Efficient Intracellular Delivery of a Pro-Apoptotic Peptide With A pH-Responsive Carrier

Cell-Based Drug Delivery Systems with Innate Homing Capability as a Novel Nanocarrier Platform

Nanoparticle-based drug delivery systems have been designed to treat various diseases. However, many problems remain, such as inadequate tumor targeting and poor therapeutic outcomes. To overcome these obstacles, cell-based drug delivery systems have been developed. Candidates for cell-mediated drug delivery include blood cells, immune cells, and stem cells with innate tumor tropism and low immunogenicity; they act as a disguise to deliver the therapeutic payload. In drug delivery systems, therapeutic agents are encapsulated intracellularly or attached to the surface of the plasma membrane and transported to the desired site. Here, we review the pros and cons of cell-based therapies and discuss their homing mechanisms in the tumor microenvironment. In addition, different strategies to load therapeutic agents inside or on the surface of circulating cells and the current applications for a wide range of disease treatments are summarized.

Biosimilars accessible in the market for the treatment of cancer

Biosimilars are the biological product clinically identical to a biologic reference standard regarding their strength, purity, and safety. A large segment of biosimilars has been developed for the treatment of cancer. This review aims to discuss various facets of biosimilars and explicates on biosimilars accessible in the market for cancer clinical intervention. It also illustrates the outcomes of recent clinical trial studies concerning biosimilars. Further, it also crosstalk the safety profiles, regulatory approval requirements, and allied challenges therein. The work will be of significant interest to researchers working in the field of biologics and biosimilars.

pH-Responsive Amphiphilic Carboxylate Polymers: Design and Potential for Endosomal Escape

The intracellular delivery of emerging biomacromolecular therapeutics, such as genes, peptides, and proteins, remains a great challenge. Unlike small hydrophobic drugs, these biotherapeutics are impermeable to the cell membrane, thus relying on the endocytic pathways for cell entry. After endocytosis, they are entrapped in the endosomes and finally degraded in lysosomes. To overcome these barriers, many carriers have been developed to facilitate the endosomal escape of these biomacromolecules. This mini-review focuses on the development of anionic pH-responsive amphiphilic carboxylate polymers for endosomal escape applications, including the design and synthesis of these polymers, the mechanistic insights of their endosomal escape capability, the challenges in the field, and future opportunities.

The principles and applications of avidin-based nanoparticles in drug delivery and diagnosis

Avidin-biotin interaction is one of the strongest non-covalent interactions in the nature. Avidin and its analogues have therefore been extensively utilized as probes and affinity matrices for a wide variety of applications in biochemical assays, diagnosis, affinity purification, and drug delivery. Recently, there has been a growing interest in exploring this non-covalent interaction in nanoscale drug delivery systems for pharmaceutical agents, including small molecules, proteins, vaccines, monoclonal antibodies, and nucleic acids. Particularly, the ease of fabrication without losing the chemical and biological properties of the coupled moieties makes the avidin-biotin system a versatile platform for nanotechnology. In addition, avidin-based nanoparticles have been investigated as diagnostic systems for various tumors and surface antigens. In this review, we will highlight the various fabrication principles and biomedical applications of avidin-based nanoparticles in drug delivery and diagnosis. The structures and biochemical properties of avidin, biotin and their respective analogues will also be discussed.

Endosomolytic Nano-Polyplex Platform Technology for Cytosolic Peptide Delivery To Inhibit Pathological Vasoconstriction

A platform technology has been developed and tested for delivery of intracellular-acting peptides through electrostatically complexed nanoparticles, or nano-polyplexes, formulated from an anionic endosomolytic polymer and cationic therapeutic peptides. This delivery platform has been initially tested and optimized for delivery of two unique vasoactive peptides, a phosphomimetic of heat shock protein 20 and an inhibitor of MAPKAP kinase II, to prevent pathological vasoconstriction (i.e., vasospasm) in human vascular tissue. These peptides inhibit vasoconstriction and promote vasorelaxation by modulating actin dynamics in vascular smooth muscle cells. Formulating these peptides into nano-polyplexes significantly enhances peptide uptake and retention, facilitates cytosolic delivery through a pH-dependent endosomal escape mechanism, and enhances peptide bioactivity in vitro as measured by inhibition of F-actin stress fiber formation. In comparison to treatment with the free peptides, which were endowed with cell-penetrating sequences, the nano-polyplexes significantly increased vasorelaxation, inhibited vasoconstriction, and decreased F-actin formation in the human saphenous vein ex vivo. These results suggest that these formulations have significant potential for treatment of conditions such as cerebral vasospasm following subarachnoid hemorrhage. Furthermore, because many therapeutic peptides include cationic cell-penetrating segments, this simple and modular platform technology may have broad applicability as a cost-effective approach for enhancing the efficacy of cytosolically active peptides.

