Promotion of Myogenic Maturation by Timely Application of Electric Field Along the Topographical Alignment

Electrical stimulation: a novel therapeutic strategy to heal biological wounds

Electrical stimulation (ES) has emerged as a powerful therapeutic modality for enhancing biological wound healing. This non-invasive technique utilizes low-level electrical currents to promote tissue regeneration and expedite the wound healing process. ES has been shown to accelerate wound closure, reduce inflammation, enhance angiogenesis, and modulate cell migration and proliferation through various mechanisms. The principle goal of wound management is the rapid recovery of the anatomical continuity of the skin, to prevent infections from the external environment and maintain homeostasis conditions inside. ES at the wound site is a compelling strategy for skin wound repair. Several ES applications are described in medical literature like AC, DC, and PC to improve cutaneous perfusion and accelerate wound healing. This review aimed to evaluate the primary factors and provides an overview of the potential benefits and mechanisms of ES in wound healing, and its ability to stimulate cellular responses, promote tissue regeneration, and improve overall healing outcomes. We also shed light on the application of ES which holds excellent promise as an adjunct therapy for various types of wounds, including chronic wounds, diabetic ulcers, and surgical incisions.

MyoFInDer: An AI-Based Tool for Myotube Fusion Index Determination

The fusion index is a key indicator for quantifying the differentiation of a myoblast population, which is often calculated manually. In addition to being time-consuming, manual quantification is also error prone and subjective. Several software tools have been proposed for addressing these limitations but suffer from various drawbacks, including unintuitive interfaces and limited performance. In this study, we describe MyoFInDer, a Python-based program for the automated computation of the fusion index of skeletal muscle. At the core of MyoFInDer is a powerful artificial intelligence-based image segmentation model. MyoFInDer also determines the total nuclei count and the percentage of stained area and allows for manual verification and correction. MyoFInDer can reliably determine the fusion index, with a high correlation to manual counting. Compared with other tools, MyoFInDer stands out as it minimizes the interoperator variability, minimizes process time and displays the best correlation to manual counting. Therefore, it is a suitable choice for calculating fusion index in an automated way, and gives researchers access to the high performance and flexibility of a modern artificial intelligence model. As a free and open-source project, MyoFInDer can be modified or extended to meet specific needs.

Bioelectronics for electrical stimulation: materials, devices and biomedical applications

Bioelectronics is a hot research topic, yet an important tool, as it facilitates the creation of advanced medical devices that interact with biological systems to effectively diagnose, monitor and treat a broad spectrum of health conditions. Electrical stimulation (ES) is a pivotal technique in bioelectronics, offering a precise, non-pharmacological means to modulate and control biological processes across molecular, cellular, tissue, and organ levels. This method holds the potential to restore or enhance physiological functions compromised by diseases or injuries by integrating sophisticated electrical signals, device interfaces, and designs tailored to specific biological mechanisms. This review explains the mechanisms by which ES influences cellular behaviors, introduces the essential stimulation principles, discusses the performance requirements for optimal ES systems, and highlights the representative applications. From this review, we can realize the potential of ES based bioelectronics in therapy, regenerative medicine and rehabilitation engineering technologies, ranging from tissue engineering to neurological technologies, and the modulation of cardiovascular and cognitive functions. This review underscores the versatility of ES in various biomedical contexts and emphasizes the need to adapt to complex biological and clinical landscapes it addresses.

Surface tension-induced biomimetic assembly of cell-laden fibrous bundle construct for muscle tissue engineering

The field of tissue engineering has been long seeking to develop functional muscle tissue that closely resembles natural muscle. This study used a bio-inspired assembly based on the surface tension mechanism to develop a novel method for engineering muscle tissue. This approach enabled uniaxially ordered electrospun fibers to naturally collide into an aligned bundle without the need for manual handling, thereby reducing cell damage during the cell culture procedure. During the assembly procedure, C2C12 myoblasts were cultured in a viscous collagen hydrogel that caused wetting while providing adequate structural stability for the cell-fiber construct. In addition, gene expression analysis of the resulting muscle-like fibril bundle revealed improved myogenic differentiation. These findings highlight the potential of using a collagen hydrogel and the surface tension mechanism to construct biologically relevant muscle tissue, offering a promising strategy that may outperform existing approaches. Overall, this study contributes to the development of advanced tissue engineering methods and brings us a step closer to creating functional muscle tissue for therapeutic and regenerative medicine applications.

