Stimulation of cell growth and neurogenesis using protein-functionalized microfibrous scaffolds and fluid flow in bioreactors

Abstract

Microfibrous viscose-rayon scaffolds functionalized with poly-L-lysine and laminin were used to culture pheochromocytoma (PC12) cells in recirculation bioreactors under bulk laminar flow conditions. To determine the effects of continuous forced convective flow on cell viability, growth, and neurogenesis, the cultures were exposed to fluid-induced shear stresses of magnitude 2.7 × 10–5 to 4.6 × 10–3 Pa for up to 12 days. The results were compared with those obtained using static scaffold and static monolayer (2D) control cultures. Cell growth rates were 1.5- to 1.8-fold greater in the bioreactor scaffold cultures relative to the controls without flow. After treatment of the cells with nerve growth factor, development and extension of neurite networks and expression of several neural differentiation markers including β3-tubulin, shootin1, and EphA2 were also substantially enhanced in the presence of fluid convection. In the control cultures without fluid flow, cell growth and differentiation were greater in the static scaffold cultures than in the static 2D monolayers. This work demonstrates the significant beneficial effects of features of the physical culture environment, such as hydrodynamic conditions and cell attachment surface geometry, in regulating culture performance. Flow devices capable of supporting long-term cell culture while delivering controlled levels of hydrodynamic shear are a valuable practical tool for promoting nerve tissue development and regeneration in vitro.