Functionalization of multilayered DNA-coatings with bone morphogenetic protein 2

The focus of the present study was to functionalize multilayered DNA-coatings with the osteoinductive factor bone morphogenetic protein 2 (BMP-2) using different loading modalities. The multilayered DNA-coatings were built up from either poly-d-lysine (PDL) or poly(allylamine hydrochloride) (PAH) and DNA using electrostatic self-assembly (ESA). The amounts of BMP-2 loaded into the multilayered DNA-coatings and its subsequent release characteristics were determined using radiolabeled BMP-2. Additionally, the effect of BMP-2 functionalized multilayered DNA-coatings on the in vitro behavior of bone marrow-derived osteoblast-like cells was evaluated in terms of proliferation, differentiation, mineralization, and cell morphology. The results demonstrate the feasibility of multilayered DNA-coatings to be functionalized by embedding BMP-2 according to three different loading modalities: superficial (s), deep (d), and double-layer (dl). BMP-2 was incorporated proportionally into the multilayered DNA-coatings as: s+(4*d)=dl. All differently loaded multilayered DNA-coatings showed an initial burst release followed by an incremental sustained release of the remaining BMP-2. In vitro experiments demonstrated that the loaded factor remained biologically active, as an accelerated calcium deposition was observed on s- and dl-loaded multilayered DNA-coatings, without affecting cell proliferation. In contrast, d-loaded multilayered DNA-coatings influenced osteoblast-like cell behavior by decreasing the deposition of calcium.