Results of retroviral and adenoviral approaches to cancer gene therapy

Microfluidic Based Physical Approaches towards Single-Cell Intracellular Delivery and Analysis

The ability to deliver foreign molecules into a single living cell with high transfection efficiency and high cell viability is of great interest in cell biology for applications in therapeutic development, diagnostics, and drug delivery towards personalized medicine. Various physical delivery methods have long demonstrated the ability to deliver cargo molecules directly to the cytoplasm or nucleus and the mechanisms underlying most of the approaches have been extensively investigated. However, most of these techniques are bulk approaches that are cell-specific and have low throughput delivery. In comparison to bulk measurements, single-cell measurement technologies can provide a better understanding of the interactions among molecules, organelles, cells, and the microenvironment, which can aid in the development of therapeutics and diagnostic tools. To elucidate distinct responses during cell genetic modification, methods to achieve transfection at the single-cell level are of great interest. In recent years, single-cell technologies have become increasingly robust and accessible, although limitations exist. This review article aims to cover various microfluidic-based physical methods for single-cell intracellular delivery such as electroporation, mechanoporation, microinjection, sonoporation, optoporation, magnetoporation, and thermoporation and their analysis. The mechanisms of various physical methods, their applications, limitations, and prospects are also elaborated.

Nano-localized single-cell nano-electroporation

The ability to deliver foreign cargos into single living cells is of great interest in cell biology and therapeutic research. Here, we have reported a single or multiple position based nano-localized single-cell nano-electroporation platform. The device consists of an array of triangular shape ITO nano-electrodes with a 70 nm gap between two nano-electrodes, each having a 40 nm tip diameter. The voltage is applied between nano-electrodes to generate an intense electric field, which electroporates multiple nano-localized regions of the targeted single-cell membrane, and biomolecules are gently delivered into cells by pressurizing pump flow, without affecting cell viability. The platform successfully delivers dyes, QDs, and plasmids into different cell types with the variation of field strength, pulse duration, and the number of pulses. This new approach allows us to analyze delivery of different biomolecules into single living cells with high transfection efficiency (>96%, for CL1-0 cells) and high cell viability (∼98%), which are potentially beneficial for cellular therapy and diagnostic purposes.

A Single-Neuron: Current Trends and Future Prospects

The brain is an intricate network with complex organizational principles facilitating a concerted communication between single-neurons, distinct neuron populations, and remote brain areas. The communication, technically referred to as connectivity, between single-neurons, is the center of many investigations aimed at elucidating pathophysiology, anatomical differences, and structural and functional features. In comparison with bulk analysis, single-neuron analysis can provide precise information about neurons or even sub-neuron level electrophysiology, anatomical differences, pathophysiology, structural and functional features, in addition to their communications with other neurons, and can promote essential information to understand the brain and its activity. This review highlights various single-neuron models and their behaviors, followed by different analysis methods. Again, to elucidate cellular dynamics in terms of electrophysiology at the single-neuron level, we emphasize in detail the role of single-neuron mapping and electrophysiological recording. We also elaborate on the recent development of single-neuron isolation, manipulation, and therapeutic progress using advanced micro/nanofluidic devices, as well as microinjection, electroporation, microelectrode array, optical transfection, optogenetic techniques. Further, the development in the field of artificial intelligence in relation to single-neurons is highlighted. The review concludes with between limitations and future prospects of single-neuron analyses.

Near-infrared nanosecond-pulsed laser-activated highly efficient intracellular delivery mediated by nano-corrugated mushroom-shaped gold-coated polystyrene nanoparticles

Here, an efficient intracellular delivery of molecules with high cell viability is reported using nanosecond-pulsed laser-activated plasmonic photoporation, mediated by high-aspect-ratio nano-corrugated mushroom-shaped gold-coated polystyrene nanoparticles (nm-AuPNPs) at near-infrared wavelength. Upon pulsed laser illumination, nm-AuPNPs exhibit greater plasmonic extinction than spherical AuPNPs, which increase their energy efficiency and reduce the necessary illumination of light, effectively controlling cell damage and improving the delivery efficiency. Nm-AuPNPs exhibit surface plasmon absorption at near infrared region with a peak at 945 nm. Pulsed laser illumination at this plasmon peak triggers explosive nanobubbles, which create transient membrane pores, allowing the delivery of dyes, quantum dots and plasmids into the different cell types. The results can be tuned by laser fluence, exposure time, molecular size and concentration of nm-AuPNPs. The best results are found for CL1-0 cells, which yielded a 94% intracellular PI dye uptake and ∼100% cell viability at 35 mJ cm-2 laser fluence for 945 nm wavelength. Thus, the presented approach has proven to have an inevitable potential for biological cell research and therapeutic applications.

