Short-term response of human osteoblast-like cells on titanium surfaces with micro- and nano-sized features

Since the way that human bone cells behave on contact with different surfaces topographies seems to be crucial to osseointegration, the aim of the present study is to evaluate the participation of some micro- and nanosized features of Ti surfaces in the short-term response of primary human osteoblast-like cells (HOC). Surfaces were prepared as ground (G-Ti), hydrofluoric acid etched (HF-Ti), and sandblasted/HF-etched (SLA-Ti), and analyzed using both three-dimensional (3D) profilometer and atomic force microscope (AFM). Cell morphology was assessed using scanning electron microscopy (SEM) after 4 and 24 h in culture. Cell viability, adhesion, and spreading were also evaluated 4 and 24 h after seeding over each surface. Data were compared by analysis of variance (ANOVA) complemented by Duncan test. Cell morphology, cell counting, and membrane integrity (Neutral Red, NR) were not affected by surface treatment at any time. However, HF-Ti presented the smallest surface area and did not increase tetrazolium hydroxide (XTT) reduction from 4 to 24 h. On the other hand, a higher level of spreading was only found on the rougher and isotropic SLA-Ti at 4 h. In conclusion, although all evaluated Ti surfaces allowed HOC short-term adhesion, the finer topography introduced by HF as single treatment did not favor HOC mitochondrial activity and spreading. The rougher and more complex SLA surface seems to provide a better substrate for HOC short-term response.