Enhanced gene transfection and induction of apoptosis in melanoma cells by branched poly(β-amino ester)s with uniformly distributed branching units

Melanoma, one of the most devastating forms of skin cancer, currently lacks effective clinical treatments. Delivery of functional genes to modulate specific protein expression to induce melanoma cell apoptosis could be a promising therapeutic approach. However, transfecting melanoma cells using non-viral methods, particularly with cationic polymers, presents significant challenges. In this study, we synthesized three branched poly(β-amino ester)s (HPAEs) with evenly distributed branching units but varying space lengths through a two-step "oligomer combination" strategy. The unique topological structure enables HPAEs to condense DNA to form nano-sized polyplexes with favorable physiochemical properties. Notably, HPAEs, especially HPAE-2 with intermediate branching unit space length, demonstrated significantly higher gene transfection efficiency than the leading commercial gene transfection reagent, jetPRIME, in human melanoma cells. Furthermore, HPAE-2 efficiently delivered the Bax-encoding plasmid into melanoma cells, leading to a pronounced pro-apoptotic effect without causing noticeable cytotoxicity. This study establishes a potent non-viral platform for gene transfection of melanoma cells by harnessing the distribution of branching units, paving the way for potential clinical applications of gene therapy in melanoma treatment.

Optimized Calcium-Phosphate-Based Co-transfection of Tau and tdTomato into Human iPSC-Derived Neurons for the Study of Intracellular Distribution of Wild-type and Mutant Human Tau

The study of Tau protein in disease-relevant neuronal cells in culture requires efficient delivery systems for transfection of exogenous Tau and also modulators and interactors of Tau. Transfection of cultivated cells using calcium phosphate precipitation is a simple and cost-effective approach, also for difficult-to-transfect and sensitive cells such as primary neurons. Because of its low cell toxicity and ease of use, the Ca2+-phosphate transfection method is one of the most widely used gene transfer procedures in neuroscience. However, Ca2+-phosphate transfection efficacy in neurons is poor, often in the range of 1-5%, limiting its use in functional investigations. Here, we outline our improved Ca2+-phosphate transfection methodology for human iPSC-derived neurons that yields a reasonable efficiency (20-30% for bright volume markers) without apparent effects on cell health. We have used it to introduce wild-type and mutant human Tau with and without co-transfection of a volume marker (used here: tdTomato). In sum, our procedure can deliver neuronal genes (e.g., MAPT) using typical eukaryotic expression vectors (e.g., using CMV promoter) and is optimized for transfection of human iPSC-derived neurons.

Optimization of piggyBac Transposon System Electrotransfection in Sheep Fibroblasts

Electroporation is a non-viral mediated transfection technique, which has the advantages of being harmless, easy to operate, and less expensive. This transfection method can be used for almost all cell types and has gradually become the preferred transfection method for mammalian gene editing. However, further improvements are needed in electroporation efficiency. There is no universal standard electrotransfection step for different types of cells, and the inappropriate electroporation parameters will result in a low transfection efficiency and high cell mortality. Here, we systematically optimized the electrotransfection parameters of piggyBac transposon system into sheep fetal fibroblasts for the first time. We found that the cell transfection efficiency and cell viability could be improved by using traditional cell culture medium DMEM/F12 as an electroporation buffer, and simultaneously using the square-wave pulsing program of 200 V, 2 pulses, 20 ms length, and 20 μg DNA (3 μg/μL) in 4 mm cuvette, and the transfection efficiency and cell viability could eventually reach 78.0% and 40.9%, respectively. The purpose of this study is to provide a method reference and theoretical basis for the plasmid electrotransfection in mammal cells.

Diffusion coefficient of cationic liposomes during lipoplex formation determines transfection efficiency in HepG2 cells

Cationic lipid-based lipoplexes are well-known for gene delivery. To determine the relationship between physicochemical characteristics and transfection efficiency, cationic liposomes of different sizes were prepared and incubated with plasmid DNA at different temperatures to form lipoplexes. We found that the liposome diffusion coefficient during lipoplex formation strongly correlated with the physicochemical characteristics of lipoplexes, accessibility of plasmid DNA in lipoplexes, and logarithm of gene expression per metabolic activity. Clathrin-mediated endocytosis was the major route for lipoplexes comprising 100 nm-liposomes, as reported previously. As liposome size increased, the major route shifted to lipid raft-mediated endocytosis. In addition, macropinocytosis was observed for all liposome sizes. The role of reactive oxygen species might depend on liposome size and endocytosis. Information from this study would be useful for understanding cationic lipoplex-mediated transfection.

saKLK1-374 is more difficult to induce KLK1 expression in normal prostate cell lines than that in prostate cancer cell lines: Rethinking the universality of RNA activation

RNA activation, as a method of regulating gene expression at the transcriptional level, is far less widely used than RNA interference because of the insufficient understanding of the mechanism and the unstable success rate. It is necessary to analyze the failure cases of RNA activation to promote the application of RNA activation. When we validated the saRNAs designed to induce KLK1 expression, we found that saKLK1-374 can upregulate KLK1 expression in prostate tumor cell lines, but failed in normal prostate cell lines. To determine whether the RNA activation of normal cells is difficult only when the target gene is KLK1, we tested p21WAF1/CIP1 as the target gene in RNA activation experiments of normal and cancer prostate cells. Next, to determine whether the above phenomenon exists in other tissues, we used normal and cancerous bladder cells to perform RNA activation experiments with KLK1 and p21WAF1/CIP1 as targets. We have also extended the time from transfection to detection to evaluate whether a longer incubation time can make saRNA upregulate the target genes in normal cells. Fluorescently labeled dsRNA was transfected to evaluate the transfection efficiency, and the expression of Ago2 and IPO8 necessary for RNA activation was also detected. The p21WAF1/CIP1 could be significantly upregulated by saRNA in prostate cancer cells, but not in normal prostate cells. The expression of KLK1 in bladder-derived cell lines was extremely low and could not be induced by saRNA. The p21WAF1/CIP1 was upregulated by saRNA to a higher extent in bladder cancer cells but to a lower extent in normal bladder cells. Prolonging incubation time could not make saRNA induce the expression of target genes in normal cells. Compared with tumor cells used in this study, normal cells had lower transfection efficiency or lower expression of Ago2 and IPO8. Although it has been currently found that normal cell lines in the prostate and bladder might be more difficult to be successfully induced target gene expression by exogenous saRNA than tumor cells due to low transfection efficiency or Ago2 and IPO8 expression, it is not certain that this phenomenon occurs in other types of tissue. However, researchers still need to pay attention to the transfection efficiency and/or the expression levels of Ago2 and IPO8 when conducting RNA activation experiments in normal cells.

Preparation and characterization of a gemini surfactant-based biomimetic complex for gene delivery

Gemini surfactants (GS) have been explored as non-viral gene delivery systems. Nevertheless, their cytotoxicity and the limitations in the in vivo studies have impeded their development. To attenuate toxicity and further explore their possibilities in gene delivery, a series of GS (18-7-18)-based gene delivery systems complexed with red blood cell membranes (RBCM) or/and DOPE-PEG₂₀₀₀ (DP) were prepared and evaluated. EGFP-encoding plasmids were delivered via GS-based complexes and the efficiency of gene transfection was evaluated by imaging of the major organs after intravenous administration in mice and qPCR quantification in hepatocytes. In order to assess the safety of GS-based complexes, the hemolysis test, serum biochemical indices, H&E staining and CCK-8 test were examined. The results revealed that EGFP was primarily expressed in livers, and all complexes showed minimal acute toxicity to major organs. Moreover, we found that the dual incorporation of RBCM and DP could significantly elevate the transfection efficiency and cell viability in hepatocytes. Overall, the results indicated that GS-based complexes possessed great potential as vectors for gene delivery both in vivo and in vitro and the dual incorporation of RBCM and DP could be a promising gene delivery approach with high transfection efficacy and low toxicity.

