Evaluating the effect of assay preparation on the uptake of gold nanoparticles by RAW264.7 cells

Multiple dyes applications for fluorescent convertible polymer capsules as macrophages tracking labels

Tracing individual cell pathways among the whole population is crucial for understanding their behavior, cell communication, migration dynamics, and fate. Optical labeling is one approach for tracing individual cells, but it typically requires genetic modification to induce the generation of photoconvertible proteins. Nevertheless, this approach has limitations and is not applicable to certain cell types. For instance, genetic modification often leads to the death of macrophages. This study aims to develop an alternative method for labeling macrophages by utilizing photoconvertible micron-sized capsules capable of easy internalization and prolonged retention within cells. Thermal treatment in a polyvinyl alcohol gel medium is employed for the scalable synthesis of capsules with a wide range of fluorescent dyes, including rhodamine 6G, pyronin B, fluorescein, acridine yellow, acridine orange, thiazine red, and previously reported rhodamine B. The fluorescence brightness, photostability, and photoconversion ability of the capsules are evaluated using confocal laser scanning microscopy. Viability, uptake, mobility, and photoconversion studies are conducted on RAW 264.7 and bone marrow-derived macrophages, serving as model cell lines. The production yield of the capsules is increased due to the use of polyvinyl alcohol gel, eliminating the need for conventional filtration steps. Capsules entrapping rhodamine B and rhodamine 6G meet all requirements for intracellular use in individual cell tracking. Mass spectrometry analysis reveals a sequence of deethylation steps that result in blue shifts in the dye spectra upon irradiation. Cellular studies on macrophages demonstrate robust uptake of the capsules. The capsules exhibit minimal cytotoxicity and have a negligible impact on cell motility. The successful photoconversion of RhB-containing capsules within cells highlights their potential as alternatives to photoconvertible proteins for individual cell labeling, with promising applications in personalized medicine.

Measuring and Modeling Macrophage Growth using a Lab-on-CMOS Capacitance Sensing Microsystem

We report on the use of a lab-on-CMOS biosensor platform for quantitatively tracking the growth of RAW 264.7 murine Balb/c macrophages. We show that macrophage growth over a wide sensing area correlates linearly with an average capacitance growth factor resulting from capacitance measurements at a plurality of electrodes dispersed in the sensing area. We further show a temporal model that captures the cell evolution in the area of interest over long periods (e.g., 30 hours). The model links the cell numbers and the average capacitance growth factor associated with the sensing area to describe the observed growth kinetics.

Integration of In Vitro and In Vivo Models to Predict Cellular and Tissue Dosimetry of Nanomaterials Using Physiologically Based Pharmacokinetic Modeling

Nanomaterials (NMs) have been increasingly used in a number of areas, including consumer products and nanomedicine. Target tissue dosimetry is important in the evaluation of safety, efficacy, and potential toxicity of NMs. Current evaluation of NM efficacy and safety involves the time-consuming collection of pharmacokinetic and toxicity data in animals and is usually completed one material at a time. This traditional approach no longer meets the demand of the explosive growth of NM-based products. There is an emerging need to develop methods that can help design safe and effective NMs in an efficient manner. In this review article, we critically evaluate existing studies on in vivo pharmacokinetic properties, in vitro cellular uptake and release and kinetic modeling, and whole-body physiologically based pharmacokinetic (PBPK) modeling studies of different NMs. Methods on how to simulate in vitro cellular uptake and release kinetics and how to extrapolate cellular and tissue dosimetry of NMs from in vitro to in vivo via PBPK modeling are discussed. We also share our perspectives on the current challenges and future directions of in vivo pharmacokinetic studies, in vitro cellular uptake and kinetic modeling, and whole-body PBPK modeling studies for NMs. Finally, we propose a nanomaterial in vitro to in vivo extrapolation via physiologically based pharmacokinetic modeling (Nano-IVIVE-PBPK) framework for high-throughput screening of target cellular and tissue dosimetry as well as potential toxicity of different NMs in order to meet the demand of efficient evaluation of the safety, efficacy, and potential toxicity of a rapidly increasing number of NM-based products.

