Gene delivery into prostate cancer cells by holmium laser application

Laser-assisted nucleic acid delivery: A systematic review

Gene therapy has become an effective treatment modality for some conditions. Laser light may augment or enhance gene therapy through photomechanical, photothermal, and photochemical. This review examined the evidence base for laser therapy to enhance nucleic acid transfection in mammalian cells. An electronic search of MEDLINE, Scopus, EMBASE, Web of Science, and Google Scholar was performed, covering all available years. The preferred reporting items for systematic reviews and meta-analyses guideline for systematic reviews was used for designing the study and analyzing the results. In total, 49 studies of laser irradiation for nucleic acid delivery were included. Key approaches were optoporation, photomechanical gene transfection, and photochemical internalization. Optoporation is better suited to cells in culture, photomechanical and photochemical approaches appear well suited to in vivo use. Additional studies explored the impact of photothermal for enhancing gene transfection. Each approach has merits and limitations. Augmenting nucleic acid delivery using laser irradiation is a promising method for improving gene therapy. Laser protocols can be non-invasive because of the penetration of desirable wavelengths of light, but it depends on various parameters such as power density, treatment duration, irradiation mode, etc. The current protocols show low efficiency, and there is a need for further work to optimize irradiation parameters.

Advanced physical techniques for gene delivery based on membrane perforation

Gene delivery as a promising and valid tool has been used for treating many serious diseases that conventional drug therapies cannot cure. Due to the advancement of physical technology and nanotechnology, advanced physical gene delivery methods such as electroporation, magnetoporation, sonoporation and optoporation have been extensively developed and are receiving increasing attention, which have the advantages of briefness and nontoxicity. This review introduces the technique detail of membrane perforation, with a brief discussion for future development, with special emphasis on nanoparticles mediated optoporation that have developed as an new alternative transfection technique in the last two decades. In particular, the advanced physical approaches development and new technology are highlighted, which intends to stimulate rapid advancement of perforation techniques, develop new delivery strategies and accelerate application of these techniques in clinic.

Intracellular Delivery by Membrane Disruption: Mechanisms, Strategies, and Concepts

Intracellular delivery is a key step in biological research and has enabled decades of biomedical discoveries. It is also becoming increasingly important in industrial and medical applications ranging from biomanufacture to cell-based therapies. Here, we review techniques for membrane disruption-based intracellular delivery from 1911 until the present. These methods achieve rapid, direct, and universal delivery of almost any cargo molecule or material that can be dispersed in solution. We start by covering the motivations for intracellular delivery and the challenges associated with the different cargo types-small molecules, proteins/peptides, nucleic acids, synthetic nanomaterials, and large cargo. The review then presents a broad comparison of delivery strategies followed by an analysis of membrane disruption mechanisms and the biology of the cell response. We cover mechanical, electrical, thermal, optical, and chemical strategies of membrane disruption with a particular emphasis on their applications and challenges to implementation. Throughout, we highlight specific mechanisms of membrane disruption and suggest areas in need of further experimentation. We hope the concepts discussed in our review inspire scientists and engineers with further ideas to improve intracellular delivery.

Physical methods for gene transfer

The key impediment to the successful application of gene therapy in clinics is not the paucity of therapeutic genes. It is rather the lack of nontoxic and efficient strategies to transfer therapeutic genes into target cells. Over the past few decades, considerable progress has been made in gene transfer technologies, and thus far, three different delivery systems have been developed with merits and demerits characterizing each system. Viral and chemical methods of gene transfer utilize specialized carrier to overcome membrane barrier and facilitate gene transfer into cells. Physical methods, on the other hand, utilize various forms of mechanical forces to enforce gene entry into cells. Starting in 1980s, physical methods have been introduced as alternatives to viral and chemical methods to overcome various extra- and intracellular barriers that limit the amount of DNA reaching the intended cells. Accumulating evidence suggests that it is quite feasible to directly translocate genes into cytoplasm or even nuclei of target cells by means of mechanical force, bypassing endocytosis, a common pathway for viral and nonviral vectors. Indeed, several methods have been developed, and the majority of them share the same underlying mechanism of gene transfer, i.e., physically created transient pores in cell membrane through which genes get into cells. Here, we provide an overview of the current status and future research directions in the field of physical methods of gene transfer.

