Enhancement of adhesion strength and cellular stiffness of osteoblasts on mirror-polished titanium surface by UV-photofunctionalization.
Ultraviolet (UV)-photofunctionalization of titanium substantially enhances the strength and quality of osseointegration by promoting osteogenic cellular attachment and proliferation. However, the mechanism underlying the initial interaction between the cells and the surface of the material remains to be elucidated, especially where the influence of surface roughness is excluded as a factor. The effect of UV-photofunctionalization on the adhesive strength and cellular stiffness of a single osteoblast and its association with the extent of cell spread, cytoskeletal development and focal adhesion assembly on a very smooth titanium surface was evaluated. Rat bone marrow-derived osteoblasts were cultured on UV-treated or untreated mirror-polished titanium disks. The mean critical shear force required to initiate detachment of a single osteoblast (n=10) was >2000nN on a UV-treated surface at 3h incubation, which was 17 times greater than that on an untreated surface. The mean total energy required to complete the detachment of osteoblasts (n=10) was consistently >60pJ on a UV-treated titanium surface after 24h culture, which was up to 42 times greater than that on an untreated surface. Cellular shear modulus, which represents cellular stiffness, was consistently greater on a UV-treated surface than on an untreated surface after 24h incubation (n=10). This strengthening of cell adhesion and cellular mechanical properties on UV-treated titanium was accompanied by enhanced cell spread and actin fiber development and increased levels of vinculin expression. These results indicate that UV-photofunctionalization substantially strengthens osteoblast retention on titanium bulk material with no topographical features, and that this is associated with enhancement of intracellular structural development during the cell adhesion process.
Yamada
M
M
Laboratory for Bone and Implant Sciences (LBIS), The Jane and Jerry Weintraub Center for Reconstructive Biotechnology, Division of Advanced Prosthodontics, Biomaterials and Hospital Dentistry, UCLA School of Dentistry, Los Angeles, CA 90095-1668, USA. masayamada@tdc.ac.jp
Miyauchi
T
T
Yamamoto
A
A
Iwasa
F
F
Takeuchi
M
M
Anpo
M
M
Sakurai
K
K
Baba
K
K
Ogawa
T
T
D000199:Actins / Q000378:metabolism; D000818:Animals; D001672:Biocompatible Materials / Q000494:pharmacology; D002448:Cell Adhesion / Q000187:drug effects; D002452:Cell Count; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D055119:Elastic Modulus / Q000187:drug effects; D022001:Focal Adhesions / Q000187:drug effects; D008297:Male; D008422:Materials Testing; D010006:Osteoblasts / Q000166:cytology* / Q000187:drug effects* / Q000378:metabolism / Q000528:radiation effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D013499:Surface Properties / Q000187:drug effects / Q000528:radiation effects; D014025:Titanium / Q000737:chemistry* / Q000494:pharmacology*; D014466:Ultraviolet Rays; D016596:Vinculin / Q000378:metabolism
D000199:Actins; D001672:Biocompatible Materials; D016596:Vinculin; D014025:Titanium