Electrical Stimulation Research Articles

HiPSC-CM Electrophysiology: Impact of Temporal Changes and Study Parameters on Experimental Reproducibility.

Human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) are frequently used for preclinical cardiotoxicity testing and remain an important tool for confirming model-based predictions of drug effects in accordance with Comprehensive in Vitro Proarrhythmia Assay (CiPA). Despite the considerable benefits hiPSC-CMs provide, concerns surrounding experimental reproducibility have emerged. We investigated the effects of temporal changes and experimental parameters on hiPSC-CM electrophysiology. iCell cardiomyocytes2 were cultured and biosignals were acquired using a microelectrode array (MEA) system (1-14 days). Continuous recordings revealed a 22.6% increase in the beating rate and 7.7% decrease in the field potential duration (FPD) during a 20-minute equilibration period. Location specific differences across a multiwell plate were also observed, with iCell cardiomyocytes2 in the outer rows beating 8.8 beats per minute (BPM) faster than the inner rows. Cardiac endpoints were also impacted by cell culture duration; from 2-14 days the beating rate decreased (-12.7 BPM), FPD lengthened (+257 ms), and spike amplitude increased (+3.3 mV). Cell culture duration (4-10 days) also impacted cardiomyocyte drug responsiveness (E-4031, nifedipine, isoproterenol). qRT-PCR results suggest that daily variations in cardiac metrics may be linked to the continued maturation of hiPSC-CMs in culture (2-30 days). Daily experiments were also repeated using a second cell line (Cor.4U). Collectively, our study highlights multiple sources of variability to consider and address when performing hiPSC-CM MEA studies. To improve reproducibility and data interpretation, MEA-based studies should establish a standardized protocol and report key experimental conditions (e.g., cell line, culture time, equilibration time, electrical stimulation settings, raw data values).

Spexin Diminishes Atrial Fibrillation Vulnerability by Acting on Galanin Receptor 2.

G protein-coupled receptors play a critical role in atrial fibrillation (AF). Spexin is a novel ligand of galanin receptors (GALRs). In this study, we investigated the regulation of spexin and GALRs on AF and the underlying mechanisms. Global spexin knockout (SPX-KO) and cardiomyocyte-specific GALRs knockout (GALR-cKO) mice underwent burst pacing electrical stimulation. Optical mapping was used to determine atrial conduction velocity and action potential duration. Atrial myocyte action potential duration and inward rectifying K+ current (IK1) were recorded using whole-cell patch clamps. Isolated cardiomyocytes were stained with Fluo-3/AM dye, and intracellular Ca2+ handling was examined by CCD camera. A mouse model of AF was established by Ang-II (angiotensin II) infusion. Spexin plasma levels in patients with AF were lower than those in subjects without AF, and knockout of spexin increased AF susceptibility in mice. In the atrium of SPX-KO mice, potassium inwardly rectifying channel subfamily J member 2 (KCNJ2) and sarcolipin (SLN) were upregulated; meanwhile, IK1 current was increased and Ca2+ handling was impaired in isolated atrial myocytes of SPX-KO mice. GALR2-cKO mice, but not GALR1-cKO and GALR3-cKO mice, had a higher incidence of AF, which was associated with higher IK1 current and intracellular Ca2+ overload. The phosphorylation level of CREB (cyclic AMP responsive element binding protein 1) was upregulated in atrial tissues of SPX-KO and GALR2-cKO mice. Chromatin immunoprecipitation confirmed the recruitment of p-CREB to the proximal promoter regions of KCNJ2 and SLN. Finally, spexin treatment suppressed CREB signaling, decreased IK1 current and intracellular Ca2+ overload, which thus reduced the inducibility of AF in Ang-II-infused mice. Spexin reduces atrial fibrillation susceptibility by inhibiting CREB phosphorylation and thus downregulating KCNJ2 and SLN transcription by GALR2 receptor. The spexin/GALR2/CREB signaling pathway represents a novel therapeutic avenue in the development of agents against atrial fibrillation.

