Several studies propose nanoparticles for tumor treatment, yet little is known about the fate of nanoparticles and intimate interactions with the heterogeneous and ever-evolving tumor environment. The latter, rich in extracellular matrix, is responsible for poor penetration of therapeutics and represents a paramount issue in cancer therapy. Hence new strategies start aiming to modulate the neoplastic stroma. From this perspective, we assessed the efficacy of 19 nm PEG-coated iron oxide nanocubes with optimized magnetic properties to mediate mild tumor magnetic hyperthermia treatment. After injection of a low dose of nanocubes (700 μg of iron) into epidermoid carcinoma xenografts in mice, we monitored the effect of heating nanocubes on tumor environment. In comparison with the long-term fate after intravenous administration, we investigated spatiotemporal patterns of nanocube distribution, evaluated the evolution of cubes magnetic properties, and examined nanoparticle clearance and degradation processes. While inside tumors nanocubes retained their magnetic properties and heating capacity throughout the treatment due to a mainly interstitial extracellular location, the particles became inefficient heaters after cell internalization and transfer to spleen and liver. Our multiscale analysis reveals that collagen-rich tumor extracellular matrix confines the majority of nanocubes. However, nanocube-mediated hyperthermia has the potential to "destructure" this matrix and improve nanoparticle and drug penetration into neoplastic tissue. This study provides insight into dynamic interactions between nanoparticles and tumor components under physical stimulation and suggests that nanoparticle-mediated hyperthermia could be used to locally modify tumor stroma and thus improve drug penetration.

Most nanoparticles for biomedical applications originate from the self-assembling of individual constituents through molecular interactions and possess limited geometry control and stability. Here, 1000 × 400 nm discoidal polymeric nanoconstructs (DPNs) are demonstrated by mixing hydrophobic and hydrophilic polymers with lipid chains and curing the resulting paste directly within silicon templates. By changing the paste composition, soft- and rigid-DPNs (s- and r-DPNs) are synthesized exhibiting the same geometry, a moderately negative surface electrostatic charge (-14 mV), and different mechanical stiffness (∼1.3 and 15 kPa, respectively). Upon injection in mice bearing nonorthotopic brain or skin cancers, s-DPNs exhibit ∼24 h circulation half-life and accumulate up to ∼20% of the injected dose per gram tumor, detecting malignant masses as small as ∼0.1% the animal weight via PET imaging. This unprecedented behavior is ascribed to the unique combination of geometry, surface properties, and mechanical stiffness which minimizes s-DPN sequestration by the mononuclear phagocyte system. Our results could boost the interest in using less conventional delivery systems for cancer theranosis.

We report upon a theoretical study of singlet exciton migration and relaxation within a model conjugated polymer chain. Starting from poly[2-methoxy-5-((2-ethylhexyl)oxy)-1,4-phenylenevinylene] polymer chains, we assume that the pi-conjugation is disrupted by conformational disorder of the chain itself, giving rise to a localized Frenkel exciton basis. Electronic coupling between segments as determined by the coupling between the transition densities of the localized excitons gives rise to delocalized exciton states. Using a kinetic Monte Carlo approach to compute the exciton transfer kinetics within the manifold of either the dressed chromophore site basis or dressed eigenstate basis, we find that the decay of the polarization anisotropy of the exciton is profoundly affected by the delocalization of the exciton over multiple basis segments. Two time scales emerge from the exciton migration simulations: a short, roughly 10 ps, time scale corresponding to rapid hopping about the initial excitation site followed by a slower, 180 ps, component corresponding to long range hopping. We also find that excitations can become trapped at long times when the hopping rate to lower-energy states is longer than the radiative lifetime of the exciton.

Atherosclerosis is an inflammatory disorder characterized by the progressive thickening of blood vessel walls eventually resulting in acute vascular syndromes. Here, intravenously injectable hybrid nanoconstructs are synthesized for tempering immune cell inflammation locally and systemically. Lipid and polymer chains are nanoprecipitated to form 100 nm spherical polymeric nanoconstructs (SPNs), loaded with methotrexate (MTX) and subsequently labeled with Cu and fluorescent probes for combined nuclear/optical imaging. Upon engulfment into macrophages, MTX SPNs intracellularly release their anti-inflammatory cargo significantly lowering the production of proinflammatory cytokine (interleukin 6 and tumor necrosis factor α) already at 0.06 mg mL of MTX. In ApoE mice, fed with high-fat diet up to 17 weeks, nuclear and optical imaging demonstrates specific accumulation of SPNs within lipid-rich plaques along the arterial tree. Histological analyses confirm SPN uptake into macrophages residing within atherosclerotic plaques. A 4-week treatment with biweekly administration of MTX SPNs is sufficient to reduce the plaque burden in ApoE mice by 50%, kept on high-fat diet for 10 weeks. Systemic delivery of MTX to macrophages via multifunctional, hybrid nanoconstructs constitutes an effective strategy to inhibit atherosclerosis progression and induce, potentially, the resorption of vascular lesions.

BackgroundRecent reports indicate that a subgroup of tumor cells named cancer stem cells (CSCs) or tumor initiating cells (TICs) are responsible for tumor initiation, growth and drug resistance. This subgroup of tumor cells has self-renewal capacity and could differentiate into heterogeneous tumor cell populations through asymmetric proliferation. The idea of CSC provides informative insights into tumor initiation, metastasis and treatment. However, the underlying mechanisms of CSCs regulating tumor behaviors are unclear due to the complex cancer system. To study the functions of CSCs in the complex tumor system, a few mathematical modeling studies have been proposed. Whereas, the effect of microenvironment (mE) factors, the behaviors of CSCs, progenitor tumor cells (PCs) and differentiated tumor cells (TCs), and the impact of CSC fraction and signaling heterogeneity, are not adequately explored yet.MethodsIn this study, a novel 3D multi-scale mathematical modeling is proposed to investigate the behaviors of CSCsin tumor progressions. The model integrates CSCs, PCs, and TCs together with a few essential mE factors. With this model, we simulated and investigated the tumor development and drug response under different CSC content and heterogeneity.ResultsThe simulation results shown that the fraction of CSCs plays a critical role in driving the tumor progression and drug resistance. It is also showed that the pure chemo-drug treatment was not a successful treatment, as it resulted in a significant increase of the CSC fraction. It further shown that the self-renew heterogeneity of the initial CSC population is a cause of the heterogeneity of the derived tumors in terms of the CSC fraction and response to drug treatments.ConclusionsThe proposed 3D multi-scale model provides a new tool for investigating the behaviors of CSC in CSC-initiated tumors, which enables scientists to investigate and generate testable hypotheses about CSCs in tumor development and drug response under different microenvironments and drug perturbations.