Protoplast isolation and transient gene expression in different petunia cultivars

The protocol optimized for Petunia hybrida cv. Mirage Rose produced high protoplast yields in 3 out of other 11 cultivars (Damask White, Dreams White, and Opera Supreme White). Factors optimized in the protoplast transfection process showed that the best transfection efficiency (80%) was obtained using 2.5 × 10⁵ protoplast density, 40% polyethylene glycol (PEG) concentration, 10 µg plasmid DNA, and 15 min of transfection time. Assessing the usability of the protocol for other cultivars (Damask White, Dreams White, and Opera Supreme White), a reasonable protoplast transfection efficiency (⁓50%) was observed in the cultivars Dreams White and Opera Supreme White, with lower efficiency (⁓50%) observed in the cv. Damask White. The transient expression of enhanced green fluorescent protein (eGFP) in the nucleus of the transfected protoplasts of all cultivars was confirmed using PCR. This system could be valuable for genome editing of unwanted genes in petunias using the clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated 9 (Cas9) technology. Furthermore, it could contribute to other studies on protein subcellular localization, protein-protein interactions, and functional gene expression in the petunias.

Nucleic acid direct delivery to fibroblasts: a review of nucleofection and applications

The fibroblast is one of the ideal target cell candidates for cell-based gene therapy approaches to promote tissue repair. Gene delivery to fibroblasts by viral transfection has been confirmed to have high transfection efficiency. However, in addition to immunogenic effects of viruses, the random integration of viral genes may damage the genome, affect the cell phenotype or even cause cancerous mutations in the transfected cells. Due to these potential biohazards and unknown long-term risks, the clinical use of viral transfection has been very limited. In contrast, initial non-viral transfection methods have been simple and safe to implement, with low immunogenicity, insertional mutagenesis, and risk of carcinogenesis, but their transfection efficiency has been relatively low. Nucleofection, a more recent non-viral transfection method, now combines the advantages of high transfection efficiency and direct nucleic acid delivery to the nucleus with a high safety.Here, we reviewed recent articles on fibroblast nucleofection, summarized different research points, improved methods and application scopes, and opened up ideas for promoting the further improvement and development of fibroblast nucleofection to meet the needs of a variety of disease research and clinical applications.

An established kidney cell line from humpback grouper (Cromileptes altivelis) and its susceptibility to bacteria and heavy metals

Humpback grouper (Cromileptes altivelis), one kind of commercial fish with considerable economic value, has been recognized as a promising candidate for mariculture. In the wake of the development of aquaculture industry, the breeding density of C. altivelis has increased gradually, which gave rise to the occurrence of various pathogenic diseases. In our research, we established a new kidney cell line (designated as CAK) from humpback grouper and evaluated its susceptibility to bacteria and heavy metals. The results of our study showed that the optimal growth temperature was 26 °C, and optimal medium was L-15 supplemented with 20% fetal bovine serum (FBS). The sequencing of 18S rRNA gene indicated that CAK cell line was derived from C. altivelis. Chromosome analysis showed that the number of chromosome in CAK was 48. After being transfected of pEGFP-N3 plasmid, high transfection efficiency of CAK was observed, suggesting the potential to be used for the study of foreign functional genes. Moreover, the bacterial susceptibility results revealed that CAK cells were sensitive to Vibrio harveyi and Edwardsiella tarda, especially V. harveyi. Meanwhile, three heavy metals (Hg, Cu, and Cd) had toxic effects on the CAK cells with a dose-dependent manner. To sum up, the CAK cell line might be an ideal tool in vitro for analyzing the function of exogenous genes, bacterial susceptibility, and toxicity assay of heavy metals.

Evaluation of pentaerythritol-based and trimethylolpropane-based cationic lipidic materials for gene delivery

The chemical and physical structure of cationic liposomes pays an important effect on their gene transfection efficiency. Investigation on the structure-function relationship of cationic liposomes will guide the design of novel cationic liposomes with high transfection efficiency and biosafety. In this paper, two novel series of lipids based on the backbone of pentaerythritol and trimethylolpropane were discovered, and their gene transfection efficiencies were assayed in vitro. The four lipids 8c, 9c, 14b, and 15b, exhibited much better transfection efficiency in the HEK293 cell lines compared with Lipo2000, lipid 9c also showed good transfection efficiency in the SW480 cell lines. And the structure-efficiency relationship revealed that a hydroxyethyl polar head group boosted transfer potency in trimethylolpropane-type lipids, but reduced in pentaerythritol-type lipids.

Maintenance and gene electrotransfer efficiency of antibiotic resistance gene-free plasmids encoding mouse, canine and human interleukin-12 orthologues

Interleukin 12 (IL-12) is a cytokine used as a therapeutic molecule in cancer immunotherapy. Gene electrotransfer mediated delivery of IL-12 gene has reached clinical evaluation in the USA using a plasmid that in addition to IL-12 gene also carry an antibiotic resistance gene needed for its production in bacteria. In Europe however, European Medicines Agency recommends against the use of antibiotics during the production of clinical grade plasmids. We have prepared several antibiotic resistance gene-free plasmids using an antibiotic-free selection strategy called operator-repressor titration, including plasmids encoding mouse, canine and human IL-12 orthologues. The aim of this study was to evaluate the maintenance of these plasmids in bacterial culture and test their transfection efficiency using gene electrotransfer. Plasmid maintenance was evaluated by determining plasmid yields and topologies after subculturing transformed bacteria. Transfection efficiency was evaluated by determining the plasmid copy number, expression and cytotoxicity after gene electrotransfer to mouse, canine and human melanoma cells. The results demonstrated that our IL-12 plasmids without an antibiotic resistance gene are stably maintained in bacteria and provide sufficient IL-12 expression after in vitro gene electrotransfer; therefore, they have the potential to proceed to further in vivo evaluation studies.

Microfluidic mechanoporation for cellular delivery and analysis

Highly efficient intracellular delivery strategies are essential for developing therapeutic, diagnostic, biological, and various biomedical applications. The recent advancement of micro/nanotechnology has focused numerous researches towards developing microfluidic device-based strategies due to the associated high throughput delivery, cost-effectiveness, robustness, and biocompatible nature. The delivery strategies can be carrier-mediated or membrane disruption-based, where membrane disruption methods find popularity due to reduced toxicity, enhanced delivery efficiency, and cell viability. Among all of the membrane disruption techniques, the mechanoporation strategies are advantageous because of no external energy source required for membrane deformation, thereby achieving high delivery efficiencies and increased cell viability into different cell types with negligible toxicity. The past two decades have consequently seen a tremendous boost in mechanoporation-based research for intracellular delivery and cellular analysis. This article provides a brief review of the most recent developments on microfluidic-based mechanoporation strategies such as microinjection, nanoneedle arrays, cell-squeezing, and hydroporation techniques with their working principle, device fabrication, cellular delivery, and analysis. Moreover, a brief discussion of the different mechanoporation strategies integrated with other delivery methods has also been provided. Finally, the advantages, limitations, and future prospects of this technique are discussed compared to other intracellular delivery techniques.

Establishment of a new fish cell line from the brain of humpback grouper (Cromileptes altivelis) and its application in toxicology and bacterial susceptibility

Cromileptes altivelis, humpback grouper, belongs to the family Epinephelidae and is one popular farmed fish species because of its high economic value and ornamental value. However, more and more diseases outbreaks have been reported with C. altivelis aquaculture. Today, a new brain cell line of C. altivelis (named CAB) was established and characterized. Our results showed that CAB cells were suitable for growth at 26 °C in L-15 medium supplemented with 15% fetal bovine serum (FBS). The results of 18S rRNA gene sequencing confirmed that CAB cell line was derived from C. altivelis. Moreover, chromosomal aneuploidy was observed in CAB cells, and the modal chromosome number of CAB cells was 48 by chromosome analysis. In addition, CAB cells could transfect pEGFP-N3 plasmid with high transfection efficiency, indicating that CAB cell line has the potential to investigate the function of exogenous genes in vitro. Furthermore, the bacterial susceptibility results suggested that CAB cells were susceptive to Vibrio harveyi and Edwardsiella tarda. And, heavy metals (Hg, Cd, and Cu) were toxic to the CAB cells, and the toxic effect was dose-dependent. In summary, the CAB cell line could be a powerful tool in vitro to study functional genes and has the potential application in bacterial susceptibility and toxicology.