Transcranial alternating current stimulation over frontal eye fields mimics attentional modulation of visual processing.

Attentional control over sensory processing has been linked to neural alpha oscillations and related inhibition of cerebral cortex. Despite the wide consensus on the functional relevance of alpha oscillations for attention, precise neural mechanisms of how alpha oscillations shape perception and how this top-down modulation is implemented in cortical networks remain unclear. Here, we tested the hypothesis that alpha oscillations in frontal eye fields (FEF) are causally involved in the top-down regulation of visual processing in humans (male and female). We applied sham-controlled, intermittent transcranial alternating current stimulation (tACS) over bilateral FEF at either 10 Hz (alpha) or 40 Hz (gamma) to manipulate attentional preparation in a visual discrimination task. Under each stimulation condition, we measured psychometric functions for contrast perception and introduced a novel linear mixed modeling approach for statistical control of neurosensory side effects of the electric stimulation. TACS at alpha frequency reduced the slope of the psychometric function, resulting in improved sub-threshold and impaired super-threshold contrast perception. Side effects on the psychometric functions were complex and showed large interindividual variability. Controlling for the impact of side effects on the psychometric parameters by using covariates in the linear mixed model analysis reduced this variability and strengthened the perceptual effect. We propose that alpha tACS over FEF mimicked a state of endogenous attention by strengthening a fronto-occipitoparietal network in the alpha band. We speculate that this network modulation enhanced phasic gating in occipitoparietal cortex leading to increased variability of single-trial psychometric thresholds, measurable as a reduction of psychometric slope.Significance statement Attention is fundamental to the voluntary control of perception and behavior. Yet, precise underlying neural mechanisms remain unclear. Here, we provide evidence for a vital role of frontal alpha oscillations in the regulation of gating of visual information by using intermittent transcranial alternating current stimulation (tACS). We show that modulation of frontal alpha oscillations affected the slope of psychometric functions of visual contrast perception, leading to contrast-dependent improvement and impairment of perception. Our data adds to work on alpha oscillations in spatial attention and studies on the psychometrics of attention. Furthermore, we introduce a novel approach for the statistical control of tACS side effects and thereby contribute to the ongoing debate on outcome variability in studies using transcranial neurostimulation methods.

Pressure injury treatment by intermittent electrical stimulation (PROTECT-2): protocol for a multicenter randomized clinical trial

BackgroundPressure ulcers account for a substantial fraction of hospital-acquired pathology, with consequent morbidity and economic cost. Treatments are largely focused on preventing further injury, whereas interventions that facilitate healing remain limited. Intermittent electrical stimulation (IES) increases local blood flow and redistributes pressure from muscle-bone interfaces, thus potentially reducing ulcer progression and facilitating healing.MethodsThe Pressure Injury Treatment by Intermittent Electrical Stimulation (PROTECT-2) trial will be a parallel-arm multicenter randomized trial to test the hypothesis that IES combined with routine care reduces sacral and ischial pressure injury over time compared to routine care alone. We plan to enroll 548 patients across various centers. Hospitalized patients with stage 1 or stage 2 sacral or ischial pressure injuries will be randomized to IES and routine care or routine care alone. Wound stage will be followed until death, discharge, or the development of an exclusion criteria for up to 3 months. The primary endpoint will be pressure injury score measured over time.DiscussionSacral and ischial pressure injuries present a burden to hospitalized patients with both clinical and economic consequences. The PROTECT-2 trial will evaluate whether IES is an effective intervention and thus reduces progression of stage 1 and stage 2 sacral and ischial pressure injuries.Trial registrationClinicalTrials.gov NCT05085288 Registered October 20, 2021.

Neuromuscular electrical stimulation for physical function maintenance during hematopoietic stem cell transplantation: Study protocol.

