Abstract
Abstract: :
Purpose: To investigate the strength of adhesion of cells to nano-structured surfaces as a function of incubation time, pattern size and shear stress by using a fluid mechanical force. Methods: SV-40 HCEC were seeded on smooth and textured silicon surfaces. The textured surfaces contained areas patterned with grooves ranging from widths of 200 nm - 4 microns, with a periodicity of twice the groove width and a depth of 350 nm. The cells were then incubated for various time periods (5 to 24 hours). After incubation the substrates were mounted in a parallel plate flow chamber and observed using an inverted microscope. The flow in the chamber was increased (corresponding with a shear force of 0 to 148 Pa) in 5-minute time steps to allow for equilibrium conditions and then images were taken prior to each time step increase. Results: Longer incubation times corresponded with stronger cell attachment. The shear stress needed for 70% cell detachment on the 400 nm grooves after 5 hours incubation was 22.7 Pa and after 24 hours incubation was 47.4 Pa. 24% of the cells on the 400nm grooves aligned their long axes parallel with the grooves (major axis made an angle of 100 or less with the grooves). Structured surfaces were found to have stronger cell attachment than planar surfaces. A shear force of 18 Pa corresponded to 70% cell detachment on the planar surface and 46% cell detachment on the 400 nm grooved surface after 5 hours incubation. Moreover, cell detachment was abrupt for the structured surfaces near the critical shear stress as compared to a more gradual change for the planar surfaces. Interestingly, cells detached at identical flow rates whether the grooves were parallel or perpendicular to the flow despite distinct differences in the morphology of the cells as they detached. Conclusions: Nano-structured substrates improve the ability of cells to withstand hydrodynamic forces similar to what may be encountered in vivo. This may provide a method to improve cell-material interactions for prosthetic devices.
Keywords: 372 cornea: epithelium • 631 wound healing • 403 extracellular matrix