Controllable Large-Scale Transfection of Primary Mammalian Cardiomyocytes on a Nanochannel Array Platform

While electroporation has been widely used as a physical method for gene transfection in vitro and in vivo, its application in gene therapy of cardiovascular cells remains challenging. Due to the high concentration of ion-transport proteins in the sarcolemma, conventional electroporation of primary cardiomyocytes tends to cause ion-channel activation and abnormal ion flux, resulting in low transfection efficiency and high mortality. In this work, a high-throughput nanoelectroporation technique based on a nanochannel array platform is reported, which enables massively parallel delivery of genetic cargo (microRNA, plasmids) into mouse primary cardiomyocytes in a controllable, highly efficient, and benign manner. A simple "dipping-trap" approach was implemented to precisely position a large number of cells on the nanoelectroporation platform. With dosage control, our device precisely titrates the level of miR-29, a potential therapeutic agent for cardiac fibrosis, and determines the minimum concentration of miR-29 causing side effects in mouse primary cardiomyocytes. Moreover, the dose-dependent effect of miR-29 on mitochondrial potential and homeostasis is monitored. Altogether, our nanochannel array platform provides efficient trapping and transfection of primary mouse cardiomyocyte, which can improve the quality control for future microRNA therapy in heart diseases.

Micro-/nanoscale electroporation

Electroporation has been one of the most popular non-viral technologies for cell transfection. However, conventional bulk electroporation (BEP) shows significant limitations in efficiency, cell viability and transfection uniformity. Recent advances in microscale-electroporation (MEP) resulted in improved cell viability. Further miniaturization of the electroporation system (i.e., nanoscale) has brought up many unique advantages, including negligible cell damage and dosage control capabilities with single-cell resolution, which has enabled more translational applications. In this review, we give an insight into the fundamental and technical aspects of micro- and nanoscale/nanochannel electroporation (NEP) and go over several examples of MEP/NEP-based cutting-edge research, including gene editing, adoptive immunotherapy, and cellular reprogramming. The challenges and opportunities of advanced electroporation technologies are also discussed.

Length of time in Ghana is associated with the likelihood of exclusive breastfeeding among Liberian refugees living in Buduburam

While literature describing immigrant's breastfeeding practices exists, especially among those living within developed countries, there is a significant gap in knowledge on how the host culture may influence the EBF behaviors of refugees, especially those living in protracted situations within sub-Saharan Africa. A cross-sectional study was conducted in the Buduburam Refugee Settlement in Ghana from July-August 2008 to explore the association between the amount of time living in Ghana and exclusive breastfeeding practices among Liberian refugees and Ghanaians in surround villages. The study included 480 women: 239 Liberians living in 12 settlement zones (in two of which Liberians and Ghanaians co-exist), 121 Ghanaians living in two settlement zones, and 120 Ghanaians living in nearby urban village of Awutu. Liberian mothers who lived in Ghana at least eight years were significantly more likely to exclusively breastfeed (OR: 1.78, 95% CI: 1.02, 3.09) compared to Ghanaian mothers living in Awutu. These findings suggest that increased time living in Buduburam improved the chances of EBF success among Liberians, perhaps as a result of unique EBF education/support opportunities offered in the settlement to Liberian refugees that were not readily available to Ghanaians. Further research to understand the "mechanisms" explaining exclusive breastfeeding differences as a function of time spent in host country is needed for improving breastfeeding support in refugee settlements and host communities.

On-Chip Clonal Analysis of Glioma-Stem-Cell Motility and Therapy Resistance

Enhanced glioma-stem-cell (GSC) motility and therapy resistance are considered to play key roles in tumor cell dissemination and recurrence. As such, a better understanding of the mechanisms by which these cells disseminate and withstand therapy could lead to more efficacious treatments. Here, we introduce a novel micro-/nanotechnology-enabled chip platform for performing live-cell interrogation of patient-derived GSCs with single-clone resolution. On-chip analysis revealed marked intertumoral differences (>10-fold) in single-clone motility profiles between two populations of GSCs, which correlated well with results from tumor-xenograft experiments and gene-expression analyses. Further chip-based examination of the more-aggressive GSC population revealed pronounced interclonal variations in motility capabilities (up to ∼4-fold) as well as gene-expression profiles at the single-cell level. Chip-supported therapy resistance studies with a chemotherapeutic agent (i.e., temozolomide) and an oligo RNA (anti-miR363) revealed a subpopulation of CD44-high GSCs with strong antiapoptotic behavior as well as enhanced motility capabilities. The living-cell-interrogation chip platform described herein enables thorough and large-scale live monitoring of heterogeneous cancer-cell populations with single-cell resolution, which is not achievable by any other existing technology and thus has the potential to provide new insights into the cellular and molecular mechanisms modulating glioma-stem-cell dissemination and therapy resistance.

