Combining dual growth factor delivery and contact guidance in electrospun nanofibrous scaffolds for peripheral nerve regeneration

Abstract

Using nanofibrous scaffolds capable of providing controlled growth factor delivery and contact guidance are advantageous in tissue engineering. The aim of this investigation was to study the fabrication of nanofibrous bicomponent scaffolds for the dual delivery of glial cell line-derived growth factor (GDNF) and nerve growth factor (NGF) and also the fabrication of aligned-fiber scaffolds providing both biochemical and topographical cues and evaluate their biological performance for peripheral nerve tissue engineering. GDNF and NGF were incorporated into core-shell structured poly(lactic-co-glycolic acid) (PLGA) and poly(D,L-lactic acid) (PDLLA) nanofibers, respectively, through emulsion electrospinning. Using dual-source dual-power electrospinning (DSDP-ES), nonwoven bicomponent scaffolds composed of GDNF/PLGA fibers and NGF/PDLLA fibers with different fiber component ratios were successfully made. The structure and properties, including in vitro release behavior and in vitro degradation, of mono- and bicomponent scaffolds were studied. Subsequently, aligned-fiber bicomponent scaffolds (GDNF/PLGA fibers and NGF/PDLLA fibers) were fabricated using DSDP-ES and high-speed electrospinning (HS-ES). Concurrent and sustained releases of GDNF and NGF from bicomponent scaffolds were achieved and their release profiles could be tuned. The aligned-fiber topography and dual and sustained delivery of growth factors were realized in aligned-fiber bicomponent scaffolds. In vitro biological investigations were conducted for both nonwoven and aligned-fiber bicomponent scaffolds. The bioactivity of GDNF and NGF was preserved to a large extent in scaffolds. Rat pheochromocytoma cells (PC12 cells) were found to attach, spread and proliferate on all scaffolds. Fibrous scaffolds alone only induced limited cell differentiation into neuron-like phenotype characterized by neurite outgrowth. The release of growth factors from scaffolds could induce much improved neurite outgrowth and neural differentiation. GDNF and NGF released from GDNF/PLGA scaffolds and NGF/PDLLA scaffolds, respectively, could induce dose-dependent neural differentiation separately. A synergistic effect of GDNF and NGF released from bicomponent scaffolds of specific component ratio on promoting neural differentiation was found. The fiber alignment in aligned-fiber bicomponent scaffolds could induce neurite outgrowth, neural differentiation and neurite alignment to certain extent. The release of growth factors and aligned-fiber morphology induced neurite alignment and much enhanced neural differentiation in a synergetic manner. The properties of bicomponent scaffolds, including excellent biocompatibility, reasonable mechanical properties, controlled degradation rate, tunable dual release behavior of growth factors and contact guidance, make these scaffolds highly promising for peripheral nerve tissue regeneration.