Palladium nanoplates scotch breast cancer lung metastasis by constraining epithelial-mesenchymal transition

Metastasis accounts for the majority of cancer deaths in many tumor types including breast cancer. Epithelial-mesenchymal transition (EMT) is the driving force for the occurrence and progression of metastasis, however, no targeted strategies to block the EMT program are currently available to combat metastasis. Diverse engineered nanomaterials (ENMs) have been reported to exert promising anti-cancer effects, however, no ENMs have been designed to target EMT. Palladium (Pd) nanomaterials, a type of ENM, have received substantial attention in nanomedicine due to their favorable photothermal performance for cancer therapeutics. Herein, Pd nanoplates (PdPL) were found to be preferentially biodistributed to both primary tumors and metastatic tumors. Importantly, PdPL showed a significant inhibition of lung metastasis with and without near-infrared (NIR) irradiation. Mechanistic investigations revealed that EMT was significantly compromised in breast cancer cells upon the PdPL treatment, which was partially due to the inhibition of the transforming growth factor-beta (TGF-β) signaling. Strikingly, the PdPL was found to directly interact with TGF-β proteins to diminish TGF-β functions in activating its downstream signaling, as evidenced by the reduced phosphorylation of Smad2. Notably, TGF-β-independent pathways were also involved in undermining EMT and other important biological processes that are necessary for metastasis. Additionally, NIR irradiation elicited synergistic effects on PdPL-induced inhibition of primary tumors and metastasis. In summary, these results revealed that the PdPL remarkably curbed metastasis by inhibiting EMT signaling, thereby indicating the promising potential of PdPL as a therapeutic agent for treating breast cancer metastasis.

Understanding the influence of experimental factors on bio-interactions of nanoparticles: Towards improving correlation between in vitro and in vivo studies

Bionanotechnology has developed rapidly over the past two decades, owing to the extensive and versatile, functionalities and applicability of nanoparticles (NPs). Fifty-one nanomedicines have been approved by FDA since 1995, out of the many NPs based formulations developed to date. The general conformation of NPs consists of a core with ligands coating their surface, that stabilizes them and provides them with added functionalities. The physicochemical properties, especially the surface composition of NPs influence their bio-interactions to a large extent. This review discusses recent studies that help understand the nano-bio interactions of iron oxide and gold NPs with different surface compositions. We discuss the influence of the experimental factors on the outcome of the studies and, thus, the importance of standardization in the field of nanotechnology. Recent studies suggest that with careful selection of experimental parameters, it is possible to improve the positive correlation between in vitro and in vivo studies. This provides a fundamental understanding of the NPs which helps in assessing their potential toxic side effects and may aid in manipulating them further to improve their biocompatibility and biosafety.

In vitro evaluation of magnetite nanoparticles in human mesenchymal stem cells: comparison of different cytotoxicity assays

This work was aimed at defining the suitable test for evaluating Fe₃O₄ NPs cytotoxicity after short-term exposure in human mesenchymal stem cells (hMSCs) using different viability tests, namely NRU, MTT and TB assays, paralleled by cell morphology analyses for cross checking. MTT and NRU data (culture medium with/without hMSCs plus Fe₃O₄NPs) indicated artificial/false increments in cell viability after Fe₃O₄NPs. These observations did not fit with the morphological analyses showing reduced cell density, loss of monolayer features, and morphological alterations at Fe₃O₄NPs ≥50 μg/ml. Fe₃O₄NPs alone induced a substantial increased absorbance at the wavelength required for MTT and NRU. A significant death (25%) of hMSC at Fe₃O₄NPs ≥10 μg/ml, with a maximum effect (45%) at 300 μg/ml after 24 h, exacerbated after 48 h, was observed when applying TB test. These results paralleled the effects on cell morphology. The optical properties and stability of Fe₃O₄NP suspension (tendency to agglomerate in a specific culture medium) represent factors that limit in vitro result interpretation. These findings suggest the non applicability of the spectrophotometric assays for hMSC culture conditions, while TB is an accurate method for determining cell viability after Fe₃O₄NP exposure in this model. In relation to NPs safety assessment: cell-based assays must be considered on case-by-case basis; selection of relevant cell models is also important for predictive toxicological studies; application of a testing strategy is fundamental for understanding the toxicity pathways driving cellular responses.

