ABSTRACT
Knowledge about biocomplexity of cell behavior in dependence on topographical characteristics is of clinical relevance for the development of implant designs in tissue engineering. The aim of this study was to find out cell architecture-cell function dependencies of human MG-63 osteoblasts on titanium (Ti) arrays with regular geometry. We compared cubic pillar structures (SU-8, dimension 3 x 3 x 5 and 5 x 5 x 5 mum) with planar samples. Electrochemical surface characterization revealed a low amount of surface energy (including polar component) for the pillar-structured surfaces, which correlated with a reduced initial cell adhesion and spreading. Confocal microscopy of cell's actin cytoskeleton revealed no stress fiber organization instead, the actin was concentrated in a surface geometry-dependent manner as local spots around the pillar edges. This altered cell architecture resulted in an impaired MG-63 cell function - the extracellular matrix proteins collagen-I and bone sialo protein (BSP-2) were synthesized at a significantly lower level on SU-8 pillar structures; this was accompanied by reduced beta3-integrin expression. To find out physicochemical factors pertaining to geometrically microstructured surfaces and their influence on adjoining biosystems is important for the development of biorelevant implant surfaces.
Subject(s)
Biocompatible Materials/chemistry , Osteoblasts/cytology , Titanium/chemistry , Actins/metabolism , Cell Adhesion , Cell Line , Cytoskeleton/metabolism , Electrochemistry , Extracellular Matrix Proteins/metabolism , Humans , Osteoblasts/metabolism , Surface PropertiesABSTRACT
The crucial factor of metal implant ingrowth in the bone is the rapid cellular acceptance. Therefore, the knowledge about additionally used adhesion mechanisms of osteoblasts, like their negatively charged hyaluronan coat, generates new surface functionalization strategies. Here, titanium was coated with a very thin, adherent, cross-linked, pinhole- and additive-free allylamine plasma polymer layer (PPAAm) resistant to hydrolysis and delamination and equipped with a high density of positively charged amino groups. This plasma polymer-functionalization of titanium is advantageous concerning osteoblastic focal adhesion formation as vinculin and paxillin, actin cytoskeleton development and, in consequence in differentiated cell functions, compared to a pure titanium surface-but similar such as the collagen I bonded surface via a polyethylenglycol-diacid (PEG DA)-spacer.
