There is a growing
need to develop novel well-characterized biological
inks (bioinks) that are customizable for three-dimensional (3D) bioprinting
of specific tissue types. Gelatin methacryloyl (GelMA) is one such
candidate bioink due to its biocompatibility and tunable mechanical
properties. Currently, only low-concentration GelMA hydrogels (≤5%
w/v) are suitable as cell-laden bioinks, allowing high cell viability,
elongation, and migration. Yet, they offer poor printability. Herein,
we optimize GelMA bioinks in terms of concentration and cross-linking
time for improved skeletal muscle C2C12 cell spreading in 3D, and
we augment these by adding gold nanoparticles (AuNPs) or a two-dimensional
(2D) transition metal carbide (MXene nanosheets) for enhanced printability
and biological properties. AuNP and MXene addition endowed GelMA with
increased conductivity (up to 0.8 ± 0.07 and 0.9 ± 0.12
S/m, respectively, compared to 0.3 ± 0.06 S/m for pure GelMA).
Furthermore, it resulted in an improvement of rheological properties
and printability, specifically at 10 °C. Improvements in electrical
and rheological properties led to enhanced differentiation of encapsulated
myoblasts and allowed for printing highly viable (97%) stable constructs.
Taken together, these results constitute a significant step toward
fabrication of 3D conductive tissue constructs with physiological
relevance.
Smooth muscle cells (SMCs) play a significant role in the pathogenesis of atherosclerosis. 2D cultures elucidated valuable information about the interaction between SMCs and extracellular matrix (ECM) components. However, 3D constructs better represent the native vascular environment. Furthermore, a limited number of studies addressed the effect of ECM stiffness on SMCs phenotype. We investigated the effect of stiffness of different ECM substrates by modulating their concentrations, including the effect on morphology, proliferation, expression of the contractile protein α-smooth muscle actin (α-SMA) and deposition of collagen type I (Col I) and collagen type III (Col III) proteins. At low concentrations of Col I gels and Col I gels supplemented with 10% fibronectin (Fn), SMCs exhibited non-elongated, 'hill-and-valley' shape and large mean cellular area, indicating a hypertrophic morphology, characteristic of the synthetic phenotype. However, with increasing concentration, mean cellular area and proliferation relative to cells cultured in 2D dropped. Whole protein secretion into the culture media and deposition of Col I and Col III generally decreased with increasing stiffness. Moreover, percentage of α-SMA+ SMCs decreased with increasing gel concentration, pointing to a shift towards the synthetic phenotype. Supplementing Col I with 10% Laminin (Ln) maintained higher cellular area and aspect ratio at all gel concentrations and did not change α-SMA expression significantly, compared to Col I alone or Col I + Fn. Overall, these results demonstrate that ECM components and stiffness could provide the tools to modulate the phenotype and function of SMCs in vitro, which allows for the control of properties of engineered tissues.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.