WEB Self-assembled fibrinogen nanofibers support fibroblast growth and migration
As a key player in blood coagulation, fibrinogen has gained increasing attention to develop nanofibrous scaffolds for wound healing applications. Such scaffolds can mimic the native blood clot environment, which serves as a provisional extracellular matrix during tissue repair. So far, fibrinogen nanofibers were mainly produced by electrospinning. However, this technique might impede the protein functionality due to the use of electric fields and organic solvents.
Therefore, we introduced salt-induced self-assembly approach to prepare nanofibrous fibrinogen scaffolds under physiological conditions. In addition, we established a patterning approach to produce binary fibrinogen scaffolds containing spatially controlled nanofibrous and planar topographies. We characterized our scaffolds with scanning electron microscopy, atomic force microscopy and tensile testing. Further, we studied their biocompatibility using NIH 3T3 fibroblasts as model system for wound healing.
Dense, porous nanofiber networks were obtained in the presence of salt with a thickness of 3 µm, whereas the absence of salt yielded planar films with a thickness around 2 µm. After cross-linking in formaldehyde vapor, the scaffolds were stable in aqueous environment and the surface topography and roughness were preserved upon rehydration. Tensile testing revealed a Young’s modulus around 1 MPa for rehydrated nanofibers while a Young’s modulus around 1 GPa for dry scaffolds.
Fibroblasts proliferated well on nanofibrous and planar scaffolds for up to 72 h with viability comparable to controls substrates. Confocal microscopy revealed a more pronounced cytoskeleton on planar than on nanofibrous fibrinogen. Cells on nanofibrous fibrinogen were smaller with many short filopodia whereas on planar fibrinogen they were larger and had few, longer filopodia. Fibroblasts appeared flat on the planar regions of binary scaffolds, while cell bodies on the nanofibrous regions appeared elevated. Live cell tracking revealed similar cell migration velocities on nanofibrous and planar regions of binary scaffolds.
In summary, we showed for the first time that self-assembled fibrinogen nanofibers support the growth of 3T3 fibroblasts. The mechanical characteristics of rehydrated fibrinogen nanofibers resembled the properties of native fibrin fibers. Therefore, our biocompatible fibrinogen nanofibers could become attractive as new cell scaffolds for future wound healing applications.