The human PMR1 endonuclease stimulates cell motility by down regulating miR-200 family microRNAs

The motility of MCF-7 cells increases following expression of a human PMR1 transgene and the current study sought to identify the molecular basis for this phenotypic change. Ensemble and single cell analyses show increased motility is dependent on the endonuclease activity of hPMR1, and cells expressing active but not inactive hPMR1 invade extracellular matrix. Nanostring profiling identified 14 microRNAs that are downregulated by hPMR1, including all five members of the miR-200 family and others that also regulate invasive growth. miR-200 levels increase following hPMR1 knockdown, and changes in miR-200 family microRNAs were matched by corresponding changes in miR-200 targets and reporter expression. PMR1 preferentially cleaves between UG dinucleotides within a consensus YUGR element when present in the unpaired loop of a stem–loop structure. This motif is present in the apical loop of precursors to most of the downregulated microRNAs, and hPMR1 targeting of pre-miRs was confirmed by their loss following induced expression and increase following hPMR1 knockdown. Introduction of miR-200c into hPMR1-expressing cells reduced motility and miR-200 target gene expression, confirming hPMR1 acts upstream of Dicer processing. These findings identify a new role for hPMR1 in the post-transcriptional regulation of microRNAs in breast cancer cells.

Serine/Threonine Kinase MLK4 Determines Mesenchymal Identity in Glioma Stem Cells in an NF-κB-dependent Manner

Activation of nuclear factor κB (NF-κB) induces mesenchymal (MES) transdifferentiation and radioresistance in glioma stem cells (GSCs), but molecular mechanisms for NF-κB activation in GSCs are currently unknown. Here, we report that mixed lineage kinase 4 (MLK4) is overexpressed in MES but not proneural (PN) GSCs. Silencing MLK4 suppresses self-renewal, motility, tumorigenesis, and radioresistance of MES GSCs via a loss of the MES signature. MLK4 binds and phosphorylates the NF-κB regulator IKKα, leading to activation of NF-κB signaling in GSCs. MLK4 expression is inversely correlated with patient prognosis in MES, but not PN high-grade gliomas. Collectively, our results uncover MLK4 as an upstream regulator of NF-κB signaling and a potential molecular target for the MES subtype of glioblastomas.

3D nanochannel electroporation for high-throughput cell transfection with high uniformity and dosage control

Of great interest to modern medicine and biomedical research is the ability to inject individual target cells with the desired genes or drug molecules. Some advances in cell electroporation allow for high throughput, high cell viability, or excellent dosage control, yet no platform is available for the combination of all three. In an effort to solve this problem, here we show a "3D nano-channel electroporation (NEP) chip" on a silicon platform designed to meet these three criteria. This NEP chip can simultaneously deliver the desired molecules into 40,000 cells per cm(2) on the top surface of the device. Each 650 nm pore aligns to a cell and can be used to deliver extremely small biological elements to very large plasmids (>10 kbp). When compared to conventional bulk electroporation (BEP), the NEP chip shows a 20 fold improvement in dosage control and uniformity, while still maintaining high cell viability (>90%) even in cells such as cardiac cells which are characteristically difficult to transfect. This high-throughput 3D NEP system provides an innovative and medically valuable platform with uniform and reliable cellular transfection, allowing for a steady supply of healthy, engineered cells.

Deterministic transfection drives efficient nonviral reprogramming and uncovers reprogramming barriers

Safety concerns and/or the stochastic nature of current transduction approaches have hampered nuclear reprogramming's clinical translation. We report a novel non-viral nanotechnology-based platform permitting deterministic large-scale transfection with single-cell resolution. The superior capabilities of our technology are demonstrated by modification of the well-established direct neuronal reprogramming paradigm using overexpression of the transcription factors Brn2, Ascl1, and Myt1l (BAM). Reprogramming efficiencies were comparable to viral methodologies (up to ~9-12%) without the constraints of capsid size and with the ability to control plasmid dosage, in addition to showing superior performance relative to existing non-viral methods. Furthermore, increased neuronal complexity could be tailored by varying BAM ratio and by including additional proneural genes to the BAM cocktail. Furthermore, high-throughput NEP allowed easy interrogation of the reprogramming process. We discovered that BAM-mediated reprogramming is regulated by AsclI dosage, the S-phase cyclin CCNA2, and that some induced neurons passed through a nestin-positive cell stage.

