Thermoresponsive Collagen/Cell Penetrating Hybrid Peptide as Nanocarrier in Targeting-Free Cell Selection and Uptake

Hybrid peptides as platform for synchronized combination therapy

Combination therapy, where two or more therapeutic agents are combined to target different cellular pathways, is an effective tool in cancer treatment but often difficult to execute. Here we present the collagen peptide-based platform that allows for synchronous and colocalized cellular delivery of three different agents. The peptide is a hybrid between collagen and cell penetrating peptide (CPP) that assembles into a heterotrimer helix and forms fully organic, high aspect ratio nanoparticles. The validity of the approach was tested with three chemically different agents (Paclitaxel, Doxorubicin, and 5-Fluorouracil; a combination used in clinical treatment of (ER)-positive and (PR)-positive breast cancer) conjugated to N-terminus of the peptide. The design of this peptide-based drug delivery system provides several advantages: it avoids drug loading problems; removes the need for orthogonal synthesis; and allows for colocalized delivery of up to three drugs (which leads to the same biodistribution for each drug). In addition, hybrid collagen/CPP peptides are known to enhance cellular uptake and improve solubility of drugs. The synergistic effect, in terms of enhanced efficacy, of the Paclitaxel-Doxorubicin-5-Fluorouracil combination was also calculated. We envision self-assembling peptides as a platform for drug codelivery that can be expanded into a library of personalized combinations that may also include other functionalities like targeting or imaging.

Higher Order Architecture of Designer Peptides Forms Bioinspired 10 nm siRNA Delivery System

The higher-order architecture observed in biological systems, like viruses, is very effective in nucleic acid transport. The replications of this system has been attempted with both synthetic and naturally occurring polymers with mixed results. Here we describe a peptide/siRNA quaternary complex that functions as an siRNA delivery system. The rational design of a peptide assembly is inspired by the viral capsids, but not derived from them. We selected the collagen peptide (COL) to provide the structural stability and the folding framework, and hybridize it with the cell penetrating peptide (CPP) that allows for effective penetration of biological barriers. The peptide/siRNA quaternary complex forms stoichiometric, 10 nm nanoparticles, that show fast cellular uptake (<30 min), effective siRNA release, and gene silencing. The complex provides capsid-like protection for siRNA against nucleases without being immunostimulatory, or cytotoxic. Our data suggests that delivery vehicles based on synthetic quaternary structures that exhibit higher-order architecture may be effective in improving delivery and release of nucleic acid cargo.

Dendritic Polyglycerol-Derived Nano-Architectures as Delivery Platforms of Gemcitabine for Pancreatic Cancer

Dendritic polyglycerol-co-polycaprolactone (PG-co-PCL)-derived block copolymers are synthesized and explored as nanoscale drug delivery platforms for a chemotherapeutic agent, gemcitabine (GEM), which is the cornerstone of therapy for pancreatic ductal adenocarcinoma (PDAC). Current treatment strategies with GEM result in suboptimal therapeutic outcome owing to microenvironmental resistance and rapid metabolic degradation of GEM. To address these challenges, physicochemical and cell-biological properties of both covalently conjugated and non-covalently stabilized variants of GEM-containing PG-co-PCL architectures have been evaluated. Self-assembly behavior, drug loading and release capacity, cytotoxicity, and cellular uptake properties of these constructs in monolayer and in spheroid cultures of PDAC cells are investigated. To realize the covalently conjugated carrier systems, GEM, in conjunction with a tertiary amine, is attached to the polycarbonate block grafted from the PG-co-PCL core. It is observed that pH-dependent ionization properties of these amine side-chains direct the formation of self-assembly of block copolymers in the form of nanoparticles. For non-covalent encapsulation, a facile "solvent-shifting" technique is adopted. Fabrication techniques are found to control colloidal and cellular properties of GEM-loaded nanoconstructs. The feasibility and potential of these newly developed architectures for designing carrier systems for GEM to achieve augmented prognosis for pancreatic cancer are reported.

Conjugation of Paclitaxel to Hybrid Peptide Carrier and Biological Evaluation in Jurkat and A549 Cancer Cell Lines

Paclitaxel (PTX) is one of the most potent cancer drugs; however, its low solubility and strong systemic side effects limit its clinical applications. To overcome these issues, new drug formulations and chemical modifications have been proposed. In this study, we present conjugation of PTX to hybrid collagen-cell penetrating peptide (COL-CPP) carriers. The peptide carrier is highly soluble and utilizes a unique stabilization strategy: folding into a triple helix. Here, we report the formation of PTX-COL-CPP prodrug that has similar drug potency as free PTX when tested in Jurkat (human T lymphocyte of acute T cell leukemia) cells but not in A549 (human epithelial of lung carcinoma) cells. Confocal images and flow cytometry show that this behavior originates from lower cellular uptake of COL-CPP and endosomal entrapment of the prodrug in A549, but not in Jurkat cells.