Hematopoietic stem cell transplantation is a common life-saving treatment for hematologic malignancies, though can lead to long-term functional impairment, fatigue, muscle atrophy, with decreased quality of life. Although traditional exercise has helped reduce these effects, it is inconsistently recommended and infrequently maintained, and most patients remain sedentary during and after treatment. There is need for alternative rehabilitation strategies, like neuromuscular electrical stimulation, that may be more amenable to the capabilities of hematopoietic stem cell transplant recipients. Patients receiving autologous HCT are being enroled in a randomized controlled trial with 1:1 (neuromuscular electrical stimulation:sham) design stratified by diagnosis and sex. Physical function, body composition, quality of life, and fatigue are assessed prior to hematopoietic stem cell transplant (prior to initiating preparatory treatment) and 24±5 days post hematopoietic stem cell transplant (Follow-up 1); physical function and quality of life are also assessed 6-months post hematopoietic stem cell transplant (Follow-up 2). The primary outcome is between-group difference in the 6-minute walk test change scores (Follow-up 1-Pre-transplant; final enrolment goal N = 23/group). We hypothesize that 1) neuromuscular electrical stimulation will attenuate hematopoietic stem cell transplant-induced adverse effects on physical function, muscle mass, quality of life, and fatigue compared to sham at Follow-up 1, and 2) Pre-transplant physical function will significantly predict fatigue and quality of life at Follow-up 2. We will also describe feasibility and acceptability of neuromuscular electrical stimulation during hematopoietic stem cell transplant. This proposal will improve rehabilitative patient care and quality of life by determining efficacy and feasibility of a currently underutilized therapeutic strategy aimed at maintaining daily function and reducing the impact of a potent and widely used cancer treatment. This trial is registered with clinicaltrials.gov (NCT04364256).

Can self-powered piezoelectric materials be used to treat disc degeneration by means of electrical stimulation?

Intervertebral disc degeneration (IDD) due to multiple causes is one of the major causes of low back pain (LBP). A variety of traditional treatments and biologic therapies are currently used to delay or even reverse IDD; however, these treatments still have some limitations. Finding safer and more effective treatments is urgent for LBP patients. With increasing reports it has been found that the intervertebral disc (IVD) can convert pressure loads from the spine into electrical stimulation in a variety of ways, and that this electrical stimulation is of great importance in modulating cell behavior, the immune microenvironment and promoting tissue repair. However, when intervertebral disc degeneration occurs, the normal structures within the IVD are destroyed. This eventually leads to a weakening or loss of self-powered. Currently various piezoelectric materials with unique crystal structures can mimic the piezoelectric effect of normal tissues. Based on this, tissue-engineered scaffolds prepared using piezoelectric materials have been widely used for regenerative repair of various types of tissues, however, there are no reports of their use for the treatment of IDD. For this reason, we propose to utilize tissue-engineered scaffolds prepared from piezoelectric biomaterials with excellent biocompatibility and self-powered properties to be implanted into degenerated IVD to help restore cell type and number, restore extracellular matrix, and modulate immune responses. It provides a feasible and novel therapeutic approach for the clinical treatment of IDD.

Depth versus surface: A critical review of subdural and depth electrodes in intracranial electroencephalographic studies.

Intracranial electroencephalographic (IEEG) recording, using subdural electrodes (SDEs) and stereoelectroencephalography (SEEG), plays a pivotal role in localizing the epileptogenic zone (EZ). SDEs, employed for superficial cortical seizure foci localization, provide information on two-dimensional seizure onset and propagation. In contrast, SEEG, with its three-dimensional sampling, allows exploration of deep brain structures, sulcal folds, and bihemispheric networks. SEEG offers the advantages of fewer complications, better tolerability, and coverage of sulci. Although both modalities allow electrical stimulation, SDE mapping can tessellate cortical gyri, providing the opportunity for a tailored resection. With SEEG, both superficial gyri and deep sulci can be stimulated, and there is a lower risk of afterdischarges and stimulation-induced seizures. Most systematic reviews and meta-analyses have addressed the comparative effectiveness of SDEs and SEEG in localizing the EZ and achieving seizure freedom, although discrepancies persist in the literature. The combination of SDEs and SEEG could potentially overcome the limitations inherent to each technique individually, better delineating seizure foci. This review describes the strengths and limitations of SDE and SEEG recordings, highlighting their unique indications in seizure localization, as evidenced by recent publications. Addressing controversies in the perceived usefulness of the two techniques offers insights that can aid in selecting the most suitable IEEG in clinical practice.

