Role of fibronectin in topographical guidance of neurite extension on electrospun fibers.
ABSTRACT Bridging of long peripheral nerve gaps remains a significant clinical challenge. Electrospun nanofibers have been used to direct and enhance neurite extension in vitro and in vivo. While it is well established that oriented fibers influence neurite outgrowth and Schwann cell migration, the mechanisms by which they influence these cells are still unclear. In this study, thin films consisting of aligned poly-acrylonitrile methylacrylate (PAN-MA) fibers or solvent casted smooth, PAN-MA films were fabricated to investigate the potential role of differential protein adsorption on topography-dependent neural cell responses. Aligned nanofiber films promoted enhanced adsorption of fibronectin compared to smooth films. Studies employing function-blocking antibodies against cell adhesion motifs suggest that fibronectin plays an important role in modulating Schwann cell migration and neurite outgrowth from dorsal root ganglion (DRG) cultures. Atomic Force Microscopy demonstrated that aligned PAN-MA fibers influenced fibronectin distribution, and promoted aligned fibronectin network formation compared to smooth PAN-MA films. In the presence of topographical cues, Schwann cell-generated fibronectin matrix was also organized in a topographically sensitive manner. Together these results suggest that fibronectin adsorption mediated the ability of topographical cues to influence Schwann cell migration and neurite outgrowth. These insights are significant to the development of rational approaches to scaffold designs to bridge long peripheral nerve gaps.
Article: The influence of fibronectin and laminin during Schwann cell migration and peripheral nerve regeneration through silicon chambers.[show abstract] [hide abstract]
ABSTRACT: The ability of extracellular proteins to influence the regenerative process was examined in Sprague-Dawley rats. Silicon chambers, filled with sterile saline solutions of cytochrome-c, fibronectin, laminin, a combination of fibronectin and laminin, or nerve growth factor were surgically implanted between the severed ends of sciatic nerves to form gaps of 18 mm. Four months later, the various groups were examined to determine the success of regeneration. The incidence of cable formation that bridged the gap was similar in all groups. The group of animals that had implants containing the combination of fibronectin/laminin had increased numbers of myelinated axons in the regenerated segment within the chamber and in the distal sciatic tributary nerves. Horseradish peroxidase labelling demonstrated that increased numbers of sensory and motor neurons in the fibronectin/laminin group had regenerated axons across the gap into the distal tributaries of the sciatic nerve. The effect of the various agents on non-neuronal cells was measured by immunohistochemical staining with S-100 antibodies to determine the effects on Schwann cell migration. Silicon chambers, filled with sterile saline solutions of fibronectin, laminin, fibronectin/laminin, nerve growth factor, or cytochrome-c, were surgically implanted to form 5 mm gaps between severed sciatic nerve ends. Ten days later, Schwann cell migration into the bridging cables was examined in each group. Analysis revealed a greater influx of Schwann cells migrating into the regenerating segments in the fibronectin, the laminin, and the combination fibronectin/laminin groups compared to the control group (cytochrome-c).Journal of Neurocytology 04/1993; 22(3):176-84. · 1.94 Impact Factor