External Electrical Stimulation Research Articles

Downregulation of miR-568 in Atrial Fibrillation Leads to Increased Expression of NAPMT and TRMP7

Aim: Atrial fibrillation (AF) is known as the most common permanent cardiac arrhythmia worldwide with its incidence and prevalence gradually increase with age and cause significant morbidity and mortality. However, the epigenetic alterations underlying the development of this disease remains less understood. MicroRNAs (miRNAs), as one of the epigenetic regulators, are small non-coding RNAs that can target multiple genes to modulate proteins in different signaling pathways. Current studies have demonstrated that miRNAs, which are pivotal regulators of gene expression, may be involved in the pathophysiology of AF. The current study aims to clarify the miRNA regulated cellular signaling in atrial fibrillation. Material and Method: An AF model was generated by providing external electrical stimulation to the HL-1 mouse cardiomyocyte cell line for 24 hours in this study. To understand the molecular mechanisms of miRNAs underlying the AF model, miRNA microarray analysis was performed. The gene sets obtained from the microarray analysis and the bioinformatically obtained putative targets were intersected and pathway enrichment analysis was performed. qRT-PCR was performed for validation of the selected miRNAs and potential targets. Results: miRNA expression profile changes between the control group without external stimulation and the samples at the end of 3-, 6-, 12- and 24-hour stimulation were compared with microarray analysis. In particular, our transcriptomic analysis showed 5 distinctively expressed miRNAs (DEmiRNAs) whose target genes are associated with cardiovascular development within the stimulated groups in HL-1 cells. Additionally, our bioinformatics analysis revealed that targets of these miRNAs are concentrated in biological processes associated with cardiovascular development: smooth muscle cell proliferation, muscle cell proliferation, cell morphogenesis involved in differentiation and regulation of cell differentiation. Specifically, qPCR-based analyses confirmed the inverse correlation of miR-568 and potential targets of this miRNA. While miR-568 expression decreased with prolonged stimulation, expression of its potential targets, NAMPT and TRPM7, increased during prolonged stimulation. Conclusion: This study supported the potential regulative role of miRNAs and their targets in the development of AF.

Conductive Polyisocyanide Hydrogels Inhibit Fibrosis and Promote Myogenesis.

Reliable in vitro models closely resembling native tissue are urgently needed for disease modeling and drug screening applications. Recently, conductive biomaterials have received increasing attention in the development of in vitro models as they permit exogenous electrical signals to guide cells toward a desired cellular response. Interestingly, they have demonstrated that they promote cellular proliferation and adhesion even without external electrical stimulation. This paper describes the development of a conductive, fully synthetic hydrogel based on hybrids of the peptide-modified polyisocyanide (PIC-RGD) and the relatively conductive poly(aniline-co-N-(4-sulfophenyl)aniline) (PASA) and its suitability as the in vitro matrix. We demonstrate that incorporating PASA enhances the PIC-RGD hydrogel's electroactive nature without significantly altering the fibrous architecture and nonlinear mechanics of the PIC-RGD network. The biocompatibility of our model was assessed through phenotyping cultured human foreskin fibroblasts (HFF) and murine C2C12 myoblasts. Immunofluorescence analysis revealed that PIC-PASA hydrogels inhibit the fibrotic behavior of HFFs while promoting myogenesis in C2C12 cells without electrical stimulation. The composite PIC-PASA hydrogel can actively change the cell fate of different cell types, providing an attractive tool to improve skin and muscle repair.

Bioelectric stimulation controls tissue shape and size

Epithelial tissues sheath organs and electro-mechanically regulate ion and water transport to regulate development, homeostasis, and hydrostatic organ pressure. Here, we demonstrate how external electrical stimulation allows us to control these processes in living tissues. Specifically, we electrically stimulate hollow, 3D kidneyoids and gut organoids and find that physiological-strength electrical stimulation of ∼ 5 - 10 V/cm powerfully inflates hollow tissues; a process we call electro-inflation. Electro-inflation is mediated by increased ion flux through ion channels/transporters and triggers subsequent osmotic water flow into the lumen, generating hydrostatic pressure that competes against cytoskeletal tension. Our computational studies suggest that electro-inflation is strongly driven by field-induced ion crowding on the outer surface of the tissue. Electrically stimulated tissues also break symmetry in 3D resulting from electrotaxis and affecting tissue shape. The ability of electrical cues to regulate tissue size and shape emphasizes the role and importance of the electrical micro-environment for living tissues.