Smaller CpG-Conjugated Gold Nanoconstructs Achieve Higher Targeting Specificity of Immune Activation

This study describes a side-by-side comparison of the in vitro immunostimulatory activity of cytosine-phosphate-guanine (CpG)-conjugated gold nanoparticles. Three different gold nanoparticle cores (13 nm spheres, 50 nm spheres, and 40 nm stars) with the same CpG surface density were investigated for toll-like receptor 9 activation. For this parameter set, 13 nm spheres displayed significantly higher specificity for targeting immune receptors and larger nanoparticles (50 nm spheres and 40 nm stars) showed higher cellular uptake and higher immune activation because of off-target effects. Changes in nanoparticle size and presentation of activating ligands affect construct-induced immune responses at different levels, and care must be taken when considering practical and global design rules for CpG delivery.

Comparative Evaluation of U.S. Brand and Generic Intravenous Sodium Ferric Gluconate Complex in Sucrose Injection: In Vitro Cellular Uptake

Iron deficiency anemia is a common clinical consequence for people who suffer from chronic kidney disease, especially those requiring dialysis. Intravenous (IV) iron therapy is a widely accepted safe and efficacious treatment for iron deficiency anemia. Numerous IV iron drugs have been approved by U.S. Food and Drug Administration (FDA), including a single generic product, sodium ferric gluconate complex in sucrose. In this study, we compared the cellular iron uptake profiles of the brand (Ferrlecit®) and generic sodium ferric gluconate (SFG) products. We used a colorimetric assay to examine the amount of iron uptake by three human macrophage cell lines. This is the first published study to provide a parallel evaluation of the cellular uptake of a brand and a generic IV iron drug in a mononuclear phagocyte system. The results showed no difference in iron uptake across all cell lines, tested doses, and time points. The matching iron uptake profiles of Ferrlecit® and its generic product support the FDA's present position detailed in the draft guidance on development of SFG complex products that bioequivalence can be based on qualitative (Q1) and quantitative (Q2) formulation sameness, similar physiochemical characterization, and pharmacokinetic bioequivalence studies.

Mesenchymal Stem Cells Engineering: Microcapsules-Assisted Gene Transfection and Magnetic Cell Separation

Stem cell engineering-the manipulation and functionalization of stem cells involving genetic modification-can significantly expand their applicability for cell therapy in humans. Toward this aim, reliable, standardized, and cost-effective methods for cell manipulation are required. Here we explore the potential of magnetic multilayer capsules to serve as a universal platform for nonviral gene transfer, stem cell magnetization, and magnetic cell separation to improve gene transfer efficiency. In particular, the following experiments were performed: (i) a study of the process of internalization of magnetic capsules into stem cells, including capsule co-localization with established markers of endo-lysosomal pathway; (ii) characterization and quantification of capsule uptake with confocal microscopy, electron microscopy, and flow cytometry; (iii) intracellular delivery of messenger RNA and separation of gene-modified cells by magnetic cell sorting (MACS); and (iv) analysis of the influence of capsules on cell proliferation potential. Importantly, based on the internalization of magnetic capsules, transfected cells became susceptible to external magnetic fields, which made it easy to enrich gene-modified cells using MACS (purity ∼95%), and also to influence their migration behavior. In summary, our results underline the high potential of magnetic capsules in stem cell functionalization, namely (i) to increase gene-transfer efficiency and (ii) to facilitate enrichment and targeting of transfected cells. Finally, we did not observe a negative impact of the capsules used on the proliferative capacity of stem cells, proving their high biocompatibility.

Algorithm-driven high-throughput screening of colloidal nanoparticles under simulated physiological and therapeutic conditions

Colloidal nanoparticles have shown tremendous potential as cancer drug carriers and as phototherapeutics. However, the stability of nanoparticles under physiological and phototherapeutic conditions is a daunting issue, which needs to be addressed in order to ensure a successful clinical translation. The design, development and implementation of unique algorithms are described herein for high-throughput hydrodynamic size measurements of colloidal nanoparticles. The data obtained from such measurements provide clinically-relevant particle size distribution assessments that are directly related to the stability and aggregation profiles of the nanoparticles under putative physiological and phototherapeutic conditions; those profiles are not only dependent on the size and surface coating of the nanoparticles, but also on their composition. Uncoated nanoparticles showed varying degrees of association with bovine serum albumin, whereas PEGylated nanoparticles did not exhibit significant association with the protein. The algorithm-driven, high-throughput size screening method described in this report provides highly meaningful size measurement patterns stemming from the association of colloidal particles with bovine serum albumin used as a protein model. Noteworthy is that this algorithm-based high-throughput method can accomplish sophisticated hydrodynamic size measurement protocols within days instead of years it would take conventional hydrodynamic size measurement techniques to achieve a similar task.