Effective cytocompatible nanovectors based on serine-derived gemini surfactants and monoolein for small interfering RNA delivery

Non-viral gene therapy based on gene silencing with small interfering RNA (siRNA) has attracted great interest over recent years. Among various types of cationic complexation agents, amino acid-based surfactants have been recently explored for nucleic acid delivery due to their low toxicity and high biocompatibility. Monoolein (MO), in turn, has been used as helper lipid in liposomal systems due to its ability to form inverted nonbilayer structures that enhance fusogenicity, thus contributing to higher transfection efficiency. In this work, we focused on the development of nanovectors for siRNA delivery based on three gemini amino acid-based surfactants derived from serine - (12Ser)₂N12, amine derivative; (12Ser)₂COO12, ester derivative; and (12Ser)₂CON12, amide derivative - individually combined with MO as helper lipid. The inclusion of MO in the cationic surfactant system influences the morphology and size of the mixed aggregates. Furthermore, the gemini surfactant:MO systems showed the ability to efficiently complex siRNA, forming stable lipoplexes, in some cases clearly depending on the MO content, without inducing significant levels of cytotoxicity. High levels of gene silencing were achieved in comparison with a commercially available standard indicating that these gemini:MO systems are promising candidates as lipofection vectors for RNA interference (RNAi)-based therapies.

Establishment and characterization of a new cell line from the muscle of humpback grouper (Cromileptes altivelis)

The humpback grouper (Cromileptes altivelis) is a commercially important species of the family Epinephelidae. With the development in aquaculture industry, C. altivelis breeding has gradually increased in volumetric production, leading to the occurrence of various diseases. In this study, we established a new cell line (CAM) derived from the muscle tissue of C. altivelis. Our results showed that the optimal growth temperature and working concentration of fetal bovine serum (FBS) of CAM cells were 28 °C and 15%, respectively. DNA sequencing and comparative analysis of 18S rRNA gene sequence showed that CAM cell line was originated from C. altivelis. Chromosome analysis showed that the modal chromosome number of CAM cells was 48. After transfection using pEGFP-N3 plasmid, CAM cells exhibited high transfection efficiency, indicating that CAM cells could be used in foreign gene expression studies. Further, cytotoxicity analysis revealed that CAM cells were sensitive to Vibrio harveyi and Edwardsiella tarda. Moreover, the cytotoxicity of heavy metals (Hg, Cd, and Cu) to CAM cells was dose-dependent. This CAM cell line might be used as an ideal tool in vitro for analyzing and understanding the mechanisms of pathogenesis, host-pathogen interactions, and toxicity assay of heavy metals.

Folic Acid/Peptides Modified PLGA-PEI-PEG Polymeric Vectors as Efficient Gene Delivery Vehicles: Synthesis, Characterization and Their Biological Performance

Polymeric vectors are safer alternatives for gene delivery owing to their advantages as compared to viral vectors. To improve the stability and transfection efficiency of poly(lactic-co-glycolic acid) (PLGA)- and poly(ethylenimine) (PEI)-based vectors, poly(ethylene glycol) (PEG), folic acid (FA), arginylglycylaspartic acid (RGD) peptides and isoleucine-lysine-valine-alanine-valine (IKVAV) peptides were employed and PLGA-PEI-PEG-FA and PLGA-PEI-PEG-RGD copolymers were synthesized. PLGA-PEI-PEG-FA/DNA, PLGA-PEI-PEG-RGD/DNA and PLGA-PEI-PEG-RGD/IKVAV/DNA nanocomplexes (NCs) were formed through bulk mixing. The structure and properties, including morphology, particle size, surface charge and DNA encapsulation, of NCs were studied. Robust NCs with spherical shape, uniform size distribution and slightly positive charge were able to completely bind DNA above their respective N/P ratios. The critical N/P ratio for PLGA-PEI-PEG-FA/DNA, PLGA-PEI-PEG-RGD/DNA and PLGA-PEI-PEG-RGD/IKVAV/DNA NCs was identified to be 12:1, 8:1 and 10:1, respectively. The covalent modification of PEI through a combination of biodegradable PLGA, hydrophilic PEG and targeting motifs significantly decreased the cytotoxicity of PEI. The developed NCs showed both N/P ratio and cell type-dependent transfection efficiency. An increase in N/P ratio resulted in increased transfection efficiency, and much improved transfection efficiency of NCs was observed above their respective critical N/P ratios. This study provides a promising means to produce polymeric vectors for gene delivery.

Systematic optimization of square-wave electroporation conditions for bovine primary fibroblasts

BACKGROUND

Gene transfer by electroporation is an established method for the non-viral mediated transfection of mammalian cells. Primary cells pose a particular challenge for electroporation-mediated gene transfer, since they are more vulnerable than immortalized cells, and have a limited proliferative capacity. Improving the gene transfer by using square wave electroporation in difficult to transfect cells, like bovine fetal fibroblasts, is a prerequisite for transgenic and further downstream experiments.

RESULTS

Here, bovine fetal fibroblasts were used for square-wave electroporation experiments in which the following parameters were systematically tested: electroporation buffer, electroporation temperature, pulse voltage, pulse duration, pulse number, cuvette type and plasmid DNA amount. For the experiments a commercially available square-wave generator was applied. Post electroporation, the bovine fetal fibroblasts were observed after 24 h for viability and reporter expression. The best results were obtained with a single 10 millisecond square-wave pulse of 400 V using 10 μg supercoiled plasmid DNA and 0.3 × 10⁶ cells in 100 μl of Opti-MEM medium in 4 mm cuvettes. Importantly, the electroporation at room temperature was considerably better than with pre-cooled conditions.

CONCLUSIONS

The optimized electroporation conditions will be relevant for gene transfer experiments in bovine fetal fibroblasts to obtain genetically engineered donor cells for somatic cell nuclear transfer and for reprogramming experiments in this species.

Highly uniform in-situ cell electrotransfection of adherent cultures using grouped interdigitated electrodes

Cell electrotransfection is an effective approach for transferring exogenous molecules into living cells by electric stimulation. The existing in-situ electrotransfection micro-devices for adherent cells exhibit the drawbacks of low transfection efficiency and low cell viability. An important reason for these drawbacks is the unequal exposure of cells to the electric field. It was found that cells growing directly below the energized electrodes experience a much lower electric field intensity when compared to the cells growing below the spacing area of the electrodes, resulting in low transfection with a strip-like pattern. Therefore, a new strategy for the in-situ electrotransfection of adherent cells growing in a standard 12-well plate is proposed in this study. By sequentially energizing electrodes arranged in a nested and non-contact manner, the cells were exposed to an overall equal intensity of the electric field, and thus a higher efficiency of transfection was achieved. The seven cell lines transfected using this method exhibited high transfection efficiency and high cell viability, demonstrating the potential for studying gene function.