Recent advances of cellular stimulation with triboelectric nanogenerators

Triboelectric nanogenerators (TENGs) are new energy collection devices that have the characteristics of high efficiency, low cost, miniaturization capability, and convenient manufacture. TENGs mainly utilize the triboelectric effect to obtain mechanical energy from organisms or the environment, and this mechanical energy is then converted into and output as electrical energy. Bioelectricity is a phenomenon that widely exists in various cellular processes, including cell proliferation, senescence, apoptosis, as well as adjacent cells' communication and coordination. Therefore, based on these features, TENGs can be applied in organisms to collect energy and output electrical stimulation to act on cells, changing their activities and thereby playing a role in regulating cellular function and interfering with cellular fate, which can further develop into new methods of health care and disease intervention. In this review, we first introduce the working principle of TENGs and their working modes, and then summarize the current research status of cellular function regulation and fate determination stimulated by TENGs, and also analyze their application prospects for changing various processes of cell activity. Finally, we discuss the opportunities and challenges of TENGs in the fields of life science and biomedical engineering, and propose a variety of possibilities for their potential development direction.

The Use of Collagen Methacrylate in Actuating Polyethylene Glycol Diacrylate-Acrylic Acid Scaffolds for Muscle Regeneration

After muscle loss or injury, skeletal muscle tissue has the ability to regenerate and return its function. However, large volume defects in skeletal muscle tissue pose a challenge to regenerate due to the absence of regenerative elements such as biophysical and biochemical cues, making the development of new treatments necessary. One potential solution is to utilize electroactive polymers that can change size or shape in response to an external electric field. Poly(ethylene glycol) diacrylate (PEGDA) is one such polymer, which holds great potential as a scaffold for muscle tissue regeneration due to its mechanical properties. In addition, the versatile chemistry of this polymer allows for the conjugation of new functional groups to enhance its electroactive properties and biocompatibility. Herein, we have developed an electroactive copolymer of PEGDA and acrylic acid (AA) in combination with collagen methacrylate (CMA) to promote cell adhesion and proliferation. The electroactive properties of the CMA + PEGDA:AA constructs were investigated through actuation studies. Furthermore, the biological properties of the hydrogel were investigated in a 14-day in vitro study to evaluate myosin light chain (MLC) expression and metabolic activity of C2C12 mouse myoblast cells. The addition of CMA improved some aspects of material bioactivity, such as MLC expression in C2C12 mouse myoblast cells. However, the incorporation of CMA in the PEGDA:AA hydrogels reduced the sample movement when placed under an electric field, possibly due to steric hindrance from the CMA. Further research is needed to optimize the use of CMA in combination with PEGDA:AA as a potential scaffold for skeletal muscle tissue engineering.

Direct modulation of microglial function by electrical field

Non-invasive electric stimulation (ES) employing a low-intensity electric current presents a potential therapeutic modality that can be applied for treating retinal and brain neurodegenerative disorders. As neurons are known to respond directly to ES, the effects of ES on glia cells are poorly studied. A key question is if ES directly mediates microglial function or modulates their activity merely via neuron-glial signaling. Here, we demonstrated the direct effects of ES on microglia in the BV-2 cells—an immortalized murine microglial cell line. The low current ES in a biphasic ramp waveform, but not that of rectangular or sine waveforms, significantly suppressed the motility and migration of BV-2 microglia in culture without causing cytotoxicity. This was associated with diminished cytoskeleton reorganization and microvilli formation in BV-2 cultures, as demonstrated by immunostaining of cytoskeletal proteins, F-actin and β-tubulin, and scanning electron microscopy. Moreover, ES of a ramp waveform reduced microglial phagocytosis of fluorescent zymosan particles and suppressed lipopolysaccharide (LPS)-induced pro-inflammatory cytokine expression in BV-2 cells as shown by Proteome Profiler Mouse Cytokine Array. The results of quantitative PCR and immunostaining for cyclooxygenase-2, Interleukin 6, and Tumor Necrosis Factor-α corroborated the direct suppression of LPS-induced microglial responses by a ramp ES. Transcriptome profiling further demonstrated that ramp ES effectively suppressed nearly half of the LPS-induced genes, primarily relating to cellular motility, energy metabolism, and calcium signaling. Our results reveal a direct modulatory effect of ES on previously thought electrically “non-responsive” microglia and suggest a new avenue of employing ES for anti-inflammatory therapy.

