Electroporation Method Research Articles

Efficient homology-directed gene editing by CRISPR/Cas9 in human stem and primary cells using tube electroporation

CRISPR/Cas9 efficiently generates gene knock-out via nonhomologous end joining (NHEJ), but the efficiency of precise homology-directed repair (HDR) is substantially lower, especially in the hard-to-transfect human stem cells and primary cells. Herein we report a tube electroporation method that can effectively transfect human stem cells and primary cells with minimal cytotoxicity. When applied to genome editing using CRISPR/Cas9 along with single stranded DNA oligonucleotide (ssODN) template in human induced pluripotent stem cells (iPSCs), up to 42.1% HDR rate was achieved, drastically higher than many reported before. We demonstrated that the high HDR efficiency can be utilized to increase the gene ablation rate in cells relevant to clinical applications, by knocking-out β2-microglobulin (B2M) in primary human mesenchymal stem cells (MSCs, 37.3% to 80.2%), and programmed death-1 (PD-1) in primary human T cells (42.6% to 58.6%). Given the generality and efficiency, we expect that the method will have immediate impacts in cell research as well as immuno- and transplantation therapies.

MiR-132-3p regulates proliferation of endothelial progenitor cells mediated by FOXO1

Objective To investigate the effect of miR-132-3p on the proliferation of endothelial progenitor cells and its regulatory mechanism in order to provide a new theoretical basis for the treatment of deep venous thrombosis. Methods Real-time quantitative PCR (qPCR) was used to detect the expression of miR-132-3p in the plasma and endothelial progenitor cells of 27 healthy volunteers and 22 thrombus patients, and in endothelial progenitor cells under normoxic and hypoxic conditions. The miR-132-3p analogue and the specific siRNA were transferred into endothelial progenitor cells by the electroporation method. The effect of miR-132-3p on the proliferation of endothelial progenitor cells was detected using MMT and Cell Counting Kit-8 (CCK-8) methods. The effects of miR-132-3p on the expression of FOXO1 in endothelial cells were analyzed using the luciferase assay and western blots. Results The expression of miR-132-3p in clinical patients with thrombosis was significantly decreased to 0.45 ± 0.05 times of that of the healthy volunteers (P<0.05). The expression of miR-132-3p in endothelial progenitor cells under hypoxia was down-regulated to (0.23 ± 0.13) times of that of under normoxia (P<0.05). The expression of miR-132-3p of experiment group under hypoxia was up-regulated to (15.72 ± 2.06) times of that of control group (P<0.05). MMT assay showed that the proliferation of cells in the experimental group under hypoxic condition was up-regulated to (7.79 ±1.37) times of that in the control group (P<0.01). CCK-8 assay showed that cell proliferation in experimental group was up-regulated to (6.46 ± 0.38) times of that in the control group (P<0.01). Software analysis showed that FOXO1 was a direct target of miR-132-3p. Luciferase activity of miR-132-3p mimics transfected endothelial progenitor cells under hypoxic conditions were 0.47 times of that in siRNA treatment group. Western blot showed that the expression of FOXO1 protein in endothelial progenitor cells transfected with miR-132-3p mimics in hypoxia was 0.18 times of that in siRNA treatment group. Conclusions Compared with healthy volunteers, miR-132-3p expression in the blood of patients with thrombosis was significantly reduced that can promote transcription of the FOXO1 gene (and protein expression) and inhibit the proliferation of endothelial progenitor cells. It could be closely related to the formation of venous thrombosis. Key words: Endothelial progenitor cells; miRNA; miRNA-132-3p; Mimic; Hypoxia; Cell proliferation; FOXO1; Thrombosis

Mechanisms of antimelanoma effect of oat β-glucan supported by electroporation

There are still not specified mechanisms how beta-glucan molecules are transported into cells. Supposing, beta-glucan toxicity against tumor cells may be related to the overexpression of the transporter responsible for the transport of glucose molecules in the cells. In this case, glucans - polymers composed of glucose units are much more up-taken by tumor than normal cells. Increased GLUT1 (Glucose Transporter Type 1) expression has been demonstrated earlier in malignant melanomas. GLUT1 expression promotes glucose uptake and cell growth in that cells. Also, in human melanoma tissues a significant correlation between GLUT1 expression and mitotic activity was found.The aim of the study was to verify if oat β-glucan (OβG) is delivered into cells by GLUT-1 membrane protein. To check it out we blocked GLUT1 transporters by an inhibitor WZB117 and then we investigated cells viability with and without reversible electroporation (EP).The obtained results bring us to elucidate the mechanism of transport of the OβG into the cells is GLUT-1 dependent and moreover can be supported by EP method.

