Artificial Skeletal Muscle Research Articles

Dynamic Electromechanical Co‐Stimulation Based Enhancement of Skeletal Muscle Tissues for Fast Biosyncretic Robots Actuation

AbstractBiosyncretic robots composed of living and synthetic materials have garnered significant attention due to their high energy conversion efficiency, good biocompatibility and human‐robot interaction safety. Among common living actuation materials, artificial skeletal muscle tissue (ASMT) stands out for its good size scalability, controllability, and potential high driving force. However, due to the low differentiation efficiency of myoblasts, the performance of ASMT lags behind that of natural skeletal muscle tissue, thereby hindering the progress of biosyncretic robots. Here, inspired by the training mode of human skeletal muscle, an electromechanical co‐stimulation system for enhancing the performance of ASMTs is proposed. This system is capable of simultaneously applying electrical and mechanical stimulation to ASMTs. Moreover, the mechanical resistance can be dynamically adjusted during ASMT growth based on real‐time measurements of the contractile force of the ASMT. The results show that the enhanced ASMTs demonstrate improved differentiation and performance and can actuate a robot at a maximum speed of 2.38 mm s−1, which is faster than those of most currently reported ASMT‐based robots. This study introduces a novel approach for enhancing the performance of ASMTs, with substantial implications for the fields of biosyncretic robots and tissue engineering.

Bone morphogenetic protein signaling inhibitor improves differentiation and function of 3D muscle construct fabricated using C2C12

Functional tissue-engineered artificial skeletal muscle tissue has great potential for pharmacological and academic applications. This study demonstrates an in vitro tissue engineering system to construct functional artificial skeletal muscle tissues using self-organization and signal inhibitors. To induce efficient self-organization, we optimized the substrate stiffness and extracellular matrix (ECM) coatings. We modified the tissue morphology to be ring-shaped under optimized self-organization conditions. A bone morphogenetic protein (BMP) inhibitor was added to improve overall myogenic differentiation. This supplementation enhanced the myogenic differentiation ratio and myotube hypertrophy in two-dimensional cell cultures. Finally, we found that myotube hypertrophy was enhanced by a combination of self-organization with ring-shaped tissue and a BMP inhibitor. BMP inhibitor treatment significantly improved myogenic marker expression and contractile force generation in the self-organized tissue. These observations indicated that this procedure may provide a novel and functional artificial skeletal muscle for pharmacological studies.

Magnetically-Assisted Microfluidic Printing for the Fabrication of Anisotropic Skeletal Muscle Structure

Microfluidic printing provides a novel tool to facilitate the bulk assembly of cell-aligned microfibers for the fabrication of artificial skeletal muscle structure. However, due to the poor controllability for the deposition position of the microfiber, it is still difficult to realize the anisotropic assembly. In this paper, we developed a magnetically-assisted microfluidic printing system to solve this problem. Magnetic nanoparticles (MNPs) were encapsulated in the microfluidic spun microfibers, and a spiral magnet was designed as a microfiber deposition substrate. A robotic visual serving was utilized to control the orifice posture of the microfluidic spinning systemrelative to the axis direction of the spiral magnet, and then the spun microfibers were continuously deposited layer by layer to form an anisotropic assembly structure. Our proposed method demonstrates that the magnetic attraction mechanism is a novel microfiber-specific micromanipulation strategy for stable deposition in liquid environment. Furthermore, the preliminary cell experiments show that our methodhas highbiocompatibility to be further used in the fabrication of anisotropic skeletal muscle tissue.

Effect of Microgravity Environment Generated by Clinostat on Artificial Skeletal Muscle

Effect of Microgravity Environment Generated by Clinostat on Artificial Skeletal Muscle

Novel platform for quantitative evaluation of medicinal efficacy based on contractility of artificial skeletal muscle

Novel platform for quantitative evaluation of medicinal efficacy based on contractility of artificial skeletal muscle

Functional Skeletal Muscle Regeneration Using Muscle Mimetic Tissue Fabricated by Microvalve-Assisted Coaxial 3D Bioprinting.

