Kinetics of bone cell organization and mineralization on materials with patterned surface chemistry

Materials with spatially resolved chemistries (i.e. patterned surfaces) have been used to guide and organize the position of mammalian cells in vitro. A common theme in guiding the spatial distribution of cells has been the use of patterned alkylsiloxanes, where one region contains an aminosilane and the other an alkylsilane. The regions of the aminosilane served as preferential sites for cell attachment and spreading, presumably dependent on the association between cell surface proteoglycans the positively charged amine. In this study, experiments were conducted with patterns of N-(2-aminoethyl)-3-aminopropyl-trimethoxysilane (EDS) and dimethyldichlorosilane (DMS) to determine the kinetics of spatial organization of bone-derived cells, and whether initial attachment and spreading affected the rate of matrix mineralization (i.e. bone formation) in extended cultures. The bone cells required the presence of serum or preadsorption of serum proteins to the patterned EDS/DMS surface to organize according to the lithographically defined surface chemistry. Time-lapse video microscopy indicated that cells were randomly distributed over the EDS/DMS surface at the time of plating, but organized on the EDS regions within 30 min. When cultures were extended for 15 and 25 days, the matrix synthesized by the cells was preferentially mineralized on the EDS chemistry. These results demonstrate the ability of surface chemistry modifications to organize cells and form mineralized tissue in vitro. The methods employed should have general value to the engineering of tissues in vitro.