Insights into Membrane Translocation of Protegrin Antimicrobial Peptides by Multistep Molecular Dynamics Simulations.

Protegrin-1 (PG-1) is a cationic arginine-rich antimicrobial peptide. It is widely accepted that PG-1 induces membrane disruption by forming pores that lead to cell death. However, the insertion mechanism for these highly cationic peptides into the hydrophobic membrane environment is still poorly understood at the molecular scale. It has previously been determined that the association of arginine guanidinium and lipid phosphate groups results in strong bidentate bonds that stabilize peptide–lipid complexes. It has also been suggested that arginine residues are able to drag phosphate groups as they insert inside the membrane to form a toroidal pore. However, whether bidentate bonds play a significant role in inducing a pore formation remains unclear. To investigate the role of bidentate complexes in PG-1 translocation, we conducted molecular dynamics simulations. Two computational electroporation methods were implemented to examine the translocation process. We found that PG-1 could insert into the membrane, provided the external electric potential is large enough to first induce a water column or a pore within the lipid bilayer membrane. We also found that the highly charged PG-1 is capable in itself of inducing molecular electroporation. Substitution of arginines with charge-equivalent lysines showed a markedly reduced tendency for insertion. This indicates that the guanidinium group likely facilitates PG-1 translocation. Potential of mean force calculations suggests that peptide insertion inside the hydrophobic environment of the membrane core is not favored. We found that formation of a water column or a pore might be a prerequisite for PG-1 translocation. We also found that PG-1 can stabilize the pore after insertion. We suggest that PG-1 could be a pore inducer and stabilizer. This work sheds some light on PG-1 translocation mechanisms at the molecular level. Methods presented in this study may be extended to other arginine-rich antimicrobial and cell-penetrating peptides.

Electroporation-assisted discrimination of normal, benign and cancerous human gastric tissues by OCT and diffuse reflectance spectra images

The purpose of this study is to illustrate experimentally the optical coherence tomography (OCT) signal slope and diffuse reflectance (DR) spectra of 30% and 80% glycerol combined with electroporation (EP) diffusion in normal, benign and cancerous human gastric tissues in vitro. The results of OCT showed that the permeability coefficients of 80% and 30% glycerol (both with and without EP) have the following trend: human cancerous gastric tissue > human benign gastric tissue > human normal gastric tissue under the same conditions. The permeability coefficient of the 30% glycerol group is larger than that of the 80% glycerol group under the same circumstances; the permeability coefficient of glycerol combined with the EP group is larger than that without the EP group under the same conditions. The permeability coefficient and the reduction of the DR spectra have perfect linear correlation (R2 = 0.9745). The research results suggest that OCT and the DR spectra combined with an optical clearing agent (glycerol) and the EP method can potentially become a powerful tool for the early diagnosis and monitoring of human gastric cancer.

N-WASP regulates cortical neuron migration through its polyPro and VCA domains

Cortical neuron migration in the developing mouse forebrain is a complex process, which contains several steps related to cytoskeleton dynamics and remodeling. Neural Wiskott-Aldrich syndrome protein (N-WASP), a member of the WASP-WAVE family, regulates actin cytoskeleton reorganization through the binding of its VCA domain to the Arp2/3 complex. Here we report expression patterns of N-WASP gene in the mouse developing embryonic cortex (E12.5~ E18.5) and find its expression levels are decreased during embryonic development. By using in utero electroporation (IUE) method, we find that either N-WASP overexpression or knockdown impairs cortical neuron migration, and the defects of cortical neuron migration caused by N-WASP overexpression are much more severe than that by its knockdown. N-WASP protein contains four domains: WH1, GBD, polyPro, and VCA. We generated a series of dominant negative N-WASP mutants by modifying these domains. Overexpression of N-WASP mutant lacking domain polyPro, VCA, or WH1, impairs cortical neuron migration. However, overexpression of N-WASP with the H208D point mutation, which abolishes the Cdc42 binding to N-WASP, causes only a marginal defect of cortical neuron migration. Finally, overexpression of the individual domain polyPro or VCA, but not WH1, can recapitulate the defects by N-WASP overexpression. However, overexpression of WH1-GBD fragment has no apparent effect on cortical neuron migration. In conclusion, our data demonstrate that N-WASP regulates cortical neuron migration mainly through its polyPro and VCA domains.