3D-printed artificial skeletal muscle, which mimics the structural and functional characteristics of native skeletal muscle, is a promising treatment method for muscle reconstruction. Although various fabrication techniques for skeletal muscle using 3D bio-printers are studied, it is still challenging to build a functional muscle structure. A strategy using microvalve-assisted coaxial 3D bioprinting in consideration of functional skeletal muscle fabrication is reported. The unit (artificial muscle fascicle: AMF) of muscle mimetic tissue is composed of a core filled with medium-based C2C12 myoblast aggregates as a role of muscle fibers and a photo cross-linkable hydrogel-based shell as a role of connective tissue in muscles that enhances printability and cell adhesion and proliferation. Especially, a microvalve system is applied for the core part with even cell distribution and strong cell-cell interaction. This system enhances myotube formation and consequently shows spontaneous contraction. A multi-printed AMF (artificial muscle tissue: AMT) as a piece of muscle is implanted into the anterior tibia (TA) muscle defect site of immunocompromised rats. As a result, the TA-implanted AMT responds to electrical stimulation and represents histologically regenerated muscle tissue. This microvalve-assisted coaxial 3D bioprinting shows a significant step forward to mimicking native skeletal muscle tissue.

Application of the Contraction Force Evaluation Technique of Artificial Skeletal Muscle Under an Electrically Stimulated Environment to the Drug Efficacy

In our previous study, we succeeded in fabricating artificial skeletal muscles using a device for supporting artificial skeletal muscles, C2C12 cells, which are mouse rhabdomere-derived cell lines, and collagen gel. Furthermore, we have developed a technique to measure the contraction force of the artificial skeletal muscle over time when it is electrically stimulated. In the present study, we utilized the results of our previous studies to quantitatively evaluate the effect of quercetin on the contraction force of artificial skeletal muscles and developed the device as an alternative to animal experiments for the evaluation of drug effects.

Experimental studies on acrylic dielectric elastomers as actuator for artificial skeletal muscle application

The application of acrylic dielectric elastomer - an electrically actuated electro active polymer for artificial muscles has been investigated to evaluate its suitability for prosthetic and orthotic devices by comparing its mechanical and electrical properties similar to that of natural skeletal muscles. Experimental studies have been performed to get the properties of acrylic dielectric elastomers for design and development of artificial skeletal muscles. Therefore, a commercially available acrylic dielectric elastomer; VHB 4910 by 3M film is subjected to uniaxial tensile tests under varying rates, stress relaxation test and loading-unloading test on the universal testing machines and undergoes an electrical actuation test after pre-straining. The results of such tests have been discussed separately and then compared with previous researches on skeletal muscles as well. Moreover, the material response is also observed highly viscous and hyper-elastic, i.e., sensitive to very high strain rates as in the case of skeletal muscles. These results can be utilised in material selection to develop dielectric elastomer actuator applications for artificial muscles.

Experimental studies on acrylic dielectric elastomers as actuator for artificial skeletal muscle application

Experimental studies on acrylic dielectric elastomers as actuator for artificial skeletal muscle application

Approaches to Quantification of Contractile Force Measurement Devices for Artificial Skeletal Muscle

Approaches to Quantification of Contractile Force Measurement Devices for Artificial Skeletal Muscle

A Mechanized Pediatric Elbow Joint Powered by a De-Based Artificial Skeletal Muscle.

To increase the acceptability of exoskeletons, there is growing attention toward finding an alternative soft actuator that can safely perform at close vicinity of the human body. In this study, we investigated the capability of the dielectric elastomer actuators (DEAs), for muscle-like actuation of rehabilitation robots. First, an artificial skeletal muscle was configured using commercially available stacked DEAs arranged in a 3x4 array of three parallel fibers consisting of four DEAs connected in series. The shortening and force generation capabilities of this artificial muscle were then measured. An alternate 3x5 version of this muscle was mounted on the forearm of an upper extremity phantom model to actuate its elbow joint. The actuation capability of this muscle was then tested under various tensile loads, 1 N to 4 N, placed at the center of mass of the forearm+hand of the phantom model. The active range of motion and angular velocity of the phantom model's tip of the hand were measured using a motion capture system. The 3×4 artificial muscle produced 30.47 N of force and 5.3 mm of maximum shortening. The 3x5 artificial muscle was capable of actuating the elbow flexion 19.5º with 16.2 º/s angular velocity in the sagittal plane, under a 1 N tensile load. The active range of motion was substantially reduced as the tensile loads increased, which limits the capability of these muscles in the current upper extremity exoskeleton design.

