Mechanical deformation and death of circulating tumor cells in the bloodstream.

The circulation of tumor cells through the bloodstream is a significant step in tumor metastasis. To better understand the metastatic process, circulating tumor cell (CTC) survival in the circulation must be explored. While immune interactions with CTCs in recent decades have been examined, research has yet to sufficiently explain some CTC behaviors in blood flow. Studies related to CTC mechanical responses in the bloodstream have recently been conducted to further study conditions under which CTCs might die. While experimental methods can assess the mechanical properties and death of CTCs, increasingly sophisticated computational models are being built to simulate the blood flow and CTC mechanical deformation under fluid shear stresses (FSS) in the bloodstream.Several factors contribute to the mechanical deformation and death of CTCs as they circulate. While FSS can damage CTC structure, diverse interactions between CTCs and blood components may either promote or hinder the next metastatic step-extravasation at a remote site. Overall understanding of how these factors influence the deformation and death of CTCs could serve as a basis for future experiments and simulations, enabling researchers to predict CTC death more accurately. Ultimately, these efforts can lead to improved metastasis-specific therapeutics and diagnostics specific in the future.

Anti-tumor effect of pH-sensitive drug-loaded nanoparticles optimized via an integrated computational/experimental approach.

The acidic pH of tumor tissue has been used to trigger drug release from nanoparticles. However, dynamic interactions between tumor pH and vascularity present challenges to optimize therapy to particular microenvironment conditions. Despite recent development of pH-sensitive nanomaterials that can accurately quantify drug release from nanoparticles, tailoring release to maximize tumor response remains elusive. This study hypothesizes that a computational modeling-based platform that simulates the heterogeneously vascularized tumor microenvironment can enable evaluation of the complex intra-tumoral dynamics involving nanoparticle transport and pH-dependent drug release, and predict optimal nanoparticle parameters to maximize the response. To this end, SPNCD nanoparticles comprising superparamagnetic cores of iron oxide (Fe3O4) and a poly(lactide-co-glycolide acid) shell loaded with doxorubicin (DOX) were fabricated. Drug release was measured in vitro as a function of pH. A 2D model of vascularized tumor growth was calibrated to experimental data and used to evaluate SPNCD effect as a function of drug release rate and tissue vascular heterogeneity. Simulations show that pH-dependent drug release from SPNCD delays tumor regrowth more than DOX alone across all levels of vascular heterogeneity, and that SPNCD significantly inhibit tumor radius over time compared to systemic DOX. The minimum tumor radius forecast by the model was comparable to previous in vivo SPNCD inhibition data. Sensitivity analyses of the SPNCD pH-dependent drug release rate indicate that slower rates are more inhibitory than faster rates. We conclude that an integrated computational and experimental approach enables tailoring drug release by pH-responsive nanomaterials to maximize the tumor response.

Nanoparticle-Based Therapies in Hypertension.

Nearly 1.4 billion people worldwide suffer from arterial hypertension, a significant risk factor for cardiovascular disease which is now the leading cause of death. Despite numerous drugs designed to treat hypertension, only ≈14% of hypertensive individuals have their blood pressure under control. A critical factor negatively impacting the efficacy of available treatments is their poor bioavailability. This leads to increased dosing requirements which can result in more side effects, resulting in patient noncompliance. A recent solution to improve dosing and bioavailability issues has been to incorporate drugs into nanoparticle carriers, with over 50 nanodrugs currently on the market across all diseases, and another 51 currently in clinical trials. Given their ability to improve solubility and bioavailability, nanoparticles may offer significant advantages in the formulation of antihypertensives to overcome pharmacokinetic shortcomings. To date, however, no antihypertensive nanoformulations have been clinically approved. This review assesses in vivo study data from preclinical antihypertensive nanoformulation development and testing. Combined, the results of these studies suggest nanoformulation of antihypertensive drugs may be a promising solution to overcome the poor efficacy of currently available antihypertensives, and with further advances has the potential to open paths for new substances that have heretofore been clinically unrealistic due to poor bioavailability.

The pleiotropic benefits of statins include the ability to reduce CD47 and amplify the effect of pro-efferocytic therapies in atherosclerosis.

