Chaotic bioprinting of skeletal muscle-like tissues

Abstract

Skeletal muscle diseases affect around 1.7 billion people worldwide, leading to pain and disability. Although conventional treatments, such as, autologous or exogenous grafts have benefited many patients, they still exhibit limitations related to the injury size, donor site morbidity and strong immune reactions. Biofabrication of skeletal muscle tissue has been proposed as a potential strategy to replace or regenerate lost or damage muscle tissue. Engineering the skeletal muscle tissue is not trivial, since skeletal muscle is a thick tissue composed of highly aligned myofibers that are perfused by blood vessel to support oxygenation and transport of nutrients. Therefore, biofabricated muscle tissues should exhibit unidirectional alignment of cells to support the formation of contractile myotubes, and vascular-like conduits to promote transference of molecules in the whole construct.

Biofabrication technologies, particularly, extrusion-based bioprinting has been widely used to fabricate skeletal muscle-like tissues, but the smallest achievable features (> 100 µm) make difficult to recreate the microarchitecture of the muscle tissue. This PhD thesis shows the use of chaotic printing for the fabrication of skeletal muscle-like constructs. Chaotic printing is an extrusion-based technique that generates multilayer scaffolds at high printing resolution (~10 µm) and high-throughput (1-2 m of filament per minute). The microlayers of the scaffold were used to promote cell alignment, to generate vascular-like microchannels (up to 31 channels of ~ 20 µm in diameter), and to accommodate several materials (up to 8 inks) in a single filament. The skeletal muscle models fabricated by chaotic printing exhibited a high cell viability (~90% during the culture time) which is hardly achieved through conventional extrusion-based processes to produce tiny features, high cellular alignment (~80% cells aligned in ± 10° in presence of multiple channels), and myogenic differentiation capabilities. Overall, this PhD thesis demonstrated the versatility of chaotic printing for the development of skeletal muscle-like constructs that resemble the native architecture of the muscle tissue.