Skeletal muscle tissue engineering (SMTE) aims to repair or regenerate defective skeletal muscle tissue lost by traumatic injury, tumor ablation, or muscular disease. However, two decades after the introduction of SMTE, the engineering of functional skeletal muscle in the laboratory still remains a great challenge, and numerous techniques for growing functional muscle tissues are constantly being developed. This article reviews the recent findings regarding the methodology and various technical aspects of SMTE, including cell alignment and differentiation. We describe the structure and organization of muscle and discuss the methods for myoblast alignment cultured in vitro. To better understand muscle formation and to enhance the engineering of skeletal muscle, we also address the molecular basics of myogenesis and discuss different methods to induce myoblast differentiation into myotubes. We then provide an overview of different coculture systems involving skeletal muscle cells, and highlight major applications of engineered skeletal muscle tissues. Finally, potential challenges and future research directions for SMTE are outlined.

Recent developments in nanotechnology have led to a method for producing free‐standing polymer nanosheets as a macromolecular organization. Compared with bulk films, the large aspect ratio of such nanosheets leads to unique physical properties, such as transparency, noncovalent adhesion, and high flexibility. Here, a biomedical application of polymer nanosheets consisting of biocompatible and biodegradable polysaccharides is reported. Micro‐scratch and bulge tests indicate that the nanosheets with a thickness of tens of nanometers have sufficient physical adhesiveness and mechanical strength for clinical use. A nanosheet of 75 nm thickness, a critical load of 9.1 × 104 N m−1, and an elastic modulus of 9.6 GPa is used for the minimally invasive repair of a visceral pleural defect in beagle dogs without any pleural adhesion caused by wound repair. For the first time, clinical benefits of sheet‐type nano‐biomaterials based on molecular organization are demonstrated, suggesting that novel therapeutic tools for overlapping tissue wounds will be possible without the need for conventional surgical interventions.

Free-standing conductive ultra-thin films based on poly(3,4-ethylenedioxythiophene)/poly (styrenesulfonate) (PEDOT/PSS) are realized. A fabrication process based on a modified Supporting Layer technique is proposed that provides for the easy production of conductive nanofilms having a very large surface area with typical thickness of tens of nanometres. The proposed free-standing nanofilms can be manipulated, folded and unfolded in water many times without suffering from cracks, disaggregation or from loss of conductive properties. After collecting them onto rigid or soft substrates, they retain their functionality. Structural and functional properties of the nanofilms are described by means of their thickness, topography, conductivity and Young's modulus. Strong dependences of these properties on residual water, post-deposition treatments and environmental moisture are clearly evidenced. Possible applications are foreseen in the field of sensing and actuation, as well as in the biomedical field, e.g. as smart substrates for cell culturing and stimulation.

Skeletal muscle tissue engineering (SMTE) aims at repairing defective skeletal muscles. Until now, numerous developments are made in SMTE; however, it is still challenging to recapitulate the complexity of muscles with current methods of fabrication. Here, after a brief description of the anatomy of skeletal muscle and a short state‐of‐the‐art on developments made in SMTE with “conventional methods,” the use of 3D bioprinting as a new tool for SMTE is in focus. The current bioprinting methods are discussed, and an overview of the bioink formulations and properties used in 3D bioprinting is provided. Finally, different advances made in SMTE by 3D bioprinting are highlighted, and future needs and a short perspective are provided.

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Surfaces with controlled micro and nanoscale topographical cues are useful as smart scaffolds and biointerfaces for cell culture. Recently, use of thin-film and surface wrinkling is emerging as a rapid unconventional method for preparing topographically patterned surfaces, especially suited for the production of smart patterns over large area surfaces. On the other hand, there is an increasing interest in employing conducting polymers as soft, biocompatible, conductive biointerfaces or as parts of bioelectronic devices. A novel convenient and versatile method is presented for producing anisotropic topographical cues at the micro- and nanoscale on conducting polymer surfaces. Micro and nanowrinkles were formed during the heat-shrinking process of a thermo-retractable polystyrene substrate. Surface wrinkling was due to the mismatch between the mechanical properties of a conducting polymer ultrathin film and the substrate. Various geometries of wrinkled structures were prepared, demonstrating the tunability of topography depending on the thickness of the conductive film. A method for patterning the conductive properties of the wrinkled substrates was also presented. Such surfaces acted as smart scaffolds for the functional alignment of cells, envisioning their electrical stimulation. Cell adhesion and proliferation were evaluated, comparing different topographies, and a preferential anisotropic alignment of C2C12 murine skeletal muscle cells along wrinkles was demonstrated. The observed trends were also confirmed concerning the formation of aligned myotubes in C2C12 differentiation stage. Furthermore, improved results in terms of aligned and mature myotube formation were obtained by co-culturing C2C12 cells with a fibroblasts feeder layer. The combination of living cells and tunable conductive nanowrinkles will represent a unique tool for the development of innovative biomedical devices.

Summary. Background: The dodecapeptide HHLGGAK-QAGDV (H12), corresponding to the fibrinogen c-chain carboxy-terminal sequence (c400-411), is a specific binding site of the ligand for platelet GPIIb/IIIa complex. We have evaluated H12-coated nanoparticles (polymerized albumin or liposome) as platelet function-supporting synthetic products. Objectives: To strengthen the hemostatic ability of H12-coated particles as a platelet substitute, we exploited installation of a drug delivery function by encapsulating adenosine diphosphate (ADP) into liposomes [H12-(ADP)-liposomes]. Methods and results: Via selective interaction with activated platelets through GPIIb/IIIa, H12-(ADP)-liposomes were capable of augmenting agonist-induced platelet aggregation by releasing ADP in an aggregation-dependent manner. When intravenously injected into rats, liposomes were readily targeted to sites of vascular injury as analyzed on computed tomography. In fact, comparable to fresh platelets, liposomes exhibited considerable hemostatic ability for correcting prolonged bleeding time in a busulphan-induced thrombocytopenic rabbit model. In addition, the liposomes showed no activating or aggregating effects on circulating platelets in normal rabbits. Conclusion: H12-(ADP)-liposome may thus offer a promising platelet substitute, being made with only synthetic materials and exerting hemostatic functions in vivo via reinforcement of primary thrombus formation by residual platelets in thrombocytopenia at sites of vascular injury, but not in circulation.