Modifying plasmid-loaded HSA-nanoparticles with cell penetrating peptides - Cellular uptake and enhanced gene delivery

Improved Reversion of Calcifications in Porcine Aortic Heart Valves Using Elastin-Targeted Nanoparticles

Calcified aortic valve disease in its final stage leads to aortic valve stenosis, limiting cardiac function. To date, surgical intervention is the only option for treating calcific aortic valve stenosis. This study combined controlled drug delivery by nanoparticles (NPs) and active targeting by antibody conjugation. The chelating agent diethylenetriaminepentaacetic acid (DTPA) was covalently bound to human serum albumin (HSA)-based NP, and the NP surface was modified using conjugating antibodies (anti-elastin or isotype IgG control). Calcification was induced ex vivo in porcine aortic valves by preincubation in an osteogenic medium containing 2.5 mM sodium phosphate for five days. Valve calcifications mainly consisted of basic calcium phosphate crystals. Calcifications were effectively resolved by adding 1-5 mg DTPA/mL medium. Incubation with pure DTPA, however, was associated with a loss of cellular viability. Reversal of calcifications was also achieved with DTPA-coupled anti-elastin-targeted NPs containing 1 mg DTPA equivalent. The addition of these NPs to the conditioned media resulted in significant regression of the valve calcifications compared to that in the IgG-NP control without affecting cellular viability. These results represent a step further toward the development of targeted nanoparticular formulations to dissolve aortic valve calcifications.

Biological Membrane-Penetrating Peptides: Computational Prediction and Applications

Peptides comprise a versatile class of biomolecules that present a unique chemical space with diverse physicochemical and structural properties. Some classes of peptides are able to naturally cross the biological membranes, such as cell membrane and blood-brain barrier (BBB). Cell-penetrating peptides (CPPs) and blood-brain barrier-penetrating peptides (B3PPs) have been explored by the biotechnological and pharmaceutical industries to develop new therapeutic molecules and carrier systems. The computational prediction of peptides’ penetration into biological membranes has been emerged as an interesting strategy due to their high throughput and low-cost screening of large chemical libraries. Structure- and sequence-based information of peptides, as well as atomistic biophysical models, have been explored in computer-assisted discovery strategies to classify and identify new structures with pharmacokinetic properties related to the translocation through biomembranes. Computational strategies to predict the permeability into biomembranes include cheminformatic filters, molecular dynamics simulations, artificial intelligence algorithms, and statistical models, and the choice of the most adequate method depends on the purposes of the computational investigation. Here, we exhibit and discuss some principles and applications of these computational methods widely used to predict the permeability of peptides into biomembranes, exhibiting some of their pharmaceutical and biotechnological applications.

Self-assembly of an aptamer-decorated chimeric peptide nanocarrier for targeted cancer gene delivery

In this study, we developed a peptide-based non-viral carrier decorated with aptamer to overcome the specific gene delivery barriers. The carrier (KLN/Apt) was designed to contain multiple functional segments, including 1) two tandem repeating units of low molecular weight protamine (LMWP) to condense DNA into stable nanosize particles and protect it from enzymatic digestion, 2) AS1411 aptamer as targeting moiety to target nucleolin and promote carrier internalization, 3) a synthetic pH-sensitive fusogenic peptide (KALA) for disrupting endosomal membranes and enhancing cytosol escape of the nanoparticles, and 4) a nuclear localization signal (NLS) for active cytoplasmic trafficking and nuclear delivery of DNA. The obtained results revealed the developed carrier capacity in terms of specific cell targeting, overcoming cellular gene delivery barriers, and mediating efficient gene transfection. The KLN/pDNA/aptamer nanoparticles offer remarkable potential for the conceptual design and formation of promising multi-functionalized carriers towards the most demanding therapeutic applications.

Albumin-Coated Single-Core Iron Oxide Nanoparticles for Enhanced Molecular Magnetic Imaging (MRI/MPI)

Colloidal stability of magnetic iron oxide nanoparticles (MNP) in physiological environments is crucial for their (bio)medical application. MNP are potential contrast agents for different imaging modalities such as magnetic resonance imaging (MRI) and magnetic particle imaging (MPI). Applied as a hybrid method (MRI/MPI), these are valuable tools for molecular imaging. Continuously synthesized and in-situ stabilized single-core MNP were further modified by albumin coating. Synthesizing and coating of MNP were carried out in aqueous media without using any organic solvent in a simple procedure. The additional steric stabilization with the biocompatible protein, namely bovine serum albumin (BSA), led to potential contrast agents suitable for multimodal (MRI/MPI) imaging. The colloidal stability of BSA-coated MNP was investigated in different sodium chloride concentrations (50 to 150 mM) in short- and long-term incubation (from two hours to one week) using physiochemical characterization techniques such as transmission electron microscopy (TEM) for core size and differential centrifugal sedimentation (DCS) for hydrodynamic size. Magnetic characterization such as magnetic particle spectroscopy (MPS) and nuclear magnetic resonance (NMR) measurements confirmed the successful surface modification as well as exceptional colloidal stability of the relatively large single-core MNP. For comparison, two commercially available MNP systems were investigated, MNP-clusters, the former liver contrast agent (Resovist), and single-core MNP (SHP-30) manufactured by thermal decomposition. The tailored core size, colloidal stability in a physiological environment, and magnetic performance of our MNP indicate their ability to be used as molecular magnetic contrast agents for MPI and MRI.