Overcoming the challenges in administering biopharmaceuticals: formulation and delivery strategies

The formulation and delivery of biopharmaceutical drugs, such as monoclonal antibodies and recombinant proteins, poses substantial challenges owing to their large size and susceptibility to degradation. In this Review we highlight recent advances in formulation and delivery strategies--such as the use of microsphere-based controlled-release technologies, protein modification methods that make use of polyethylene glycol and other polymers, and genetic manipulation of biopharmaceutical drugs--and discuss their advantages and limitations. We also highlight current and emerging delivery routes that provide an alternative to injection, including transdermal, oral and pulmonary delivery routes. In addition, the potential of targeted and intracellular protein delivery is discussed.

Controlled apoptosis by a thermally toggled nanoscale amplifier of cellular uptake

Internalization into cancer cells is a significant challenge in the delivery of many anticancer therapeutics. Drug carriers can address this challenge by facilitating cellular uptake of cytotoxic cargo in the tumor, while preventing cellular uptake in healthy tissues. Here we describe an extrinsically controlled drug carrier, a nanopeptifier, that amplifies cellular uptake by modulating the activity of cell-penetrating peptides with thermally toggled self-assembly of a genetically encoded polypeptide nanoparticle. When appended with a proapoptotic peptide, the nanopeptifier creates a cytotoxic switch, inducing apoptosis only in its self-assembled state. The nanopeptifier provides a new approach to tune the cellular uptake and activity of anticancer therapeutics by an extrinsic thermal trigger.

Biodegradable In Situ Gel-Forming Controlled Drug Delivery System Based on Thermosensitive Poly(ε-caprolactone)-Poly(ethylene glycol)-Poly(ε-caprolactone) Hydrogel

Traditional drug delivery systems which are based on multiple dosing regimens usually pose many disadvantages such as poor compliance of patients and drug plasma level variation. To overcome the obstacles of traditional drug formulations, novel drug delivery system PCL-PEG-PCL hydrogels have been purposed in this study. Copolymers were synthesized by rapid microwave-assisted and conventional synthesis methods. Polymer characterizations were done using gel permeation chromatography and (1)H-NMR. Phase transition behavior was evaluated by inverting tube method and in vitro drug release profile was determined using naltrexone hydrochloride and vitamin B(12) as drug models. The results indicated that loaded drug structure and copolymer concentration play critical roles in release profile of drugs from these hydrogels. This study also confirmed that synthesis of copolymer using microwave is the most effective method for synthesis of this kind of copolymer.

Delivery and biodistribution of siRNA for cancer therapy: challenges and future prospects

RNAi-based approaches provide a promising therapeutic modality for the treatment of cancer. The inaccessibility of tumors in different cancer types necessitates the development of safe, specific and efficient systemic delivery systems to meet therapeutic need. The translation of siRNA-based cancer therapeutics to the clinic is hindered by several challenges associated with the cargo (siRNA) and the delivery system, including susceptibility to nucleases; insufficient circulation half-life due to phagocytosis by the reticuloendothelial system, transient and poor biodistribution in the tumor tissue; cellular uptake; inability to escape endosomes and release into the cytosolic compartment for an RNAi-mediated effect; microRNA-like unintended off-target effects; undesirable immune stimulation; and carrier-related toxicity. This review provides an overview of the pharmacokinetic and biodistribution challenges witnessed in the delivery of siRNA when administered systemically. It also describes the current delivery approaches using liposome-, polymer- and peptide-based delivery systems shown to elicit significant gene silencing and tumor growth regression in proof-of-concept studies. As part of future perspectives, delivery agents that showed significant efficacy in preclinical rodent models and clinical trials are also reviewed.