Effect of cell-extracellular matrix interaction on myogenic characteristics and artificial skeletal muscle tissue

Although various types of artificial skeletal muscle tissue have been reported, the contractile forces generated by tissue-engineered artificial skeletal muscles remain to be improved for biological model and clinical applications. In this study, we investigated the effects of extracellular matrix (ECM) and supplementation of a small molecule, which has been reported to enhance α7β1 integrin expression (SU9516), on cell migration speed, cell fusion rate, myoblast (mouse C2C12cells) differentiation and contractile force generation of tissue-engineered artificial skeletal muscles. When cells were cultured on varying ECM coated-surfaces, we observed significant enhancement in the migration speed, while the myotube formation (differentiation ratio) decreased in all except for cells cultured on Matrigel coated-surfaces. In contrast, SU9516 supplementation resulted in an increase in both the myotube width and differentiation ratio. Following combined culture with a Matrigel-coated surface and SU9516 supplementation, myotube width was further increased. Additionally, contractile forces produced by the tissue-engineered artificial skeletal muscles was augmented following combined culture. These findings indicate that regulation of the cell-ECM interaction is a promising approach to improve the function of tissue-engineered artificial skeletal muscles.

Design and Construction of A Continuous Quantitative Force Measurement Microdevice for Artificial Skeletal Muscle

Design and Construction of A Continuous Quantitative Force Measurement Microdevice for Artificial Skeletal Muscle

Artificial Skeletal Muscle Contraction Device for Elucidating The Mechanism of Myokine Production

Artificial Skeletal Muscle Contraction Device for Elucidating The Mechanism of Myokine Production

Potential Therapies Using Myogenic Stem Cells Combined with Bio-Engineering Approaches for Treatment of Muscular Dystrophies.

Muscular dystrophies (MDs) are a group of heterogeneous genetic disorders caused by mutations in the genes encoding the structural components of myofibres. The current state-of-the-art treatment is oligonucleotide-based gene therapy that restores disease-related protein. However, this therapeutic approach has limited efficacy and is unlikely to be curative. While the number of studies focused on cell transplantation therapy has increased in the recent years, this approach remains challenging due to multiple issues related to the efficacy of engrafted cells, source of myogenic cells, and systemic injections. Technical innovation has contributed to overcoming cell source challenges, and in recent studies, a combination of muscle resident stem cells and gene editing has shown promise as a novel approach. Furthermore, improvement of the muscular environment both in cultured donor cells and in recipient MD muscles may potentially facilitate cell engraftment. Artificial skeletal muscle generated by myogenic cells and muscle resident cells is an alternate approach that may enable the replacement of damaged tissues. Here, we review the current status of myogenic stem cell transplantation therapy, describe recent advances, and discuss the remaining obstacles that exist in the search for a cure for MD patients.

Three-Dimensional Human iPSC-Derived Artificial Skeletal Muscles Model Muscular Dystrophies and Enable Multilineage Tissue Engineering

SummaryGenerating human skeletal muscle models is instrumental for investigating muscle pathology and therapy. Here, we report the generation of three-dimensional (3D) artificial skeletal muscle tissue from human pluripotent stem cells, including induced pluripotent stem cells (iPSCs) from patients with Duchenne, limb-girdle, and congenital muscular dystrophies. 3D skeletal myogenic differentiation of pluripotent cells was induced within hydrogels under tension to provide myofiber alignment. Artificial muscles recapitulated characteristics of human skeletal muscle tissue and could be implanted into immunodeficient mice. Pathological cellular hallmarks of incurable forms of severe muscular dystrophy could be modeled with high fidelity using this 3D platform. Finally, we show generation of fully human iPSC-derived, complex, multilineage muscle models containing key isogenic cellular constituents of skeletal muscle, including vascular endothelial cells, pericytes, and motor neurons. These results lay the foundation for a human skeletal muscle organoid-like platform for disease modeling, regenerative medicine, and therapy development.