The pleiotropic benefits of statins may result from their impact on vascular inflammation. The molecular process underlying this phenomenon is not fully elucidated. Here, RNA sequencing designed to investigate gene expression patterns following CD47-SIRPα inhibition identifies a link between statins, efferocytosis, and vascular inflammation. In vivo and in vitro studies provide evidence that statins augment programmed cell removal by inhibiting the nuclear translocation of NFκB1 p50 and suppressing the expression of the critical 'don't eat me' molecule, CD47. Statins amplify the phagocytic capacity of macrophages, and thus the anti-atherosclerotic effects of CD47-SIRPα blockade, in an additive manner. Analyses of clinical biobank specimens suggest a similar link between statins and CD47 expression in humans, highlighting the potential translational implications. Taken together, our findings identify efferocytosis and CD47 as pivotal mediators of statin pleiotropy. In turn, statins amplify the anti-atherosclerotic effects of pro-phagocytic therapies independently of any lipid-lowering effect.

Molecular Immune Targeted Imaging of Tumor Microenvironment.

Novel targeted therapies are rapidly emerging for the treatment of cancer. With the advent of new immune targeting agents, understanding the changes in the tumor microenvironment (TME) is critical. Given the complexity and several cellular mechanisms and factors that play a role in the TME, novel imaging methods to assess and evaluate the dynamic changes in the TME during treatment are needed. Several techniques are being developed for imaging TME including optical, fluorescence and photoacoustic methods. Positron emission tomography (PET) imaging can be used to track the dynamics of different molecular targets in the TME in live animals and in humans. Several novel PET imaging probes including radiolabeled antibodies, antibody fragments, and small molecules have been developed with many more that are under development preclinically and in early human studies. This review is a brief overview of some of the PET agents that are either in the preclinical developmental phase or undergoing early clinical studies.

Ultra-selective carbon nanotubes for photoacoustic imaging of inflamed atherosclerotic plaques.

Disruption of vulnerable atherosclerotic plaques often leads to myocardial infarction and stroke, the leading causes of morbidity and mortality in the United States. A diagnostic method that detects high-risk atherosclerotic plaques at early stages could prevent these sequelae. The abundance of immune cells in the arterial wall, especially inflammatory Ly-6Chi monocytes and foamy macrophages, is indicative of plaque inflammation, and may be associated with plaque vulnerability. Hence, we sought to develop a new method that specifically targets these immune cells to offer clinically-relevant diagnostic information about cardiovascular disease. We combine ultra-selective nanoparticle targeting of Ly-6Chi monocytes and foamy macrophages with clinically-viable photoacoustic imaging (PAI) in order to precisely and specifically image inflamed plaques ex vivo in a mouse model that mimics human vulnerable plaques histopathologically. Within the plaques, high-dimensional single-cell flow cytometry (13-parameter) showed that our nanoparticles were almost-exclusively taken up by the Ly-6Chi monocytes and foamy macrophages that heavily infiltrate plaques. PAI identified inflamed atherosclerotic plaques that display ~6-fold greater signal compared to controls (P<0.001) six hours after intravenous injection of ultra-selective carbon nanotubes, with in vivo corroboration via optical imaging. Our highly selective strategy may provide a targeted, non-invasive imaging strategy to accurately identify and diagnose inflamed atherosclerotic lesions.

Self-assembled peptide and protein nanostructures for anti-cancer therapy: Targeted delivery, stimuli-responsive devices and immunotherapy.

Self-assembled peptides and proteins possess tremendous potential as targeted drug delivery systems and key applications of these well-defined nanostructures reside in anti-cancer therapy. Peptides and proteins can self-assemble into nanostructures of diverse sizes and shapes in response to changing environmental conditions such as pH, temperature, ionic strength, as well as host and guest molecular interactions; their countless benefits include good biocompatibility and high loading capacity for hydrophobic and hydrophilic drugs. These self-assembled nanomaterials can be adorned with functional moieties to specifically target tumor cells. Stimuli-responsive features can also be incorporated with respect to the tumor microenvironment. This review sheds light on the growing interest in self-assembled peptides and proteins and their burgeoning applications in cancer treatment and immunotherapy.

Nanomaterials to target immunity.

Critical advances have recently been made in the field of immunotherapy, contributing to an improved understanding of how to harness and balance the power of immune responses in the treatment of diseases such as cancer, cardiovascular disease, infectious diseases, and autoimmune diseases. Combining nanomedicine with immunotherapy provides the opportunity for customization, rational design, and targeting to minimize side effects and maximize efficacy. This review highlights current developments in the design and utilization of nano-based immunotherapy systems, including how rationally-designed nanosystems can target and modify immune cells to modulate immune responses in a therapeutic manner. We discuss the following topics: targeted immuno-engineered nanoformulations, commercial formulations, clinical applicability, challenges associated with current approaches, and future directions.