A mechanistic explanation of the inhibitory role of the protein corona on liposomal gene expression

The past three decades have witnessed fast advances in the use of cationic liposome-DNA complexes (lipoplexes) for gene delivery applications. However, no lipoplex formulation has reached into the clinical practice so far. The primary drawback limiting clinical use of lipoplexes is the lack of mechanistic understanding of their low transfection efficiency (TE) in vivo. In physiological environments, lipoplexes are coated by a protein corona (PC) that mediates the interactions with the cell machinery. Here we show that the formation of PC can change the interactions of multicomponent (MC) lipoplexes with our cell model (i.e., HeLa). At the highest lipoplex concentration, the formation of PC can reduce the TE of MC lipoplexes from 60% to <5%. Combining dynamic light scattering and synchrotron small-angle X-ray scattering (SAXS), we clarify that the formation of PC modifies physical-chemical properties of MC lipoplexes so as to affect their TE. Moreover, we examined single transfection barriers by a combination of fluorescence-activated cell sorting, single-cell real-time fluorescence confocal microscopy, and synchrotron SAXS. We demonstrate that PC formation has the ability to modify the relative contribution of caveolae-mediated endocytosis and macropinocytosis in lipoplexes uptake, in favor of the latter, increasing accumulation of PC-decorated lipoplexes into degradative lysosomal compartments. Finally, we report evidences that PC reduces the structural stability of lipoplexes against solubilization by cellular lipids, likely favoring premature DNA release and cytosolic digestion by DNAase. These combined effects revealed here offer a comprehensive mechanistic explanation on the reason behind reduction in gene expression of MC lipoplexes.

Enhanced transfection efficiency by using a novel semi-attachment method in cell line and primary cells

DNA transfection in cells is a key technique in biological studies. Cationic liposomes can form nanoparticle complexes with DNA and are widely used for gene delivery in mammalian cells. However, the major drawback of cationic liposomes is their low transfection efficiency in hard-to-transfect cells, such as primary cultured cells. In this study, we established a novel semi-attachment transfection method that showed remarkably improved transfection efficiency compared with traditional forward transfection method.

Sonoporation as an Approach for siRNA delivery into T cells

Delivery of small interfering RNAs (siRNAs) into primary T cells is quite challenging because they are non-proliferating cells and are difficult to transfect with non-viral approaches. Because sonoporation is independent of the proliferation status of cells and siRNA acts in the cell cytoplasm, we investigated whether sonoporation could be used to deliver siRNA into mouse and human T cells. Cells mixed with Definity microbubbles and siRNA were sonicated with a non-focused transducer of center frequency 2.20 MHz producing ultrasound at a 10% duty cycle, pulse repetition frequency of 2.20 kHz and spatial average temporal average ultrasound intensity of 1.29 W/cm² for 5 s and then examined for siRNA fluorescence by flow cytometry analysis. These sonoporation conditions resulted in high-efficiency transfection of siRNA in mouse and human T cells. Further, the efficacy of siRNA delivery by sonoporation was illustrated by the successful visualization of decreased methylation-controlled J protein expression in mouse and human CD8 T cells via Western blot analysis. The results provide the first evidence that sonoporation is a novel approach to delivery of siRNA into fresh isolated mouse and human T cells in vitro, and might be used for in vivo studies in the future.

[PD-1 expression, mRNA level and cytotoxicity changes in CD19CAR-T cells]

目的

探讨CD19 CAR-T细胞培养过程中其PD-1蛋白、mRNA水平及细胞杀伤活性变化。

方法

收集6例外周血PD-1高表达恶性淋巴瘤患者、6例健康志愿者的外周血T细胞，作为CAR-T培养的T细胞来源。流式细胞术检测PD-1蛋白表达、PCR法检测PD-1 mRNA水平，CCK-8法检测细胞增殖，LDH法检测细胞杀伤活性。

结果

①PD-1高表达患者T细胞来源CD19 CAR-T细胞，与志愿者T细胞来源者相比，转染率无差异（P>0.05）；②PD-1高表达T细胞来源CAR-T细胞与PD-1抑制剂联合与否，以及健康志愿者CAR-T之间，细胞增殖差异无统计学意义（P>0.05）；③PD-1高表达T细胞与CAR-T细胞对淋巴瘤细胞株杀伤活性，低于二者联合PD-1抑制剂及志愿者CAR-T细胞（P<0.001），而PD-1高表达T细胞来源CAR-T细胞联合PD-1抑制剂与健康志愿者CAR-T细胞间差异无统计学意义（P>0.05）；④各组细胞培养过程中PD-1表达均下降，差异无统计学意义（P>0.05），但各组细胞培养过程中，PD-1 mRNA的变化差异无统计学意义（P>0.05）；⑤PD-1高表达T细胞来源CAR-T收获后，与PD-1抑制剂共培养与否，其PD-1表达差异无统计学意义（P>0.05），但CAR-T与淋巴瘤细胞株接触后，其PD-1表达随培养时间延长而增高，加入PD-1抑制剂可拮抗该作用；各组间PD-1 mRNA的变化差异无统计学意义（P>0.05）。

结论

PD-1高表达T细胞来源CAR-T细胞与肿瘤细胞接触后，其PD-1表达随培养时间延长而增高；而包括PD-1抑制剂在内，不能改变其PD-1 mRNA的表达。

Sugar alcohol-based polymeric gene carriers: Synthesis, properties and gene therapy applications

Advances in the field of nanomedicine have led to the development of various gene carriers with desirable cellular responses. However, unfavorable stability and physicochemical properties have hindered their applications in vivo. Therefore, multifunctional, smart nanocarriers with unique properties to overcome such drawbacks are needed. Among them, sugar alcohol-based nanoparticle with abundant surface chemistry, numerous hydroxyl groups, acceptable biocompatibility and biodegradable property are considered as the recent additions to the growing list of non-viral vectors. In this review, we present some of the major advances in our laboratory in developing sugar-based polymers as non-viral gene delivery vectors to treat various diseases. We also discuss some of the open questions in this field. STATEMENT OF SIGNIFICANCE: Recently, the development of sugar alcohol-based polymers conjugated with polyethylenimine (PEI) has attracted tremendous interest as gene delivery vectors. First, the natural backbone of polymers with their numerous hydroxyl groups display a wide range of hyperosmotic properties and can thereby enhance the cellular uptake of genetic materials via receptor-mediated endocytosis. Second, conjugation of a PEI backbone with sugar alcohols via Michael addition contributes to buffering capacity and thereby the proton sponge effect. Last, sugar alcohol based gene delivery systems improves therapeutic efficacy both in vitro and in vivo.

Development of a novel DsRed-NLS vector with a monopartite classical nuclear localization signal

The nuclear localization signal (NLS) marks proteins for transport to the nucleus and is used in various applications in many fields. NLSs are used to achieve efficient and stable transport of biomolecules. Previously, commercial vectors used in NLS studies contained three iterations of the NLS sequence, but these sequences can affect experimental results and alter protein function. Here, we investigated a new vector using a single classical NLS sequence with a mutation in pDsRed2-C1-wt to reduce experimental artifacts. In the newly constructed pDsRed2-C1-1NLS vector, the NLS sequence is placed near the multiple cloning sites of pDsRed2-C1-wt, and the multiple cloning site region was designed to facilitate insertion of the desired gene by site-directed mutagenesis. Fluorescent protein expression in the nucleus can be visually confirmed. The results show that the fluorescent protein was bound to the transport protein. The constructed vector had a cell survival rate of 89-95% and a transfection efficiency of 39-56% when introduced into animal cells, which are similar to those of other NLS vectors. Additionally, the constructed NLS vector can be used to demonstrate complementary binding between target proteins, and that the target protein is transported by the NLS transport system. Especially, we show that the vector can be useful for experiments involving the S100A10 gene. In addition, the constructed vector is useful for studies of genes and proteins that show potential for gene therapy or drug delivery applications.

Improved synthesis and characterization of cholesteryl oleate-loaded cationic solid lipid nanoparticles with high transfection efficiency for gene therapy applications

The development of new nanoparticle formulations that are capable of high transfection efficiency without toxicity is essential to provide new tools for gene therapy. However, the issues of complex, poorly reproducible manufacturing methods, and low efficiencies during in vivo testing have prevented translation to the clinic. We have previously reported the use of cholesteryl oleate as a novel excipient for solid lipid nanoparticles (SLNs) for the development of highly efficient and nontoxic nucleic acid delivery carriers. Here, we performed an extensive characterization of this novel formulation to make the scale up under Good Manufacturing Practice (GMP) possible. We also describe the complete physicochemical and biological characterization of cholesteryl oleate-loaded SLNs to ensure the reproducibility of this formula and the preservation of its characteristics before and after the lyophilization process. We defined the best manufacturing method and studied the influence of some parameters on the obtained nanoparticles using the Quality by Design (ICH Q8) guideline to obtain cholesteryl oleate-loaded SLNs that remain stable during storage and guarantee in vitro nucleic acid delivery efficacy. Our results indicate that this improved formulation is suitable for gene therapy with the possibility of scale-up the manufacturing of nanoparticles under GMP conditions.

