Muscle tissue engineering is a subset of the general field of tissue engineering, which studies the combined use of cells and scaffolds to design therapeutic tissue implants. Within the clinical setting, muscle tissue engineering involves the culturing of cells from the patient's own body or from a donor, development of muscle tissue with or without the use of scaffolds, then the insertion of functional muscle tissue into the patient's body. Ideally, this implantation results in full regeneration of function and aesthetic within the patient's body. Outside the clinical setting, muscle tissue engineering is involved in drug screening, hybrid mechanical muscle actuators, robotic devices, and the development of cell-cultured meat meat as a new food source. Innovations within the field of muscle tissue engineering seek to repair and replace defective muscle tissue, thus returning normal function.The practice begins by harvesting and isolating muscle cells from a donor site, then culturing those cells in media. The cultured cells form cell sheets and finally muscle bundles which are implanted into the patient.
Overview Muscle is a naturally aligned organ, with individual muscle fibers packed together into larger units called muscle fascicles. The uniaxial alignment of muscle fibers allows them to simultaneously contract in the same direction and properly propagate force on the bones via the tendons. Approximately 45% of the human body is composed of muscle tissue, and this tissue can be classified into three different groups: skeletal muscle, cardiac muscle, and smooth muscle. Muscle plays a role in structure, stability, and movement in mammalian bodies. The basic unit for a muscle is a muscle fiber, which is made up of myofilaments actin and myosin. This muscle fiber contains sarcomeres which generate the force required for contraction. A major focus of muscle tissue engineering is to create constructs with the functionality of native muscle and ability to contract. To this end, alignment of the tissue engineered construct is extremely important. It has been shown that cells grown on substrates with alignment cues form more robust muscle fibers. Several other design criteria considered in muscle tissue engineering include the scaffold porosity, stiffness, biocompatibility, and degradation timeline. Substrate stiffness should ideally be in the myogenic range, which has been shown to be 10-15 kPa. The purpose of muscle tissue engineering is to reconstruct functional muscular tissue which has been lost via traumatic injury, tumor ablation, or functional damage caused by myopathies. Until now, the only method used to restore muscular tissue function and aesthetic was free tissue transfer. Full function is typically not restored, however, which results in donor site morbidity and volume deficiency. The success of tissue engineering as it pertains to the regeneration of skin, cartilage, and bone indicates that the same success will be found in engineering muscular tissue. Early innovations in the field yielded in vitro cell culturing and regeneration of muscle tissue which would be implanted in the body, but advances in recent years have shown that there may be potential for in vivo muscle tissue engineering using scaffolding.
Etymology The term muscle tissue engineering, while it is a subset of the much larger discipline, tissue engineering, was first coined in 1988 when Herman Vandenburgh, a surgeon, cultured avian myotubes in collagen-coated culture plates. This started a new era of in vitro tissue engineering. The ideal was officially adopted in 1988 in Vandenburgh's publication titled Maintenance of Highly Contractile Tissue-Cultured Avian Skeletal Myotubes in Collagen Gel. In 1989, the same group determined that mechanical stimulation of myoblasts in vitro facilitates engineered skeletal muscle growth.
History
19th Century A rudimentary understanding of muscle tissue began to develop as early as 1835, when embryonic myogenesis was first described. In the 1860s, it was shown that muscle is capable of regeneration and an experimental regeneration was conducted to better understand the specific method by which this was done in vivo. Following this discovery, muscle generation and degeneration in man were described for the first time. Researchers consequently assessed several aspects of muscle regeneration in vivo, including "the continuous or discontinuous regeneration depending on tissue type" to increase functional understanding of the phenomena. It was not until the 1960s, however, that researchers determined what components were required for muscle regeneration.
20th Century In 1957, it was determined via DNA content that myoblasts proliferate, but myonuclei do not. Following this discovery, the satellite cell was experimentally uncovered by Mauro and Katz as stem cells which sit on the surface of the myofibre and have the capability to differentiate into muscle cells. Satellite cells provide myoblasts for growth, differentiation, and repair of muscle tissue. Muscle tissue engineering officially began as a discipline in 1988 when Herman Vandenburgh cultured avian myotubes in collagen-coated culture plates. Following this development, it was found in 1989 that mechanical stimulation of myoblasts in vitro facilitates engineered skeletal muscle growth. Most of the modern innovations in the field of muscle tissue engineering are found in the 21st century.
… excerpt ends here. Continue reading the full article.