Effects of Electric Field‐Modulated Conductive Hydrogel on Osseoperception and Osseointegration of Dental Implants

AbstractAchieving optimal implant restoration hinges on both robust osseointegration as the structural foundation and favorable osseoperception for advanced masticatory function. The significance of nerve innervation in the peri‐implant environment as the cornerstone of osseointegration and osseoperception is often underestimated. Despite the integral role of endogenous electric fields (EFs) in the human body, particularly in electrosensitive tissues like nerve tissue, the current approach involving external electrical stimulation is invasive and not clinically applicable. The present study introduces a conductive hydrogel designed to respond to endogenous EFs, aiming to foster nerve regeneration around dental implants to coordinate both osseointegration and osseoperception. The hydrogel promotes neurite outgrowth by upregulating intracellular Ca2+ concentration and activating subsequent pathways. Furthermore, the enhanced release of neuropeptides from neurocells improves the osteogenesis of osteoblasts. The impact of the conductive hydrogel on osseointegration and osseoperception is also thoroughly investigated in vivo. This conductive hydrogel represents a unique strategy for enhancing osseointegration and osseoperception within the endogenous EFs of the peri‐implant environment. This advancement opens the door to achieving the physiological and psychological integration of dental implants.

Regional differences in electroactive response of the sclera.

The sclera exhibits mechanical response when subjected to an external electric stimulation. The scleral electroactive response is a function of its charge density, mechanical properties, thickness, and strength of the applied electric voltage. The primary objective of the present work was to investigate the regional differences in the electroactive response of porcine sclera. To this end, we cut scleral strips in meridional directions from superior-temporal, superior-nasal, inferior-temporal, and inferior-nasal quadrants. In addition, we excised samples circumferentially from the posterior, equatorial, and anterior regions. The electroactive bending response of these samples was measured under 10 and 15 V in 0.15 M NaCl solution. The meridional samples were tested under two different configurations by clamping them either from their anterior or posterior end. It was observed that the scleral electroactive deformation increased with increasing the the electric voltage. Furthermore, regardless of the region from which meridional strips were excised, their electroactive response was considerably larger when they were clamped from their anterior end. Unlike meridional strips, the electroactive response of circumferential samples was significantly dependent on the location, that is, the average maximum bending angle of posterior samples was significantly larger than that of equatorial and anterior strips. The regionally different electroactive bending response of the sclera was discussed in terms of the variation in its biochemical and biomechanical properties throughout the eyeball.

Selective Electroporation of Tumor Cells Under AC Radiofrequency Stimulation - A Numerical Study.

Self-consistent evaluations of membrane electroporation along with local heating in single spherical cells arising from external AC radiofrequency electrical stimulation have been carried out. The present numerical study seeks to determine whether healthy and malignant cells exhibit separate electroporative responses with regards to operating frequency. It is shown that cells of Burkitt's lymphoma would respond to frequencies >4.5 MHz, while normal B-cells would have negligible porative effects in that higher frequency range. Similarly, a frequency separation between the response of healthy T-cells and malignant species is predicted with a threshold of about 4 MHz for cancer cells. The present simulation technique is general and so would be able to ascertain the beneficial frequency range for different cell types. The demonstration of higher frequencies to induce poration in malignant cells, while having minimal affecting healthy ones, suggests the possibility of selective electrical targeting for tumor treatments and protocols. It also opens the doorway for tabulating selectivity enhancement regimes as a guide for parameter selection towards more effective treatments while minimizing deleterious effects on healthy cells and tissues.