Estimating transfection efficiency in differentiated and undifferentiated neural cells

Objective

Delivery of constructs for silencing or over-expressing genes or their modified versions is a crucial step for studying neuronal cell biology. Therefore, efficient transfection is important for the success of these experimental techniques especially in post-mitotic cells like neurons. In this study, we have assessed the transfection rate, using a previously established protocol, in both primary cortical cultures and neuroblastoma cell lines. Transfection efficiencies in these preparations have not been systematically determined before.

Results

Transfection efficiencies obtained herein were (10–12%) for neuroblastoma, (5–12%) for primary astrocytes and (1.3–6%) for primary neurons. We also report on cell-type specific transfection efficiency of neurons and astrocytes within primary cortical cultures when applying cell-type selective transfection protocols. Previous estimations described in primary cortical or hippocampal cultures were either based on general observations or on data derived from unspecified number of biological and/or technical replicates. Also to the best of our knowledge, transfection efficiency of pure primary neuronal cultures or astrocytes cultured in the context of pure or mixed (neurons/astrocytes) population cultures have not been previously determined. The transfection strategy used herein represents a convenient, and a straightforward tool for targeted cell transfection that can be utilized in a variety of in vitro applications.

Electronic supplementary material

The online version of this article (10.1186/s13104-019-4249-5) contains supplementary material, which is available to authorized users.

Lipid nanoparticles for delivery of messenger RNA to the back of the eye

Retinal gene therapy has had unprecedented success in generating treatments that can halt vision loss. However, immunogenic response and long-term toxicity with the use of viral vectors remain a concern. Non-viral vectors are relatively non-immunogenic, scalable platforms that have had limited success with DNA delivery to the eye. Messenger RNA (mRNA) therapeutics has expanded the ability to achieve high gene expression while eliminating unintended genomic integration or the need to cross the restrictive nuclear barrier. Lipid-based nanoparticles (LNPs) remain at the forefront of potent delivery vectors for nucleic acids. Herein, we tested eleven different LNP variants for their ability to deliver mRNA to the back of the eye. LNPs that contained ionizable lipids with low pKa and unsaturated hydrocarbon chains showed the highest amount of reporter gene transfection in the retina. The kinetics of gene expression showed a rapid onset (within 4 h) that persisted for 96 h. The gene delivery was cell-type specific with majority of the expression in the retinal pigmented epithelium (RPE) and limited expression in the Müller glia. LNP-delivered mRNA can be used to treat monogenic retinal degenerative disorders of the RPE. The transient nature of mRNA-based therapeutics makes it desirable for applications that are directed towards retinal reprogramming or genome editing. Overall, non-viral delivery of RNA therapeutics to diverse cell types within the retina can provide transformative new approaches to prevent blindness.

Preparation of gene drug delivery systems of cationic peptide lipid with 0G-PAMAM as hydrophilic end and its biological properties evaluation

As an efficient gene delivery, non-viral vectors should have high transfection efficiency, excellent endosomal escape, low cytotoxicity, and the ability to rapidly release the gene into the cytoplasm.Cationic liposome have been widely used as efficient gene carriers, but the cytotoxicity, rapid degradation and low cellular uptake are major drawback impeding its further appolication. Herein, with double lauric acid as hydrophobic chains, tartaric acid as skeleton, 0 generation PAMAM modified with lysine as hydrophilic head, a new type cationic peptide lipid was synthetised. The alkyl chain promote lipid across cell membranes and with membrane fusion, 0 generation PAMAM modified with lysine hydrophilic end amino can contain a large number of protons which can change into ammonium and combine with the DNA negatively charge phosphate groups. It is expected that this carrier has low toxicity, high transfection efficiency and targeting property. By adjusting the cationic liposome/gene weight ratio, the transfection system was optimized to improved gene transfection efficiency, reduce cytotoxicity, and increase property and stability, etc.

Optimising genetic transformation of Trypanosoma cruzi using hydroxyurea-induced cell-cycle synchronisation

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A straightforward method for optimising Trypanosoma cruzi transfection efficiency.

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Facilitated by hydroxyurea-induced cell-cycle synchronization.

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Applicable to both episomal and integrative-mediated transformation.

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Reduces the time required to generate genetically modified cell lines.

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Increases the number of stably transformed clones.

The limited flexibility and time-consuming nature of the genetic manipulation procedures applicable to Trypanosoma cruzi continue to restrict the functional dissection of this parasite. We hypothesised that transformation efficiency could be enhanced if electroporation was timed to coincide with DNA replication. To test this, we generated epimastigote cultures enriched at the G1/S boundary using hydroxyurea-induced cell-cycle synchronisation, and then electroporated parasites at various time points after release from the cell-cycle block. We found a significant increase in transformation efficiency, with both episomal and integrative constructs, when cultures were electroporated 1 h after hydroxyurea removal. It was possible to generate genetically modified populations in less than 2 weeks, compared to the normal 4–6 weeks, with a 5 to 8-fold increase in the number of stably transformed clones. This straightforward optimisation step can be widely applied and should help streamline functional studies in T. cruzi.

Cationic lipid/DNA complexes manufactured by microfluidics and bulk self-assembly exhibit different transfection behavior

Recent advances in biochemical and biophysical research have been achieved through the employment of microfluidic devices. Microfluidic mixing of therapeutic agents with biomaterials yields systems with finely tuned physical-chemical properties for applications in drug and gene delivery. Here, we investigate the role of preparation technology (microfluidic mixing vs. bulk self-assembly) on the transfection efficiency (TE) and cytotoxicity of multicomponent cationic liposome/DNA complexes (lipoplexes) in live Chinese hamster ovarian (CHO) cells. Decoupling TE and cytotoxicity allowed us to combine them in a unique coherent vision. While bulk self-assembly produces highly efficient and highly toxic MC lipoplexes, microfluidics manufacture leads to less efficient, but less cytotoxic complexes. This discrepancy is ascribed to two main factors controlling lipid-mediated cell transfection, i.e. the lipoplex concentration at the cell surface and the lipoplex arrangement at the nanoscale. Further research is required to optimize microfluidic manufacturing of lipoplexes to obtain highly efficient and not cytotoxic gene delivery systems.

ε-Poly-l-Lysine/plasmid DNA nanoplexes for efficient gene delivery in vivo

The present work addresses the development and characterization of ε-Poly-l-Lysine/pDNA polyplexes and evaluation for their improved transfection efficacy and safety as compared to polyplexes prepared using Poly-l-Lysine and SuperFect®. Self-assembling polyplexes were prepared by varying the N/P ratio to obtain the optimum size, a net positive zeta potential and gel retardation. The stability in presence of DNase I and serum was assured using gel retardation assay. Their appreciable uptake in MCF-7 and 3.5, 3.79 and 4.79-fold higher transfection compared to PLL/pDNA polyplexes and 1.60, 1.53 and 1.79-fold higher transfection compared to SuperFect®/pDNA polyplexes in MCF-7, HeLa and HEK-293 cell lines respectively, affirmed the enhanced transfection of ε-PLL/pDNA polyplexes which was well supported with in vivo transfection and gene expression studies. The <8% in vitro hemolysis and >98% viability of MCF-7, HeLa and HEK-293 cells in presence of ε-PLL/pDNA polyplexes addressed their safety, which was also ensured using in vivo toxicity studies, where hemocompatibility, unaltered levels of biochemical markers and histology of vital organs confirmed ε-PLL to be an effective and safer alternative for non-viral genetic vectors.

