Impact of scaffold micro and macro architecture on Schwann cell proliferation under dynamic conditions in a rotating wall vessel bioreactor

Abstract

Over the last decade tissue engineering has emerged as a powerful alternative to regenerate lost tissues owing to trauma or tumor. Evidence shows that Schwann cell containing scaffolds have improved performance in vivo as compared to scaffolds that depend on cellularization post implantation. However, owing to limited supply of cells from the patients themselves, several approaches have been taken to enhance cell proliferation rates to produce complete and uniform cellularization of scaffolds. The most common approach is the application of a bioreactor to enhance cell proliferation rate and therefore reduce the time needed to obtain sufficiently significant number of glial cells, prior to implantation.In this study, we show the application of a rotating wall bioreactor system for studying Schwann cell proliferation on nanofibrous spiral shaped scaffolds, prepared by solvent casting and salt leaching techniques. The scaffolds were fabricated from polycaprolactone (PCL), which has ideal mechanical properties and upon degradation does not produce acidic byproducts. The spiral scaffolds were coated with aligned or random nanofibers, produced by electrospinning, to provide a substrate that mimics the native extracellular matrix and the essential contact guidance cues.At the 4 day time point, an enhanced rate of cell proliferation was observed on the open structured nanofibrous spiral scaffolds in a rotating wall bioreactor, as compared to static culture conditions. However, the cell proliferation rate on the other contemporary scaffolds architectures such as the tubular and cylindrical scaffolds show reduced cell proliferation in the bioreactor as compared to static conditions, at the same time point. Moreover, the rotating wall bioreactor does not alter the orientation or the phenotype of the Schwann cells on the aligned nanofiber containing scaffolds, wherein, the cells remain aligned along the length of the scaffolds. Therefore, these open structured spiral scaffolds pre-cultured with Schwann cells, in bioreactors could potentially shorten the time needed for grafts for peripheral nerve regeneration.

Electrospun Nanofibrous Materials for Neural Tissue Engineering

“…However, the increase in expression of P0, a myelin-specific gene, was only observed on the aligned PCL scaffolds suggesting promotion of Schwann cell maturation is more favored on aligned fibrous scaffolds as opposed to random mats [23]. A spiral construct incorporated with electrospun random and aligned PCL fibrous meshes improved rat Schwann cell attachment as compared to other porous PCL scaffolds without fibers in both static and dynamic culture conditions [24]. Cells showed maximum alignment and largest neurite outgrowth on aligned fibrous PLGA meshes in the presence of fluid shear stresses of 0.50 Pa and 0.25 Pa, respectively [25].…”

Biomimetic electrospun nanofibrous structures for tissue engineering

“…Another approach for fabricating biomimetic spiral shaped scaffolds involved coating electrospun nanofibers on spiral scaffolds, to provide a substrate that imitates the native ECM and the essential contact guidance cues 10,74 . The spiral structure with open geometries, large surface areas, and porosity is helpful for improving nutrient transport and cell penetration into the scaffolds, which is otherwise limited in conventional tissue-engineered scaffolds for large bone defect repair 10 .…”

Optimizing parameters on alignment of PCL/PGA nanofibrous scaffold: An artificial neural networks approach

“…Among these, orientation of nanofibrous scaffolds can affect cell proliferation [15,20], differentiation [21][22][23], and morphology [12,17] as well as ECM production [24]. For example, Choi et al have shown that aligned nanofibers not only promote alignment of myotubes but also substantially increase the length of produced myotubes [9].…”