Synergistic effects of electroactive antibacterial material and electrical stimulation in enhancing skin tissue regeneration: A next-generation dermal wound dressing.

We aimed to develop an electroactive antibacterial material for the treatment of skin wound diseases. To this aim, we modified chitosan (CS), a biocompatible polymer, by coupling it with graphene (rGO) and an antimicrobial polypeptide DOPA-PonG1. The material's effect on skin injury healing was studied in combination with external electrical stimulation (EEM). The structure, surface composition, and hydrophilicity of the modified CS materials were evaluated using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and contact angle measurements. We studied NIH3T3 cells cultured with modified materials and subjected to EEM to assess viability, adhesion, and tissue repair-related gene expression. SEM data demonstrated that rGO was distributed uniformly on the surface of the CS material, increasing surface roughness, and antimicrobial peptides had minimal impact on surface morphology. FTIR confirmed the uniform distribution of rGO and antibacterial peptides on the material surface. Both rGO and DOPA-PonG1 enhanced the hydrophilicity of CS materials, with rGO also improving tensile strength. The dual modification of CS with rGO and DOPA-PonG1 synergistically increased antibacterial efficacy. Cellular events and gene expression relevant to tissue repair process were enhanced by these modifications. Furthermore, EEM accelerated epidermal regeneration more than the material alone. In a rat skin wound model, DOPA-PonG1@CS/rGO dressing combined with electrical stimulation exhibited accelerated healing of skin defect. Overall, our results demonstrate that CS materials modified with rGO and DOPA-PonG1 have increased hydrophilicity, antibacterial characteristics, and tissue regeneration capacities. This modified material in conjunction with EEM hold promise for the clinical management for dermal wounds.

Mass production of lumenogenic human embryoid bodies and functional cardiospheres using in-air-generated microcapsules

Organoids are engineered 3D miniature tissues that are defined by their organ-like structures, which drive a fundamental understanding of human development. However, current organoid generation methods are associated with low production throughputs and poor control over size and function including due to organoid merging, which limits their clinical and industrial translation. Here, we present a microfluidic platform for the mass production of lumenogenic embryoid bodies and functional cardiospheres. Specifically, we apply triple-jet in-air microfluidics for the ultra-high-throughput generation of hollow, thin-shelled, hydrogel microcapsules that can act as spheroid-forming bioreactors in a cytocompatible, oil-free, surfactant-free, and size-controlled manner. Uniquely, we show that microcapsules generated by in-air microfluidics provide a lumenogenic microenvironment with near 100% efficient cavitation of spheroids. We demonstrate that upon chemical stimulation, human pluripotent stem cell-derived spheroids undergo cardiomyogenic differentiation, effectively resulting in the mass production of homogeneous and functional cardiospheres that are responsive to external electrical stimulation. These findings drive clinical and industrial adaption of stem cell technology in tissue engineering and drug testing.

The guiding effect of local field potential during deep brain stimulation surgery for programming in Parkinson's disease patients.

Parkinson's disease (PD) patients undergoing deep brain stimulation (DBS) surgery require subsequent programming, which is complex and cumbersome. The local field potential (LFP) in the deep brain is associated with motor symptom improvement. The current study aimed to identify LFP biomarkers correlated with improved motor symptoms in PD patients after DBS and verify their guiding role in postoperative programming. Initially, the study included 36 PD patients undergoing DBS surgery. Temporary external electrical stimulation was performed during electrode implantation, and LFP signals around the electrode contacts were collected before and after stimulation. The stimulating contact at 6 months of programming was regarded as the optimal and effective stimulating contact. The LFP signal of this contact during surgery was analyzed to identify potential LFP biomarkers. Next, we randomly assigned another 30 PD patients who had undergone DBS to physician empirical programming and LFP biomarker-guided programming groups and compared the outcomes. In the first part of the study, LFP signals of electrode contacts changed after electrical stimulation. Electrical stimulation reduced gamma energy and the beta/alpha oscillation ratio. The different programming method groups were compared, indicating the superiority of beta/alpha oscillations ratio-guided programming over physician experience programming for patients' improvement rate (IR) of UPDRS-III. There were no significant differences in the IR of UPDRS-III, post-LED, IR-PDQ39, number of programmings, and the contact change rate between the gamma oscillations-guided programming and empirical programming groups. Overall, the findings reveal that gamma oscillations and the beta/alpha oscillations ratio are potential biomarkers for programming in PD patients after DBS. Instead of relying solely on spike action potential signals from single neurons, LFP biomarkers can provide the appropriate depth for electrode placement.