Non-viral and viral delivery solutions for next generation cell therapy

Abstract The successes of chimeric antigen receptor (CAR) T cells in treating blood cancers have highlighted the cell therapy era. However, the difficulty of delivering molecules into immune cells has been an obstacle to more rapid advancement. Here we present an innovative large-scale Lentivirus (LV) production system as a solution to lower the cost and time of viral production. On the other hand, the next generation cell therapy will rely heavily on gene editing, especially in a safer non-viral integration manner. We have demonstrated that our novel non-viral all-in-one electroporation method provides high efficiency of gene knock-in in primary T cells. The new LV production system was developed for the clinical grade production of lentiviral vectors (LVVs) on a large-scale serum-free suspension platform. This technology employs a newly developed propriety set of GMP reagents comprising of culture media, suspension cells, transfection reagent and boosting enhancers. The system is able to deliver greater than 1 × 108 (TU/mL) functional titer with un-concentrated LVVs. For CRISPR/Cas9 gene editing in primary T cells, we were able to reach more than 90% knockout efficiency for most genes we tested, including T cell receptor (TCR), with Cas9 RNP electroporation using Neon Transfection System. More importantly, gene knock-in efficiency can be reached to greater than 30% with all-in-one electroporation, which delivers Cas9 RNP and donor DNA in one reaction using our newly developed electroporation buffer. Moreover, TCR knockout in addition to a knock-in at another locus can also be done in a single electroporation using our all-in-one method, which is ideal for developing next generation CAR and TCR-T cells.

Establishment of a genetic transformation system for hairy root culture of Erigeron breviscapus

The electroporation method was performed to transfer plasmid DNA of PBI-1300 carrying GFP gene into Agrobacterium rhizogenes C₅₈C₁ strains. Mediated by A. rhizogenes C₅₈C₁, the GFP gene were transformed into Erigeron breviscapus aseptic leaves by leaf disc method, then the hairy roots were induced and the infected hairy roots were screened by hygromycin resistance. The chromosomal DNA of the hairy root was used as the templates for the PCR amplification with the GFP-specific primers and then the expected amplified DNA bands appeared, the green fluorescent of GFP in the cut hairy roots was observed by two-photon microscope. These results indicated that GFP gene was integrated into the genome of E. breviscapus and was expressed stably. This study laid the groundwork for foreign gene high-efficiency expression inthe genetic transformation system for hairy root culture of E. breviscapus.

The effects of different concentrations of ccBA-GFP promoter with electroporation methods on the quality of koi sperm (Cyprinus carpio var. koi)

The effectiveness of the use of promoter concentration which will be inserted into the Koi sperm as the medium of gene transfer is important. The objective of this research is to find out the influence of the adding of different concentrations of the ccBA-GFP promoter with electroporation methods to the motility, viability and the fertilization rate of the Koi sperm. This study was conducted at Central Lab of Life Sciences Brawijaya University in April 2017. Electroporation methods were conducted by using 30-volt voltage, 4 times shocks with 0.5 seconds per shock. The treatment of different concentration was done through 3 types of ccBA-GFP promoter concentration, namely: 10 ng/µl, 30 ng/µl, and 50 ng/µl. The best motility percentage with the score of 4 is at the treatment A (10ng/µl concentration), the best viability percentage is 77.83 % at the treatment A (10 ng/µl concentration) and the best fertilization rate is 73.09 % at the treatment A (10 ng/µl concentration). The result shows that there is a relationship between the treatment given to the motility and viability of the Koi sperm, at which, the higher the shocks, the lower the percentage of the motility and viability of the Koi sperm.

