Modulation of PEI-Mediated Gene Transfection through Controlling Cytoskeleton Organization and Nuclear Morphology via Nanogrooved Topographies

Chiral Cell Nanomechanics Originated in Clockwise/Counterclockwise Biofunctional Microarrays to Govern the Nuclear Mechanotransduction of Mesenchymal Stem Cells

Cell chirality is extremely important for the evolution of cell morphogenesis to manipulate cell performance due to left-right asymmetry. Although chiral micro- and nanoscale biomaterials have been developed to regulate cell functions, how cell chirality affects cell nanomechanics to command nuclear mechanotransduction was ambiguous. In this study, chiral engineered microcircle arrays were prepared by photosensitive cross-linking synthesis on cell culture plates to control the clockwise/counterclockwise geometric topology of stem cells. Asymmetric focal adhesion and cytoskeleton structures could induce chiral cell nanomechanics measured by atomic force microscopy (AFM) nanoindentation in left-/right-handed stem cells. Cell nanomechanics could be enhanced when the construction of mature focal adhesion and the assembly of actin and myosin cytoskeletons were well organized in chiral engineered stem cells. Curvature angles had a negative effect on cell nanomechanics, while cell chirality did not change cytoskeletal mechanics. The biased cytoskeleton tension would engender different nuclear mechanotransductions by yes-associated protein (YAP) evaluation. The chiral stimuli were delivered into the nuclei to oversee nuclear behaviors. A strong cell modulus could activate high nuclear DNA synthesis activity by mechanotransduction. The results will bring the possibility of understanding the interplay of chiral cell nanomechanics and mechanotransduction in nanomedicines and biomaterials.

Cellular nanomechanics derived from pattern-dependent focal adhesion and cytoskeleton to balance gene transfection of malignant osteosarcoma

Gene transfection was supposed to be the most promising technology to overcome the vast majority of diseases and it has been popularly reported in clinical applications of gene therapy. In spite of the rapid development of novel transfection materials and methods, the influence of morphology-dependent nanomechanics of malignant osteosarcoma on gene transfection is still unsettled. In this study, cell spreading and adhesion area was adjusted by the prepared micropatterns to regulate focal adhesion (FA) formation and cytoskeletal organization in osteosarcoma cells. The micropattern-dependent FA and cytoskeleton could induce different cellular nanomechanics to affect cell functions. Our results indicated that transfection efficiency was improved with enlarging FA area and cell nanomechanics in micropatterned osteosarcoma. The difference of gene transfection in micropatterned cells was vigorously supported by cellular internalization capacity, Ki67 proliferation ability and YAP mechanotranduction through the regulation of focal adhesion and cytoskeletal mechanics. This study is an attempt to disclose the relationship of cell nanomechanics and gene transfection for efficient gene delivery and develop multifunctional nanomedicine biomaterials for accurate gene therapy in osteosarcoma cells.

Generating Human Induced Pluripotent Stem Cell Via Low-Dose Polyethylenimine-Mediated Transfection: An Optimized Protocol

Human dermal fibroblasts (HDFs) can be reprogrammed through different strategies to generate human induced pluripotent stem cells (hiPSCs). However, most of these strategies require high-cost materials and specific equipment not readily accessible in most laboratories. Hence, liposomal and virus-based techniques can replace with polyethylenimine (PEI)-mediated transfection to overcome these challenges. However, few researchers have addressed the PEI's ability to transfect HDFs. This study used PEI reagent to transfer oriP/EBNA1-based vector into HDFs to produce hiPSC lines. We first described conditions allowing the efficient transfection of HDFs with low cytotoxicity and without specific types of equipment and optimized several parameters relevant to the transfection procedure. We then monitored the effect of different N/P ratios on transfection efficiency and cytotoxicity using flow cytometry and fluorescent microscopy. By the results, we found that transfection efficiency was greatly affected by plasmid DNA concentration, PEI concentration, order of combining reagents, serum presence in polyplexes, and the duration of serum starvations. Moreover, using the optimized condition, we found that the N/P ratio of 3 achieved the highest percentage of HDFs positive for green fluorescent protein plasmid (∼40%) with minimal cell toxicity. We finally generated hiPSCs using the optimized protocol and oriP/EBNA1-based vectors. We confirmed hiPSC formation by characterizing tests: alkaline phosphatase staining, immunocytochemistry assay, real-time PCR analysis, in vitro differentiation into three germ layers, and karyotyping test. In conclusion, our results indicated that 25 kDa branched PEI could efficiently transfect HDFs toward generating hiPSCs via a simple, cost-effective, and optimized condition.

Vibropolyfection: coupling polymer-mediated gene delivery to mechanical stimulation to enhance transfection of adherent cells

BACKGROUND

With the success of recent non-viral gene delivery-based COVID-19 vaccines, nanovectors have gained some public acceptance and come to the forefront of advanced therapies. Unfortunately, the relatively low ability of the vectors to overcome cellular barriers adversely affects their effectiveness. Scientists have thus been striving to develop ever more effective gene delivery vectors, but the results are still far from satisfactory. Therefore, developing novel strategies is probably the only way forward to bring about genuine change. Herein, we devise a brand-new gene delivery strategy to boost dramatically the transfection efficiency of two gold standard nucleic acid (NA)/polymer nanoparticles (polyplexes) in vitro.

