Synergistic effect of surface modification and scaffold design of bioplotted 3-D poly-ε-caprolactone scaffolds in osteogenic tissue engineering

The hydrophobic nature and the regular scaffold architecture of bioplotted poly(ε-caprolactone) (PCL) scaffolds present some hurdles for homogeneous tissue formation and differentiation. The current hypothesis is that a synergistic effect of applied surface modification and scaffold design enhances colonization and osteogenic differentiation. First, PCL scaffolds with a 0/90° lay-down pattern (0/90) were plotted and subjected to an oxygen plasma (O2) or multistep surface modification, including post-argon 2-amino-ethylmethacrylate grafting (AEMA), followed by immobilization of gelatin type B (gelB) and physisorption of fibronectin (gelB Fn). Secondly, scaffolds of different designs were plotted (0/90° shift (0/90 S), 0/45° and 0/90° with narrow pores (0/90 NP)) and subjected to the double protein coating. Preosteoblasts were cultured on the scaffolds and the seeding efficiency, colonization and differentiation were studied. The data revealed that a biomimetic surface modification improved colonization (gelB Fn > gelB > AEMA > O2). Compact scaffold architectures (0/90 NP, 0/45, 0/90 S > 0/90) positively influenced the seeding efficiency and differentiation. Interestingly, the applied surface modification had a greater impact on colonization than the scaffold design. In conclusion, the combination of a double protein coating with a compact design enhances tissue formation in the plotted PCL scaffolds.