Potential use of superparamagnetic iron oxide nanoparticles for in vitro and in vivo bioimaging of human myoblasts

Myocardial infarction (MI) is one of the most frequent causes of death in industrialized countries. Stem cells therapy seems to be very promising for regenerative medicine. Skeletal myoblasts transplantation into postinfarction scar has been shown to be effective in the failing heart but shows limitations such, e.g. cell retention and survival. We synthesized and investigated superparamagnetic iron oxide nanoparticles (SPIONs) as an agent for direct cell labeling, which can be used for stem cells imaging. High quality, monodisperse and biocompatible DMSA-coated SPIONs were obtained with thermal decomposition and subsequent ligand exchange reaction. SPIONs’ presence within myoblasts was confirmed by Prussian Blue staining and inductively coupled plasma mass spectrometry (ICP-MS). SPIONs’ influence on tested cells was studied by their proliferation, ageing, differentiation potential and ROS production. Cytotoxicity of obtained nanoparticles and myoblast associated apoptosis were also tested, as well as iron-related and coating-related genes expression. We examined SPIONs’ impact on overexpression of two pro-angiogenic factors introduced via myoblast electroporation method. Proposed SPION-labeling was sufficient to visualize firefly luciferase-modified and SPION-labeled cells with magnetic resonance imaging (MRI) combined with bioluminescence imaging (BLI) in vivo. The obtained results demonstrated a limited SPIONs’ influence on treated skeletal myoblasts, not interfering with basic cell functions.

Artocarpus altilis compound based study for anti-cancer proliferation on Hela cell via electroporation method

Survivors of cancer often have multiple permanent side effects due to the usage of drugs during the therapy. This study combining the compound artocarpus altilis and the optimized electroporation method for maximum HeLa cancer cell anti-proliferation activity. Artocarpus altilis or also known as sukun, is a natural compound, which has the capability to treat cancer as it has anti-proliferation effect in cancerous cells. Hence, in this current work, voltage amplitude of 200V/cm, 400V/cm, 600V/cm, 800V/cm, 100V/cm with 30µs of pulse duration used in electroporating HeLa cancer cell to look at the effects on cell’s extension, cell size and growth rate. However, this study requires further investigation to identify the optimal electroporation conditions that can be applied to effectively deliver the artocarpus altilis extracts to the HeLa cancer cells in order to inhibit its proliferation.

Overcoming Antimicrobial Resistance in Bacteria Using Bioactive Magnetic Nanoparticles and Pulsed Electromagnetic Fields.

Nisin is a known bacteriocin, which exhibits a wide spectrum of antimicrobial activity, while commonly being inefficient against Gram-negative bacteria. In this work, we present a proof of concept of novel antimicrobial methodology using targeted magnetic nisin-loaded nano-carriers [iron oxide nanoparticles (NPs) (11–13 nm) capped with citric, ascorbic, and gallic acids], which are activated by high pulsed electric and electromagnetic fields allowing to overcome the nisin-resistance of bacteria. As a cell model the Gram-positive bacteria Bacillus subtilis and Gram-negative Escherichia coli were used. We have applied 10 and 30 kV cm-1 electric field pulses (100 μs × 8) separately and in combination with two pulsed magnetic field protocols: (1) high dB/dt 3.3 T × 50 and (2) 10 mT, 100 kHz, 2 min protocol to induce additional permeabilization and local magnetic hyperthermia. We have shown that the high dB/dt pulsed magnetic fields increase the antimicrobial efficiency of nisin NPs similar to electroporation or magnetic hyperthermia methods and a synergistic treatment is also possible. The results of our work are promising for the development of new methods for treatment of the drug-resistant foodborne pathogens to minimize the risks of invasive infections.

Reproductive technologies for the generation and maintenance of valuable animal strains.

