Fig. 2: Categorization and examples of strategies for biofabrication of muscle tissue.

Application-specific modi operandi for muscle tissue fabrication (a). According to the application, different degrees of physico-chemical bulk material modification and spatio-temporal structure modulation are applied for different examples found in the literature. The latter can be subdivided into biohybrid reinforcement (e–g), and supply structure integration (b–d). Live-Dead staining of actively perfused (b, left) vs. non-perfused (b, right) tissues as well as the measured cell viability as a function of the distance to the nutritional channel (c), exemplarily outline the importance of supply channel integration in thick tissues. The self-assembling capacity of vascular structures in bulk materials demonstrates the different potencies of compact (d, left) and highly porous scaffolds (d, right).(From ref. ²¹ Reprinted with permission from AAAS.) Biohybrid reinforcement was shown to strengthen cell alignment (e–g) and promote the mechanical properties of hydrogels (f, g)²³ (difference in the morphological characteristics of a scaffold with different fiber diameters. by Xie et al (CC BY 4.0)). For instance, spacer fabric integration increased Young’s modulus of low concentrated collagen (Col) and alginate (Alg) hydrogels by several orders of magnitude (g)²² (Warp-knitted spacer fabric design and Morphological and mechanical analysis of warp-knitted spacer fabrics by Schäfer et al. (CC BY 4.0)).