Gum polysaccharide/nanometal hybrid biocomposites in cancer diagnosis and therapy.

Biopolymers are of prime importance among which gum polysaccharides hold an eminent standing owing to their high availability and non-toxic nature. Gum biopolymers offer a greener alternative to synthetic polymers and toxic chemicals in the synthesis of metal nanostructures. Metal nanostructures accessible via eco-friendly means endow astounding characteristics to gum-based biocomposites in the field of diagnosis and therapy towards cancer diseases. In this review, assorted approaches for the assembly of nanomaterials mediated by gum biopolymers are presented and their utility in cancer diagnosis and therapy, e.g., bioimaging, radiotherapy, and phototherapy, are deliberated to provide a groundwork for future stimulative research.

Reduction Triggered In Situ Polymerization in Living Mice.

"Smart" biomaterials that are responsive to physiological or biochemical stimuli have found many biomedical applications for tissue engineering, therapeutics, and molecular imaging. In this work, we describe in situ polymerization of activatable biorthogonal small molecules in response to a reducing environment change in vivo. We designed a carbohydrate linker- and cyanobenzothiazole-cysteine condensation reaction-based small molecule scaffold that can undergo rapid condensation reaction upon physiochemical changes (such as a reducing environment) to form polymers (pseudopolysaccharide). The fluorescent and photoacoustic properties of a fluorophore-tagged condensation scaffold before and after the transformation have been examined with a dual-modality optical imaging method. These results confirmed the in situ polymerization of this probe after both local and systemic administration in living mice.

Nano-immunoimaging.

Immunoimaging is a rapidly growing field stoked in large part by the intriguing triumphs of immunotherapy. On the heels of immunotherapy's successes, there exists a growing need to evaluate tumor response to therapy particularly immunotherapy, stratify patients into responders vs. non-responders, identify inflammation, and better understand the fundamental roles of immune system components to improve both immunoimaging and immunotherapy. Innovative nanomaterials have begun to provide novel opportunities for immunoimaging, in part due to their sensitivity, modularity, capacity for many potentially varied ligands (high avidity), and potential for multifunctionality/multimodality imaging. This review strives to comprehensively summarize the integration of nanotechnology and immunoimaging, and the field's potential for clinical applications.

Optical Microscopy and Coherence Tomography of Cancer in Living Subjects.

Intravital microscopy (IVM) and optical coherency tomography (OCT) are two powerful optical imaging tools that allow visualization of dynamic biological activities in living subjects with subcellular resolutions. Recent advances in labeling and label-free techniques empower IVM and OCT for a wide range of preclinical and clinical cancer imaging, providing profound insights into the complex physiological, cellular, and molecular behaviors of tumors. Preclinical IVM and OCT have elucidated many otherwise inscrutable aspects of cancer biology, while clinical applications of IVM and OCT are revolutionizing cancer diagnosis and therapies. We review important progress in the fields of IVM and OCT for cancer imaging in living subjects, highlighting key technological developments and their emerging applications in fundamental cancer biology research and clinical oncology investigation.

Nanoparticles decorated with granulocyte-colony stimulating factor for targeting myeloid cells.

Dysregulated myeloid cell activity underlies a variety of pathologies, including immunosuppression in malignant cancers. Current treatments to alter myeloid cell behavior also alter other immune cell subpopulations and nonimmune cell types with deleterious side effects. Therefore, improved selectivity of myeloid treatment is an urgent need. To meet this need, we demonstrate a novel, targeted nanoparticle system that achieves superior myeloid selectivity both in vitro and in vivo. This system comprises: (1) granulocyte-colony stimulating factor (G-CSF) as a targeting ligand to promote accumulation in myeloid cells, including immunosuppressive myeloid-derived suppressor cells (MDSCs); (2) albumin nanoparticles 100-120 nm in diameter that maintain morphology and drug payload in simulated physiological conditions; and (3) a fluorophore that enables nanoparticle tracking and models a therapeutic molecule. Here, we show that this strategy achieves high myeloid uptake in mixed primary immune cells and that nanoparticles successfully infiltrate the 4T1 triple-negative breast tumor murine microenvironment, where they preferentially accumulate in myeloid cells in a mouse model. Further development will realize diagnostic myeloid cell tracking applications and therapeutic delivery of myeloid-reprogramming drugs.

Pro-efferocytic nanoparticles are specifically taken up by lesional macrophages and prevent atherosclerosis.