Many types of mutant and genetically engineered strains have been produced in various animal species. Their numbers have dramatically increased in recent years, with new strains being rapidly produced using genome editing techniques. In the rat, it has been difficult to produce knockout and knock-in strains because the establishment of stem cells has been insufficient. However, a large number of knockout and knock-in strains can currently be produced using genome editing techniques, including zinc-finger nuclease (ZFN), transcription activator-like effector nuclease (TALEN), and the clustered regularly interspaced short palindromic repeats (CRISPR) and CRISPR-associated protein 9 (Cas9) system. Microinjection technique has also contributed widely to the production of various kinds of genome edited animal strains. A novel electroporation method, the “Technique for Animal Knockout system by Electroporation (TAKE)” method, is a simple and highly efficient tool that has accelerated the production of new strains. Gamete preservation is extremely useful for maintaining large numbers of these valuable strains as genetic resources in the long term. These reproductive technologies, including microinjection, TAKE method, and gamete preservation, strongly support biomedical research and the bio-resource banking of animal models. In this review, we introduce the latest reproductive technologies used for the production of genetically engineered animals, especially rats, using genome editing techniques and the efficient maintenance of valuable strains as genetic resources. These technologies can also be applied to other laboratory animals, including mice, and domestic and wild animal species.

Live-cell microscopy of meiosis in spermatocytes.

For the analysis of the molecular mechanisms underlying mammalian meiosis, the establishment of a transient gene expression system for meiocytes has been long awaited. We have established an efficient in vivo electroporation method for live mouse testis and demonstrate short-term transgene expression in spermatocytes. By expressing specific marker proteins fused with GFP, this technique is applicable not only to fixed cell observations after transgene expression but also to live imaging to dissect dynamic cellular events in live spermatocytes. The protocol is also adapted to the dissection of mutant phenotypes with defective chromosome movement during meiotic prophase I, as well as a phenotype rescue assay by expressing functional cDNAs in mutant testes.

Efficient Gene Transfer to Myelinating Schwann Cells in the Rodent Sciatic Nerve Using In Vivo Electroporation.

To study the signaling mechanism of the development and maintenance of myelinating Schwann cells (SCs) in the peripheral nervous system, in vivo techniques for SC-selective gene manipulation are useful. The present protocol describes an in vivo electroporation method that allows efficient transfection of myelinating SCs in rodent sciatic nerves. This technique allows us to introduce the genes of interest into myelinating SCs by simply applying electric pulses to the sciatic nerve after plasmid DNA injection.

Investigating Evolutionarily Conserved Molecular Mechanisms Controlling Gene Expression in the Notochord.

Ascidian embryos have been employed as model systems for studies of developmental biology for well over a century, owing to their desirable blend of experimental advantages, which include their rapid development, traceable cell lineage, and evolutionarily conserved morphogenetic movements. Two decades ago, the development of a streamlined electroporation method drastically reduced the time and cost of transgenic experiments, and, along with the elucidation of the complete genomic sequences of several ascidian species, propelled these simple chordates to the forefront of the model organisms available for studies of regulation of gene expression. Numerous ascidian sequences with tissue-specific enhancer activity were isolated and rapidly characterized through systematic in vivo experiments that would require several weeks in most other model systems. These cis-regulatory sequences include a large collection of notochord enhancers, which have been used to visualize notochord development in vivo, to generate mutant phenotypes, and to knock down genes of interest. Moreover, their detailed characterization has allowed the reconstruction of different branches of the notochord gene regulatory network. This chapter describes how the use of transgenic techniques has rendered the ascidian Ciona a competitive model organism for studies of notochord development, evolution, and gene regulation.

Sonic Hedgehog Regulation of the Neural Precursor Cell Fate During Chicken Optic Tectum Development.

During nervous system development, neurons project axons over long distances to reach the appropriate targets for correct neural circuit formation. Sonic hedgehog (Shh) is a secreted protein and plays a key role in regulating vertebrate embryogenesis, especially in central nervous system (CNS) patterning, including neuronal migration and axonal projection in the brain and spinal cord. In the developing ventral midbrain, Shh is sufficient to specify a striped pattern of cell fates. Little is known about the molecular mechanisms underlying the Shh regulation of the neural precursor cell fate during the optic tectum development. Here, we aimed at studying how Shh might regulate chicken optic tectum patterning. In the present study, in ovo electroporation methods were employed to achieve the overexpression of Shh in the optic tectum during chicken embryo development. Besides, the study combined in ovo electroporation and neuron isolation culturing to study the function of Shh in vivo and in vitro. The fluorescent immunohistochemistry methods were used to check the related indicators. The results showed that Shh overexpression caused 87.8% of cells to be distributed to the stratum griseum central (SGC) layer, while only 39.3% of the GFP-transfected cells resided in the SGC layer in the control group. Shh overexpression also reduced the axon length in vivo and in vitro. In conclusion, we provide evidence that Shh regulates the neural precursor cell fate during chicken optic tectum development. Shh overexpression impairs neuronal migration and may affect the fate determination of transfected neurons.