Synergistic stimulation of surface topography and biphasic electric current promotes muscle regeneration

Developing a universal culture platform that manipulates cell fate is one of the most important tasks in the investigation of the role of the cellular microenvironment. This study focuses on the application of topographical and electrical field stimuli to human myogenic precursor cell (hMPC) cultures to assess the influences of the adherent direction, proliferation, and differentiation, and induce preconditioning-induced therapeutic benefits. First, a topographical surface of commercially available culture dishes was achieved by femtosecond laser texturing. The detachable biphasic electrical current system was then applied to the hMPCs cultured on laser-textured culture dishes. Laser-textured topographies were remarkably effective in inducing the assembly of hMPC myotubes by enhancing the orientation of adherent hMPCs compared with flat surfaces. Furthermore, electrical field stimulation through laser-textured topographies was found to promote the expression of myogenic regulatory factors compared with nonstimulated cells. As such, we successfully demonstrated that the combined stimulation of topographical and electrical cues could effectively enhance the myogenic maturation of hMPCs in a surface spatial and electrical field-dependent manner, thus providing the basis for therapeutic strategies.

The Bumpy Road to Stem Cell Therapies: Rational Design of Surface Topographies to Dictate Stem Cell Mechanotransduction and Fate

Cells sense and respond to a variety of physical cues from their surrounding microenvironment, and these are interpreted through mechanotransductive processes to inform their behavior. These mechanisms have particular relevance to stem cells, where control of stem cell proliferation, potency, and differentiation is key to their successful application in regenerative medicine. It is increasingly recognized that surface micro- and nanotopographies influence stem cell behavior and may represent a powerful tool with which to direct the morphology and fate of stem cells. Current progress toward this goal has been driven by combined advances in fabrication technologies and cell biology. Here, the capacity to generate precisely defined micro- and nanoscale topographies has facilitated the studies that provide knowledge of the mechanotransducive processes that govern the cellular response as well as knowledge of the specific features that can drive cells toward a defined differentiation outcome. However, the path forward is not fully defined, and the "bumpy road" that lays ahead must be crossed before the full potential of these approaches can be fully exploited. This review focuses on the challenges and opportunities in applying micro- and nanotopographies to dictate stem cell fate for regenerative medicine. Here, key techniques used to produce topographic features are reviewed, such as photolithography, block copolymer lithography, electron beam lithography, nanoimprint lithography, soft lithography, scanning probe lithography, colloidal lithography, electrospinning, and surface roughening, alongside their advantages and disadvantages. The biological impacts of surface topographies are then discussed, including the current understanding of the mechanotransductive mechanisms by which these cues are interpreted by the cells, as well as the specific effects of surface topographies on cell differentiation and fate. Finally, considerations in translating these technologies and their future prospects are evaluated.

Pillar-Based Mechanical Induction of an Aggressive Tumorigenic Lung Cancer Cell Model

Tissue microarchitecture imposes physical constraints to the migration of individual cells. Especially in cancer metastasis, three-dimensional structural barriers within the extracellular matrix are known to affect the migratory behavior of cells, regulating the pathological state of the cells. Here, we employed a culture platform with micropillar arrays of 2 μm diameter and 16 μm pitch (2.16 micropillar) as a mechanical stimulant. Using this platform, we investigated how a long-term culture of A549 human lung carcinoma cells on the (2.16) micropillar-embossed dishes would influence the pathological state of the cell. A549 cells grown on the (2.16) micropillar array with 10 μm height exhibited a significantly elongated morphology and enhanced migration even after the detachment and reattachment, as evidenced in the conventional wound-healing assay, single-cell tracking analysis, and in vivo tumor colonization assays. Moreover, the pillar-induced morphological deformation in nuclei was accompanied by cell-cycle arrest in the S phase, leading to suppressed proliferation. While these marked traits of morphology-migration-proliferation support more aggressive characteristics of metastatic cancer cells, typical indices of epithelial-mesenchymal transition were not found, but instead, remarkable traces of amoeboidal transition were confirmed. Our study also emphasizes the importance of mechanical stimuli from the microenvironment during pathogenesis and how gained traits can be passed onto subsequent generations, ultimately affecting their pathophysiological behavior. Furthermore, this study highlights the potential use of pillar-based mechanical stimuli as an in vitro cell culture strategy to induce more aggressive tumorigenic cancer cell models.