Electrical properties of biodegradable chitosan-calcium phosphate nerve conduits doped with inorganic nanoparticles

Biodegradable nerve conductors are based on chitosan-calcium phosphate (CS/CaP) doped with nanoparticles of multiwalled carbon nanotubes (MWCNT+Fe), graphene oxide (GO), magnetite (Fe3O4) of various nanoparticle concentrations (NpC). Drug release and electrical properties were studied depending on the polarity, voltage, and electrode configuration (in-in, in-out), which reflect nerve regeneration inside the conduit and external electrical stimulation. The NpC of 150 μg/ml provides the highest electrical conductivity (EC) of 150MWCNT+Fe in-in. 150GO is more effective in the in-out configuration. The 300GO sample has an in-out electrical conductivity of 0.71∙ 10−2 S/cm, which is close to the natural nerve conductivity of 2.35∙10−2 S/cm. Nanoparticles in the CS/CaP matrix when interacting with the physiological solution ions can create new mechanisms for the current passage or neutralize existing ones. All samples are characterized by the absence of "burst drug release". Pregabalin (PG) release from Fe-containing samples is controlled by diffusion (first-order model), and from GO-containing – by diffusion and degradation of the matrix (second-order model).

Dual-modal artificial synapse based on a lead-free halide Cu2AgBiI6 for image processing and information encryption

The lead-free perovskite-inspired materials are regarded as one of the alternatives to lead-based perovskite for the preparation of neuromorphic devices due to their low toxicity, excellent optical and transport properties. Herein, a two-terminal artificial synapse was fabricated based on a novel lead-free halide Cu2AgBiI6 thin film. The fabricated device exhibited the versatile synaptic behavior whether subjected to external electrical or optical stimulation benefitting from the excellent photoelectric characteristics of Cu2AgBiI6. Furthermore, the intrinsic photovoltaic feature of Cu2AgBiI6 enabled the device with capabilities of operating in a self-powered mode under optical stimulation. The device successfully imitated the retina’s capacity for color perception by employing optical pulses of various wavelengths. The dependence of the device response on the optical pulse frequency allowed it to function as a high-pass filter for image sharpening. At last, the device was applied for the information encryption and decryption transmission based on a constructed password book including 128 common characters and numbers, which shows great potential for information encryption and decryption transmission. The comprehensive characters of the device display great superiority over other artificial synaptic devices.

Beyond CPAP: modifying upper airway output for the treatment of OSA.

Obstructive Sleep Apnea (OSA) is exceedingly common but often under-treated. Continuous positive airway pressure (CPAP) has long been considered the gold standard of OSA therapy. Limitations to CPAP therapy include adherence and availability. The 2021 global CPAP shortage highlighted the need to tailor patient treatments beyond CPAP alone. Common CPAP alternative approaches include positional therapy, mandibular advancement devices, and upper airway surgery. Upper airway training consists of a variety of therapies, including exercise regimens, external neuromuscular electrical stimulation, and woodwind instruments. More invasive approaches include hypoglossal nerve stimulation devices. This review will focus on the approaches for modifying upper airway muscle behavior as a therapeutic modality in OSA.