Protein-Based Nanoparticles as Drug Delivery Systems

Nanoparticles have been extensively used as carriers for the delivery of chemicals and biomolecular drugs, such as anticancer drugs and therapeutic proteins. Natural biomolecules, such as proteins, are an attractive alternative to synthetic polymers commonly used in nanoparticle formulation because of their safety. In general, protein nanoparticles offer many advantages, such as biocompatibility and biodegradability. Moreover, the preparation of protein nanoparticles and the corresponding encapsulation process involved mild conditions without the use of toxic chemicals or organic solvents. Protein nanoparticles can be generated using proteins, such as fibroins, albumin, gelatin, gliadine, legumin, 30Kc19, lipoprotein, and ferritin proteins, and are prepared through emulsion, electrospray, and desolvation methods. This review introduces the proteins used and methods used in generating protein nanoparticles and compares the corresponding advantages and disadvantages of each.

Reversion of arterial calcification by elastin-targeted DTPA-HSA nanoparticles

Generalized arterial calcification of infancy (GACI) and pseudoxanthoma elasticum (PXE) are characterized by pathologic calcifications in the media of large- and medium sized arteries. GACI is associated with biallelic mutations in ENPP1 in the majority of cases, whereas mutations in ABCC6 are known to cause PXE. Different treatment approaches including bisphosphonates and orally administered pyrophosphate (PP_i) were investigated in recent years, but reversion of calcification could not be achieved. With this study, we pursued the idea of a combination of controlled drug delivery through nanoparticles and active targeting via antibody conjugation to develop a treatment for GACI and PXE. To establish a suitable drug delivery system, the chelating drug diethylenetriamine pentaacetic acid (DTPA) was conjugated to nanoparticles composed of human serum albumin (HSA) as biodegradable and non-toxic particle matrix. To accomplish an active targeting of the elastic fibers exposed through calcification of the affected areas, the nanoparticle surface was functionalized with an anti-elastin antibody. Cytotoxicity and cell interaction studies revealed favorable preconditions for the intended i.v. application. The chelating ability was evaluated in vitro and ex vivo on aortic ring culture isolated from two mouse models of GACI and PXE. The positive results led to the conclusion that the produced nanoparticles might be a promising therapy in the treatment of GACI and PXE.

Delivery of miRNA-29b Using R9-LK15, a Novel Cell-Penetrating Peptide, Promotes Osteogenic Differentiation of Bone Mesenchymal Stem Cells

Delivery of osteogenesis-promoting microRNAs (miRNAs) is a promising approach to enhance bone regeneration. In this study, we generated nanocomplexes comprising the novel cell-penetrating peptide R9-LK15 and miR-29b and investigated their effects on osteogenic differentiation of bone mesenchymal stem cells (BMSCs). R9-LK15/miR-29b nanocomplexes were prepared and characterized. The transfection efficiency, cell viability, and osteogenic differentiation were investigated. The results showed that R9-LK15 maintained the stability of miR-29b in serum for up to 24 h. Moreover, R9-LK15 efficiently delivered miR-29b into BMSCs; the transfection efficiency was ~10-fold higher than that achieved using Lipofectamine 2000. The Cell Counting Kit-8 assay showed that R9-LK15 and R9-LK15/miR-29b nanocomplexes had negligible cytotoxic effects on BMSCs. Delivery of R9-LK15/miR-29b nanocomplexes promoted osteogenic differentiation of BMSCs and extracellular matrix mineralization by upregulating alkaline phosphatase expression and downregulating histone deacetylase-4 expression. In general, we developed a novel miRNA delivery system that has a high transfection efficiency and promotes osteogenic differentiation.

Smart Cell-Penetrating Peptide-Based Techniques for Intracellular Delivery of Therapeutic Macromolecules

Many therapeutic macromolecules must enter cells to take their action. However, their treatment outcomes are often hampered by their poor transportation into target cells. Therefore, efficient intracellular delivery of these macromolecules is critical for improving their therapeutic efficacy. Cell-penetrating peptide (CPP)-based approaches are one of the most efficient methods for intracellular delivery of macromolecular therapeutics. Nevertheless, poor specificity is a significant concern for systemic administrated CPP-based delivery systems. This chapter will review recent advances in CPP-mediated macromolecule delivery with a focus on various smart strategies which not only enhance the intracellular delivery but also improve the targeting specificity.

Stimuli-responsive nanocarriers for intracellular delivery

The emergence of different nanoparticles (NPs) has made a significant revolution in the field of medicine. Different NPs in the form of metallic NPs, dendrimers, polymeric NPs, carbon quantum dots and liposomes have been functionalized and used as platforms for intracellular delivery of biomolecules, drugs, imaging agents and nucleic acids. These NPs are designed to improve the pharmacokinetic properties of the drug, improve their bioavailability and successfully surpass physiological or pathological obstacles in the biological system so that therapeutic efficacy is achieved. In this review I present some of the current approaches used in intracellular delivery systems, with a focus on various stimuli-responsive nanocarriers, including cell-penetrating peptides, to highlight their various biomedical applications.