Understanding osteoblast responses to stiff nanotopographies through experiments and computational simulations

Abstract

An increasing number of studies have demonstrated the positive role nanotopographies can have toward promoting various cell functions. However, the relevant mechanism(s) behind this improvement in biological interactions at the cell-material interface is not well understood. For this reason, here, osteoblast (bone forming cell) functions (including adhesion, proliferation, and differentiation) on two carefully-fabricated diamond films with dramatically-different topographies were tested and modeled. The results over all the time periods tested revealed greater cell responses on nanocrystalline diamond (NCD, grain sizes <100 nm) compared to submicron crystalline diamond (SMCD, grain sizes 200-1000 nm). To understand this positive impact of cell responses per stiff nanotopographies, cell filopodia extension and cell spreading were studied through computational simulations and the results suggested that increasing the lateral dimensions or height of nanometer surface features could inhibit cell filopodia extension and, ultimately, decrease cell spreading. The computational simulation results were further verified by live cell imaging (LCI) experiments. This study, thus, describes a possible new approach to investigate (through experiments and computational simulation) the mechanisms behind nanotopography-enhanced cell functions.

Biomaterial nanotopography-mediated cell responses: experiment and modeling

“…In particular, it was found that rationally designed NCD topography and nanoscale roughness (RMS roughness typically <25 nm) could enhance both short-term (adhesion, proliferation) and long-term functions (differentiation and bone synthesis) of osteoblast compared to micron or submicron crystalline diamond (MCD) [51][52][53]. Figure 5 shows images of osteoblast adhered on NCD or MCD substrates, where significant difference in cell morphology can be seen.…”

“…For example, filopodia formation of human osteoblast on MCD and NCD substrates, with distinct topographies but similar surface chemistry and hydrophobicity (surface energy), has been examined [53]. Interestingly, filopodia of osteoblasts cultured on MCD films tend to converge to specific sites on the diamond surface, while radial and parallel filopodia are formed on the NCD substrate.…”

“…Experimental evidence has shown that the growth speed of filopodia can be significantly reduced by surface roughness [53]. However, up to date, very few theoretical attempts have been made to examine this issue.…”

Effective cell collection method using collagenase and ultrasonic vibration

“…The state of the filopodia may reflect the proliferative ability of cells. 25 The filopodia of cells collected by the collagenase-USV treatment were denser than those of cells collected by the trypsin-pipetting treatment.…”

Biofunctional Sr- and Si-loaded titania nanotube coating of Ti surfaces by anodization-hydrothermal process

“…1 However, this nanothick passive layer is not inert to corrosive attack when subjected to aggressive biological conditions (eg, pH variation, presence of fluorides, and surface wear). 2 The intrinsic bioinertness of Ti surfaces and its alloys usually results in poor osseointegration due to insufficient bone formation, which then increases the risk of instability after surgical procedures.…”