Development of efficient macromolecular prodrugs derived from dendritic polyglycerol

Magnetically-activated, nanostructured cellulose for efficient capture of circulating tumor cells from the blood sample of head and neck cancer patients

In this report, the relative efficiency of cellulose nanocrystals (CNCs) and nanofibers (CNFs) to capture circulating tumor cells (CTCs) from the blood sample of head and neck cancer (HNC) patients was evaluated. Detection and enumeration of CTCs are critical for monitoring cancer progression. Both types of nanostructured cellulose were chemically modified with Epithelial Cell Adhesion Molecule (EpCAM) antibody and iron oxide nanoparticles. The EpCAM antibody facilitated the engagement of CTCs, promoting entrapment within the cellulose cage structure. Iron oxide nanoparticles, on the other hand, rendered the cages activatable via the use of a magnet for the capture and separation of entrapped CTCs. The efficiency of the network structures is shown in head and neck cancer (HNC) patients' blood samples. It was observed that the degree of chemical functionalization of hydroxyl groups located within the CNCs or CNFs with anti-EpCAM determined the efficiency of the system's interaction with CTCs. Further, our result indicated that inflexible scaffolds of nanocrystals interacted more efficiently with CTCs than that of the fibrous CNF scaffolds. Network structures derived from CNCs demonstrated comparable CTC capturing efficiency to commercial standard, OncoDiscover®. The output of the work will provide the chemical design principles of cellulosic materials intended for constructing affordable platforms for monitoring cancer progression in 'real time'.

Cellulose Mediated Transferrin Nanocages for Enumeration of Circulating Tumor Cells for Head and Neck Cancer

Herein we report a hierarchically organized, water-dispersible 'nanocage' composed of cellulose nanocrystals (CNCs), which are magnetically powered by iron oxide (Fe₃O₄) nanoparticles (NPs) to capture circulating tumor cells (CTCs) in blood for head and neck cancer (HNC) patients. Capturing CTCs from peripheral blood is extremely challenging due to their low abundance and its account is clinically validated in progression-free survival of patients with HNC. Engaging multiple hydroxyl groups along the molecular backbone of CNC, we co-ordinated Fe₃O₄ NPs onto CNC scaffold, which was further modified by conjugation with a protein - transferrin (Tf) for targeted capture of CTCs. Owing to the presence of Fe₃O₄ nanoparticles, these nanocages were magnetic in nature, and CTCs could be captured under the influence of a magnetic field. Tf-CNC-based nanocages were evaluated using HNC patients' blood sample and compared for the CTC capturing efficiency with clinically relevant Oncoviu platform. Conclusively, we observed that CNC-derived nanocages efficiently isolated CTCs from patient's blood at 85% of cell capture efficiency to that of the standard platform. Capture efficiency was found to vary with the concentration of Tf and Fe₃O₄ nanoparticles immobilized onto the CNC scaffold. We envision that, Tf-CNC platform has immense connotation in 'liquid biopsy' for isolation and enumeration of CTCs for early detection of metastasis in cancer.

A Facile, One-Pot, Surfactant-Free Nanoprecipitation Method for the Preparation of Nanogels from Polyglycerol⁻Drug Conjugates that Can Be Freely Assembled for Combination Therapy Applications

A well-established strategy to treat drug resistance is the use of multiple therapeutics. Polymer-based drug delivery systems (DDS) can facilitate a simultaneous delivery of two or more drugs. In this study, we developed and synthesized a dendritic polyglycerol (PG) nanogel (NG) system that allows for free combination of different fixed ratios of active compound conjugates within a single NG particle. As a proof of concept, we synthesized NGs bearing the chemotherapeutic agent doxorubicin (DOX) and paclitaxel (PTX) in different ratios, as well as conjugated dye molecules. Our combination PG NGs were formed by simply mixing PG–drug/dye conjugates bearing free thiol groups with PG-acrylate in an inverse surfactant-free nanoprecipitation method. With this method we obtained PG-NGs in the size range of 110–165 nm with low polydispersity indices. Solubility of hydrophobic PTX was improved without the need for additional solubilizing agents such as polyethylene glycol (PEG). Interestingly, we found that our NGs made from PG-DOX conjugates have a high quenching efficiency for DOX, which could be interesting for theranostic purposes.

