Influence of Topological Cues on Fibronectin Adsorption and Contact Guidance of Fibroblasts on Microgrooved Titanium

Abstract

The choice of suitable nano- and microstructures of biomaterials is crucial for successful implant integration within the human body. In particular, surface characteristics affect the adsorption of various extra cellular matrix proteins. This work illustrates the interaction of protein adsorption and early cell adhesion on bulk microstructured titanium surfaces with parallel grooves of 27 to 35 μm widths and 15 to 19 μm depths, respectively. In contact with low concentrated fibronectin solutions, distinct adsorption patterns are observed on the edges of the ridges. Moreover, NIH/3T3 fibroblasts cultured in serum-free medium for 1 h, 3 h, and 1 day show enhanced early cell adhesion on fibronectin coated samples compared to uncoated ones. In fact, early adhesion and cell contacts occur mainly on the groove edges where fibronectin adsorption was preferentially detected. Such adsorption patterns support cellular contact guidance on short time scales since the adsorbed fibronectin proteins acted as a chemical boundary superimposing the topographical cues of the grooved microstructure. In fibronectin-free conditions, this chemical boundary is absent after cell seeding and initial cell-surface interaction. Here, cellular fibronectin released by the fibroblasts adsorbs along the grooves after 3 h and contact guidance occurs delayed. After 1 day, cell adhesion and cell morphology on uncoated and fibronectin coated titanium microgrooves were nearly equilibrated. Thus, surface structures can promote directed adsorption of low concentrated fibronectin, which, furthermore, facilitates early cell adhesion. These results give rise to new developments in surface engineering of biomedical implants for improved osseointegration.