D24 - Generation of three-dimensional artificial skeletal muscle constructs from human pluripotent stem cells for complex disease modelling of muscular dystrophies

D24 - Generation of three-dimensional artificial skeletal muscle constructs from human pluripotent stem cells for complex disease modelling of muscular dystrophies

Effect of heat stress on contractility of tissue-engineered artificial skeletal muscle.

The effects of heat stress on tissue like skeletal muscle have been widely studied. However, the mechanism responsible for the effect of heat stress is still unclear. A useful experimental tissue model is necessary because muscle function in cell culture may differ from native muscle and measuring its contractility is difficult. We previously reported three-dimensional tissue-engineered artificial skeletal muscle (TEM) that can be easily set in a measurement apparatus for quantitative evaluation of contractility. We have now applied TEM to the investigation of heat stress. We analyzed contractility immediately after thermal exposure at 39°C for 24 or 48h to evaluate the acute effects and after thermal exposure followed by normal culture to evaluate the aftereffects. Peak twitch contractile force and time-to-peak twitch were used as contractile parameters. Heat stress increased the TCF in the early stage (1week) after normal culture; the TCF decreased temporarily in the middle to late stages (2-3weeks). These results suggest that heat stress may affect both myoblast fusion and myotube differentiation in the early stage of TEM culture, but not myotube maturation in the late stage. The TCF increase rate with thermal exposure was significantly higher than that without thermal exposure. Although detailed analysis at the molecular level is necessary for further investigation, our artificial skeletal muscle may be a promising tool for heat stress investigation.

Microfluidic-enhanced 3D bioprinting of aligned myoblast-laden hydrogels leads to functionally organized myofibers invitro and invivo.

We present a new strategy for the fabrication of artificial skeletal muscle tissue with functional morphologies based on an innovative 3D bioprinting approach. The methodology is based on a microfluidic printing head coupled to a co-axial needle extruder for high-resolution 3D bioprinting of hydrogel fibers laden with muscle precursor cells (C2C12). To promote myogenic differentiation, we formulated a tailored bioink with a photocurable semi-synthetic biopolymer (PEG-Fibrinogen) encapsulating cells into 3D constructs composed of aligned hydrogel fibers. After 3-5 days of culture, the encapsulated myoblasts started migrating and fusing, forming multinucleated myotubes within the 3D bioprinted fibers. The obtained myotubes showed high degree of alignment along the direction of hydrogel fiber deposition, further revealing maturation, sarcomerogenesis, and functionality. Following subcutaneous implantation in the back of immunocompromised mice, bioprinted constructs generated organized artificial muscle tissue invivo. Finally, we demonstrate that our microfluidic printing head allows to design three dimensional multi-cellular assemblies with an exquisite compartmentalization of the encapsulated cells. Our results demonstrate an enhanced myogenic differentiation with the formation of parallel aligned long-range myotubes. The approach that we report here represents a robust and valid candidate for the fabrication of macroscopic artificial muscle to scale up skeletal muscle tissue engineering for human clinical application.

Could a functional artificial skeletal muscle be useful in muscle wasting?

Regardless of the underlying cause, skeletal muscle wasting is detrimental for a person's life quality, leading to impaired strength, locomotion, and physiological activity. Here, we propose a series of studies presenting tissue engineering-based approaches to reconstruct artificial muscle in vitro and in vivo. Skeletal muscle tissue engineering is attracting more and more attention from scientists, clinicians, patients, and media, thanks to the promising results obtained in the last decade with animal models of muscle wasting. The use of novel and refined biomimetic scaffolds mimicking three-dimensional muscle environment, thus supporting cell survival and differentiation, in combination with well characterized myogenic stem/progenitor cells, revealed the noteworthy potential of these technologies for creating artificial skeletal muscle tissue. In vitro, the production of three-dimensional muscle structures offer the possibility to generate a drug-screening platform for patient-specific pharmacological treatment, opening new frontiers in the development of new compounds with specific therapeutic actions. In vivo, three-dimensional artificial muscle biomimetic constructs offer the possibility to replace, in part or entirely, wasted muscle by means of straight reconstruction and/or by enhancing endogenous regeneration. Reports of tissue engineering approaches for artificial muscle building appeared in large numbers in the specialized press lately, advocating the suitability of this technology for human application upon scaling up and a near future applicability for medical care of muscle wasting. http://links.lww.com/COCN/A9