Bioinspired extracellular vesicle-coated silica nanoparticles as selective delivery systems

In recent years, there has been a breakthrough in the integration of artificial nanoplatforms with natural biomaterials for the development of more efficient drug delivery systems. The formulation of bioinspired nanosystems, combining the benefits of synthetic nanoparticles with the natural features of biological materials, provides an efficient strategy to improve nanoparticle circulation time, biocompatibility and specificity toward targeted tissues. Among others biological materials, extracellular vesicles (EVs), membranous structures secreted by many types of cells composed by a protein rich lipid bilayer, have shown a great potential as drug delivery systems themselves and in combination with artificial nanoparticles. The reason for such interest relays on their natural properties, such as overcoming several biological barriers or migration towards specific tissues. Here, we propose the use of mesoporous silica nanoparticles (MSNs) as efficient and versatile nanocarriers in combination with tumor derived extracellular vesicles (EVs) for the development of selective drug delivery systems. The hybrid nanosystems demonstrated selective cellular internalization in parent cells, indicating that the EV targeting capabilities were efficiently transferred to MSNs by the developed coating strategy. As a result, EVs-coated MSNs provided an enhanced and selective intracellular accumulation of doxorubicin and a specific cytotoxic activity against targeted cancer cells, revealing these hybrid nanosystems as promising candidates for the development of targeted treatments.

Protein-imprinted polymers: How far have "plastic antibodies" come?

Antibodies are highly selective and sensitive, making them the gold standard for recognition affinity tools. However, their production cost is high and their downstream processing is time-consuming. Molecularly imprinted polymers (MIPs) are tailor-made by incorporating specific molecular recognition sites in their structure, thus translating into receptor-like activity mode of action. The interest in molecular imprinting technology, applied to biomacromolecules, has increased in the past decade. MIPs, produced using biomolecules as templates, commonly referred to as "plastic antibodies" or "artificial receptors", have been considered as suitable cheaper and easy to produce alternatives to antibodies. Research on MIPs, designed to recognize proteins or peptides is particularly important, with potential contributions towards biomedical applications, namely biosensors and targeted drug delivery systems. This mini review will cover recent advances on (bio)molecular imprinting technology, where proteins or peptides are targeted or mimicked for sensing and therapeutic applications. Polymerization methods are reviewed elsewhere, being out of the scope of this review. Template selection and immobilization approaches, monomers and applications will be discussed, highlighting possible drawbacks and gaps in research.

Nanotechnology applications for cardiovascular disease treatment: Current and future perspectives

A large majority of cardiovascular nanomedicine research has focused on fabricating designer nanoparticles for improved targeting as a means to overcome biological barriers. For cardiac related disorders, such as atherosclerosis, hypertension, and myocardial infarction, designer micro or nanoparticles are often administered into the vasculature or targeted vessel with the hope to circumvent problems associated with conventional drug delivery, including negative systemic side effects. Additionally, novel nano-drug carriers that enter circulation can be selectively uptaken by immune cells with the intended purpose that they modulate inflammatory processes and migrate locally to plaque for therapeutic payload delivery. Indeed, innovative design in nanoparticle composition, formulation, and functionalization has advanced the field as a means to achieve therapeutic efficacy for a variety of cardiac disease indications. This perspective aims to discuss these advances and provide new interpretations of how nanotechnology can be best applied to aid in cardiovascular disease treatment. In an effort to spark discussions on where the field of research should go, we share our outlook in new areas of nanotechnological inclusion and integration, such as in vascular, implantable, or wearable device technologies as well as nanocomposites and nanocoatings. Further, as cardiovascular diseases (CVD) increasingly claim a number of lives globally, we propose more attention should be placed by researchers on nanotechnological approaches for risk factor treatment to aid in early prevention and treatment of CVD.

