3D printed magneto-active microfiber scaffolds for remote stimulation of 3Din vitroskeletal muscle models

Abstract

Tunable culture platforms that guide cellular organization and mechanically stimulate skeletal muscle development are still unavailable due to limitations in biocompatibility and actuation triggered without contact. This study reports the rational design and fabrication of magneto-active microfiber meshes with controlled hexagonal microstructures via melt electrowriting (MEW) of a thermoplastic/graphene/iron oxide composite. In situ deposition of iron oxide nanoparticles on oxidized graphene yielded homogeneously dispersed magnetic particles with sizes above 0.5 micrometer and low aspect ratio, preventing cellular internalization and toxicity. With these fillers, homogeneous magnetic composites with very high magnetic filler content (up to 10 wt.%) were obtained and successfully processed in a solvent-free manner for the first time. MEW of magnetic composites enabled the skeletal muscle-inspired design of hexagonal scaffolds with tunable fiber diameter, reconfigurable modularity, and zonal distribution of magneto-active and nonactive material. Importantly, the hexagonal microstructures displayed elastic deformability under tension, mitigating the mechanical limitations due to high filler content. External magnetic fields below 300 mT were sufficient to trigger out-of-plane reversible deformation leading to effective end-to-end length decrease up to 17%. Moreover, C2C12 myoblast culture on 3D Matrigel/collagen/MEW scaffolds showed that the presence of magnetic particles in the scaffolds did not significantly affect viability after 8 days with respect to scaffolds without magnetic filler. Importantly, in vitro culture demonstrated that myoblasts underwent differentiation at similar rates regardless of the presence of magnetic filler. Overall, these innovative microfiber scaffolds were proven as a magnetically deformable platform suitable for dynamic culture of skeletal muscle with potential for in vitro disease modeling.

Volumetric Printing Across Melt Electrowritten Scaffolds Fabricates Multi‐Material Living Constructs with Tunable Architecture and Mechanics

“…Moreover, while this study focused on the advantage of producing mechanically competent grafts even when using soft hydrogels for tissue culture, previous literature provides consistent data that certain cell types, including different types of muscle cells, are able to align following the directionality of the MEW fibers, even when these are embedded in a hydrogel matrix. [41,87,88] Future research on VolMEW could investigate this potential, for example, to guide cell orientation in vessels including, for example, a smooth muscle cell layer. Freedom of design in this contactless printing approach allows to produce architectures that cannot be easily obtained with other methods, and can therefore be potentially applied to produce patient-specific in vitro models, in which the effect of flow as a function of the (vascular) geometry, could be studied.…”

Materials and Strategies to Enhance Melt Electrowriting Potential

“…In a similar approach, Cedillo-Servin and colleagues proposed the use of magneto-active scaffolds for remote stimulation of 3D in vitro skeletal muscle models. [99] In this case, oxidized graphene nanoplatelets functionalized with iron oxide (rGNP@) were employed as fillers in a PCL matrix, and samples with 0, 2, and 10 wt% of rGNP@ were successfully processed by MEW, though a decrease in the printing quality was observed as the amount of filler increased. All samples exhibited a similar fiber size of 20 μm, which was further tuned by adjusting the printing conditions.…”

Crafting Tissue Complexity

“…Moreover, while this study focused on the advantage of producing mechanically competent grafts even when using soft hydrogels for tissue culture, previous literature provide consistent data that certain cell types, including different types of muscle cells, are able to align following the directionality of the MEW fibers, even when these are embedded in a hydrogel matrix. [167,200,334] Future research on VolMEW could investigate this potential, for example to guide cell orientation in vessels including, i.e., a smooth muscle cell layer.…”