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International Journal of Bioprinting Light-based muscle bioprinting with bioglass

remarkable efforts to leverage recent advances in but such a state can negatively impact cellular viability and
biomaterials, biophysics, and biomedical engineering to elongation during culture. 14,15
tackle the challenges posed by diseases such as muscular To address the challenges inherent in extrusion-
dystrophy, volumetric muscle loss, or aging. The current based bioprinting, researchers have explored alternative
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medical standard for treating significant muscle damage bioprinting techniques, including light-based bioprinting
is the implantation of autografts of healthy muscle tissue. (LBB) using lithography. By using light to polymerize
However, this procedure has significant constraints due to photosensitive bioinks layer-by-layer, this technique offers
the shortage of donors and a potential loss of function or the potential to create high-resolution 3D structures
morbidity at the donor site. These constraints have driven without exerting mechanical stresses in the process that
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multiple research attempts to develop synthetic graft can affect the cell viability and cell elongation of the printed
substitutes similar to native tissue. tissues. Nevertheless, there are several inherent constraints
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Muscle tissue is a mesodermal soft tissue formed during of the process that need to be considered. 12,13,16
the embryonic development process called myogenesis. Light-based bioprinting techniques rely on using
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Morphological characteristics of muscles, such as the specific wavelength of light to polymerize photosensitive
shape of fibers, the number of nuclei, and the length of materials. Several factors should be taken into account
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sarcomeres, determine the response to stimulus and the type before using this type of technique, such as the output power
of muscle function as smooth, cardiac, or skeletal muscle. density of the light, the exposure time on each layer, and the
Skeletal muscle tissue engineering involves restoration of scattering of light through the material. The output power
skeletal muscle functions affected by myopathies. Skeletal density of the light will have a direct effect on how much
muscle fibers are heterogeneous and are categorized as time it will take to polymerize the biomaterial; therefore, a
fast (type 1) and slow (type II) in adults. Despite recent higher value will result in a faster print. In LBB, wavelength
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advancements in tissue engineering, in vitro manufacture and exposure time are essential parameters that are required
of fully functional muscle is still not yet possible. to be balanced to minimize cell damage without losing the
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Bioprinting or biofabrication comprises technologies to capability to achieve crosslinking. Prolonged exposure
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allocate small units of cells and materials with micrometric times can lead to a reduction of cellular viability. The
precision to form 3D structures similar to particular third factor, light scattering, caused by material properties,
type of tissues. These structures are cell-laden scaffolds directly impacts bioprinting resolution. It occurs when
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that play a crucial role in controlling and guiding tissue light disperses, polymerizing biomaterial in unintended
regeneration, providing a supportive environment for cell areas. To address this issue, photosensitive bioinks can
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growth and development. Engineering of muscle fibers be enhanced with non-cytotoxic anti-scattering factors,
in vitro requires the culture of myoblasts in an anisotropic which act as effective light filters. 17–20 It is crucial to ensure
complex environment to promote their alignment, that all these factors together pose no harm to the cells
fusion, and myogenesis. Patterning of cells, selection involved in the bioprinting process. Printing tissues with
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of bioactive material, and biomolecular factors allow to high cell viability under varying printing conditions using
produce constructs that exhibit enhanced complexity in LBB remains challenging. 15
three dimensions and repeatability compared to more One of the most critical factors in bioprinting is the
conventional methods. 8,9,11 biomaterial or bioink used during the process, since

Extrusion-based bioprinting is currently the most this material, usually a hydrogel, enables the culture and
widely used technology for tissue biofabrication. However, maturation of the cells while providing mechanical stability
several studies indicate that the extrusion process can to the 3D-printed structure. Choosing or formulating the
create unfavorable shear stress conditions that are harmful appropriate bioink to be used in a bioprinting process is
to cells. The shear stress generated at the nozzle tip can an essential task during the design and evaluation of an
reduce cell viability and limit the maximum achievable experimental study. The bioink composition influences
resolution in 3D printing (>100 μm). In extrusion- relevant properties such as mechanical stability,
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based bioprinting, bioinks should exhibit shear-thinning conductivity, and viscosity of the biomaterial and directly
behavior to facilitate flow during extrusion without exerting affects the resolution and cell viability of the 3D bioprinting
detrimental shear stresses on cells that may compromise process.
their integrity during printing. 12,13 However, they should Gelatin methacryloyl (GelMA) is one of the most
also be self-supporting, a condition that is often achieved used hydrogels in bioprinting owing to its practicality
through high polymer concentrations and viscosity values, and versatility. Derived from collagen (gelatin being

Volume 10 Issue 4 (2024) 550 doi: 10.36922/ijb.1830