'Polymorphism-aided' Selective Targeting and Inhibition of Caspase-6 by a Novel Allosteric Inhibitor Towards Efficient Alzheimer's Disease Treatment

The predominance of Alzheimer's disease (AD) among the aged remains a global challenge. As such, the search for alternative and effective therapeutic options continuous unabated. Among the therapeutic targets explored over the years toward impeding the progression of AD is caspase-6 (Casp6), although selectively targeting Casp6 remains a challenge due to high homology with other members of the caspase family. Methyl 3-[(2,3-dihydro-1-benzofuran-2-yl formamido) methyl]-5-(furan-2-amido) benzoate (C13), a novel allosteric inhibitor, is reportedly shown to exhibit selective inhibition against mutant human Casp6 variants (E35K). However, structural and atomistic insights accounting for the reported inhibitory prowess of C13 remains unresolved. In this study, we seek to unravel the mechanistic selectivity of C13 coupled with the complementary effects of E35K single-nucleotide polymorphism (SNP) relative to Casp6 inhibition. Analyses of binding dynamics revealed that the variant Lysine-35 mediated consistent high-affinity interactions with C13 at the allosteric site, possibly forming the molecular basis of the selectivity of C13 as well as its high binding free energy as estimated. Analysis of residue interaction network around Glu35 and Lys35 revealed prominent residue network distortions in the mutant Casp6 conformation evidenced by a decrease in node degree, reduced number of edges and an increase short in path length relative to a more compact conformation in the wild system. The relatively higher binding free energy of C13 coupled with the stronger intermolecular interactions elicited in the mutant conformation further suggests that the mutation E35K probably favours the inhibitory activity of C13. Further analysis of atomistic changes showed increased C-α atom deviations consistent with structural disorientations in the mutant Casp6. Structural Insights provided could open up a novel paradigm of structure-based design of selective allosteric inhibition of Casp6 towards the treatment of neurodegenerative diseases.

Structural And Computational Perspectives of Selectively Targeting Mutant Proteins

Diseases are often caused by mutant proteins. Many drugs have limited effectiveness and/or toxic side effects because of a failure to selectively target the disease-causing mutant variant, rather than the functional wild type protein. Otherwise, the drugs may even target different proteins with similar structural features. Designing drugs that successfully target mutant proteins selectively represents a major challenge. Decades of cancer research have led to an abundance of potential therapeutic targets, often touted to be "master regulators". For many of these proteins, there are no FDA-approved drugs available; for others, off-target effects result in dose-limiting toxicity. Cancer-related proteins are an excellent medium to carry the story of mutant-specific targeting, as the disease is both initiated and sustained by mutant proteins; furthermore, current chemotherapies generally fail at adequate selective distinction. This review discusses some of the challenges associated with selective targeting from a structural biology perspective, as well as some of the developments in algorithm approach and computational workflow that can be applied to address those issues. One of the most widely researched proteins in cancer biology is p53, a tumor suppressor. Here, p53 is discussed as a specific example of a challenging target, with contemporary drugs and methodologies used as examples of burgeoning successes. The oncogene KRAS, which has been described as "undruggable", is another extensively investigated protein in cancer biology. This review also examines KRAS to exemplify progress made towards selective targeting of diseasecausing mutant proteins. Finally, possible future directions relevant to the topic are discussed.

Potential anticancer agent for selective damage to mitochondria or lysosomes: Naphthalimide-modified fluorescent biomarker half-sandwich iridium (III) and ruthenium (II) complexes

In this work, five naphthalimide-modified half-sandwich iridium and ruthenium complexes ([(η⁵-Cp^x)Ir(NˆN)Cl]PF₆, [(η⁶-p-cym)Ru(NˆN)Cl]PF₆) have been presented. The anticancer activities of the complexes against various cancer cell lines were investigated, among them, complexes 2 and 4 showed better anticancer activity than cisplatin, and their anticancer activity is better than complex 5 without fluorophore. In addition, a series of biological tests of complex 2 were performed using flow cytometry, the results indicated that the complex could induce cell death in a variety of ways. By changing of the ligands, the complexes exhibited different photophysical properties, and the mechanism of action of the complexes entering the cell and inducing apoptosis are different. Moreover, complex 2 successfully targeted mitochondria, while complex 4 targeted lysosomes, causing mitochondrial damage and lysosomal damage to induce apoptosis. Excitingly, complex 2 has good antimetastatic ability to cancer cells. Furthermore, complexes 2 and 4 did not have a significant effect on the NADH binding reaction, but they had a moderate binding ability to BSA.