A method for high transfection efficiency in THP-1 suspension cells without PMA treatment

Adherent cells such as mouse RAW cells or human cancer U2OS cells are beneficial to DNA transfection, with 20%-60% transfection efficiency. However, this DNA transfection is rarely used on suspension cells due to its low transfection efficiency (≤5%). We recently found a new DNA transfection method to increase the efficiency up to 13.5% in suspension cells without PMA treatment. We also found that DNA transfection of human TNFAIP1 or CXCL1 recombinant plasmid DNA in THP-1 cells induces a high level of TNF-α protein. Overall, this new method is simple yet efficient and can be used for the overexpression of DNA in suspension cells.

A review on cationic lipids with different linkers for gene delivery

Cationic lipids have become known as one of the most versatile tools for the delivery of DNA, RNA and many other therapeutic molecules, and are especially attractive because they can be easily designed, synthesized and characterized. Most of cationic lipids share the common structure of cationic head groups and hydrophobic portions with linker bonds between both domains. The linker bond is an important determinant of the chemical stability and biodegradability of cationic lipid, and further governs its transfection efficiency and cytotoxicity. Based on the structures of linker bonds, they can be grouped into many types, such as ether, ester, amide, carbamate, disulfide, urea, acylhydrazone, phosphate, and other unusual types (carnitine, vinyl ether, ketal, glutamic acid, aspartic acid, malonic acid diamide and dihydroxybenzene). This review summarizes some research results concerning the nature (such as the structure and orientation of linker groups) and density (such as the spacing and the number of linker groups) of linker bond for improving the chemical stability, biodegradability, transfection efficiency and cytotoxicity of cationic lipid to overcome the critical barriers of in vitro and in vivo transfection.

Superior transfection efficiency of phagocytic astrocytes by large chitosan/DNA nanoparticles

PURPOSE

Mechanism study of why astrocytes isolated from experimental autoimmune encephalomyelitis (EAE)-induced B6 mice or after being exposed to inflammatory factors had the highest transfection efficiency to larger-sized, but not compacted, pspCS/pDNA particles.

METHODS

Phosphorylatable short peptide conjugated chitosan (pspCS) was compounded with plasmid DNA (pDNA) at different N:P ratios to form pspCS/pDNA particles of different size and zeta potentials. These pspCS/pDNA particles were used for the transfection of astrocytes isolated from either EAE induced or healthy B6 mice. Transfection efficiency and cell permeability of the particles were determined by the internalization of radio [H3]-labeled plasmid and the expression of a luciferase reporter gene respectively. Phagocytosis of EAE-astrocytes was determined by the internalization of FITC labeled dextran beads. By comparing the transfection efficiency of differently-sized pspCS/pDNA particles to normal and phagocytic astrocytes, with or without cytochalasin D, a phagocytosis inhibitor, in the presence, the contribution of phagocytosis to cell permeability and transfection efficiency was evaluated.

RESULTS

In vivo EAE-induction or in vitro inflammatory factors treatment transferred normal astrocytes to be phagocytic astrocytes which underwent phagocytosis, had the highest cell permeability and transfection efficiency to larger-sized pspCS/pDNA particles formed at lower N:P ratios. When phagocytosis was inhibited by cytochalasin D, both cell permeability and transfection efficiency of phagocytic astrocytes to larger were significantly decreased. Thereafter, particle size, not zeta potential, was verified as the key factor for determining whether the particles could be phagocytosed. In addition phagocytosis was successfully induced in ARPE-19 cells as well, which also improved the transfection efficiency of larger pspCS/pDNA particles.

CONCLUSION

A generally accepted concept is that the internalization of cationic polymer/pDNA particles, chitosan-DNA complex for instance, is mainly through the procedure of endocytosis of the transfected cells. More compacted particles with higher zeta potential were used to be considered had higher cell permeability and transfection efficiency. However, here we reported that phagocytosis is another important procedure for determining internalization and transfection efficiency of cationic polymer/pDNA nanoparticles, especially for advanced transfection efficiency of large pspCS/pDNA particles. Thus, for gene delivery applications, the environmental condition of the target cells should be seriously considered for selecting an appropriate gene transfer strategies.

A smart gene delivery platform: Cationic oligomer

Low transfection efficiency and high cytotoxicity of polymeric gene carriers have hampered the application of numerous polycations for gene therapy. To overcome this barrier, a cationic glycoconjugate of kanamycin and di(ethylene glycol) diacrylate was prepared via a facile approach. Nuclear magnetic resonance, Fourier transform infrared spectroscopy, and size exclusion chromatography were employed to investigate the resulting materials. Agarose gel electrophoresis, atomic force microscopy, and circular dichroism spectroscopy were used to record the interaction of the cationic oligomer and plasmid DNA. Finally, the cytotoxicity and transfection efficiency were evaluated by using COS-7 cells. The results indicated that cationic oligomers had been obtained and plasmid DNA was condensed into nanocomplexes, with a high transfection efficiency of the oligomer and a low toxicity in COS-7 cell line. It provided a novel perspective to develop gene carrier, with better safety and greater transfection efficiency, compared to traditional high molecular weight polymers.

Optimizing conditions for calcium phosphate mediated transient transfection

BACKGROUND

Calcium phosphate mediated transfection has been used for delivering DNA into mammalian cells in excess of 30 years due to its most low cost for introducing recombinant DNA into culture cells. However, multiple factors affecting the transfect efficiency are commonly recognized meanwhile for years, the low transfection efficiency of this approach on higher differentiated and non-tumor cells such as CHO and C2C12 limits its application on research.

RESULTS

In this paper, we systematically evaluated the possible factors affecting the transfection rate of this approach. Two categories, calcium phosphate-DNA co-precipitation and on-cell treatments were set for optimization of plasmid DNA transfection into CHO and C2C12 cell-lines. Throughout experimentation of these categories such as buffer system, transfection media and time, glycerol shocking and so on, we optimized the best procedure to obtain the highest efficiency ultimately. During calcium phosphate DNA-precipitation, the transfection buffer is critical condition optimized with HBS at pH 7.10 (P = 0.013 compared to HEPES in CHO). In the transfection step, FBS is a necessary component in transfection DMEM for high efficiency (P = 0.0005 compared to DMEM alone), and high concentration of co-precipitated particles applied to cultured cells in combination with intermittent vortexing is also crucial to preserve the efficiency. For 6-well culture plates, 800 µl of co-precipitated particles (11.25 µg/mL of cDNA) in 1 well is the optimal (P = 0.007 compared to 200 µl). For the highest transfection efficiency, the most important condition is glycerol in shock treatment (P = 0.002 compared to no shock treatment in CHO, and P = 0.008 compared to no shock treatment in C2C12) after a 6 h incubation (P = 0.004 compared to 16 h in CHO, and P = 0.039 compared to 16 h in C2C12) on cultured cells.

CONCLUSIONS

Calcium phosphate mediated transfection is the most low-cost approach to introduce recombinant DNA into culture cells. However, the utility of this procedure is limited in highly-differentiated cells. Here we describe the specific HBS-buffered saline, PH, glycerol shock, vortex strength, transfection medium, and particle concentrations conditions necessary to optimize this transfection method in highly differentiated cells.