FROM THE CLINICAL EDITOR

In the field of regenerative medicine, the ability to direct cell fate by nuclear reprogramming is an important facet in terms of clinical application. In this article, the authors described their novel technique of cell reprogramming through overexpression of the transcription factors Brn2, Ascl1, and Myt1l (BAM) by in situ electroporation through nanochannels. This new technique could provide a platform for further future designs.

Nanochannel Electroporation as a Platform for Living Cell Interrogation in Acute Myeloid Leukemia

A living cell interrogation platform based on nanochannel electroporation is demonstrated with analysis of RNAs in single cells. This minimally invasive process is based on individual cells and allows both multi-target analysis and stimulus-response analysis by sequential deliveries. The unique platform possesses a great potential to the comprehensive and lysis-free nucleic acid analysis on rare or hard-to-transfect cells.

Dielectrophoresis-assisted 3D nanoelectroporation for non-viral cell transfection in adoptive immunotherapy

Current transfection technologies lead to significant inter-clonal variations. Previously we introduced a unique electrotransfection technology, Nanochannel-Electroporation (NEP), which can precisely and benignly transfect small cell populations (~100-200 cells) with single-cell resolution. Here we report on the development of a novel 3D NEP system for large scale transfection. A properly-engineered array of nanochannels, capable of handling/transfecting ~60 000 cells cm(-2), was fabricated using cleanroom technologies. Positive dielectrophoresis was used to selectively position cells on the nanochannels, thus allowing highly efficient transfection. Single-cell dosage control was demonstrated using both small and large molecules, and different cell types. The potential clinical relevance of this system was tested with difficult-to-transfect natural killer cell suspensions, and plasmids encoding for the chimeric antigen receptor (CAR), a model of high relevance for adoptive immunotherapy. Our results show significantly higher CAR transfection efficiencies for the DEP-NEP system (>70% vs. <30%), as well as enhanced cell viabilities.

Targeted delivery of tumor suppressor microRNA-1 by transferrin-conjugated lipopolyplex nanoparticles to patient-derived glioblastoma stem cells

OBJECTIVE

Among heterogeneous glioblastoma multiforme (GBM) cells, glioblastoma stem cells (GSCs) is a subpopulation having a critical role in tumor initiation and therapy resistance. Thus targeting GSCs would be an essential step to completely eradicate this lethal disease. MicroRNA-1 (miR-1) expression is deregulated in GBM patients and restoration of miR-1 by viral-vector in GBM cells has been demonstrated to inhibit tumor initiation and attenuate cell migration. Here, we show that a transferrin-targeting non-invasive nanoparticle delivery system (Tf-NP) can efficiently deliver miR-1 to GBM patient-derived GSC-enriched sphere cultures (GBM spheres).

METHODS

Delivery efficiency of the transferrin- targeting non-invasive nanoparticle was investigated by flow cytometry and further confirmed by confocal microscopy. The levels of miR-1 and its target molecules in GBM spheres were measured by qRT-PCR and immunoblotting. Migration capacity of Tf-NP-miR-1 treated GBM spheres were evaluated by transwell migration assay.

RESULTS

Tf-NPmiR- 1 treatment resulted in an over 200-fold increase of mature miR-1 compared to free miR-1 and Tf-NP-miR negative control (Tf-NP-miR-NC). Transferrin-mediated NP delivery resulted in a 3-fold higher delivery efficiency compared to NP without transferrin modification. Tf-NP-miR-1 treatment on GBM spheres significantly inhibited migration of GBM spheres by 30-50% with associated decline of MET and EGFR expression. Our data supported that Tf-NP could be used as an efficient and effective delivery system which has high potential to benefit the development of miR-based therapeutics for GBM treatment.

Microwell array-mediated delivery of lipoplexes containing nucleic acids for enhanced therapeutic efficacy

Many delivery methods have been developed to improve the therapeutic efficacy and facilitate the clinical translation of nucleic acids-based therapeutics. We present a facile microwell array to mediate the delivery of nucleic acids carried by lipoplexes, which combines the advantages of lipoplexes as an efficient carrier system, the surface mediated delivery, and the control of surface topography. This method shows much higher transfection efficiency than conventional transfection method for oligodeoxynucleotides and microRNAs, and thus significantly reduces the effective therapeutic dosages. Microwell array is also a very flexible platform. Multifunctional lipoplexes containing both nucleic acid therapeutics and imaging reagents can be easily prepared in the microwell array and efficiently delivered to cells, demonstrating its potential applications in theranostic medicine.