Selective intrafascicular stimulation of myelinated and unmyelinated nerve fibers through a longitudinal electrode: A computational study

Carbon nanotube (CNT) fiber electrodes have demonstrated exceptional spatial selectivity and sustained reliability in the context of intrafascicular electrical stimulation, as evidenced through rigorous animal experimentation. A significant presence of unmyelinated C fibers, known to induce uncomfortable somatosensory experiences, exists within peripheral nerves. This presence poses a considerable challenge to the excitation of myelinated Aβ fibers, which are crucial for tactile sensation. To achieve nuanced tactile sensory feedback utilizing CNT fiber electrodes, the selective stimulation of Aβ sensory afferents emerges as a critical factor.In confronting this challenge, the present investigation sought to refine and apply a rat sciatic-nerve model leveraging the capabilities of the COMSOL-NEURON framework. This approach enables a systematic evaluation of the influence exerted by stimulation parameters and electrode geometry on the activation dynamics of both myelinated Aβ and unmyelinated C fibers. The findings advocate for the utilization of current pulses featuring a pulse width of 600 μs, alongside the deployment of CNT fibers characterized by a diminutive diameter of 10 μm, with an exclusively exposed cross-sectional area, to facilitate reduced activation current thresholds. Comparative analysis under monopolar and bipolar electrical stimulation conditions revealed proximate activation thresholds, albeit with bipolar stimulation exhibiting superior fiber selectivity relative to its monopolar counterpart. Concerning pulse waveform characteristics, the adoption of an anodic-first biphasic stimulation modality is favored, taking into account the dual criteria of activation threshold and fiber selectivity optimization. Consequently, this investigation furnishes an efficacious stimulation paradigm for the selective activation of touch-related nerve fibers, alongside provisioning a comprehensive theoretical foundation for the realization of natural tactile feedback within the domain of prosthetic hand applications.

Wired for Success: Probing the Effect of Tissue-Engineered Neural Interface Substrates on Cell Viability.

This study investigates the electrochemical behavior of GelMA-based hydrogels and their interactions with PC12 neural cells under electrical stimulation in the presence of conducting substrates. Focusing on indium tin oxide (ITO), platinum, and gold mylar substrates supporting conductive scaffolds composed of hydrogel, graphene oxide, and gold nanorods, we explored how the substrate materials affect scaffold conductivity and cell viability. We examined the impact of an optimized electrical stimulation protocol on the PC12 cell viability. According to our findings, substrate selection significantly influences conductive hydrogel behavior, affecting cell viability and proliferation as a result. In particular, the ITO substrates were found to provide the best support for cell viability with an average of at least three times higher metabolic activity compared to platinum and gold mylar substrates over a 7 day stimulation period. The study offers new insights into substrate selection as a platform for neural cell stimulation and underscores the critical role of substrate materials in optimizing the efficacy of neural interfaces for biomedical applications. In addition to extending existing work, this study provides a robust platform for future explorations aimed at tailoring the full potential of tissue-engineered neural interfaces.

Deep Learning-based Thigh Muscle Investigation Using MRI For Prosthetic Development for Patients Undergoing Total Knee Replacement (TKR).

