Evaluation of Cell Migration Through Electrospun PCL Fiber Mats With Controlled Thickness

Electrospun fiber mats are widely studied as scaffolds, yet cell migration in the thickness (z) direction remains poorly understood. In this study, poly(ε-caprolactone) (PCL) mats with reproducibly controlled thicknesses were prepared by conventional electrospinning, using optical transmittance monitoring only to determine the collection endpoint based on a previously established calibration. NIH3T3 fibroblasts and human umbilical vein endothelial cells (HUVECs) were seeded to evaluate vertical migration through the mats. Cell penetration from the top to the bottom surface was quantified using confocal microscopy and MTT assays. Scanning electron microscopy (SEM) images were additionally used to confirm fibrous morphology and to measure fiber diameter. Mat thickness had a marked effect on migration: in 40-μm mats, cells localized mainly at the top and bottom surfaces, whereas in 80-μm mats, cells were also distributed within the interior. Although differences in proliferation were observed between cell types and mat structures, both NIH3T3 cells and HUVECs showed lower apparent top-to-bottom transition rates in thicker mats. A mathematical model was applied to describe migration and proliferation dynamics, enabling quantitative comparison across conditions. These findings demonstrate that scaffold thickness strongly influences vertical cell migration and internal cell retention in electrospun fiber mats, providing useful design insights for biomaterial scaffolds in tissue engineering.