Electrically Sensitive Plasmonic Photonic Crystals for Dynamic Upconversion Manipulation

AbstractLocal optical field modulation using plasmonic materials or photonic crystals provides a powerful strategy for enhancing upconversion emission of lanthanide‐doped upconversion nanocrystals (UCNPs). However, it is restricted to static UC enhancement and the corresponding dynamic modulation of UC is yet to be reported, limiting its practical applications in information devices. Here, a dynamic UC modulation system is reported through electric stimulation by integrating UCNPs with electrically sensitive WO3−x plasmonic photonic crystals (PPCs). The tunable emission enhancement of UCNPs varying from five to 26 folds is achieved in WO3−x PPCs/UCNPs hybrids through external electric stimulation within +1.6 and −1.6 V. It stems from the reversible control of the photonic bandgaps and localized surface plasmon resonance of WO3−x PPCs, ascribed to the variation of refractive index and oxygen vacancy of WO3−x, induced by the reversible change of atomic ratio of W5+ to W6+ under different applied voltages. Moreover, the electrically triggered information encryption devices are developed, employing a programmable logic gate array based on WO3−x PPCs/UCNPs with the ability to convert information‐encrypted electrical signals into visible patterns. These observations offer a new attempt to manipulate the UC and will simulate the new applications in the display and optical storage devices.

Evaluation of visual acuity in dry AMD patients after microcurrent electrical stimulation

BackgroundTo assess micro current to improve vision for dry age-related macular degeneration. Dry age-related macular degeneration is a major cause of blindness, disability, and severe erosion of quality of life, throughout the world. Beyond nutritional supplementation, there is no approved therapy.MethodsThis was a prospective randomized sham controlled clinical trial for participants with confirmed dry AMD with documented visual loss. Participants were randomized three to one, to receive transpalpebral external micro current electrical stimulation with the MacuMira device. The Treatment group received four treatments in the first two weeks, and two further treatments at weeks 14 and 26. Differences in BCVA and contrast sensitivity (CS) were estimated with mixed-effects repeated measures analysis of variance.ResultsChange of visual acuity with ETDRS assessment of number of letters read (NLR) and contrast sensitivity at week 4 and 30, compared to the first visit, between 43 treatment and 19 sham control participants. The Sham Control group had NLR of 24.2 (SD 7.1) at baseline, 24.2 (SD 7.2) at 4 weeks, and 22.1 (SD7.4) at 30 weeks. The Treatment group had NLR of 19.6 (SD 8.9) at baseline, 27.6 (SD 9.1) at 4 weeks, and 27.8 (SD 8.4) at 30 weeks. The change in NLR from baseline in the Treatment compared to the Sham control group was 7.7 (95% CI 5.7, 9.7, p < 0.001) at 4 weeks and 10.4 (95% CI 7.8, 13.1, p < 0.001) at 30 weeks. There were similar benefits in CS.ConclusionsThis pilot study of transpalpebral microcurrent demonstrated improved visual measures and is very encouraging as a potential treatment for dry AMD.Trial Registration: NCT02540148, ClinicalTrials.gov.

Physiological loading-induced streaming potentials in osteogenesis imperfecta bone

Mechanical loading on bone generates streaming potentials (SPs) and streaming currents (SCs) in lacunar-canalicular fluid which act as stimuli to bone cells namely osteocytes. It is observed that both lacunar and vascular porosity significantly affect streaming potentials and thus the bone remodelling activities. Increased porosity levels associated with bone disorders such as especially osteogenesis imperfecta (OI) and osteoporosis considerably reduce SPs which may further negatively affect bone’s mechanoregulation. This could also be a possible reason for reduced mechanosensitivity of OI and osteoporotic bones to exogenous mechanical stimulation. There is hardly any work in the literature which explored the physiological loading induced SPs and SCs in healthy versus OI bone. Accordingly, the present study attempts to address the two important questions: (i) how does physiological gait loading generate SPs and SCs in Healthy versus OI osteons? (ii) Can mechanical and electrical stimuli be effectively utilised to enhance SPs and SCs in OI bone? A transversely isotropic-poroelastic osteon model is developed to compute SPs and SCs in interstitial fluid flow in response to exogenous mechanical and electrical stimulations. The outcomes indicate that streaming potentials and current significantly decrease in OI bone, whereas, loading frequency and electrical field has potential to enhance SPs and SCs in OI bone. The present study concludes that physical exercises in presence of external electrical stimulation may potentially enhance SPs and SCs in interstitial bone fluid to improve remodelling activities OI bone for naturally strengthening.