Selective Targeting of CD133-Expressing Glioblastoma Stem Cells Using Lentiviral Vectors

Several lines of evidence suggest a cellular hierarchy in glioblastoma (GBM). In this hierarchy, GBM stem-like cells (GSCs) play critical roles in tumor progression and recurrence, by virtue of their robust tumor-propagating potential and resistance to conventional chemoradiotherapy. Therefore, targeting GSCs holds significant therapeutic promise. Expression of CD133 (PROM1), a cell surface glycoprotein, has been associated with the GSC phenotype and used as a GSC marker. Here, we describe a protocol that allows the selective lentiviral transduction of CD133-expressing GBM cells. This selectivity is conferred by pseudotyping the lentiviral envelope with a single-chain antibody against an extracellular epitope on CD133. We previously demonstrated the efficacy and specificity of this lentiviral vector using patient-derived GBM cultures. This chapter outlines the preparation of the vector and the transduction of human GBM cells.

Characterization of parasite-specific indels and their proposed relevance for selective anthelminthic drug targeting

Insertions and deletions (indels) are important sequence variants that are considered as phylogenetic markers that reflect evolutionary adaptations in different species. In an effort to systematically study indels specific to the phylum Nematoda and their structural impact on the proteins bearing them, we examined over 340,000 polypeptides from 21 nematode species spanning the phylum, compared them to non-nematodes and identified indels unique to nematode proteins in more than 3000 protein families. Examination of the amino acid composition revealed uneven usage of amino acids for insertions and deletions. The amino acid composition and cost, along with the secondary structure constitution of the indels, were analyzed in the context of their biological pathway associations. Species-specific indels could enable indel-based targeting for drug design in pathogens/parasites. Therefore, we screened the spatial locations of the indels in the parasite's protein 3D structures, determined the location of the indel and identified potential unique drug targeting sites. These indels could be confirmed by RNA-Seq data. Examples are presented illustrating the close proximity of some indels to established small-molecule binding pockets that can potentially facilitate selective targeting to the parasites and bypassing their host, thus reducing or eliminating the toxicity of the potential drugs. This study presents an approach for understanding the adaptation of pathogens/parasites at a molecular level, and outlines a strategy to identify such nematode-selective targets that remain essential to the organism. With further experimental characterization and validation, it opens a possible channel for the development of novel treatments with high target specificity, addressing both host toxicity and resistance concerns.

Anti-EGFR antibody conjugated organic-inorganic hybrid lipid nanovesicles selectively target tumor cells

Chemical conjugation of anti-epidermal growth factor receptor monoclonal antibodies (anti-EGFR mAbs) to organic-inorganic hybrid liposomal immunocerasomes via maleimide-thiol coupling chemistry is explored as a mechanism for selectively targeting cancer cells. The cellular uptake and internalization of immunocerasomes are investigated in A431 cells that express an abnormally high level of EGFR, DU145 cells that overexpress EGFR, and HL-60 cells that are used as a negative control. The internalization study reveals a strong correlation between the receptor-mediated endocytosis of immunocerasomes and the membrane expression of EGFR. Further, free anti-EGFR mAbs and immunocerasomes conjugated with anti-EGFR mAbs at nanomolar doses display similar anti-proliferative effects on A431 cells. Additionally, serum proteins greatly reduce the cellular uptake of cerasomes that is mediated by non-specific receptors, but have no adverse effects on the specific EGFR-mediated delivery of immunocerasomes to A431 cells.