Construction of cell-containing, anisotropic, three-dimensional collagen fibril scaffolds using external vibration and their influence on smooth muscle cell phenotype modulation.

Numerous methods have been developed for preparing guiding channels/tracks to promote the alignment of highly oriented cell types. However, these manufacture methods cannot fabricate interconnected guiding channels within three-dimensional (3D) scaffolds. Providing a suitable architectural scaffold for cell attachment could lead cells to more rapidly display a desired phenotype and perform their unique functions. Previously, we developed a simple device composed of a pneumatic membrane that can generate a tunable vibration frequency to apply physical stimulation for fabricating a 3D aligned collagen fibril matrix with the characteristic D-period structure in one step. In the present study, we aimed to evaluate the cellular responses of thoracic aortic smooth muscle cells (A7r5) incorporated during the fabrication of 3D-aligned collagen fibrils with D-periods and compared these cells with those incorporated in a 3D, randomly distributed collagen matrix and in a two-dimensional (2D) aligned substrate after up to 10 days of culture. The results consistently demonstrated that A7r5 cells cultured within the 3D and 2D anisotropic matrices were aligned. Cells cultured in the 3D aligned scaffolds exhibited a higher proliferation rate as well as higher F-actin and smoothelin expression levels compared with cells cultured in 3D randomly distributed scaffolds. Together, these results indicate that a 3D-reconstituted, anisotropic collagen matrix fabricated by our process provides synergistic effects of tension stimulation and matrix stiffness on encapsulated cells and can direct A7r5 cells to transform from a synthetic phenotype into a contractile state.

External vibration enhances macromolecular crowding for construction of aligned three-dimensional collagen fibril scaffolds.

There are many techniques for preparing two-dimensional aligned fibril matrices. However, the critical problem associated with these techniques is the destruction of the native structure (e.g., the α-helix) of the proteins. Moreover, most of these techniques cannot create a three-dimensional (3D), aligned reconstituted collagen fibril matrix in one step. In this study, we used a simple device composed of a pneumatic membrane that generates a tunable vibration frequency to apply physical stimulation to fabricate a 3D, aligned collagen fibril matrix with the characteristic D-period structure of collagen in one step. Using second harmonic images, we demonstrated that the aligned, reconstituted collagen fibrils preserve the native collagen D-period structure. The average angular deviation of fibril alignment was reduced to 25.01 ± 4.2° compared with the 39.7 ± 2.19° of alignment observed for the randomly distributed fibril matrix. In addition, the ultimate tensile strength of the aligned matrix when force was applied in the direction parallel to the fiber orientation was higher than that of the randomly oriented matrix. The aligned reconstituted collagen fibril matrix also enhanced the expression of smoothelin (a specific marker of contractile phenotype) of thoracic aortic smooth muscle cell (A7r5) relative to the randomly distributed collagen fibril matrix.