Precisely Assembled Nanofiber Arrays as a Platform to Engineer Aligned Cell Sheets for Biofabrication

Abstract

A hybrid cell sheet engineering approach was developed using ultra-thin nanofiber arrays to host the formation of composite nanofiber/cell sheets. It was found that confluent aligned cell sheets could grow on uniaxially-aligned and crisscrossed nanofiber arrays with extremely low fiber densities. The porosity of the nanofiber sheets was sufficient to allow aligned linear myotube formation from differentiated myoblasts on both sides of the nanofiber sheets, in spite of single-side cell seeding. The nanofiber content of the composite cell sheets is minimized to reduce the hindrance to cell migration, cell-cell contacts, mass transport, as well as the foreign body response or inflammatory response associated with the biomaterial. Even at extremely low densities, the nanofiber component significantly enhanced the stability and mechanical properties of the composite cell sheets. In addition, the aligned nanofiber arrays imparted excellent handling properties to the composite cell sheets, which allowed easy processing into more complex, thick 3D structures of higher hierarchy. Aligned nanofiber array-based composite cell sheet engineering combines several advantages of material-free cell sheet engineering and polymer scaffold-based cell sheet engineering; and it represents a new direction in aligned cell sheet engineering for a multitude of tissue engineering applications.

Novel class of collector in electrospinning device for the fabrication of 3D nanofibrous structure for large defect load‐bearing tissue engineering application

“…This possibility of increasing the pore size and lowering the compactness, enable the cells to push back the fibers and diffuse to the inner regions of the scaffold. By this characteristic, cells diffused easily across the thickness and reached the deepest regions of the 3D structure after 7 days of being cultured, without the need of dynamic cell culture system (which usually used for thick scaffolds) or loading the cells during the scaffold fabrication process . Compared to the on‐site cell spraying method during electrospinning, and also stacking seeded layers on top of each other, our new approach has many advantages including prevention of probable contamination during simultaneous electrospinning and cell spraying.…”

“…On the contrary, in the literature articles, there is no exact control over the porosity and pore size enhancement of 3D electrospun structures. 21,[38][39][40][41]45,50,51 Besides, many works on fabrication of 3D scaffolds lack the possibility of easy cell diffusion, such as in post-assembly or stacking of conventional electrospun layers [23][24][25][26][27][28][29][33][34][35][36][42][43][44] . In the introduced technique, micro-thickness of each individual inner layer along the entire thickness of the scaffold and formation of the 3D pores that directly affect the facility of cellular movement and diffusion between layers can be adjusted by the variation in the thickness of the spring side wires (Fig.…”

“…To overcome these drawbacks, the ES process should be modified to produce 3D thick structures with adequate porosity and appropriate pore dimensions to allow for cell infiltration and growth in a 3D biomimetic nanofibrous environment. Many attempts have been made to reach this aim including stacking electrospun layers and membrane, combination of micro and nanofibers, assembly of spinned nanofibers, post‐processing the electrospun mats with laser, ultrasonic vibration or mechanical expansion,rolling or folding the fibers, accelerated solidification, variation in surface resistivity of spinning fibers,alteration of the electric field, changing the solution properties, using liquid flow in the spinning fiber path, and using sacrificing components …”

“…In spite of the wide range of studies performed on preparation of highly porous 3D scaffolds by electrospinning, structures with adequate porosity and proper pore size for cell infiltration in the millimeter scale have not been reported yet. In fact, the nanofibrous scaffolds so far described in the literature showed cell colonization only in the range of few hundred microns of depth from the cultured surface .…”

“…To overcome these drawbacks, the ES process should be modified to produce 3D thick structures with adequate porosity and appropriate Correspondence to: H. Mirzadeh; e-mail: mirzadeh@aut.ac.Ir pore dimensions to allow for cell infiltration and growth in a 3D biomimetic nanofibrous environment. Many attempts have been made to reach this aim including stacking electrospun layers and membrane, [23][24][25][26][27][28][29] combination of micro and nanofibers, [30][31][32] assembly of spinned nanofibers, [33][34][35][36] post-processing the electrospun mats with laser, ultrasonic vibration or mechanical expansion, [37][38][39][40][41] rolling or folding the fibers, [42][43][44] accelerated solidification, 45 variation in surface resistivity of spinning fibers, 46,47 alteration of the electric field, 48 changing the solution properties, 49 using liquid flow in the spinning fiber path, 21,50,51 and using sacrificing components. [52][53][54][55] In spite of the wide range of studies performed on preparation of highly porous 3D scaffolds by electrospinning, 21, structures with adequate porosity and proper pore size for cell infiltration in the millimeter scale have not been reported yet.…”