RESULTS

We conceived a device to generate milli-to-nanoscale vibrational cues as a function of the frequency set, and deliver vertical uniaxial displacements to adherent cells in culture. A short-lived high-frequency vibrational load (t = 5 min, f = 1,000 Hz) caused abrupt and extensive plasmalemma outgrowths but was safe for cells as neither cell proliferation rate nor viability was affected. Cells took about 1 hr to revert to quasi-naïve morphology through plasma membrane remodeling. In turn, this eventually triggered the mechano-activated clathrin-mediated endocytic pathway and made cells more apt to internalize polyplexes, resulting in transfection efficiencies increased from 10-to-100-fold. Noteworthy, these results were obtained transfecting three cell lines and hard-to-transfect primary cells.

CONCLUSIONS

In this work, we focus on a new technology to enhance the intracellular delivery of NAs and improve the transfection efficiency of non-viral vectors through priming adherent cells with a short vibrational stimulation. This study paves the way for capitalizing on physical cell stimulation(s) to significantly raise the effectiveness of gene delivery vectors in vitro and ex vivo.

Topography-Mediated Enhancement of Nonviral Gene Delivery in Stem Cells

Gene delivery holds great promise for bioengineering, biomedical applications, biosensors, diagnoses, and gene therapy. In particular, the influence of topography on gene delivery is considered to be an attractive approach due to low toxicity and localized delivery properties. Even though many gene vectors and transfection systems have been developed to enhance transfection potential and combining it with other forms of stimulations could even further enhance it. Topography is an interesting surface property that has been shown to stimulate differentiation, migration, cell morphology, and cell mechanics. Therefore, it is envisioned that topography might also be able to stimulate transfection. In this study, we tested the hypothesis “topography is able to regulate transfection efficiency”, for which we used nano- and microwave-like topographical substrates with wavelengths ranging from 500 nm to 25 µm and assessed the transfectability of human bone marrow-derived mesenchymal stem cells (hBM-MSCs) and myoblasts. For transfection, Lipofectamine 2000 and a gene encoding plasmid for red-fluorescent protein (m-Cherry) were used and topography-induced cell morphology and transfection efficiency was analyzed. As a result, topography directs cell spreading, elongation, and proliferation as well as the transfection efficiency, which were investigated but were found not to be correlated and dependent on the cell type. A 55% percent improvement of transfection efficiency was identified for hBM-MSCs grown on 2 µm wrinkles (24.3%) as compared to hBM-MSCs cultured on flat controls (15.7%). For myoblast cells, the highest gene-expression efficiency (46.1%) was observed on the 10 µm topography, which enhanced the transfection efficiency by 64% as compared to the flat control (28.1%). From a qualitative assessment, it was observed that the uptake capacity of cationic complexes of TAMRA-labeled oligodeoxynucleotides (ODNs) was not topography-dependent but that the intracellular release was faster, as indicated by the positively stained nuclei on 2 μm for hBM-MSCs and 10 μm for myoblasts. The presented results indicate that topography enhances the gene-delivery capacity and that the responses are dependent on cell type. This study demonstrates the important role of topography on cell stimulation for gene delivery as well as understanding the uptake capacity of lipoplexes and may be useful for developing advanced nonviral gene delivery strategies.

Physical and mechanical cues affecting biomaterial-mediated plasmid DNA delivery: insights into non-viral delivery systems

BACKGROUND

Whilst traditional strategies to increase transfection efficiency of non-viral systems aimed at modifying the vector or the polyplexes/lipoplexes, biomaterial-mediated gene delivery has recently sparked increased interest. This review aims at discussing biomaterial properties and unravelling underlying mechanisms of action, for biomaterial-mediated gene delivery. DNA internalisation and cytoplasmic transport are initially discussed. DNA immobilisation, encapsulation and surface-mediated gene delivery (SMD), the role of extracellular matrix (ECM) and topographical cues, biomaterial stiffness and mechanical stimulation are finally outlined.

MAIN TEXT

Endocytic pathways and mechanisms to escape the lysosomal network are highly variable. They depend on cell and DNA complex types but can be diverted using appropriate biomaterials. 3D scaffolds are generally fabricated via DNA immobilisation or encapsulation. Degradation rate and interaction with the vector affect temporal patterns of DNA release and transgene expression. In SMD, DNA is instead coated on 2D surfaces. SMD allows the incorporation of topographical cues, which, by inducing cytoskeletal re-arrangements, modulate DNA endocytosis. Incorporation of ECM mimetics allows cell type-specific transfection, whereas in spite of discordances in terms of optimal loading regimens, it is recognised that mechanical loading facilitates gene transfection. Finally, stiffer 2D substrates enhance DNA internalisation, whereas in 3D scaffolds, the role of stiffness is still dubious.