A prosthetic device is designed based on the quantitative analysis of muscle MRI which will improve the muscle control achieved with functional electrical stimulation/ guided robotic exoskeletons. Electromyography (EMG) provides muscle functionality information while MRI provides the physiological and functionality of muscles. The sensor feedbacks were used for the bionic prosthesis, but the length of muscle using image processing was not correlated. To investigate and perform qualitative and quantitative assessment of thigh muscle using MRI. The objective of the work is to improve the existing VAG signal classification method to diagnose abnormality using MRI for patients undergoing Total knee replacement (TKR). A deep learning method for qualitative and quantitative assessment of thigh muscle is done using MRI. In existing prosthetic devices, electrical measurements of a person's muscles are obtained using surface or implantable electrodes. Several methods were used for the classification and diagnostic processes. The existing methods have drawbacks in feature extraction and require experts to design the system. This work combines medical image processing and orthopaedic prosthetics to develop a therapeutic method. This design provides much more precise control of prosthetic limbs using the image processing technique. The hybrid CNN swarm-based method measures the muscle structure and functions. Along with the sensor readings, these details are combined for prosthetic control. The implementation was carried out in MATLAB, Sketchuppro, and Arduino IDE. A combined swarm intelligence and deep learning method were proposed for qualitative and quantitative assessment of thigh muscle. The prosthetic device choice was done from the scanned MRI image like Humerus-T prosthetics, segmental prosthesis and arthrodesis prosthesis. The investigation was done for the Total knee replacement (TKR) approach.

Targeting the left DLPFC and right VLPFC in unmarried romantic relationship breakup (love trauma syndrome) with intensified electrical stimulation: A randomized, single-blind, parallel-group, sham-controlled study

BackgroundEnding a romantic relationship is one of the most painful losses an adult experience. Neuroimaging studies suggest that there is a neuropsychological link between breakup experiences and bereaved individuals, and that specific prefrontal regions are involved. The aim of this study was to determine whether enhancement of left DLPFC and right VLPFC activity with a novel intensified anodal transcranial direct current stimulation protocol reduces core symptoms of love trauma syndrome (LTS) and improves treatment-related variables. MethodsIn this randomized, sham-controlled, single-blind parallel trial, we assessed the efficacy of an intensified anodal stimulation protocol (20 min, twice-daily sessions with 20 min intervals, 5 consecutive days) with two montages (left DLPFC vs right VLPFC) to reduce love trauma symptoms. 36 participants with love trauma syndrome were randomized in three tDCS condition (left DLPFC, right VLPFC, sham stimulation). LTS symptoms, treatment-related outcome variables (depressive state, anxiety, emotion regulation, positive and negative affect), and cognitive functions were assessed before, right after, and one month after intervention. ResultsBoth DLPFC and VLPFC protocols significantly reduced LTS symptoms, and improved depressive state and anxiety after the intervention, as compared to the sham group. The improving effect of the DLPFC protocol on love trauma syndrome was significantly larger than that of the VLPFC protocol. For emotion regulation and positive and negative affect, improved regulation of emotions and positive affect and reduced negative affect were revealed after intervention in the two real stimulation conditions compared to the sham. For cognitive functions, no significant difference was observed between the groups, but again a positive effect of intervention within groups in the real stimulation conditions (DLPFC and VLPFC) was found for most components of the cognitive tasks. ConclusionsEnhancement of left DLPFC and right VLPFC activity with intensified stimulation improves LTS symptoms and treatment-related variables. For LTS symptoms, DLPFC stimulation was more efficient than VLPFC stimulation., For the other variables, no significant difference was observed between these two stimulation groups. These promising results require replication in larger trials.

Effects of electrical stimulation on carbon sequestration of photosynthetic bacteria: Response of the photosynthetic unit to electrical stimulation