Atherosclerosis is the process that underlies heart attack and stroke. A characteristic feature of the atherosclerotic plaque is the accumulation of apoptotic cells in the necrotic core. Prophagocytic antibody-based therapies are currently being explored to stimulate the phagocytic clearance of apoptotic cells; however, these therapies can cause off-target clearance of healthy tissues, which leads to toxicities such as anaemia. Here we developed a macrophage-specific nanotherapy based on single-walled carbon nanotubes loaded with a chemical inhibitor of the antiphagocytic CD47-SIRPα signalling axis. We demonstrate that these single-walled carbon nanotubes accumulate within the atherosclerotic plaque, reactivate lesional phagocytosis and reduce the plaque burden in atheroprone apolipoprotein-E-deficient mice without compromising safety, and thereby overcome a key translational barrier for this class of drugs. Single-cell RNA sequencing analysis reveals that prophagocytic single-walled carbon nanotubes decrease the expression of inflammatory genes linked to cytokine and chemokine pathways in lesional macrophages, which demonstrates the potential of 'Trojan horse' nanoparticles to prevent atherosclerotic cardiovascular disease.

Nanotherapeutic Shots through the Heart of Plaque.

The past several decades have brought significant advances in the application of clinical and preclinical nanoparticulate drugs in the field of cancer, but nanodrug development in cardiovascular disease has lagged in comparison. Improved understanding of the spatiotemporal kinetics of nanoparticle delivery to atherosclerotic plaques is required to optimize preclinical nanodrug delivery and to drive their clinical translation. Mechanistic studies using super-resolution and correlative light microscopy/electron microscopy permit a broad, ultra-high-resolution picture of how endothelial barrier integrity impacts the enhanced permeation and retention (EPR) effect for nanoparticles as a function of both atherosclerosis progression and metabolic therapy. Studies by Beldman et al. in the December issue of ACS Nano suggest atherosclerotic plaque progression supports endothelial junction stabilization, which can reduce nanoparticle entry into plaques, and metabolic therapy may induce similar effects. Herein, we examine the potential for advanced dynamic intravital microscopy-based mechanistic studies of nanoparticle entry into atherosclerotic plaques to shed light on the advantages of free extravasation versus immune-mediated nanoparticle uptake for effective clinical translation. We further explore the potential combination of metabolic therapy with another emerging cardiovascular disease treatment paradigm-efferocytosis stimulation-to enhance atherosclerotic plaque regression.

Quantitative Drug Release Monitoring in Tumors of Living Subjects by Magnetic Particle Imaging Nanocomposite.

In vivo drug release monitoring provides accurate and reliable information to guide drug dosing. Image-based strategies for in vivo monitoring are advantageous because they are non-invasive and provide visualization of the spatial distribution of drug, but those imaging modalities in use (e.g., fluorescence imaging (FI) and magnetic resonance imaging (MRI)) remain inadequate because of the low tissue penetration depth (for FI) or difficulty with quantification of release rate and signal convolution with noise sources (for MRI). Magnetic particle imaging (MPI), employing superparamagnetic nanoparticles as the contrast agent and sole signal source, enables large tissue penetration and quantifiable signal intensity. These properties make it ideal for application to in vivo drug release monitoring. In this work, we design a superparamagnetic Fe3O4 nanocluster@poly(lactide-co-glycolide acid) core-shell nanocomposite loaded with a chemotherapy drug (doxorubicin) which serves as a dual drug delivery system and MPI quantification tracer. The as-prepared nanocomposite can degrade under a mild acidic microenvironment (pH = 6.5), which induces a sustained release of doxorubicin and gradual decomposition of the Fe3O4 nanocluster, causing the MPI signal changes. We showed that nanocomposite-induced MPI signal changes display a linear correlation with the release rate of doxorubicin over time (R2 = 0.99). Utilizing this phenomenon, we successfully established quantitative monitoring of the release process in cell culture. We then performed in vivo drug release monitoring in a cancer therapy setting using a murine breast cancer model by injecting the nanocomposite, monitoring the drug release, and assessing the induced tumor cell kill. This study provides an improved solution for in vivo drug release monitoring compared to other available monitoring strategies. This translational strategy using a biocompatible polymer-coated iron oxide nanocomposite will be promising in future clinical use.

Extravasation of Brownian Spheroidal Nanoparticles through Vascular Pores.

