FIG. 4.

Skeletal muscle engineering strategies. (a) Development of vascularized skeletal muscle tissue using (i) decellularized scaffold stained for angiogenic response after implantation (15 days), alfa-SMA (green), vWF (red), and DAPI (blue). (ii) Vascularized muscle bundle engineering highlighting the formation of vasculature channels and showing sprouting of HUVECs toward muscle fiber and formation of capillary networks (muscle fiber indicated by arrow). Muscle bundle and microvasculature formed using a hydrogel casting and injection method, as reported by Osaki et al. Sample stained using Phalloidin (green), DAPI (blue), and α-actinin (red). (iii) and (iv) Printing of decellularized vascularized muscle using (iii) mixed population of human skeletal myoblasts (hSKM cells) and HUVECs, and (iv) coaxial printing with decellularized vascular tissue containing HUVECs on the shell of the fiber and skeletal muscle decellularized tissue containing hSKM cells localized to the core. Samples stained using CD31 (green), DAPI (blue), and MHC (red). (b) The role of architecture in maturation of myotubules. Top: SEM images of chitosan scaffolds prepared from solutions of (i) 8% or (ii) 12% chitosan concentrations. Bottom: images were obtained by immunocytostaining, MHC staining, and nuclei staining upon cells grown on the (iii) 8% and (iv) 12% chitosan scaffolds. Scale bars: (i) and (ii) 150, (iii) 60, and (iv) 50 μm. (a) (i) Reproduced with permission from Alvarez Fallas et al., Int. J. Mol. Sci. 19(5), 1319 (2018). Copyright 2018 Authors, licensed under a Creative Commons Attribution (CC BY) license.¹²⁶ (ii) Reproduced with permission from Osaki et al., Biomaterials 156, 65–76 (2018). Copyright 2018 Authors, licensed under a CC-BY-NC-ND 4.0 license.¹²⁷ (iii) and (iv) Reprinted with permission from Choi et al., Biomaterials 206, 160–169 (2019). Copyright 2019 Elsevier.¹⁴⁵ (b) Adapted with permission from Jana et al., Adv. Healthcare Mater. 2(4), 557–561. Copyright 2013 Wiley.⁸⁸