Bioelectrochemical systems have been used to enhance the carbon sequestration of photosynthetic bacteria (PSB), but it is unclear whether the electrical stimulation affects the structure of membrane proteins involved in photochemical activity. In this study, the rate of CO2 fixation in the photosynthetic bacteria R. palustris increased with electrical stimulation, and the enhancement partly remained even after the power off. The CO2 fixation rate in electrical-stimulated PSB was 10% higher than in non-stimulated PSB, and the activity of the CO2 fixation enzyme Rubisco was 16% higher. This resulted from the improved light utilization efficiency of the photosynthetic units in R. palustris after electrical stimulation, particularly due to the enhancement of the primary reaction mediated by the light capture protein RC-LH1. The molar extinction coefficient of the light capture protein RC-LH1 increased from 3301 cm−1 mM−1 to 3733 cm−1 mM−1, and the maximum rate of the primary reaction increased from 6.88 × 10−3 e−RC−1s−1 to 8.66 × 10−3 e−RC−1s−1. Circular dichroism spectroscopy and Fourier transform infrared spectroscopy indicated that the electrical stimulation increased the dipole moment of the α-helix in RC-LH1 to facilitate the quinone transport in the primary reaction. Nuclear magnetic resonance spectroscopy revealed that the electrical stimulation increased the formation of hydrogen bonds in bacteriochlorophyll a for electron transition. This study investigated the response of photosynthetic bacteria to electrical stimulation, providing a distinct outlook on the electrochemical regulation of photosynthesis for carbon capture.

Self-oscillating polymeric refrigerator with high energy efficiency.

Electrocaloric1,2 and electrostrictive3,4 effects concurrently exist in dielectric materials. Combining these two effects could achieve the lightweight, compact localized thermal management that is promised by electrocaloric refrigeration5. Despite a handful of numerical models and schematic presentations6,7, current electrocaloric refrigerators still rely on external accessories to drive the working bodies8-10 and hence result in a low device-level cooling power density and coefficient of performance (COP). Here we report an electrocaloric thin-film device that uses the electro-thermomechanical synergy provided by polymeric ferroelectrics. Under one-time a.c. electric stimulation, the device is thermally and mechanically cycled by the working body itself, resulting in an external-driver-free, self-cycling, soft refrigerator. The prototype offers a directly measured cooling power density of 6.5 W g-1 and a peak COP exceeding 58 under a zero temperature span. Being merely a 30-µm-thick polymer film, the device achieved a COP close to 24 under a 4 K temperature span in an open ambient environment (32% thermodynamic efficiency). Compared with passive cooling, the thin-film refrigerator could immediately induce an additional 17.5 K temperature drop against an electronic chip. The soft, polymeric refrigerator can sense, actuate and pump heat to provide automatic localized thermal management.

Electroencephalographic indices for clinical endpoints during propofol anesthesia in infants-an early phase propofol biomarker-finding study.

Unlike expired sevoflurane concentration, propofol lacks a biomarker for its brain effect site concentration (Ce), leading to dosing imprecision particularly in infants. Electroencephalography (EEG) monitoring can serve as a biomarker for propofol Ce, yet proprietary EEG indices are not validated in infants. We evaluated spectral edge frequency (SEF95) as a propofol anesthesia biomarker in infants. We hypothesized that the SEF95 targets will vary for different clinical stimuli and an inverse relationship existed between SEF95 and propofol plasma concentration. This prospective study enrolled infants (3-12 months) to determine the SEF95 ranges for three clinical endpoints of anesthesia (consciousness-pacifier placement, pain-electrical nerve stimulation, and intubation-laryngoscopy) and correlation between SEF95 and propofol plasma concentration at steady state. Dixon's Up-Down method was used to determine target SEF95 for each clinical endpoint. Centered isotonic regression determined the dose-response function of SEF95 where 50% and 90% of infants (ED50 and ED90) did not respond to the clinical endpoint. Linear mixed-effect model determined the association of propofol plasma concentration and SEF95. Of 49 enrolled infants, 44 evaluable (90%) showed distinct SEF95 for endpoints: pacifier (ED50 21.4Hz, ED90 19.3Hz), electrical stimulation (ED50 12.6Hz, ED90 10.4Hz), and laryngoscopy (ED50 8.5Hz, ED90 5.2Hz). From propofol 0.5-6 μg/ml, a 1 Hz SEF95 increase was linearly correlated to a 0.24 (95% CI: 0.19 - 0.29, p<0.001) μg/mL decrease in plasma propofol concentration (marginal R 2 = 0.55). SEF95 can be a biomarker for propofol anesthesia depth in infants, potentially improving dosing accuracy and utilization of propofol anesthesia in this population.