Cationic Liposomes Modified with Polyallylamine as a Gene Carrier: Preparation, Characterization and Transfection Efficiency Evaluation

Purpose: Cationic polymers and cationic liposomes have shown to be effective non-viral gene delivery vectors. In this study, we tried to improve the transfection efficiency by employing the advantages of both. Methods: For this purpose, modified polyallylamines (PAAs) were synthesized. These modifications were done through the reaction of PAA (15 KDa) with acrylate and 6-bromoalkanoic acid derivatives. Liposomes comprising of these cationic polymers and cationic lipid were prepared and extruded through polycarbonate filters to obtain desired size. Liposome-DNA nanocomplexes were prepared in three carrier to plasmid (C/P) ratios. Size, zeta potential and DNA condensation ability of each complex were characterized separately and finally transfection efficiency and cytotoxicity of prepared vectors were evaluated in Neuro2A cell line. Results: The results showed that mean particle size of all these nanocomplexes was lower than 266 nm with surface charge of 22.0 to 33.9 mV. Almost the same condensation pattern was observed in all vectors and complete condensation was occurred at C/P ratio of 1.5. The lipoplexes containing modified PAA 15 kDa with 10% hexyl acrylate showed the highest transfection efficacy and lowest cytotoxicity in C/P ratio of 0.5. Conclusion: In some cases nanocomplexes consisting of cationic liposome and modified PAA showed better transfection activity and lower cytotoxicity compared to PAA.

Peptide-Mediated Tumor Targeting by a Degradable Nano Gene Delivery Vector Based on Pluronic-Modified Polyethylenimine

Polyethylenimine (PEI) is considered to be a promising non-viral gene delivery vector. To solve the toxicity versus efficacy and tumor-targeting challenges of PEI used as gene delivery vector, we constructed a novel non-viral vector DR5-TAT-modified Pluronic-PEI (Pluronic-PEI-DR5-TAT), which was based on the attachment of low-molecular-weight polyethylenimine (LMW-PEI) to the amphiphilic polymer Pluronic to prepare Pluronic-modified LMW-PEI (Pluronic-PEI). This was then conjugated to a multifunctional peptide containing a cell-penetrating peptide (TAT) and a synthetic peptide that would bind to DR5-a receptor that is overexpressed in cancer cells. The vector showed controlled degradation, favorable DNA condensation and protection performance. The Pluronic-PEI-DR5-TAT/DNA complexes at an N/P ratio of 15:1 were spherical nanoparticles of 122 ± 11.6 nm and a zeta potential of about 22 ± 2.8 mV. In vitro biological characterization results indicated that Pluronic-PEI-DR5-TAT/DNA complexes had a higher specificity for the DR5 receptor and were taken up more efficiently by tumor cells than normal cells, compared to complexes formed with PEI 25 kDa or Pluronic-PEI. Thus, the novel complexes showed much lower cytotoxicity to normal cells and higher gene transfection efficiency in tumor cells than that exhibited by PEI 25 kDa and Pluronic-PEI. In summary, our novel, degradable non-viral tumor-targeting vector is a promising candidate for use in gene therapy.

Cationic Lipid-Based Nucleic Acid Vectors

The delivery of nucleic acids into cells remains an important laboratory cell culture technique and potential clinical therapy, based upon the initial cellular uptake, then translation into protein (in the case of DNA), or gene deletion by RNA interference (RNAi). Although viral delivery vectors are more efficient, the high production costs, limited cargo capacity, and the potential for clinical adverse events make nonviral strategies attractive. Cationic lipids are the most widely applied and studied nonviral vectors; however, much remains to be solved to overcome limitations of these systems. Advances in the field of cationic lipid-based nucleic acid (lipoplex) delivery rely upon the development of robust and reproducible lipoplex formulations, together with the use of cell culture assays. This chapter provides detailed protocols towards the formulation, delivery, and assessment of in vitro cationic lipid-based delivery of DNA.

Gene Delivery Method Using Photo-Responsive Poly(β-Amino Ester) as Vectors

Nonviral vectors show great potential in delivering nucleic acids (NA) into many mammalian cells to achieve efficient gene transfection. Among these, cationic polymer is one of the most widely used nonviral gene delivery vectors, forming the polymer/NA complexes for the intracellular transportation and release of the genetic materials into the target mammalian cells. Here we describe the poly(β-amino ester) (PBAE) with the photo-responsive domain built in the polymers, as a UV-light-responsive nonviral gene delivery vector to deliver and release plasmid DNA (pDNA) into HeLa cells and achieve enhanced transfection efficiency.

Cationic lioposomes with folic acid as targeting ligand for gene delivery

In our previous Letter, we have carried out the synthesis of a novel DDCTMA cationic lipid which was formulated with DOPE for gene delivery. Herein, we used folic acid (FA) as targeting ligand and cholesterol (Chol) as helper lipid instead of DOPE for enhancing the stability of the liposomes. These liposomes were characterized by dynamic laser scattering (DLS), transmission electron microscopy (TEM) and agarose gel electrophoresis assays of pDNA binding affinity. The lipoplexes were prepared by using different weight ratios of DDCTMA/Chol (1:1, 2:1, 3:1, 4:1) liposomes and different concentrations of FA (50-200μg/mL) combining with pDNA. The transfection efficiencies of the lipoplexes were evaluated using pGFP-N2 and pGL3 plasmid DNA against NCI-H460 cells in vitro. Among them, the optimum gene transfection efficiency with DDCTMA/Chol (3:1)/FA (100μg/mL) was obtained. The results showed that FA could improve the gene transfection efficiencies of DDCTMA/Chol cationic liposome. Our results also convincingly demonstrated FA (100μg/mL)-coated DDCTMA/Chol (3:1) cationic liposome could serve as a promising candidate for the gene delivery.

A novel chimeric influenza virosome containing Vesicular stomatitis G protein as a more efficient gene delivery system

OBJECTIVES

To enhance the efficiency of influenza virosome-mediated gene delivery by engineering this virosome.

RESULTS

A novel chimeric influenza virosome was constructed containing the glycoprotein of Vesicular stomatitis virus (VSV-G), along with its own hemagglutinin protein. To optimize the transfection efficiency of both chimeric and influenza cationic virosomes, HEK cells were transfected with plasmid DNA and virosomes and the transfection efficiency was assessed by FACS analysis. The chimeric virosome was significantly more efficient in mediating transfection for all amounts of DNA and virosomes compared to the influenza virosome.

CONCLUSIONS

Chimeric influenza virosome, including VSV-G, is superior to the conventional influenza virosome for gene delivery.

Conjugates of small targeting molecules to non-viral vectors for the mediation of siRNA

To use siRNA (small interfering RNA) for gene therapy, a gene delivery system is often necessary to overcome several challenging requirements including rapid excretion, low stability in blood serum, non-specific accumulation in tissues, poor cellular uptake and inefficient intracellular release. Active and/or passive targeting should help the delivery system to reach the desired tissue or cell, to be internalized, and to deliver siRNA to the cytoplasm so that siRNA can inhibit protein synthesis. This review covers conjugates of small targeting molecules and non-viral delivery systems for the mediation of siRNA, with a focus on their transfection properties in order to help the development of new and efficient siRNA delivery systems, as the therapeutic solutions of tomorrow.

STATEMENT OF SIGNIFICANCE

The delivery of siRNA into cells or tissues remains to be a challenge for its applications, an alternative strategy for siRNA delivery systems is direct conjugation of non-viral vectors with targeting moieties for cellular delivery. In comparison to macromolecules, small targeting molecules have attracted great attention due to their many potential advantages including significant simplicity and ease of production, good repeatability and biodegradability. This review will focus on the most recent advances in the delivery of siRNA using conjugates of small targeting molecules and non-viral delivery systems. Based the editor's suggestions, we hope the revised manuscript could provide more profound understanding to the conjugates of targeting molecules to vectors for mediation of siRNA.

