Cell orientation and regulation of cell-cell communication in human mesenchymal stem cells on different patterns of electrospun fibers.

Cell behavior can be manipulated by the topography of the culture surface. In this study, we examined the intercellular communication and osteogenic differentiation of mesenchymal stem cells (MSCs) grown on electrospun fibers with different orientations and densities. Human bone marrow-derived MSCs (hMSCs) were seeded on poly(ε-caprolactone) (PCL) electrospun scaffolds composed of aligned (1D) or cross-aligned (2D) fibers (1.0-1.2 µm diameter) with high, medium, or low fiber densities. It was found that cells preferred to adhere onto electrospun PCL fibers rather than on the flat substrate. The immunofluorescence staining showed that the expression of vinculin, a focal adhesion protein, was limited to the periphery and the two extremities of aligned cells on the edge of the fibers. Electron microscopy showed that cells extended their lamellipodia across the adjacent fibers and proliferated along the direction of fibers. Cells grown on 1D fibrous scaffolds at all fiber densities had an obvious alignment. On 2D fibers, a higher degree of cell alignment was observed at the higher fiber density. On 1D scaffolds, the gap junction intercellular communication (GJIC) quantified by the lucifer yellow dye transfer assay was significantly promoted in the aligned cells in the direction parallel to the fibers but was abolished in the direction perpendicular to the fibers. The expression of osteogenic marker genes (RUNX2, ALP, and OCN) was significantly enhanced in seven days by culture on 1D but not 2D fibers. It was thus proposed that the promoted osteogenic differentiation of hMSCs may be associated with the fiber-guided and directional induction of GJIC.