Looking both ways: Electroactive biomaterials with bidirectional implications for dynamic cell-material crosstalk.

Cells exist in natural, dynamic microenvironmental niches that facilitate biological responses to external physicochemical cues such as mechanical and electrical stimuli. For excitable cells, exogenous electrical cues are of interest due to their ability to stimulate or regulate cellular behavior via cascade signaling involving ion channels, gap junctions, and integrin receptors across the membrane. In recent years, conductive biomaterials have been demonstrated to influence or record these electrosensitive biological processes whereby the primary design criterion is to achieve seamless cell-material integration. As such, currently available bioelectronic materials are predominantly engineered toward achieving high-performing devices while maintaining the ability to recapitulate the local excitable cell/tissue microenvironment. However, such reports rarely address the dynamic signal coupling or exchange that occurs at the biotic-abiotic interface, as well as the distinction between the ionic transport involved in natural biological process and the electronic (or mixed ionic/electronic) conduction commonly responsible for bioelectronic systems. In this review, we highlight current literature reports that offer platforms capable of bidirectional signal exchange at the biotic-abiotic interface with excitable cell types, along with the design criteria for such biomaterials. Furthermore, insights on current materials not yet explored for biointerfacing or bioelectronics that have potential for bidirectional applications are also provided. Finally, we offer perspectives aimed at bringing attention to the coupling of the signals delivered by synthetic material to natural biological conduction mechanisms, areas of improvement regarding characterizing biotic-abiotic crosstalk, as well as the dynamic nature of this exchange, to be taken into consideration for material/device design consideration for next-generation bioelectronic systems.

Electrical and immune stimulation-based hydrogels synergistically realize scarless wound healing via amplifying endogenous electrophysiological function and promoting Macrophage Phenotype-Switching

Scars are a consequence of the wound healing process, and scarless wound healing remains a substantial clinical challenge. In this study, conductive hydrogels (named sHA/G-GM) were developed to synergistically realize scarless wound healing through electrical and immune stimulation. sHA/G-GM was prepared as high-sulfated hyaluronan (sHA) modified graphene (sHA/G) homodispersing in gelatin methacrylate, and sHA/G was released and absorbed by cytomembranes. In vitro (human scar fibroblasts and mouse primary macrophages) and in vivo (rat wound models and rabbit ear wound models) studies were conducted and demonstrated that sHA/G-GM not only improves conductivity to fibroblast activity regulation but also combines with interleukin-4 to promote macrophage phenotype switching. These results strongly suggest that sHA/G-GM synergistically amplifies endogenous electrophysiological functions and modulates the immune microenvironment to realize scarless wound healing. Therefore, the electrical and immune stimulation-based sHA/G-GM provide an effective approach to synergistically realize scarless wound healing in the future.

Physiological paradigm for assessing reward prediction and extinction using cortical direct current potential responses in rats

Anticipating positive outcomes is a core cognitive function in the process of reward prediction. However, no neurophysiological method objectively assesses reward prediction in basic medical research. In the present study, we established a physiological paradigm using cortical direct current (DC) potential responses in rats to assess reward prediction. This paradigm consisted of five daily 1-h sessions with two tones, wherein the rewarded tone was followed by electrical stimulation of the medial forebrain bundle (MFB) scheduled at 1000 ms later, whereas the unrewarded tone was not. On day 1, both tones induced a negative DC shift immediately after auditory responses, persisting up to MFB stimulation. This negative shift progressively increased and peaked on day 4. Starting from day 3, the negative shift from 600 to 1000 ms was significantly larger following the rewarded tone than that following the unrewarded tone. This negative DC shift was particularly prominent in the frontal cortex, suggesting its crucial role in discriminative reward prediction. During the extinction sessions, the shift diminished significantly on extinction day 1. These findings suggest that cortical DC potential is related to reward prediction and could be a valuable tool for evaluating animal models of depression, providing a testing system for anhedonia.