Protein-based soft actuator with high photo-response and easy modulation for anisotropic cell alignment and proliferation in a liquid environment

Cell alignment and elongation, which are critical factors correlated with differentiation and maturation in cell biology and tissue engineering, have been widely studied in organisms. Several strategies such as external mechanical strain, geometric topography, micropatterning approaches, and microfabricated substrates have been developed to guide cell alignment, but these methodologies cannot be used for easily denatured natural proteins to modulate the cell behaviour. Herein, for the first time, a novel biocompatible light-controlled protein-based bilayer soft actuator composed of elastin-like polypeptides (ELPs), silk fibroin (SF), graphene oxide (GO), and reduced graphene oxide (rGO), named ESGRG, is developed for efficiently driving cellular orientation and elongation with anisotropic features on soft actuator via remote NIR laser exposure. The actuation of ESGRG could be manipulated by modulating the intensity of NIR and the relative ratio of GO to rGO for promoting myoblasts alignment and nucleus elongation to generate different motions. The results indicate that the YAP and MHC protein expression of C2C12 skeletal muscle cells on ESGRG can be rapidly induced and enhanced by controlling the relative ratio of rGO/GO = 1/4 at a multiple-cycle stimulation with a very low power intensity of 1.2 W cm^-2 in friendly liquid environments. This study demonstrates that the ESGRG hydrogel actuator system can modulate the cell-level behaviors via light-driven cyclic bending-motions and can be utilized in applications of soft robotic and tissue engineering such as artificial muscle and maturation of cardiomyocytes.

Towards bioengineered skeletal muscle: recent developments in vitro and in vivo

Skeletal muscle is a functional tissue that accounts for approximately 40% of the human body mass. It has remarkable regenerative potential, however, trauma and volumetric muscle loss, progressive disease and aging can lead to significant muscle loss that the body cannot recover from. Clinical approaches to address this range from free-flap transfer for traumatic events involving volumetric muscle loss, to myoblast transplantation and gene therapy to replace muscle loss due to sarcopenia and hereditary neuromuscular disorders, however, these interventions are often inadequate. The adoption of engineering paradigms, in particular materials engineering and materials/tissue interfacing in biology and medicine, has given rise to the rapidly growing, multidisciplinary field of bioengineering. These methods have facilitated the development of new biomaterials that sustain cell growth and differentiation based on bionic biomimicry in naturally occurring and synthetic hydrogels and polymers, as well as additive fabrication methods to generate scaffolds that go some way to replicate the structural features of skeletal muscle. Recent advances in biofabrication techniques have resulted in significant improvements to some of these techniques and have also offered promising alternatives for the engineering of living muscle constructs ex vivo to address the loss of significant areas of muscle. This review highlights current research in this area and discusses the next steps required towards making muscle biofabrication a clinical reality.

Hepatic patch by stacking patient-specific liver progenitor cell sheets formed on multiscale electrospun fibers promotes regenerative therapy for liver injury

Recently, use of cell sheets with bio-applicable fabrication materials for transplantation has been an attractive approach for the treatment of patients with liver failure. However, renewable and scalable cell sources for engineered tissue patches remain limited. We previously reported a new type of proliferating bipotent human chemically derived hepatic progenitor cells (hCdHs) developed by small molecule-mediated reprogramming. Here, we developed a patient-specific hepatic cell sheet constructed from liver biopsy-derived hCdHs on a multiscale fibrous scaffold by combining electrospinning and three-dimensional printing. Analysis of biomaterial composition revealed that the high-density electrospun sheet was superior in increasing the functional properties of hCdHs. Furthermore, the hepatic patch assembled by multilayer stacking with alternate cell sheets of hCdHs and human umbilical vein endothelial cells (HUVECs) recapitulated a liver tissue-like structure, with histological and morphological shape and size similar to those of primary human hepatocytes, and exhibited a significant increase in hepatic functions such as albumin secretion and activity of cytochrome P450 during in vitro hepatic differentiation compared with that in hCdH cells cultured in a two-dimensional monolayer. Interestingly, in the hepatic patch, the induction of functional hepatocytes was associated with both the electrospun fibrous-facilitated oncostatin M signaling and selective activation of AKT signaling by HUVECs. Notably, upon transplantation into a mouse model of therapeutic liver repopulation, the hepatic patch effectively repopulated the damaged parenchyma and induced the restoration of liver function with healthy morphology in the lobe and an improved survival rate (>70%) in mice. Overall, these results suggested that liver biopsy-derived hCdHs can be an efficient alternative source for developing hepatic cell sheets and patches with potential clinical applications in tissue engineering to advance liver regeneration.

