Improved drug delivery to cancer cells: a method using magnetoliposomes that target epidermal growth factor receptors

Nanosized Delivery Systems for Therapeutic Proteins: Clinically Validated Technologies and Advanced Development Strategies

The impact of protein therapeutics in healthcare is steadily increasing, due to advancements in the field of biotechnology and a deeper understanding of several pathologies. However, their safety and efficacy are often limited by instability, short half-life and immunogenicity. Nanodelivery systems are currently being investigated for overcoming these limitations and include covalent attachment of biocompatible polymers (PEG and other synthetic or naturally derived macromolecules) as well as protein nanoencapsulation in colloidal systems (liposomes and other lipid or polymeric nanocarriers). Such strategies have the potential to develop next-generation protein therapeutics. Herein, we review recent research progresses on these nanodelivery approaches, as well as future directions and challenges.

The Potential of Magnetic Nanoparticles for Diagnosis and Treatment of Cancer Based on Body Magnetic Field and Organ-on-the-Chip

Cancer is an abnormal cell growth which tends to proliferate in an uncontrolled way and, in some cases, leads to metastasis. If cancer is left untreated, it can immediately cause death. The use of magnetic nanoparticles (MNPs) as a drug delivery system will enable drugs to target tissues and cell types precisely. This study describes usual strategies and consideration for the synthesis of MNPs and incorporates payload drug on MNPs. They have advantages such as visual targeting and delivering which will be discussed in this review. In addition, we considered body magnetic field to make drug delivery process more effective and safer by the application of MNPs and tumor-on-chip.

Epidermal growth factor receptor-targeted immune magnetic liposomes capture circulating colorectal tumor cells efficiently

AIM

To compare the capacity of newly developed epidermal growth factor receptor (EGFR)-targeted immune magnetic liposomes (EILs) vs epithelial cell adhesion molecule (EpCAM) immunomagnetic beads to capture colorectal circulating tumor cells (CTCs).

METHODS

EILs were prepared using a two-step method, and the magnetic and surface characteristics were confirmed. The efficiency of capturing colorectal CTCs as well as the specificity were compared between EILs and EpCAM magnetic beads.

RESULTS

The obtained EILs had a lipid nanoparticle structure similar to cell membrane. Improved binding with cancer cells was seen in EILs compared with the method of coupling nano/microspheres with antibody. The binding increased as the contact time extended. Compared with EpCAM immunomagnetic beads, EILs captured more CTCs in peripheral blood from colorectal cancer patients. The captured cells showed consistency with clinical diagnosis and pathology. Mutation analysis showed same results between captured CTCs and cancer tissues.

CONCLUSION

EGFR antibody-coated magnetic liposomes show high efficiency and specificity in capturing colorectal CTCs.

Magnetoliposomes and their potential in the intelligent drug-delivery field

Research advancements for magnetically guided drug delivery encompass not only the improvement of the design, synthesis and evaluation of more selective nanomaterials bearing magnetic properties, but also the optimization of the transport and delivery of magnetic agents. Such versatile platforms can be utilized for simultaneously carrying therapeutics and diagnostics.

Unique diagnostic and therapeutic roles of porphyrins and phthalocyanines in photodynamic therapy, imaging and theranostics

Porphyrinic molecules have a unique theranostic role in disease therapy; they have been used to image, detect and treat different forms of diseased tissue including age-related macular degeneration and a number of different cancer types. Current focus is on the clinical imaging of tumour tissue; targeted delivery of photosensitisers and the potential of photosensitisers in multimodal biomedical theranostic nanoplatforms. The roles of porphyrinic molecules in imaging and pdt, along with research into improving their selective uptake in diseased tissue and their utility in theranostic applications are highlighted in this Review.