CONCLUSION

Although it is recognised that biomaterials allow the creation of tailored non-viral gene delivery systems, there still are many outstanding questions. A better characterisation of endocytic pathways would allow the diversion of cell adhesion processes and cytoskeletal dynamics, in order to increase cellular transfection. Further research on optimal biomaterial mechanical properties, cell ligand density and loading regimens is limited by the fact that such parameters influence a plethora of other different processes (e.g. cellular adhesion, spreading, migration, infiltration, and proliferation, DNA diffusion and release) which may in turn modulate gene delivery. Only a better understanding of these processes may allow the creation of novel robust engineered systems, potentially opening up a whole new area of biomaterial-guided gene delivery for non-viral systems.

Harnessing the perinuclear actin cap (pnAC) to influence nanocarrier trafficking and gene transfection efficiency in skeletal myoblasts using nanopillars

Gene transfection is important in biotechnology and is used to modify cells intrinsically. It can be conducted in cell suspension or after cell adhesion, where the efficiency is dependent on many factors such as the type of nanocarrier used and cell division processes. Anchor-dependent cells are sensitive to the substrate they are attached to and adapt their behavior accordingly, including plasmid trafficking during gene transfection. Previously, it was shown in our group that the cytoskeleton is an essential factor in influencing gene transfection in skeletal myoblasts using nanogrooves as a substrate. In this study, the effect of the cytoskeleton on gene transfection efficiency of skeletal myoblasts was studied using various nanopillars and nanocarriers. Nanopillars with different diameters (200-1000 nm) and depths (200 or 400 nm) were fabricated using colloidal self-assembly and reactive ion etching. All surfaces were treated with oxygen plasma or polydopamine (PD) to further control cell morphology. Plasmid DNA was delivered into cells using jetPRIME or Lipofectamine 3000 nanocarriers. After screening hundreds of images, two distinguishable F-actin distributions were found, i.e., cells with or without a perinuclear actin cap (pnAC). Cells attached to nanopillars, especially the deep pillars, had a smaller spreading area, shorter F-actin, more 3D-like cell nuclei, and a lower percentage of pnAC, which lead to a higher gene transfection efficiency using jetPRIME. On the other hand, cells attached to the shallow nanopillars or flat surfaces had a larger spreading area, longer F-actin, more 2D-like cell nuclei, and a higher percentage of pnAC that facilitates gene transfection using Lipofectamine. The effects of cell density, cytoskeleton (cytoD), and focal adhesions (RGD) on gene transfection were also studied, and the results were consistent with our hypothesis that F-actin distribution is one of the critical factors in gene transfection. In conclusion, pnAC plays a vital role in the intracellular trafficking of nanocarrier/plasmid complexes and this study provides new insights into gene transfection in anchor-dependent cells. STATEMENT OF SIGNIFICANCE: This study provides a new perspective in gene transfection using attached cells where perinuclear actin cap (pnAC) is an essential factor involved in transfection efficiency. A series of nanopillars were used to harness cell and cytoskeleton morphology. Two distinguishable cytoskeletal structures were found including cells with or without pnAC. 2D-like cells with pnAC facilitate gene delivery using liposome-based nanocarriers, while 3D-like cells without pnAC benefit gene delivery using cationic polymer-based nanocarriers. This study reveals the importance of the cytoskeleton during gene transfection that is beneficial in tissue transfection.

Mechanical Effect on Gene Transfection Based on Dielectric Elastomer Actuator

Gene transfection has been widely applied in genome function and gene therapy. Although many efforts have been focused on designing carrier materials and transfection methods, the influence of mechanical stimulation on gene transfection efficiency has rarely been studied. Herein, dielectric elastomer actuator (DEA)-based stimulation bioreactors are designed to generate tensile and contractile stress on cells simultaneously. With the example of the EGFP transfection, cells with high membrane tension in the stretching stimulation regions had lower transfection efficiency, while the transfection efficiency of cells in the compressing regions tended to increase. Besides, the duty cycle and loading frequency of the applied stress on cells were also important factors that affect gene transfection efficiency. Furthermore, the pathways of cell endocytosis with the effect of mechanical stimulation were explored on the mechanism for the change of EGFP transfection efficiency. This design of the DEA-based bioreactor, as a strategy to study gene transfection efficiency, could be helpful for developing efficient transfection methods.

Shaping Cell Fate: Influence of Topographical Substratum Properties on Embryonic Stem Cells

Development of multicellular organisms is a highly orchestrated process, with cells responding to factors and features present in the extracellular milieu. Changes in the surrounding environment help decide the fate of cells at various stages of development. This review highlights recent research that details the effects of mechanical properties of the surrounding environment and extracellular matrix and the underlying molecular mechanisms that regulate the behavior of embryonic stem cells (ESCs). In this study, we review the role of mechanical properties during embryogenesis and discuss the effect of engineered microtopographies on ESC pluripotency.