Generation of porous 3D-scaffolds based on electrospun nanofibers
Introduction The utilization of electrospun scaffolds is limited due to the restricted size of the mesh openings. In most cases the size of the openings prevents cell migration into the scaffolds, which leaves a narrow range of applications that are confined to impervious membranes. Therefore, the fiber network has to be loosened to extend the scaffold on a cellular level to the 3. dimension. A promising approach is the addition of porogens during the spinning process. After a selective extraction of these additives, 3D-scaffolds with additional pores and extended mesh openings can be generated. Methods Materials for the development of porous 3D nanofiber scaffolds, were carbon as a stiff, non-degradable material on the one hand, and polycaprolacton (PCL) as a more flexible and degradable material on the other hand. Porous 3D carbon nano fiber scaffolds were generated by electrospinning of polyacrylonitrile and strewing of NaCl particles during the spinning process and a final carbonization. The process of using NaCl as porogens for extended mesh structures was assigned to the generation of 3D PCL nano fiber scaffolds. Cell compatibility and migration into the scaffolds was evaluated with several cell types. Additionally, the compatibility of the 3D carbon nano fiber scaffold was tested in vivo. Results and Discussion SEM analysis of the porous scaffolds revealed an extended fiber network with increased mesh-openings up to 75 mm². The variation of NaCl particle sizes as well as the usage of sacrificial fibers allowed the adjustment of the fiber structure, concerning mesh opening sizes and size distribution, pore sizes, fiber orientation and scaffold thickness. In vitro tests with hdF and SMCs demonstrated the migration of the cells into the scaffolds and proved therefore the realization of a 3D scaffold on the cellular level. Additionally, the integration of the scaffolds into tissues in vitro and in vivo described the advantages of porous fibrous 3D scaffolds.