Enhanced osteoblastic cell initial behavior on light-induced super-amphiphilic titanium surface

Initial behavior of osteoblastic cells on implant surfaces is crucial at the early stage of osseointegration. Accelerated cell proliferation and differentiation following increased cell attachment may lead to rapider establishment of osseointegration. We previously demonstrated that UV treatment of titanium, acquired with superhydrophilicity, resulted in increased osteoblastic proliferation and mineralization in vitro and rapider and more complete establishment of osseointegration in vivo. However, the initial behavior of osteoblasts on UV-treated titanium surfaces is not still clear. Objectives: The objective of this study was to examine the effects of light treatment on initial behaviors of osteoblastic cells. Methods: Rat bone marrow-derived osteoblastic cells were cultured on either machined or acid-etched titanium disks with or without UV light treatment. The cell attachment, and cytoskeleton-related gene expression and cytoskeleton structures were evaluated by hematocytometer at 1 and 3 hours, and RT-PCR and actin staining using phallotoxins at 3 hours post-seeding, respectively. Further, protein attractiveness and cell adhesion strength were also evaluated for the acid-etched surfaces by BCA protein assay at 2 and 24 hours and detachment assay at days 1 and 3 post-seeding, respectively. Results: The cell attachment was increased 100% on light-treated machined and acid-etched surfaces at 3 hours post-seeding compared to untreated surfaces (p<0.01). Expression of cytoskeleton-related genes; Cdc42, Rac1, RhoA, were similar or slightly upregulated on the light-treated surfaces, supporting microscopic observation of cell spreading. Albumin adsorption and cell adhesion strength to the light-treated acid-etched surface were greater than to the untreated one (approximately 2.6 and 2.2 times for protein assay, and 2.1 and 3.7 times for detachment assay, respectively, p<0.01). Conclusion: UV light treatment of titanium surfaces provokes an acceleration and enhancement of a series of initial cellular events on titanium surfaces, including cell attachment, spread, development of cytoskeleton and adhesion capacity, accompanied with the enhanced protein adsorption.