Current Trends of Microfluidic Single-Cell Technologies

The investigation of human disease mechanisms is difficult due to the heterogeneity in gene expression and the physiological state of cells in a given population. In comparison to bulk cell measurements, single-cell measurement technologies can provide a better understanding of the interactions among molecules, organelles, cells, and the microenvironment, which can aid in the development of therapeutics and diagnostic tools. In recent years, single-cell technologies have become increasingly robust and accessible, although limitations exist. In this review, we describe the recent advances in single-cell technologies and their applications in single-cell manipulation, diagnosis, and therapeutics development.

Gold nanoparticles electroporation enhanced polyplex delivery to mammalian cells

Nonviral methods have been explored as the replacement of viral systems for their low toxicity and immunogenicity. However, they have yet to reach levels competitive to their viral counterparts. In this paper, we combined physical and chemical methods to improve the performance of polyplex delivery of DNA and small interfering RNA. Specifically, gold nanoparticles (AuNPs) were used to carry polyplex (a chemical approach) while electroporation (a physical approach) was applied for fast and direct cytosolic delivery. In this hybrid approach, cationic polymer molecules condense and/or protect genetic probes as usual while AuNPs help fix polycations to reduce their cytotoxicity and promote the transfection efficiency of electroporation. AuNPs of various sizes were first coated with polyethylenimine, which were further conjugated with DNA plasmids or small interfering RNA molecules to form AuNPs-polyplex. The hybrid nanoparticles were then mixed with cells and introduced into cell cytosol by electroporation. The delivery efficiency was evaluated with both model anchor cells (i.e., NIH/3T3) and suspension cells (i.e., K562), together with their impact on cell viability. We found that AuNP-polyplex showed 1.5∼2 folds improvement on the transfection efficiency with no significant increase of toxicity when compared to free plasmid delivery by electroporation alone. Such a combination of physical and chemical delivery concept may stimulate further exploration in the delivery of various therapeutic materials for both in vitro and in vivo applications.

Single-cell electroporation using proton beam fabricated biochips

We report the design and fabrication of a novel single cell electroporation biochip featuring high aspect ratio nickel micro-electrodes with smooth side walls between which individual cells are attached. The biochip is fabricated using Proton Beam Writing (PBW), a new direct write lithographic technique capable of fabricating high quality high-aspect-ratio nano and microstructures. By applying electrical impulses across the biochip electrodes, SYTOX® Green nucleic acid stain is incorporated into mouse neuroblastoma (N2a) cells and observed via green fluorescence when the stain binds with DNA inside the cell nucleus. Three parameters; electric field strength, pulse duration, and numbers of pulses have been investigated for the single cell electroporation process. The results indicate high transfection rates as well as cell viability of 82.1 and 86.7% respectively. This single cell electroporation system may represent a promising method for the introduction of a wide variety of fluorophores, nanoparticles, quantum dots, DNAs and proteins into cells.

Semicontinuous flow electroporation chip for high-throughput transfection on mammalian cells

We have recently developed a semicontinuous flow electroporation (SFE) device for in vitro DNA delivery. Cells mixed with plasmid DNA continuously flowed through a serpentine channel, the side walls of which also serving as electrodes. With the use of pWizGFP plasmid and K562 cells as a model system, SFE showed better transgene expression (10-15%) compared to a commercial electroporation system. Quantitative results via MTS assay also revealed a 50% or higher cell viability. Similar observations were also found with pWizGFP transfection to mouse embryonic stem cells. Such improvements were attributed to less gas formation and Joule heating in SFE.

Treatment of breast cancer with chemotherapy in combination with filgrastim: approaches to improving therapeutic outcome

Chemotherapy improves disease-free and overall survival in breast cancer, and its benefit is directly related to the percentage of the planned dose that is actually administered. In all current chemotherapeutic regimens, a substantial proportion of patients have reductions and/or delays in dosage due to side effects. In about half such cases, the delays or reductions are related to neutropenia. Overall, approximately 30% of patients have a reduction to less than 85% of the planned dosage. Women aged > or = 50 years are more likely to experience a reduction or delay in dose. Dose-intense regimens (excluding myeloablative high-dose chemotherapy) which increase the dose of chemotherapy or reduce the interval between cycles, or both, are a promising approach now under investigation. The human granulocyte colony-stimulating factor filgrastim reduces the incidence of neutropenia and facilitates adherence to full dose intensity in both standard and dose-intensified regimens. A model based on the first-cycle absolute neutrophil count nadir has been developed and validated to determine which patients should receive filgrastim. A cost benefit associated with the use of filgrastim in patients with breast cancer has been realised. This may lead to a re-evaluation of the current treatment guidelines.