Facilitation of Osteogenic Differentiation of hASCs on PEDOT:PSS/MXene Composite Sponge with Electrical Stimulation

Innovations in biomedical tissue engineering are on the increase as many researchers look for ways to develop biological scaffolds for cells. Studies have shown that the application of external force and electrical stimulation (ES) promotes stem cell chondrogenic and osteogenic differentiation. Therefore, bioscaffolds sensitive to external stimuli can not only influence the cell behavior with their native physical and biochemical properties but also act as a mediator receiving an outside-in signal to alter the cellular activities under specific conditions. For the first time, the synthetic polymer poly(3,4-ethylene dioxythiophene):polystyrene sulfonate) (PEDOT:PSS) was combined with a two-dimensional, nanoconducting material, titanium carbide (MXene, Ti3C2X3), to prepare three-dimensional (3D) conductive scaffolds. Some studies have shown that MXene has good biocompatibility, osteoinductivity, and bone regeneration activity. The PEDOT:PSS/MXene scaffold was applied to the osteogenic differentiation of hASCs, and ES was used to enhance the osteogenic differentiation. The results showed that the conductive scaffold had low cytotoxicity to hASCs, which could grow and migrate in the 3D scaffold. In addition, osteogenic-specific gene expression significantly differed when the ES was applied. We propose that this PEDOT:PSS/MXene scaffold may serve as a platform for the study of osteogenic differentiation of stem cells with ES and may potentially be ex vivo fabricated as a tissue engineering construct for studying other modes of other ESs such as direct current, capacitive, or inductive coupling in a 3D environment.

Method of diagnosing some diseases of the neuro-muscular system and features of data processing in software

Electromyostimulation is a method of restorative treatment based on electrical stimulation of nerves and muscles. The electric current, which is used in electrical stimulation to obtain induced muscle contractions, is characterized by a large number of different parameters. However, not every possible option of electrical stimulation is highly effective. To solve the task of diagnosing some diseases of the neuromuscular system, it is important to organize the software by analyzing the parameters of the evoked potentials. Therefore, the object of research is the processes of skeletal muscle contraction under the influence of natural electrical pulses of the nervous system or under the influence of external electrical stimulation. The subject of research is models describing the processes in muscles during contraction and methods of data processing. In the course of the study, such research methods as mathematical modeling methods and methods of processing medical and biological data were used. The paper examines the experimental strength-duration dependence of skeletal muscle and obtained mathematical models for the normal state of the neuromuscular apparatus and different degrees of denervation. On the basis of electrodiagnosis of a patient with impaired motor functions, the dynamics of changes in the patient's condition and the effectiveness of treatment were traced. Based on the results of the study, an analysis of the parameters of the evoked potentials of the stimulation electromyogram during adaptive electrostimulation was carried out in order to control its effectiveness or establish a diagnosis in some diseases of the neuromuscular system. This made it possible to develop a method for correcting errors in the interpretation of one of the quality parameters and increase the reliability of the diagnosis. The obtained results can be used in the improvement of technical devices for electrostimulation therapy, as well as control of the effectiveness of rehabilitation procedures.

Deformation Performance of Pt-IPMC Based on Experiment and Simulation Research

Ionic polymer metal composite (IPMC) is an intelligent material that can bend rapidly to produce large deformation and large strain when subjected to external electrical stimulation. And it is widely used in the actuation of underwater bionic robots. In this paper, two sets of IPMCs were fabricated by chemical reduction on the surface of commercial Nafion films. An experimental platform was built, the maximum displacement of IPMCs was 13.07 mm and the maximum output force was 12.14 mN, and it is found that IPMCs with high driving performance could generate displacements of 3.47 mm∼0.26 mm under high frequency voltage. The piezoelectric bicrystal model of IPMC was constructed and validated by Pearson correlation, proving that the model can effectively predict the experimental values and providing theoretical support for the subsequent research on the tail fin drive of IPMC miniature robot fish.

