On predicting heterogeneity in nanoparticle dosage.

Nanoparticles are increasingly employed as a vehicle for the targeted delivery of therapeutics to specific cell types. However, much remains to be discovered about the fundamental biology that dictates the interactions between nanoparticles and cells. Accordingly, few nanoparticle-based targeted therapeutics have succeeded in clinical trials. One element that hinders our understanding of nanoparticle-cell interactions is the presence of heterogeneity in nanoparticle dosage data obtained from standard experiments. It is difficult to distinguish between heterogeneity that arises from stochasticity in nanoparticle-cell interactions, and that which arises from heterogeneity in the cell population. Mathematical investigations have revealed that both sources of heterogeneity contribute meaningfully to the heterogeneity in nanoparticle dosage. However, these investigations have relied on simplified models of nanoparticle internalisation. Here we present a stochastic mathematical model of nanoparticle internalisation that incorporates a suite of relevant biological phenomena such as multistage internalisation, cell division, asymmetric nanoparticle inheritance and nanoparticle saturation. Critically, our model provides information about nanoparticle dosage at an individual cell level. We perform model simulations to examine the influence of specific biological phenomena on the heterogeneity in nanoparticle dosage in the absence of heterogeneity in the cell population. Under certain modelling assumptions, we derive analytic approximations of the nanoparticle dosage distribution. We demonstrate that the analytic approximations are accurate, and show that nanoparticle dosage can be described by a Poisson mixture distribution with rate parameters that are a function of Beta-distributed random variables. We discuss the implications of the analytic results with respect to parameter estimation and model identifiability from standard experimental data. Finally, we highlight extensions and directions for future research.

Experimental Quantification of Interactions Between Drug Delivery Systems and Cells In Vitro: A Guide for Preclinical Nanomedicine Evaluation.

A major component of designing drug delivery systems concerns how to amplify or attenuate interactions with specific cell types. For instance, a chemotherapeutic might be functionalized with an antibody to enhance binding to cancer cells ("targeting") or functionalized with polyethylene glycol to help evade immune cell recognition ("stealth"). Even at a cellular level, optimizing the binding and uptake of a drug carrier is a complex biological design problem. Thus, it is valuable to separate how strongly a new carrier interacts with a cell from the functional efficacy of a carrier's cargo once delivered to that cell. To continue the chemotherapeutic example, "how well it binds to a cancer cell" is a separate problem from "how well it kills a cancer cell". Quantitative in vitro assays for the latter are well established and usually rely on measuring viability. However, most published research on cell-carrier interactions is qualitative or semiquantitative. Generally, these measurements rely on fluorescent labeling of the carrier and, consequently, report interactions with cells in relative or arbitrary units. However, this work can be standardized and be made absolutely quantitative with a small number of characterization experiments. Such absolute quantification is valuable, as it facilitates rational, inter- and intra-class comparisons of various drug delivery systems-nanoparticles, microparticles, viruses, antibody-drug conjugates, engineered therapeutic cells, or extracellular vesicles. Furthermore, quantification is a prerequisite for subsequent meta-analyses or in silico modeling approaches. In this article, video guides, as well as a decision tree for how to achieve in vitro quantification for carrier drug delivery systems, are presented, which take into account differences in carrier size and labeling modality. Additionally, further considerations for the quantitative assessment of advanced drug delivery systems are discussed. This is intended to serve as a valuable resource to improve rational evaluation and design for the next generation of medicine.

An Inspiring Journey of Hope and Persistence: Life Lessons with Françoise Barré-Sinoussi.

Three early-career female virologists sat down with a distinguished Nobel laureate to discuss two pandemics, 39 years apart [...].

In Vivo T Cell-Targeting Nanoparticle Drug Delivery Systems: Considerations for Rational Design.

T cells play an important role in immunity and repair and are implicated in diseases, including blood cancers, viral infections, and inflammation, making them attractive targets for the treatment and prevention of diseases. Over recent years, the advent of nanomedicine has shown an increase in studies that use nanoparticles as carriers to deliver therapeutic cargo to T cells for ex vivo and in vivo applications. Nanoparticle-based delivery has several advantages, including the ability to load and protect a variety of drugs, control drug release, improve drug pharmacokinetics and biodistribution, and site- or cell-specific targeting. However, the delivery of nanoparticles to T cells remains a major technological challenge, which is primarily due to the nonphagocytic nature of T cells. In this review, we discuss the physiological barriers to effective T cell targeting and describe the different approaches used to deliver cargo-loaded nanoparticles to T cells for the treatment of disease such as T cell lymphoma and human immunodeficiency virus (HIV). In particular, engineering strategies that aim to improve nanoparticle internalization by T cells, including ligand-based targeting, will be highlighted. These nanoparticle engineering approaches are expected to inspire the development of effective nanomaterials that can target or manipulate the function of T cells for the treatment of T cell-related diseases.

Acoustofection: High-Frequency Vibrational Membrane Permeabilization for Intracellular siRNA Delivery into Nonadherent Cells.

The internalization of therapeutic molecules into cells-a critical step in enabling a suite of autologous ex vivo gene and cell therapies-is highly regulated by the lipid barrier imposed by the cell membrane. Strategies to increase the efficiency of delivering these exogenous payloads into the cell, while maintaining the integrity of both the therapeutic molecules to be delivered as well as the host cells they are delivered to, are therefore required. This is especially the case for suspension cells that are particularly difficult to transfect. In this work, we show that it is possible to enhance the uptake of short interfering RNA (siRNA) into nonadherent Jurkat and HuT 78 cells with a rapid poration-free method involving high-frequency (MHz order) acoustic excitation. The 2-fold enhancement in gene knockdown is almost comparable with that obtained with conventional nucleofection, which is among the most widely used intracellular delivery methods, but with considerably higher cell viabilities (>91% compared to approximately 76%) owing to the absence of pore formation. The rapid and effective delivery afforded by the platform, together with its low cost and scalability, therefore renders it a potent tool in the cell engineering pipeline.

TB-IRIS pathogenesis and new strategies for intervention: Insights from related inflammatory disorders.

In almost one in five HIV/tuberculosis (TB) co-infected patients, initiation of antiretroviral therapy (ART) is complicated by TB immune reconstitution inflammatory syndrome (TB-IRIS). Corticosteroids have been suggested for treatment of severe cases, however no therapy is currently licensed for TB-IRIS. Hence, there is a strong need for more specific therapeutics, and therefore, a better understanding of TB-IRIS pathogenesis. Immune reconstitution following ART is a precariously balanced functional restoration of adaptive immunity. In those patients predisposed to disease, an incomplete activation of the innate immune system leads to a hyper-inflammatory response that comprises partially overlapping innate, adaptive and effector arms, eventually leading to clinical symptoms. Interestingly, many of these pathological mechanisms are shared by related inflammatory disorders. We here describe therapeutic strategies that originate from these other disciplines and discuss their potential application in TB-IRIS. These new avenues of interventions range from final-phase treatment of symptoms to early-phase prevention of disease onset. In conclusion, we propose a novel approach for the discovery and development of therapeutics, based on an updated model of TB-IRIS pathogenesis. Further experimental studies validating the causal relationships in the proposed model could greatly contribute to providing a solid immunological basis for future clinical trials on TB-IRIS therapeutics.