In modern cancer treatment, there is significant interest in studying the use of drug molecules either directly injected into the bloodstream or delivered by nanoparticle (NP) carriers of various shapes and sizes. During treatment, these carriers may extravasate through pores in the tumor vasculature that form during angiogenesis. We provide an analytical, computational, and experimental examination of the extravasation of point particles (e.g., drug molecules) and finite-sized spheroidal particles. We study the advection-diffusion process in a model microvasculature, consisting of a shear flow over and a pressure-driven suction flow into a circular pore in a flat surface. For point particles, we provide an analytical formula [Formula: see text] for the dimensionless Sherwood number S, i.e., the extravasation rate, in terms of the pore entry resistance (Damköhler number κ), the shear rate (Péclet number P), and the suction flow rate (suction strength Q). Brownian dynamics (BD) simulations verify this result, and our simulations are then extended to include finite-sized NPs, in which no analytical solutions are available. BD simulations indicate that particles of different geometries have drastically different extravasation rates in different flow conditions. In general, extreme aspect ratio particles provide a greater flux through the pore because of favorable alignment with streamlines entering the pore and less hindered interaction with the pore. We validate the BD simulations by measuring the in vitro transport of both bacteriophage MS2 (a spherical NP) and free dye (a model drug molecule) across a porous membrane. Despite their vastly different sizes, BD predicts S = 8.53 E-4 and S = 27.6 E-4, and our experiments agree favorably, with Sexp=10.6 E-4± 1.75 E-4 and Sexp=16.3 E-4 ± 3.09 E-4, for MS2 and free dye, respectively, thus demonstrating the practical utility of our simulation framework.

Cancer Immunotherapy Getting Brainy: Visualizing the Distinctive CNS Metastatic Niche to Illuminate Therapeutic Resistance.

The advent of cancer immunotherapy (CIT) and its success in treating primary and metastatic cancer may offer substantially improved outcomes for patients. Despite recent advancements, many malignancies remain resistant to CIT, among which are brain metastases, a particularly virulent disease with no apparent cure. The immunologically unique niche of the brain has prompted compelling new questions in immuno-oncology such as the effects of tissue-specific differences in immune response, heterogeneity between primary tumors and distant metastases, and the role of spatiotemporal dynamics in shaping an effective anti-tumor immune response. Current methods to examine the immunobiology of metastases in the brain are constrained by tissue processing methods that limit spatial data collection, omit dynamic information, and cannot recapitulate the heterogeneity of the tumor microenvironment. In the current review, we describe how high-resolution, live imaging tools, particularly intravital microscopy (IVM), are instrumental in answering these questions. IVM of pre-clinical cancer models enables short- and long-term observations of critical immunobiology and metastatic growth phenomena to potentially generate revolutionary insights into the spatiotemporal dynamics of brain metastasis, interactions of CIT with immune elements therein, and influence of chemo- and radiotherapy. We describe the utility of IVM to study brain metastasis in mice by tracking the migration and growth of fluorescently-labeled cells, including cancer cells and immune subsets, while monitoring the physical environment within optical windows using imaging dyes and other signal generation mechanisms to illuminate angiogenesis, hypoxia, and/or CIT drug expression within the metastatic niche. Our review summarizes the current knowledge regarding brain metastases and the immune milieu, presents the current status of CIT and its prospects in targeting brain metastases to circumvent therapeutic resistance, and proposes avenues to utilize IVM to study CIT drug delivery and therapeutic efficacy in preclinical models that will ultimately facilitate novel drug discovery and innovative combination therapies.

Nanomaterials for In Vivo Imaging.

In vivo imaging, which enables us to peer deeply within living subjects, is producing tremendous opportunities both for clinical diagnostics and as a research tool. Contrast material is often required to clearly visualize the functional architecture of physiological structures. Recent advances in nanomaterials are becoming pivotal to generate the high-resolution, high-contrast images needed for accurate, precision diagnostics. Nanomaterials are playing major roles in imaging by delivering large imaging payloads, yielding improved sensitivity, multiplexing capacity, and modularity of design. Indeed, for several imaging modalities, nanomaterials are now not simply ancillary contrast entities, but are instead the original and sole source of image signal that make possible the modality's existence. We address the physicochemical makeup/design of nanomaterials through the lens of the physical properties that produce contrast signal for the cognate imaging modality-we stratify nanomaterials on the basis of their (i) magnetic, (ii) optical, (iii) acoustic, and/or (iv) nuclear properties. We evaluate them for their ability to provide relevant information under preclinical and clinical circumstances, their in vivo safety profiles (which are being incorporated into their chemical design), their modularity in being fused to create multimodal nanomaterials (spanning multiple different physical imaging modalities and therapeutic/theranostic capabilities), their key properties, and critically their likelihood to be clinically translated.