Degradable, Dendritic Polyols on a Branched Polyphosphazene Backbone

Herein, we present the design, synthesis, and characterization of fully degradable, hybrid, star-branched dendritic polyols. First multiarmed polyphosphazenes were prepared as a star-branched scaffold which upon functionalization produced globular branched hydroxyl-functionalized polymers with over 1700 peripheral functional end groups. These polyols with unique branched architectures could be prepared with controlled molecular weights and relatively narrow dispersities. Furthermore, the polymers are shown to undergo hydrolytic degradation to low molecular weight degradation products, the rate of which could be controlled through postpolymerization functionalization of the phosphazene backbone.

PEGylated dendritic polyglycerol conjugate targeting NCAM-expressing neuroblastoma: Limitations and challenges

Neural cell adhesion molecule (NCAM) is found to be a stem-cell marker in several tumor types and its overexpression is known to correlate with increased metastatic capacity. To combine extravasation- and ligand-dependent targeting to NCAM overexpressing-cells in the tumor microenvironment, we developed a PEGylated NCAM-targeted dendritic polyglycerol (PG) conjugate. Here, we describe the synthesis, physico-chemical characterization and biological evaluation of a PG conjugate bearing the mitotic inhibitor paclitaxel (PTX) and an NCAM-targeting peptide (NTP). PG-NTP-PTX-PEG was evaluated for its ability to inhibit neuroblastoma progression in vitro and in vivo as compared to non-targeted derivatives and free drug. NCAM-targeted conjugate inhibited the migration of proliferating endothelial cells, suggesting it would be able to inhibit tumor angiogenesis. The targeting conjugate provided an improved binding and uptake on IMR-32 cells compared to non-targeted control. However, these results did not translate to our in vivo model on orthotopic neuroblastoma bearing mice.

Dendritic polyglycerol nanoparticles show charge dependent bio-distribution in early human placental explants and reduce hCG secretion

A thorough understanding of nanoparticle bio-distribution at the feto-maternal interface will be a prerequisite for their diagnostic or therapeutic application in women of childbearing age and for teratologic risk assessment. Therefore, the tissue interaction of biocompatible dendritic polyglycerol nanoparticles (dPG-NPs) with first- trimester human placental explants were analyzed and compared to less sophisticated trophoblast-cell based models. First-trimester human placental explants, BeWo cells and primary trophoblast cells from human term placenta were exposed to fluorescence labeled, ∼5 nm dPG-NPs, with differently charged surfaces, at concentrations of 1 µM and 10 nM, for 6 and 24 h. Accumulation of dPGs was visualized by fluorescence microscopy. To assess the impact of dPG-NP on trophoblast integrity and endocrine function, LDH, and hCG releases were measured. A dose- and charge-dependent accumulation of dPG-NPs was observed at the early placental barrier and in cell lines, with positive dPG-NP-surface causing deposits even in the mesenchymal core of the placental villi. No signs of plasma membrane damage could be detected. After 24 h we observed a significant reduction of hCG secretion in placental explants, without significant changes in trophoblast apoptosis, at low concentrations of charged dPG-NPs. In conclusion, dPG-NP’s surface charge substantially influences their bio-distribution at the feto-maternal interface, with positive charge facilitating trans-trophoblast passage, and in contrast to more artificial models, the first-trimester placental explant culture model reveals potentially hazardous influences of charged dPG-NPs on early placental physiology.

Acid-sensitive lipidated doxorubicin prodrug entrapped in nanoemulsion impairs lung tumor metastasis in a breast cancer model

Aim: To develop an acid-sensitive lipidated, doxorubicin (Dox) prodrug (C16-Dox) to be entrapped in lipid nanoemulsion (NE-C16-Dox) as a nanocarrier to treat breast cancer models (in vitro and in vivo). Results: We report the efficacy of NE-C16-Dox in in vitro experiments, as well as the improved chemotherapeutic index and tumor-control efficacy compared with treatment with free Dox in an in vivo murine 4T1 breast cancer model. In addition, NE-C16-Dox allowed the use of a higher dose of Dox, acceptable biocompatibility and a significant reduction in lung metastasis. Conclusion: Taken together, these results indicate that NE-C16-Dox is promising for breast cancer treatment, thus creating possibilities to translate these nanotechnology concepts to clinical applications.

