Osteogenic Differentiation of Bone Marrow-DerivedMesenchymal Stem Cells in Electrospun Silica Nonwoven Fabrics

摘要

Silica nonwoven fabrics (SNFs) with enough mechanical strength are candidates as implantable scaffolds. Culture of cells therein is expected to affect the proliferation and differentiation of the cells through cell–cell and cell–SNF interactions. In this study, we examined three-dimensional (3D) SNFs as a scaffold of mesenchymal stem cells (MSCs) for bone tissue engineering applications. The interconnected highly porous microstructure of 3D SNFs is expected to allow omnidirectional cell–cell interactions, and the morphological similarity of a silica nanofiber to that of a fibrous extracellular matrix can contribute to the promotion of cell functions. 3D SNFs were prepared by the sol–gel process, and their mechanical properties were characterized by the compression test and rheological analysis. In the compression test, SNFs showed a compressive elastic modulus of over 1 MPa and a compressive strength of about 200 kPa. These values are higher than those of porous polystyrene disks used for in vitro 3D cell culture. In rheological analysis, the elasticmodulus and fracture stress were 3.27 ± 0.54 kPa and 25.9 ±8.3 Pa, respectively. Then, human bone marrow-derived MSCs were culturedon SNFs, and the effects on proliferation and osteogenic differentiationwere evaluated. The MSCs seeded on SNF proliferated, and the thicknessof the cell layer became over 80 μm after 14 days of culture.The osteogenic differentiation of MSCs on SNFs was induced by theculture in the commercial osteogenic differentiation medium. The alkalinephosphatase activity of MSCs on SNFs increased rapidly and remainedhigh up to 14 days and was much higher than that on two-dimensionaltissue culture-treated polystyrene. The high expression of RUNX2 and intense staining by alizarin red s after differentiationsupported that SNFs enhanced the osteogenic differentiation of MSCs.Furthermore, permeation analysis of SNFs using fluorescein isothiocyanate-dextransuggested a sufficient permeability of SNFs for oxygen, minerals,nutrients, and secretions, which is important for maintaining thecell viability and vitality. These results suggested that SNFs arepromising scaffolds for the regeneration of bone defects using MSCs,originated from highly porous and elastic SNF characters.