title: Neurite outgrowth in fibrin gels is regulated by substrate stiffness.
abstract: Fibrin is a promising matrix for use in promoting nerve repair given its natural occurrence in peripheral nerve injuries, and the biophysical properties of this matrix can be regulated to modulate tissue regeneration. In this study, we examined the effect of physical and mechanical properties of fibrin gels on dorsal root ganglia (DRG) neurite extension. Increases in fibrinogen concentration increased the number of fibrin strands, resulting in decreased pore size and increased stiffness. Neurite extension was reduced when DRG explants were cultured within fibrin gels of increasing fibrinogen concentrations (from 9.5 to 141 mg/mL). The addition of NaCl also increased the number of fibrin strands, reducing fiber diameter and porosity, while increasing mechanical strength, and reductions in neurite extension correlated with increases in NaCl content. We determined that neurite extension within fibrin gels is dependent on fibrinolysis and is mediated by the secretion of serine proteases and matrix metalloproteinases by entrapped DRGs, as confirmed by culturing cells in the presence of inhibitors against these enzymes and real-time-polymerase chain reaction. Taken together, the results of this study provide new insight into the effect of fibrin gel biophysical properties on neurite extension and suggest new opportunities to improve the efficacy of these materials when used as nerve guidance conduits.
authors: Department of Biomedical Engineering, UC Davis, Davis, CA 95616, USA.
authors: Alan J
authors: AJ
authors: Man
authors: Hillary E
authors: HE
authors: Davis
authors: Aki
authors: A
authors: Itoh
authors: Jonathan Kent
authors: JK
authors: Leach
authors: Peter
authors: P
authors: Bannerman
mesh_terms: D000818:Animals; D005337:Fibrin / Q000494:pharmacology* / Q000648:ultrastructure; D005340:Fibrinogen / Q000494:pharmacology; D005727:Ganglia, Spinal / Q000187:drug effects / Q000254:growth & development; D005782:Gels / Q000494:pharmacology*; D006801:Humans; D061965:Matrix Metalloproteinase Inhibitors; D020782:Matrix Metalloproteinases / Q000235:genetics / Q000378:metabolism; D055595:Mechanical Phenomena / Q000187:drug effects*; D051379:Mice; D008810:Mice, Inbred C57BL; D016501:Neurites / Q000187:drug effects* / Q000378:metabolism*; D011480:Protease Inhibitors / Q000494:pharmacology; D059748:Proteolysis / Q000187:drug effects; D057057:Serine Proteases / Q000235:genetics / Q000378:metabolism; D012965:Sodium Chloride / Q000494:pharmacology; D013997:Time Factors
chemical_list: D005782:Gels; D061965:Matrix Metalloproteinase Inhibitors; D011480:Protease Inhibitors; D012965:Sodium Chloride; D005337:Fibrin; D005340:Fibrinogen; D057057:Serine Proteases; D020782:Matrix Metalloproteinases