Magnetic tweezers-based 3D microchannel electroporation for high-throughput gene transfection in living cells

A novel high-throughput magnetic tweezers-based 3D microchannel electroporation system capable of transfecting 40 000 cells/cm(2) on a single chip for gene therapy, regenerative medicine, and intracellular detection of target mRNA for screening cellular heterogeneity is reported. A single cell or an ordered array of individual cells are remotely guided by programmable magnetic fields to poration sites with high (>90%) cell alignment efficiency to enable various transfection reagents to be delivered simultaneously into the cells. The present technique, in contrast to the conventional vacuum-based approach, is significantly gentler on the cellular membrane yielding >90% cell viability and, moreover, allows transfected cells to be transported for further analysis. Illustrating the versatility of the system, the GATA2 molecular beacon is delivered into leukemia cells to detect the regulation level of the GATA2 gene that is associated with the initiation of leukemia. The uniform delivery and a sharp contrast of fluorescence intensity between GATA2 positive and negative cells demonstrate key aspects of the platform for gene transfer, screening and detection of targeted intracellular markers in living cells.

Effect of nonendocytic uptake of nanoparticles on human bronchial epithelial cells

The toxicity of artificial nanoparticles is a major concern in industrial applications. Cellular uptake of hard nanoparticles could follow either endocytic or nonendocytic pathways, leading to different stimuli to the cells. Yet the cellular responses to nanoparticles following different pathways have not been compared due to the lack of an independent nonendocytic delivery method. We applied a unique delivery method, nanochannel electroporation (NEP), to produce predominantly nonendocytic uptakes of quantum dots (Q-dots) and multiwalled carbon nanotubes (MWCNTs) with different chemical modifications. NEP delivery bypassed endocytosis by electrophoretic injection of nanoparticles into human bronchial epithelial (BEAS-2B) cells at different dosages. Conventional exposure by direct nanoparticle suspending in cell culture medium was also performed as control. The dosage-dependent responses to nanoparticles under different uptake pathways were compared. Fluorescence colocalization demonstrated that nanoparticles followed both endocytic and nonendocytic pathways for cell entry in contact exposure, whereas NEP delivery of nanoparticles bypassed endocytosis. Nonendocytic entry resulted in much higher oxidation stress and, for MWCNTs, more cell death in BEAS-2B cells. Despite the observation that most nanoparticles were taken up by cells through endocytosis, the minor nonendocytic entry of nanoparticles seemed to dominate the overall cellular response in conventional contact exposure. Our finding suggests that prevention against nonendocytic uptake could help reduce the toxicity of hard nanoparticles.

DNA translocation through short nanofluidic channels under asymmetric pulsed electric field

Investigation of single molecule DNA dynamics in confined environments has led to important applications in DNA analysis, separation, and sequencing. Here, we studied the electrophoretic transport of DNA molecules through nanochannels shorter than the DNA contour length and calculated the associated translocation time curves. We found that the longer T4 DNA molecules required a longer time to traverse a fixed length nanochannel than shorter λ DNA molecules and that the translocation time decreased with increasing electric field which agreed with theoretical predictions. We applied this knowledge to design an asymmetric electric pulse and demonstrate the different responses of λ and T4 DNA to the pulses. We used Brownian dynamics simulations to corroborate our experimental results on DNA translocation behaviour. This work contributes to the fundamental understanding of polymer transport through nanochannels and may help in designing better separation techniques in the future.

Atomic carbide bonding leading to superior graphene networks

A versatile method for achieving atomic carbide-bonded graphene networks on both metallic and non-metallic substrates is described. This consists of vacuum-assisted thermal exfoliation and floatation of functional graphenes at elevated temperatures, followed by deposition on substrates and in situ formation of carbide bonds. The cross-linked graphene networks with an interlayer distance of angstroms exhibits a unique combination of unprecedented properties.

Surface-mediated nucleic acid delivery by lipoplexes prepared in microwell arrays

Many delivery methods have been developed to improve the therapeutic efficacy and facilitate the clinical translation of nucleic acid-based therapeutics. A facile surface-mediated nucleic acid delivery by lipoplexes is prepared in a microwell array, which combines the advantages of lipoplexes as an efficient carrier system, surface-mediated delivery, and the control of surface topography. Uniform disc-like lipoplexes containing nucleic acids are formed in the microwell array with a diameter of ∼818 nm and thickness of ∼195 nm. The microwell array-mediated delivery of lipoplexes containing FAM-oligodeoxynucleotides is ∼18.6 and ∼10.6 times more efficient than the conventional transfection method in an adherent cell line (A549 non-small cell lung cancer cells) and a suspension cell line (KG-1a acute myelogenous leukemia cells), respectively. MicroRNA-29b is then used as a model nucleic acid to investigate the therapeutic efficacy of lipoplexes delivered by the microwell array. Compared to conventional transfection methods, the effective therapeutic dosage of microRNA-29b is reduced from the microgram level to the nanogram level by lipoplexes prepared in the microwell array. The microwell array is also a very flexible platform. Both nucleic acid therapeutics and imaging reagents are incorporated in lipoplexes and successfully delivered to A549 cells, demonstrating its potential applications in theranostic medicine.