Characterization and Investigation of Redox-Sensitive Liposomes for Gene Delivery

A number of smart nonviral gene delivery vectors relying on bioresponsiveness have been introduced in the past few years to overcome the limits of the first generation of gene carriers. Among them, redox-sensitive lipidic and polymeric vectors exploit the presence of disulfide bonds in their structure to take advantage of the highly reductive intracellular milieu and to promote complex unpacking and nucleic acids release after cellular uptake (disulfide linker strategy). Glutathione (GSH) has been often identified as the leading actor in the intracellular reduction of bioreducible vectors but their actual mechanisms of action have been rarely investigated in depth and doubts about the real effectiveness of the disulfide linker strategy have been raised. Herein, we outline a simple protocol for the preparation and investigation of nano-sized reducible cationic liposomes, focusing on their thorough characterization and optimization as gene delivery vectors. In addition, we carefully describe the techniques and procedures necessary for the assessment of the bioreducibility of the vectors and to demonstrate that the GSH-mediated intracellular cleavage of disulfide bonds is a pivotal step in their transfection process. Liposomes composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), 1,2-dioleoyl-sn-glycero-3-phosphatidylethanolamine (DOPE), and of the reducible cationic lipid SS14 are reported as a practical example but the proposed protocol can be easily shifted to other formulations of reducible lipids/liposomes and to reducible polymers.

Delivery of an adenovirus vector plasmid by ultrapure oligochitosan based polyplexes

Ultrapure oligochitosans have been recently reported as efficient non-viral vectors for the delivery of pCMS-EGFP plasmid (5.5kbp) to the cornea and retina. However, the delivery of oncolytic adenoviral plasmids (40kbp) represents a unique challenge. In this work, we elaborated self assembled O15 and O25 UOC/pAdTLRGD polyplexes, and we studied the influence of the N/P ratio, the pH of the transfection medium and the salt concentration on the particle size and zeta potential by an orthogonal experimental design. All polyplexes showed a particle size lower than 200nm and a positive zeta potential. These parameters were influenced by the N/P ratio, salt concentration, and pH of the transfection medium. The selected polyplexes were able to bind, release, and protect the plasmid from DNase degradation. Transfection experiments in HEK293 and A549 cell lines demonstrated that UOC/pAdTLRGD polyplexes were able to deliver the plasmid and transfect both cell lines. These results suggest that O15 and O25 UOC based polyplexes are suitable for future in vivo applications.

New serine-derived gemini surfactants as gene delivery systems

Gemini surfactants have been extensively used for in vitro gene delivery. Amino acid-derived gemini surfactants combine the special aggregation properties characteristic of the gemini surfactants with high biocompatibility and biodegradability. In this work, novel serine-derived gemini surfactants, differing in alkyl chain lengths and in the linker group bridging the spacer to the headgroups (amine, amide and ester), were evaluated for their ability to mediate gene delivery either per se or in combination with helper lipids. Gemini surfactant-based DNA complexes were characterized in terms of hydrodynamic diameter, surface charge, stability in aqueous buffer and ability to protect DNA. Efficient formulations, able to transfect up to 50% of the cells without causing toxicity, were found at very low surfactant/DNA charge ratios (1/1-2/1). The most efficient complexes presented sizes suitable for intravenous administration and negative surface charge, a feature known to preclude potentially adverse interactions with serum components. This work brings forward a new family of gemini surfactants with great potential as gene delivery systems.

Gene delivery efficiency and intracellular trafficking of novel poly(allylamine) derivatives

Non-viral gene carriers for safe and efficient gene transfection have become of particular interest among researchers of different disciplines ranging from physical chemistry to biotechnology. Recently polymeric vectors have been extensively studied as potentially new gene transfer agents. Until now most of the research efforts were made to optimize the gene-to-polymer weight ratio of polyplexes for safe and efficient gene transfection. In this work, we report on the development of novel poly(allylamine) derivatives with different balance of the primary, secondary, tertiary, and quaternary amino groups. All derivatives were able to complex pDNA into polyplexes at low gene-to-polymer weight ratios i.e., 1:1 or 1:2. Moreover, the examined polyplexes were less cytotoxic and showed better transfection efficiency when compared to linear poly(ethyleneimine). These results indicate that the presence of quaternary ammonium groups is important in the formation of stable polyplexes. Polymers with all types of amino groups showed large potential for gene delivery. Furthermore, polyplexes with such derivatives were well internalized by cells and ended up into acidic late endosomes.

Bis-quaternary gemini surfactants as components of nonviral gene delivery systems: a comprehensive study from physicochemical properties to membrane interactions

Gemini surfactants have been successfully used as components of gene delivery systems. In the present work, a family of gemini surfactants, represented by the general structure [CmH2m+1(CH3)2N(+)(CH2)sN(+)(CH3)2CmH2m+1]2Br(-), or simply m-s-m, was used to prepare cationic gene carriers, aiming at their application in transfection studies. An extensive characterization of the gemini surfactant-based complexes, produced with and without the helper lipids cholesterol and DOPE, was carried out in order to correlate their physico-chemical properties with transfection efficiency. The most efficient complexes were those containing helper lipids, which, combining amphiphiles with propensity to form structures with different intrinsic curvatures, displayed a morphologically labile architecture, putatively implicated in the efficient DNA release upon complex interaction with membranes. While complexes lacking helper lipids were translocated directly across the lipid bilayer, complexes containing helper lipids were taken up by cells also by macropinocytosis. This study contributes to shed light on the relationship between important physico-chemical properties of surfactant-based DNA vectors and their efficiency to promote gene transfer, which may represent a step forward to the rational design of gene delivery systems.

Poly(ethyleneimine) functionalized carbon nanotubes as efficient nano-vector for transfecting mesenchymal stem cells

For gene and drug delivery applications, carbon nanotubes (CNTs) have to be functionalized in order to become compatible with aqueous media and bind with genetic materials. In this study, combination of polyethyleneimine (PEI) grafted multi-walled carbon nanotubes (PEI-g-MWCNTs) and chitosan substrate is used as an efficient gene delivery system for transfection of hard-to-transfect bone marrow mesenchymal stem cells (BMSCs) with enhanced green fluorescent protein (EGFP) gene. Fourier transform infrared (FT-IR) spectra, dynamic light scattering (DLS) analysis and zeta potential measurements are used to characterize binding of PEI, particle size distribution and colloidal stability of the functionalized CNTs, respectively. DNA binding affinity, cellular uptake, transfection efficiency and possible cytotoxicity are also tested by agarose gel electrophoresis, flow cytometry, cytochemisty and MTT assay. The results demonstrate that cytotoxic effect of PEI-g-MWCNTs is negligible under optimal transfection condition. In consistency with high cellular uptake (>82%), PEI-g-MWCNTs give higher delivery of EGFP into the BMSCs which results in a more sustained expression of the model gene (EGFP) in short-term culture. These results suggest that PEI-g-MWCNTs in corporation with chitosan substrates would be a promising delivery system for BMSCs, a cell type with relevancy in the regenerative medicine and clinical applications.

Selective transfection with osmotically active sorbitol modified PEI nanoparticles for enhanced anti-cancer gene therapy

Polysorbitol-mediated transporter (PSMT) has been previously shown to achieve high transfection efficiency with minimal cytotoxicity. Polysorbitol backbone possesses osmotic properties and leads to enhanced cellular uptake. The PSMT/pDNA nanoparticles were prepared and the particle size, surface charge of the nanoparticles was determined for the study. PSMT delivers genes into cells by the caveolae mediated endocytic pathway. Caveolae expression is usually altered in transformed cancer cells. Transfection through the caveolae may help PSMT to selectively transfect cancer cells rather than normal cells. Transfection of the luciferase gene by PSMT was tested in various cell types including cancer cell lines, primary cells, and immortalized cells. Luciferase transgene expression mediated by PSMT was remarkably increased in HeLa cells compared to expression using the control carrier Lipofectamine. Moreover, the toxicity of PSMT was comparable to the control carrier (Lipofectamine) in the same cells. Selective transfection of cancer cells using PSMT was further confirmed by co-culture of cancer and normal cells, which showed that transgene expression was pre-dominantly achieved in cancer cells. A functional p53 gene was also delivered into HeLa cells using PSMT and the selective transgene expression of p53 protein in cancer cells was analyzed through western blotting and confocal microscopy. HeLa cells transfected with PSMT/p53 plasmid nanoparticles showed cellular damage and apoptosis, which was confirmed through propidium iodide staining.