes produced excellent gene transfection abilities in EGFR-positive liver cancer cells in vitro and in vivo.

Poly(β-amino amine) cross-linked PEIs as highly efficient gene vectors

To increase the release of DNA into the cytoplasm and further improve transgene expression of nucleic acid novel polymeric gene carriers were prepared which would be biodegradable under the reducing conditions in the cytoplasm. Disulfide-containing poly(β-amino amine)s were first synthesized and then used to cross-link low molecular weight polyethyleneimine (1800 Da) through Michael addition to obtain SS-PBAA-PEIs as the final gene carriers. The physicochemical characteristics of SS-PBAA-PEI/DNA complexes were characterized. In vitro transfection mediated by the SS-PBAA-PEIs under serum conditions was carried out. Cell uptake of the gene delivery systems was observed by confocal laser scanning microscopy. The results of the physicochemical characterisation demonstrated that the SS-PBAA-PEIs could efficiently condense DNA. In vitro transfection under serum conditions showed that SS-PBAA-PEIs had comparable or even higher transfection efficiencies than 25 kDa PEI. And SS-PBAA-PEIs showed much lower cytotoxicity compared with 25 kDa PEI. In summary, the SS-PBAA-PEIs possess great potential as non-viral gene vectors and exhibit high transfection efficiency under serum conditions.

Avidin-biotin technology in targeted therapy

IMPORTANCE OF THE FIELD

The goal of drug targeting is to increase the concentration of the drug in the vicinity of the cells responsible for disease without affecting healthy cells. Many approaches in cancer treatment are limited because of their broad range of unwanted side effects on healthy cells. Targeting can reduce side effects and increase efficacy of drugs in the patient.

AREAS COVERED IN THIS REVIEW

Avidin, originally isolated from chicken eggs, and its bacterial analogue, streptavidin, from Streptomyces avidinii, have extremely high affinity for biotin. This unique feature is the basis of avidin-biotin technology. This article reviews the current status of avidin-biotin systems and their use for pretargeted drug delivery and vector targeting.

WHAT THE READER WILL GAIN

The reader will gain an understanding of the following approaches using the avidin-biotin system: i) targeting antibodies and therapeutic molecules are administered separately leading to a reduction of drug dose in normal tissues compared with conventional (radio)immunotherapies; ii) introducing avidin gene into specific tissues by local gene transfer, which subsequently can sequester and concentrate considerable amounts of therapeutic ligands; and iii) enabling transductional targeting of gene therapy vectors.

TAKE HOME MESSAGE

Avidin and biotin technology has proved to be an extremely versatile tool with broad applications, such as pretargeting, delivering avidin gene into cells enabling targeting of biotinylated compounds and targeting of viral vectors.