Seminal plasma S100A8/A9 as a potential biomarker of genital tract inflammation

Abstract Infections and inflammatory reactions in the male genital tract are the leading causes of male infertility with a prevalence of 6%–10%, primarily affecting testicular and epididymal function and ultimately compromising sperm quality. However, most infertile patients with genital infection/inflammation are asymptomatic and easily overlooked. Traditional indicators, including white blood cells, elastase, and other components in semen, can reflect inflammation of the genital tract, but there is still a lack of a uniform standard method of detection. Therefore, it is necessary to explore reliable markers in semen that reflect the inflammatory status of the genital tract. Using the experimental autoimmune orchitis (EAO) model to simulate noninfectious chronic orchitis, we successfully collected ejaculated seminal fluid from EAO rats using optimized electrical stimulation devices. Proteomic analysis was performed using isobaric tags for relative and absolute quantification (iTRAQ). Compared to the control group, 55 upregulated and 105 downregulated proteins were identified in seminal plasma samples from the EAO group. In a preliminary screening, the inflammation-related protein S100A8/A9 was upregulated. We further verified that S100A8/A9 was increased in seminal plasma and highly expressed in testicular macrophages of the EAO model. In patients with oligoasthenospermia and genital tract infections, we also found that S100A8/A9 levels were remarkably increased in seminal plasma and testicular macrophages. S100A8/A9 in semen may be a potential biomarker for chronic genital inflammation. Our study provides a new potential biomarker for early diagnosis and further understanding of male infertility caused by genital inflammation.

Long-term stimulation by implanted pacemaker enables non-atrophic treatment of bilateral vocal fold paresis in a human-like animal model

A wide variety of treatments have been developed to improve respiratory function and quality of life in patients with bilateral vocal fold paresis (BVFP). One experimental method is the electrical activation of the posterior cricoarytenoid (PCA) muscle with a laryngeal pacemaker (LP) to open the vocal folds. We used an ovine (sheep) model of unilateral VFP to study the long-term effects of functional electrical stimulation on the PCA muscles. The left recurrent laryngeal nerve was cryo-damaged in all animals and an LP was implanted except for the controls. After a reinnervation phase of six months, animals were pooled into groups that received either no treatment, implantation of an LP only, or implantation of an LP and six months of stimulation with different duty cycles. Automated image analysis of fluorescently stained PCA cross-sections was performed to assess relevant muscle characteristics. We observed a fast-to-slow fibre type shift in response to nerve damage and stimulation, but no complete conversion to a slow-twitch-muscle. Fibre size, proportion of hybrid fibres, and intramuscular collagen content were not substantially altered by the stimulation. These results demonstrate that 30 Hz burst stimulation with duty cycles of 40% and 70% did not induce PCA atrophy or fibrosis. Thus, long-term stimulation with an LP is a promising approach for treating BVFP in humans without compromising muscle conditions.

Electrowriting patterns and electric field harness directional cell migration for skin wound healing

Directional cell migration is a crucial step in wound healing, influenced by electrical and topographic stimulations. However, the underlying mechanism and the combined effects of these two factors on cell migration remain unclear. This study explores cell migration under various combinations of guided straight line (SL) spacing, conductivity, and the relative direction of electric field (EF) and SL. Electrowriting is employed to fabricate conductive (multiwalled carbon nanotube/polycaprolactone (PCL)) and nonconductive (PCL) SL, with narrow (50 μm) and wide (400 μm) spacing that controls the topographic stimulation strength. Results show that various combinations of electrical and topographic stimulation yield significantly distinct effects on cell migration direction and speed; cells migrate fastest with the most directivity in the case of conductive, narrow-spacing SL parallel to EF. A physical model based on intercellular interactions is developed to capture the underlying mechanism of cell migration under SL and EF stimulations, in agreement with experimental observations. In vivo skin wound healing assay further confirmed that the combination of EF (1 V cm−1) and parallelly aligned conductive fibers accelerated the wound healing process. This study presents a promising approach to direct cell migration and enhance wound healing by optimizing synergistic electrical and topographic stimulations.