External bioelectric control of tissue hydrostatic pressure and ion pumping.

Direct-Current (DC) currents exist throughout the body and regulate cellular responses spanning directed cell migration (electrotaxis) to transcriptional regulation. New approaches using electrical cues to control biological systems are, therefore, quite exciting, and we have previously demonstrated electrically programmable collective migration in epithelia. Here, we demonstrate those same cues reprogramming 3D growth in lumenized tissues such as hollow kidney spheroids and intestinal organoids. We found that electrical stimulation induces a rapid, powerful, and reversible swelling in these tissues, and we discuss how external electrical stimulation can control the inflation of lumenized structures and cellular mechanisms mediating the response. We first studied hollow kidney spheroids within a hydrogel integrated into our SCHEEPDOG electrobioreactor. This allowed 3D, timelapse imaging during electrical stimulation. Hollow spheroids inflated nearly 3X by volume relative to control spheroids within 4 hrs of stimulation. The rate and magnitude of inflation increased with increasing electric field strength, and overly strong field gradients induced ‘popping’. We hypothesized that the dense actomyosin network at the apical surface of the structures provided a physical limit to the inflation response, and showed that inhibiting actomyosin contractility prevented popping and increased the maximum swelling volume. We used ion channel inhibitors to determine that the majority of the response can be attributed to the CFTR ion channel (apical chloride channel) and NKCC (basal sodium/potassium channel). Our computational model relating direct-current fields, electrochemistry, and hydrostatic pressure capture many of these effects, as well as predicting asymmetric ion distributions around spheroids. Interestingly, 3D cross-sections of inflated tissues reveal asymmetric cell shapes on the anode/cathode cysts of the spheroids. We have recently confirmed that mouse intestinal organoids also inflate upon field stimulation in a CFTR-mediated fashion, and are exploring other lumenized tissues to assess the generality of this phenomenon.

Polylactic Acid/Polyaniline Nanofibers Subjected to Pre- and Post-Electrospinning Plasma Treatments for Refined Scaffold-Based Nerve Tissue Engineering Applications

Composite biopolymer/conducting polymer scaffolds, such as polylactic acid (PLA)/ polyaniline (PAni) nanofibers, have emerged as popular alternative scaffolds in the electrical-sensitive nerve tissue engineering (TE). Although mimicking the extracellular matrix geometry, such scaffolds are highly hydrophobic and usually present an inhomogeneous morphology with massive beads that impede nerve cell-material interactions. Therefore, the present study launches an exclusive combinatorial strategy merging successive pre- and post-electrospinning plasma treatments to cope with these issues. Firstly, an atmospheric pressure plasma jet (APPJ) treatment was applied on PLA and PLA/PAni solutions prior to electrospinning, enhancing their viscosity and conductivity. These liquid property changes largely eliminated the beaded structures on the nanofibers, leading to uniform and nicely elongated fibers having average diameters between 170 and 230 nm. After electrospinning, the conceived scaffolds were subjected to a N2 dielectric barrier discharge (DBD) treatment, which significantly increased their surface wettability as illustrated by large decreases in water contact angles for values above 125° to values below 25°. X-ray photoelectron spectroscopy (XPS) analyses revealed that 3.3% of nitrogen was implanted on the nanofibers surface in the form of C-N and N-C=O functionalities upon DBD treatment. Finally, after seeding pheochromocytoma (PC-12) cells on the scaffolds, a greatly enhanced cell adhesion and a more dispersive cell distribution were detected on the DBD-treated samples. Interestingly, when the APPJ treatment was additionally performed, the extension of a high number of long neurites was spotted leading to the formation of a neuronal network between PC-12 cell clusters. In addition, the presence of conducting PAni in the scaffolds further promoted the behavior of PC-12 cells as illustrated by more than a 40% increase in the neurite density without any external electrical stimulation. As such, this work presents a new strategy combining different plasma-assisted biofabrication techniques of conducting nanofibers to create promising scaffolds for electrical-sensitive TE applications.