Tailoring Polymer-Based Nanoassemblies for Stimuli-Responsive Theranostic Applications

Polymer assemblies on the nanoscale represent a powerful toolbox for the design of theranostic systems when combined with both therapeutic compounds and diagnostic reporting ones. Here, recent advances in the design of theranostic systems for various diseases, containing-in their architecture-either polymers or polymer assemblies as one of the building blocks are presented. This review encompasses the general principles of polymer self-assembly, from the production of adequate copolymers up to supramolecular assemblies with theranostic functionality. Such polymer nanoassemblies can be further tailored through the incorporation of inorganic nanoparticles to endow them with multifunctional therapeutic and/or diagnostic features. Systems that change their architecture or properties in the presence of stimuli are selected, as responsivity to changes in the environment is a key factor for enhancing efficiency. Such theranostic systems are based on the intrinsic properties of copolymers or one of the other components. In addition, systems with a more complex architecture, such as multicompartments, are presented. Selected systems indicate the advantages of such theranostic approaches and provide a basis for further developments in the field.

Tumor targeting, trifunctional dendritic wedge

We report in vitro and in vivo evaluation of a newly designed trifunctional theranostic agent for targeting solid tumors. This agent combines a dendritic wedge with high boron content for boron neutron capture therapy or boron MRI, a monomethine cyanine dye for visible-light fluorescent imaging, and an integrin ligand for efficient tumor targeting. We report photophysical properties of the new agent, its cellular uptake and in vitro targeting properties. Using live animal imaging and intravital microscopy (IVM) techniques, we observed a rapid accumulation of the agent and its retention for a prolonged period of time (up to 7 days) in fully established animal models of human melanoma and murine mammary adenocarcinoma. This macromolecular theranostic agent can be used for targeted delivery of high boron load into solid tumors for future applications in boron neutron capture therapy.

Polymeric theranostics: using polymer-based systems for simultaneous imaging and therapy

Polymer-based nanomedicine is a large and fast growing field. Polymer-based systems have been extensively used as therapeutic carriers as well as bioimaging agents for example in tumour diagnosis. However, fewer polymeric systems have been able to combine both therapy and imaging in a new field that is called theranostics (theragnostics). This review aims to summarise the recent developments and trends on polymeric theranostics. Four different types of therapies/treatments are examined namely drug delivery, gene delivery, photodynamic therapy and hyperthermia treatment combined with different imaging moieties like magnetic resonance imaging agents, fluorescent agents and microbubbles for ultrasound imaging.

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).

Antiangiogenic antitumor activity of HPMA copolymer-paclitaxel-alendronate conjugate on breast cancer bone metastasis mouse model

Polymer therapeutics have shown promise as tumor-targeted drug delivery systems in mice. The multivalency of polymers allows the attachment of different functional agents to a polymeric backbone, including chemotherapeutic and antiangiogenic drugs, as well as targeting moieties, such as the bone-targeting agent alendronate (ALN). We previously reported the conjugation of ALN and the chemotherapeutic drug paclitaxel (PTX) with N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer. The in vitro physicochemical properties, cancer cytotoxicity and antiangiogenic activity of HPMA copolymer-PTX-ALN conjugate were extensively characterized. The reported results warranted in vivo evaluations of the conjugate. In this manuscript, we evaluated the in vivo anticancer and antiangiogenic activity of HPMA copolymer-PTX-ALN conjugate. The conjugate exhibited an antiangiogenic effect by decreasing microvessel density (MVD), and inducing apoptotic circulating endothelial cells (CEC) following treatment of the mice. Using intravital imaging system and mCherry-labeled breast cancer cell lines, we were able to monitor noninvasively the progression of orthotopic metastatic tumors injected into the tibia of the mice. HPMA copolymer-PTX-ALN conjugate showed the greatest antitumor efficacy on mCherry-labeled 4T1 mammary adenocarcinoma inoculated into the tibia, as compared with PTX alone or in combination with ALN. Treatment with the bone-targeted polymeric conjugate demonstrated improved efficacy, was better tolerated, and was more easily administered intravenously than the clinically used PTX formulated in Cremophor/ethanol.