Micro/nanoscale technologies for the development of hormone-expressing islet-like cell clusters

Insulin-expressing islet-like cell clusters derived from precursor cells have significant potential in the treatment of type-I diabetes. Given that cluster size and uniformity are known to influence islet cell behavior, the ability to effectively control these parameters could find applications in the development of anti-diabetic therapies. In this work, we combined micro and nanofabrication techniques to build a biodegradable platform capable of supporting the formation of islet-like structures from pancreatic precursors. Soft lithography and electrospinning were used to create arrays of microwells (150-500 μm diameter) structurally interfaced with a porous sheet of micro/nanoscale polyblend fibers (~0.5-10 μm in cross-sectional size), upon which human pancreatic ductal epithelial cells anchored and assembled into insulin-expressing 3D clusters. The microwells effectively regulated the spatial distribution of the cells on the platform, as well as cluster size, shape and homogeneity. Average cluster cross-sectional area (~14000-17500 μm(2)) varied in proportion to the microwell dimensions, and mean circularity values remained above 0.7 for all microwell sizes. In comparison, clustering on control surfaces (fibers without microwells or tissue culture plastic) resulted in irregularly shaped/sized cell aggregates. Immunoreactivity for insulin, C-peptide and glucagon was detected on both the platform and control surfaces; however, intracellular levels of C-peptide/cell were ~60 % higher on the platform.

Microfabricated mimics of in vivo structural cues for the study of guided tumor cell migration

Guided cell migration plays a crucial role in tumor metastasis, which is considered to be the major cause of death in cancer patients. Such behavior is regulated in part by micro/nanoscale topographical cues present in the parenchyma or stroma in the form of fiber-like and/or conduit-like structures (e.g., white matter tracts, blood/lymphatic vessels, subpial and subperitoneal spaces). In this paper we used soft lithography micromolding to develop a tissue culture polystyrene platform with a microscale surface pattern that was able to induce guided cell motility along/through fiber-/conduit-like structures. The migratory behaviors of primary (glioma) and metastatic (lung and colon) tumors excised from the brain were monitored via time-lapse microscopy at the single cell level. All the tumor cells exhibited axially persistent cell migration, with percentages of unidirectionally motile cells of 84.0 ± 3.5%, 58.3 ± 6.8% and 69.4 ± 5.4% for the glioma, lung, and colon tumor cells, respectively. Lung tumor cells showed the highest migratory velocities (41.8 ± 4.6 μm h(-1)) compared to glioma (24.0 ± 1.8 μm h(-1)) and colon (26.7 ± 2.8 μm h(-1)) tumor cells. This platform could potentially be used in conjunction with other biological assays to probe the mechanisms underlying the metastatic phenotype under guided cell migration conditions, and possibly by itself as an indicator of the effectiveness of treatments that target specific tumor cell motility behaviors.

Micropatterned thermoresponsive surfaces by polymerization of monomer crystals: modulating cellular morphology and cell-substrate interactions

A novel and facile approach has been developed to create thermoresponsive surfaces with macroscale patterns together with microscale features. The surface patterns were formed by applying macroscale nucleation agent patterns onto saturated N-isopropylacrylamide monomer solution membranes to induce the divergent growth of needlelike monomer crystals; the patterned monomer crystals were then photopolymerized to form patterned thermoresponsive films. A series of analytical tools (i.e., scanning electron microscopy, profilometry, and contact angle measurement) were used to characterize the properties of the patterned films. Cell coculture on this patterned thermoresponsive films enables cell separation and sorting by modulating temperature- and topography-dependent cell-substrate interactions and cell morphology, respectively. This versatile technique allows the formation of various macroscale patterns with microscale features over large areas, and on most solid substrates, within minutes, all of this without the need for expensive equipment and facilities. Such patterned surfaces can act as both in vitro tumor models and separation platforms for cancer studies. This method can also be applied to other cell-based biological studies and clinical applications.