Single-cell optoporation and transfection using femtosecond laser and optical tweezers

In this paper, we demonstrate a new single-cell optoporation and transfection technique using a femtosecond Gaussian laser beam and optical tweezers. Tightly focused near-infrared (NIR) femtosecond laser pulse was employed to transiently perforate the cellular membrane at a single point in MCF-7 cancer cells. A distinct technique was developed by trapping the microparticle using optical tweezers to focus the femtosecond laser precisely on the cell membrane to puncture it. Subsequently, an external gene was introduced in the cell by trapping and inserting the same plasmid-coated microparticle into the optoporated cell using optical tweezers. Various experimental parameters such as femtosecond laser exposure power, exposure time, puncture hole size, exact focusing of the femtosecond laser on the cell membrane, and cell healing time were closely analyzed to create the optimal conditions for cell viability. Following the insertion of plasmid-coated microparticles in the cell, the targeted cells exhibited green fluorescent protein (GFP) under the fluorescent microscope, hence confirming successful transfection into the cell. This new optoporation and transfection technique maximizes the level of selectivity and control over the targeted cell, and this may be a breakthrough method through which to induce controllable genetic changes in the cell.

Physical non-viral gene delivery methods for tissue engineering

The integration of gene therapy into tissue engineering to control differentiation and direct tissue formation is not a new concept; however, successful delivery of nucleic acids into primary cells, progenitor cells, and stem cells has proven exceptionally challenging. Viral vectors are generally highly effective at delivering nucleic acids to a variety of cell populations, both dividing and non-dividing, yet these viral vectors are marred by significant safety concerns. Non-viral vectors are preferred for gene therapy, despite lower transfection efficiencies, and possess many customizable attributes that are desirable for tissue engineering applications. However, there is no single non-viral gene delivery strategy that "fits-all" cell types and tissues. Thus, there is a compelling opportunity to examine different non-viral vectors, especially physical vectors, and compare their relative degrees of success. This review examines the advantages and disadvantages of physical non-viral methods (i.e., microinjection, ballistic gene delivery, electroporation, sonoporation, laser irradiation, magnetofection, and electric field-induced molecular vibration), with particular attention given to electroporation because of its versatility, with further special emphasis on Nucleofection™. In addition, attributes of cellular character that can be used to improve differentiation strategies are examined for tissue engineering applications. Ultimately, electroporation exhibits a high transfection efficiency in many cell types, which is highly desirable for tissue engineering applications, but electroporation and other physical non-viral gene delivery methods are still limited by poor cell viability. Overcoming the challenge of poor cell viability in highly efficient physical non-viral techniques is the key to using gene delivery to enhance tissue engineering applications.

Optical injection of mammalian cells using a microfluidic platform

The use of a focused laser beam to create a sub-micron hole in the plasma membrane of a cell (photoporation), for the selective introduction of membrane impermeable substances (optical injection) including nucleic acids (optical transfection), is a powerful technique most commonly applied to treat single cells. However, particularly for femtosecond photoporation, these studies have been limited to low throughput, small-scale studies, because they require sequential dosing of individual cells. Herein, we describe a microfluidic photoporation system for increased throughput and automated optical injection of cells. Hydrodynamic focusing is employed to direct a flow of single-file cells through a focused femtosecond laser beam for photoporation. Upon traversing the beam, a number of transient pores potentially open across the extracellular membrane, which allows the uptake of the surrounding fluid media into the cytoplasm, also containing the chosen injection agent. The process is entirely automated and a rate of 1 cell/sec could readily be obtained, enabling several thousand cells to be injected per hour using this system. The efficiency of optically injecting propidium iodide into HEK293 mammalian cells was found to be 42 ± 8%, or 28 ± 4% taking into account the requirement of post-injection viability, as tested using Calcein AM. This work now opens the way for combining photoporation with microfluidic analyses, sorting, purification or on-chip cell culture studies.

Single cell optical transfection

The plasma membrane of a eukaryotic cell is impermeable to most hydrophilic substances, yet the insertion of these materials into cells is an extremely important and universal requirement for the cell biologist. To address this need, many transfection techniques have been developed including viral, lipoplex, polyplex, capillary microinjection, gene gun and electroporation. The current discussion explores a procedure called optical injection, where a laser field transiently increases the membrane permeability to allow species to be internalized. If the internalized substance is a nucleic acid, such as DNA, RNA or small interfering RNA (siRNA), then the process is called optical transfection. This contactless, aseptic, single cell transfection method provides a key nanosurgical tool to the microscopist-the intracellular delivery of reagents and single nanoscopic objects. The experimental possibilities enabled by this technology are only beginning to be realized. A review of optical transfection is presented, along with a forecast of future applications of this rapidly developing and exciting technology.

Cellular laserfection

Many studies in modern biology often rely on the introduction of a foreign molecule (i.e., transfection), be it DNA plasmids, siRNA molecules, protein biosensors, labeled tracers, and so on, into cells in order to answer the important questions of today's science. Many different methods have been developed over time to facilitate cellular transfection, but most of these methods were developed to work with a specific type of molecule (usually DNA plasmids) and none work well enough with difficult, sensitive, or primary cells to meet the needs of current life science researchers. A novel procedure that uses laser light to gently permeabilize large number of cells in a very short time has been developed and is described in detail in this chapter. This method allows difficult cells to be efficiently transfected in a high-throughput manner, with a wide variety of molecules, with extremely low toxicity.