Potential of amino acid/dipeptide monoester prodrugs of floxuridine in facilitating enhanced delivery of active drug to interior sites of tumors: a two-tier monolayer in vitro study

PURPOSE

To evaluate the advantages of amino acid/dipeptide monoester prodrugs for cancer treatments by assessing the uptake and cytotoxic effects of floxuridine prodrugs in a secondary cancer cell monolayer following permeation across a primary cancer cell monolayer.

METHODS

The first Capan-2 monolayer was grown on membrane transwell inserts; the second monolayer was grown at the bottom of a plate. The permeation of floxuridine and its prodrugs across the first monolayer and the uptake and cell proliferation assay on secondary layer were sequentially determined.

RESULTS

All floxuridine prodrugs exhibited greater permeation across the first Capan-2 monolayer than the parent drug. The correlation between uptake and growth inhibition in the second monolayer with intact prodrug permeating the first monolayer suggests that permeability and enzymatic stability are essential for sustained action of prodrugs in deeper layers of tumors. The correlation of uptake and growth inhibition were vastly superior for dipeptide prodrugs to those obtained with mono amino acid prodrugs.

CONCLUSIONS

Although a tentative general overall correlation between intact prodrug and uptake or cytotoxic action was obtained, it appears that a mixture of floxuridine prodrugs with varying beneficial characteristics may be more effective in treating tumors.

Stimuli-responsive liposome-nanoparticle assemblies

INTRODUCTION

Nanoscale assemblies are needed that achieve multiple therapeutic objectives, including cellular targeting, imaging, diagnostics and drug delivery. These must exhibit high stability, bioavailability and biocompatibility, while maintaining or enhancing the inherent activity of the therapeutic cargo. Liposome-nanoparticle assemblies (LNAs) combine the demonstrated potential of liposome-based therapies, with functional nanoparticles. Specifically, LNAs can be used to concentrate and shield the nanoparticles and, in turn, stimuli-responsive nanoparticles that respond to external fields can be used to control liposomal release. The ability to design LNAs via nanoparticle encapsulation, decoration or bilayer-embedment offers a range of configurations with different structures and functions.

AREAS COVERED

This paper reviews the current state of research and understanding of the design, characterization and performance of LNAs. A brief overview is provided on liposomes and nanoparticles for therapeutic applications, followed by a discussion of the opportunities and challenges associated with combining the two in a single assembly to achieve controlled release via light or radiofrequency stimuli.

EXPERT OPINION

LNAs offer a unique opportunity to combine the therapeutic properties of liposomes and nanoparticles. Liposomes act to concentrate small nanoparticles and shield nanoparticles from the immune system, while the nanoparticle can be used to initiate and control drug release when exposed to external stimuli. These properties provide a platform to achieve nanoparticle-controlled liposomal release. LNA design and application are still in infancy. Research concentrating on the relationships among LNA structure, function and performance is essential for the future clinical use of LNAs.

Magnetic activated release of umbelliferone from lipid matrices

Lipid matrices containing dispersed superparamagnetic iron oxide (SPIO) particles were investigated as a magnetic field-responsive drug delivery system. Lipid matrices were prepared by combining myristyl alcohol, fatty acid coated SPIO particles, and umbelliferone (UMB). With placement of the matrices into the release medium, initial UMB release was fast but fell to zero indicating a burst effect. With application of an alternating magnetic field, additional UMB was released. The rate and extent of magnetic field-stimulated release increased with UMB load but not SPIO content. Differences between oleic and myristic acid coated SPIO appeared to be a result of phase separation. UMB release coincided with matrix melting, which can be controlled by the SPIO content and external magnetic field as shown by theoretical analysis. While significant technological issues remain, the foundation for developing magnetic field-stimulated drug delivery systems has been established.

In vivo distribution of polymeric nanoparticles at the whole-body, tumor, and cellular levels

PURPOSE

Block copolymer micelles (BCMs) were functionalized with indium-111 and/or epidermal growth factor (EGF), which enabled investigation of the in vivo transport of passively and actively targeted BCMs. The integration of conventional and image-based techniques afforded novel quantitative means to achieve an in-depth insight into the fate of polymeric nanoparticles in vivo.