Carbon Nanomaterials for Electro-Active Structures: A Review

The use of electrically conductive materials to impart electrical properties to substrates for cell attachment proliferation and differentiation represents an important strategy in the field of tissue engineering. This paper discusses the concept of electro-active structures and their roles in tissue engineering, accelerating cell proliferation and differentiation, consequently leading to tissue regeneration. The most relevant carbon-based materials used to produce electro-active structures are presented, and their main advantages and limitations are discussed in detail. Particular emphasis is put on the electrically conductive property, material synthesis and their applications on tissue engineering. Different technologies, allowing the fabrication of two-dimensional and three-dimensional structures in a controlled way, are also presented. Finally, challenges for future research are highlighted. This review shows that electrical stimulation plays an important role in modulating the growth of different types of cells. As highlighted, carbon nanomaterials, especially graphene and carbon nanotubes, have great potential for fabricating electro-active structures due to their exceptional electrical and surface properties, opening new routes for more efficient tissue engineering approaches.

Electrical stimulation as a novel tool for regulating cell behavior in tissue engineering

Recently, electrical stimulation as a physical stimulus draws lots of attention. It shows great potential in disease treatment, wound healing, and mechanism study because of significant experimental performance. Electrical stimulation can activate many intracellular signaling pathways, and influence intracellular microenvironment, as a result, affect cell migration, cell proliferation, and cell differentiation. Electrical stimulation is using in tissue engineering as a novel type of tool in regeneration medicine. Besides, with the advantages of biocompatible conductive materials coming into view, the combination of electrical stimulation with suitable tissue engineered scaffolds can well combine the benefits of both and is ideal for the field of regenerative medicine. In this review, we summarize the various materials and latest technologies to deliver electrical stimulation. The influences of electrical stimulation on cell alignment, migration and its underlying mechanisms are discussed. Then the effect of electrical stimulation on cell proliferation and differentiation are also discussed.

The rationale and emergence of electroconductive biomaterial scaffolds in cardiac tissue engineering

The human heart possesses minimal regenerative potential, which can often lead to chronic heart failure following myocardial infarction. Despite the successes of assistive support devices and pharmacological therapies, only a whole heart transplantation can sufficiently address heart failure. Engineered scaffolds, implantable patches, and injectable hydrogels are among the most promising solutions to restore cardiac function and coax regeneration; however, current biomaterials have yet to achieve ideal tissue regeneration and adequate integration due a mismatch of material physicochemical properties. Conductive fillers such as graphene, carbon nanotubes, metallic nanoparticles, and MXenes and conjugated polymers such as polyaniline, polypyrrole, and poly(3,4-ethylendioxythiophene) can possibly achieve optimal electrical conductivities for cardiac applications with appropriate suitability for tissue engineering approaches. Many studies have focused on the use of these materials in multiple fields, with promising effects on the regeneration of electrically active biological tissues such as orthopedic, neural, and cardiac tissue. In this review, we critically discuss the role of heart electrophysiology and the rationale toward the use of electroconductive biomaterials for cardiac tissue engineering. We present the emerging applications of these smart materials to create supportive platforms and discuss the crucial role that electrical stimulation has been shown to exert in maturation of cardiac progenitor cells.

An overview of advanced biocompatible and biomimetic materials for creation of replacement structures in the musculoskeletal systems: focusing on cartilage tissue engineering

Tissue engineering, as an interdisciplinary approach, is seeking to create tissues with optimal performance for clinical applications. Various factors, including cells, biomaterials, cell or tissue culture conditions and signaling molecules such as growth factors, play a vital role in the engineering of tissues. In vivo microenvironment of cells imposes complex and specific stimuli on the cells, and has a direct effect on cellular behavior, including proliferation, differentiation and extracellular matrix (ECM) assembly. Therefore, to create appropriate tissues, the conditions of the natural environment around the cells should be well imitated. Therefore, researchers are trying to develop biomimetic scaffolds that can produce appropriate cellular responses. To achieve this, we need to know enough about biomimetic materials. Scaffolds made of biomaterials in musculoskeletal tissue engineering should also be multifunctional in order to be able to function better in mechanical properties, cell signaling and cell adhesion. Multiple combinations of different biomaterials are used to improve above-mentioned properties of various biomaterials and to better imitate the natural features of musculoskeletal tissue in the culture medium. These improvements ultimately lead to the creation of replacement structures in the musculoskeletal system, which are closer to natural tissues in terms of appearance and function. The present review article is focused on biocompatible and biomimetic materials, which are used in musculoskeletal tissue engineering, in particular, cartilage tissue engineering.

