Lipid Analysis of MG63 Cells Grown on Different Titanium Surfaces

Objectives: The composition and its change in cellular lipid have been suggested as potential regulators of the protein activity or signal transfer, with the resultant regulation of gene expression and cell functions including cell proliferation, differentiation and morphology. Surface properties of titanium (Ti) implants have been shown to have effects on cell behaviors in vitro. Therefore, the study of total cellular lipids and its change in the osteoblast cells will give valuable initiating information for the understanding of Ti surface signaling and surface-dependent biological response.

Methods: Experimental Ti groups were machined (group M), and then sandblasted with aluminum oxide particles of different sizes (group S1~S3) for different roughness. The surface characteristics of specimens were inspected. We analyzed total lipids and its side chain in MG63 human osteoblast-like cells grown on prepared surfaces using high performance liquid chromatography and gas liquid chromatography.

Results: The prepared Ti specimens with sandblasting demonstrate well-controlled surface roughness feature. Major changes observed were a sevenfold elevation of phosphatidic acid (PA), a threefold increase of alkyldiacylglycerol (ADG) and decrease of phosphatidylcholine (PC) on rough Ti surfaces. Acyl side chain analysis revealed a substantial elevation of arachidonate composition in major phospholipids and an unusually high content of polyunsaturated fatty acids (67 %, mol/mol) in ADG as surface roughness increase. By comparing the acyl chains of the PA with those of other phospholipids, PA appeared to originate from PC through phospholipse D (PLD) action.

Conclusion: This study demonstrates for the first time that Ti surface roughness alters compositions of MG63 total cellular lipid and its side chain. A change of composition and fatty acid in the cell membrane with subsequent modifications in fluidity and permeability has been proposed. The changes of cell permeability affect to the lipid metabolism back again and exert significant influences on the cellular behavior.