METHODS

Pharmacokinetics and biodistribution studies were performed in athymic mice bearing human breast xenografts to evaluate the whole-body transport of NT-BCMs (non-targeted, EGF-) and T-BCMs (targeted, EGF+). The intratumoral distribution of BCMs was investigated using MicroSPECT/CT and autoradiographic imaging, complemented with quantitative MATLAB® analyses. Tumors were fractionated for quantifying intracellular uptake of BCMs via γ-counting.

RESULTS

The intratumoral distribution of NT-BCMs and T-BCMs were found to be heterogeneous, and positively correlated with tumor vascularization (r>0.68 ± 0.04). The enhanced in vivo cell uptake and cell membrane binding of T-BCMs were found to delay their clearance from tumors overexpressing EGFR, and therefore resulted in enhanced tumor accumulation for the T-BCMs in comparison to the NT-BCMs.

CONCLUSIONS

Adequate passive targeting is required in order to achieve effective active targeting. Tumor physiology has a significant impact on the transvascular and intratumoral transport of passively and actively targeted BCMs.

Physical mechanisms and methods employed in drug delivery to tumors

In addition to several well-known drug delivery strategies developed to facilitate effective chemotherapy with anticancer agents, some new approaches have been recently established, based on specific effects arising from the applications of ultrasound, magnetic and electric fields on drug delivery systems. This paper gives an overview of newly developed methods of drug delivery to tumors and of the related anticancer therapies based on the combined use of different physical methods and specific drug carriers. The conventional strategies and new approaches have been put into perspective to revisit the existing and to propose new directions to overcome the threatening problem of cancer diseases.

Surface functionalization of magnetoliposomes in view of improving iron oxide-based magnetic resonance imaging contrast agents: Anchoring of gadolinium ions to a lipophilic chelate

Small unilamellar phospholipid vesicles containing the phosphatidylethanolamine-diethylene triamine pentaacetic acid (PE-DTPA) conjugate as one of the building stones were constructed. The ability of these colloids to complex gadolinium(III) ions at the surface of both the inner and outer bilayer shells was verified using a colorimetric method with Arsenazo III as a dye indicator. On incubation of these functionalized vesicles with magnetoliposomes (MLs, nanometer-sized magnetite cores encapsulated in a phospholipid bilayer), PE-DTPA percolates into the ML coat. The PE-DTPA content could be fine-tuned by varying the conjugate concentration in the donor vesicles. In the experimental conditions applied, up to 500 Gd(3+) ions were immobilized per ML colloid. The resulting ML-Gd(3+) complexes might have great potential, for example, as a novel magnetic resonance imaging contrast agent.

A dual-ligand approach for enhancing targeting selectivity of therapeutic nanocarriers

Conjugation of ligands to nano-scale drug carriers targeting over-expressed cell surface receptors is a promising approach for delivery of therapeutic agents to tumor cells. However, most commonly utilized ligands are directed at receptors expressed not only on target cells but also on other cells in the body, leading to unintended uptake in these off-target cells. In this study, a novel, dual-ligand approach is reported, which targets tumor cells while sparing off-target cells by exploiting the fact that tumor cells typically over-express multiple types of surface receptors. This approach was tested in the human KB cell line, which over-expresses both folate receptor (FR) and the epidermal growth factor receptor (EGFR). Liposomal nanocarriers loaded with doxorubicin and bearing controlled numbers of both folic acid and a monoclonal antibody against the EGFR were designed. Cytotoxicity was used to determine targeting selectivity of the designed carriers in vitro by utilizing KB cells expressing both FR and EGFR and off-target control cells in which one or both receptors were blocked. The data demonstrates that nanocarriers can be designed to achieve toxicity only when all targeted receptors are available, providing an approach to improve selectivity over current single-ligand approaches.