6-Desaturase-Like Encoding Gene Introduction in Catfish (Clarias gariepinus)

African catfish (Clarias gariepinus) is one of the economically valuable aquaculture fish species in Indonesia. This research was aimed to produce F0 transgenic catfish carrying masou salmon Δ6-desaturase-like (OmΔ6FAD) gene. The Δ6-desaturase enzyme is involved in highly unsaturated fatty acid biosynthesis. Transgenic catfish was produced by sperm-mediated gene transfer using electroporation method. In this study, as the first step, sperms were electroporated with three different OmΔ6FAD concentration (25, 50, and 100 µg mL-1) to have the highest sperm viability after electroporation (125 V/cm, pulse frequency 5 times, pulse length 30 millisecond, pulse interval 0.1 second). The highest sperm viability and sperm carrying OmΔ6FAD were obtain at 100 µg mL-1. This concentration was then used to produce F0 transgenic catfish in the second step. Sperm motility, sperm viability, fertilization rate, hatching rate, and larval survival at 14 days after hatching were the same as the controls (p&gt;0.05). Genomic DNA was extracted from caudal fin and then used as template to identify transgenic F0 by PCR method using specific primer for OmΔ6FAD gene. The PCR result showed that 53.84% of F0 carried OmΔ6FAD gene. The result of fatty acid analysis showed that EPA and DHA contents of F0 transgenic fish and non-transgenic fish were similar. Keywords: catfish, Δ6-desaturase-like gene, fatty acids, electroporation

Generation of gene-edited rats by delivery of CRISPR/Cas9 protein and donor DNA into intact zygotes using electroporation

The generation of gene-edited animals using the CRISPRs/Cas9 system is based on microinjection into zygotes which is inefficient, time consuming and demands high technical skills. We report the optimization of an electroporation method for intact rat zygotes using sgRNAs and Cas9 protein in combination or not with ssODNs (~100 nt). This resulted in high frequency of knockouts, between 15 and 50% of analyzed animals. Importantly, using ssODNs as donor template resulted in precise knock-in mutations in 25–100% of analyzed animals, comparable to microinjection. Electroporation of long ssDNA or dsDNA donors successfully used in microinjection in the past did not allow generation of genome-edited animals despite dsDNA visualization within zygotes. Thus, simultaneous electroporation of a large number of intact rat zygotes is a rapid, simple, and efficient method for the generation of a variety of genome-edited rats.

Inducing Cre-lox Recombination in Mouse Cerebral Cortex Through &lt;em&gt;In Utero&lt;/em&gt; Electroporation

Cell-autonomous neuronal functions of genes can be revealed by causing loss or gain of function of a gene in a small and sparse population of neurons. To do so requires generating a mosaic in which neurons with loss or gain of function of a gene are surrounded by genetically unperturbed tissue. Here, we combine the Cre-lox recombination system with in utero electroporation in order to generate mosaic brain tissue that can be used to study the cell-autonomous function of genes in neurons. DNA constructs (available through repositories), coding for a fluorescent label and Cre recombinase, are introduced into developing cortical neurons containing genes flanked with loxP sites in the brains of mouse embryos using in utero electroporation. Additionally, we describe various adaptations to the in utero electroporation method that increase survivability and reproducibility. This method also involves establishing a titer for Cre-mediated recombination in a sparse or dense population of neurons. Histological preparations of labeled brain tissue do not require (but can be adapted to) immunohistochemistry. The constructs used guarantee that fluorescently labeled neurons carry the gene for Cre recombinase. Histological preparations allow morphological analysis of neurons through confocal imaging of dendritic and axonal arbors and dendritic spines. Because loss or gain of function is achieved in sparse mosaic tissue, this method permits the study of cell-autonomous necessity and sufficiency of gene products in vivo.