Physicochemically Tuned Myofibroblasts for Wound Healing Strategy

Normal healing of skin wounds involves a complex interplay between many different cellular constituents, including keratinocytes, immune cells, fibroblasts, myofibroblasts, as well as extracellular matrices. Especially, fibroblasts play a critical role in regulating the immune response and matrix reconstruction by secreting many cytokines and matrix proteins. Myofibroblasts, which are differentiated form of fibroblasts, feature high cellular contractility and encourage the synthesis of matrix proteins to promote faster closure of the wounds. We focus on the functional characteristics of these myofibroblasts as the healing strategy for severe wounds where the surplus amount of matrix proteins could be beneficial for better regeneration. In this study, we first employed multiple physicochemical cues, namely topographical alignment, TGF-β1, and electrical field (EF), to induce differentiation of dermal fibroblasts into myofibroblasts, and to further activate the differentiated cells. We then used these cells in a mouse wound model to verify their potential as a transplantable substitute for the severe wound. Our results confirmed that physicochemically stimulated myofibroblasts promoted faster healing of the wound compared to the case with non-stimulated myofibroblasts through elevated matrix reconstruction in the mouse model. Conclusively, we propose the utilization of physicochemically tuned myofibroblasts as a novel strategy for promoting better healing of moderate to severe wounds.

Development of Microfluidic Stretch System for Studying Recovery of Damaged Skeletal Muscle Cells

The skeletal muscle occupies about 40% mass of the human body and plays a significant role in the skeletal movement control. Skeletal muscle injury also occurs often and causes pain, discomfort, and functional impairment in daily living. Clinically, most studies observed the recovery phenomenon of muscle by massage or electrical stimulation, but there are limitations on quantitatively analyzing the effects on recovery. Although additional efforts have been made within in vitro biochemical research, some questions still remain for effects of the different cell microenvironment for recovery. To overcome these limitations, we have developed a microfluidic system to investigate appropriate conditions for repairing skeletal muscle injury. First, the muscle cells were cultured in the microfluidic chip and differentiated to muscle fibers. After differentiation, we treated hydrogen peroxide and 18% axial stretch to cause chemical and physical damage to the muscle fibers. Then the damaged muscle fibers were placed under the cyclic stretch condition to allow recovery. Finally, we analyzed the damage and recovery by quantifying morphological change as well as the intensity change of intracellular fluorescent signals and showed the skeletal muscle fibers recovered better in the cyclic stretched condition. In total, our in situ generation of muscle damage and induction recovery platform may be a key system for investigating muscle recovery and rehabilitation.

Bioreactor model of neuromuscular junction with electrical stimulation for pharmacological potency testing

In vitro models of the neuromuscular junction (NMJ) are emerging as a valuable tool to study synaptogenesis, synaptic maintenance, and pathogenesis of neurodegenerative diseases. Many models have previously been developed using a variety of cell sources for skeletal muscle and motoneurons. These models can advanced by integrating beneficial features of the native developmental milieu of the NMJ. We created a functional in vitro model of NMJ by bioreactor cultivation of transdifferentiated myocytes and stem cell-derived motoneurons, in the presence of electrical stimulation. In conjunction with a coculture medium, electrical stimulation resulted in improved maturation and function of motoneurons and myocytes, as evidenced by mature cellular structures, increased expression of neuronal and muscular genes, clusterization of acetylcholine receptors (AChRs) in the vicinity of motoneurons, and the response to glutamate stimulation. To validate the model and demonstrate its utility for pharmacological testing, we documented the potency of drugs that affect key pathways during NMJ signal transduction: (i) acetylcholine (ACh) synthesis, (ii) ACh vesicular storage, (iii) ACh synaptic release, (iv) AChR activation, and (v) ACh inactivation in the synaptic cleft. The model properly responded to the drugs in a concentration-dependent manner. We thus propose that this in vitro model of NMJ could be used as a platform in pharmacological screening and controlled studies of neuromuscular diseases.