Tolerogenic modulation of the immune response by oligoglycerol- and polyglycerol-peptide conjugates

Peptide-based therapy is a promising strategy for antigen-specific immunosuppression to treat or even heal autoimmune diseases with significantly reduced adverse effects compared to conventional therapies. However, there has been no major success due to the drawbacks of native peptides, i.e., limited bioavailability. Considering the importance and limitations of peptide-based therapies for treatment of autoimmune diseases, we designed and constructed oligoglycerol (OG)- and polyglycerol (PG)-based peptide conjugates. They were evaluated for their biological activity (in vitro and in vivo), bioavailability, and tolerogenic potential. Among the OG- and PG-peptide constructs, PG-peptide constructs exhibited an extended bioavailability compared to OG-peptide constructs and unconjugated peptide. Interestingly, size, structure, and linker chemistry played a critical role for the tolerogenic capacity of the constructs. The PG-peptide construct bound via an ester linkage was the most tolerogenic conjugate, while the PG-peptide construct bound via an amide induced stronger proliferation, but also higher TNF production and lower frequencies of Foxp3(+) regulatory T-cells. Therefore, we conclude that PG-peptide conjugates bound via an ester linkage are not only promising candidates for tolerogenic vaccination, but also open a new avenue toward the application of peptides for the treatment of autoimmune diseases.

Controlling the actuation of therapeutic nanomaterials: enabling nanoparticle-mediated drug delivery

The implementation of biofunctionalized nanoparticles (NPs) as potential therapeutic materials has seen exponential growth in recent years due to their unique ability to overcome the constraints of current medicine. This has been largely driven by significant advances on a number of basic research fronts including high-quality NP synthesis, bioconjugation, cellular delivery and the controlled release or ‘actuation’ of NP-associated cargos. Cumulatively, these are the key enabling tools for the full realization of NP-mediated drug delivery. In this review, the authors’ focus is on recent developments in methodologies for the controlled actuation of therapeutic NPs. The authors discuss the critical requirements for their integration into biological systems and highlight examples from the recent literature where controlled NP actuation has been successfully demonstrated. The current state of therapeutic NPs in the clinical setting is summarized and the article concludes with a brief perspective of how we can expect to see this emerging field develop in the coming years.

Stimuli-responsive polymeric nanocarriers for the controlled transport of active compounds: concepts and applications

The use of polymeric nanocarriers to transport active compounds like small-molecular drugs, peptides, or genes found an increased attention throughout the different fields of natural sciences. Not only that these nanocarriers enhance the properties of already existing drugs in terms of solubility, bioavailability, and prolonged circulation times, furthermore they can be tailor-made in such a manner that they selectively release their cargo at the desired site of action. For the triggered release, these so-called smart drug delivery systems are designed to react on certain stimuli like pH, temperature, redox potential, enzymes, light, and ultrasound. Some of these stimuli are naturally occurring in vivo, for example the difference in pH in different cellular compartments while others are caused by the disease, which is to be treated, like differences in pH and temperature in some tumor tissues. Other external applied stimuli, like light and ultrasound, allow the temporal and spatial control of the release, since they are not triggered by any biological event. This review gives a brief overview about some types of stimuli-responsive nanocarriers with the main focus on organic polymer-based systems. Furthermore, the different stimuli and the design of corresponding responsive nanocarriers will be discussed with the help of selected examples from the literature.

Multifunctional dendritic polymers in nanomedicine: opportunities and challenges

Nanotechnology has resulted in materials that have greatly improved the effectiveness of drug delivery because of their ability to control matter on the nanoscale. Advanced forms of nanomedicine have been synthesized for better pharmacokinetics to obtain higher efficacy, less systemic toxicity, and better targeting. These criteria have long been the goal in nanomedicine, in particular, for systemic applications in oncological disorders. Now, the "holy grail" in nanomedicine is to design and synthesize new advanced macromolecular nanocarriers and to translate them from lab to clinic. This review describes the current and future perspectives of nanomedicine with particular emphasis on the clinical targets in cancer and inflammation. The advanced forms of liposomes and polyethylene glycol (PEG) based nanocarriers, as well as dendritic polymer conjugates will be discussed with particular attention paid to designs, synthetic strategies, and chemical pathways. In this critical review, we also report on the current status and perspective of dendritic polymer nanoconjugate platforms (e.g. polyamidoamine dendrimers and dendritic polyglycerols) for cellular localization and targeting of specific tissues (192 references).