one of the important properties of nanofibers is the high surface area to volume ratio, which has positive effect on cell attachment and cell growth.

Nanofibers increase area to cell adhesion; besides, they modify chemical, mechanical properties and geometric features like roughness. For example, in bone tissue engineering, roughness must be of the same order of size of osteoblasts to impact attachment and growing velocity ( you can see the paper: The mechanical properties and osteoconductivity of hydroxyapatite bone scaffolds with multi-scale porosity). You can use this fact to regulate cell growth.