Effect of functionalized polycaprolactone on the behaviour of murine preosteoblasts

The efficiency of biomaterials used in bone repair depends greatly on their ability to interact with bone cells. Hence, we have functionalized polycaprolactone (PCL) films by peptides derived from the bone sialoprotein containing RGD sequence (pRGD), to increase their ability to interact with murine MC3T3-E1 preosteoblasts, and favour cell response to recombinant human bone morphogenetic protein-2 (rhBMP-2). RGE peptides (pRGE) were used as negative controls. The PCL films were hydrolyzed with NaOH and then carboxylic acid groups were activated to allow chemisorption of the peptides. Alkaline treatment increased the hydrophilicity of PCL films without significantly change their roughness. Peptide immobilization on PCL was checked by X-ray photoelectron spectroscopy. Hydrolyzed PCL films (Hydro PCL), which adsorbed fibronectin and vitronectin from serum after 1 h incubation, prevented the spreading of MC3T3-E1 preosteoblasts, while films bearing pRGD or pRGE did not. In contrast, MC3T3-E1 preosteoblasts attached to pRGD and incubated for 1 h in serum-free medium spread better than cells on Hydro PCL or pRGE. Only cells on pRGD had organized cytoskeleton, phosphorylated focal adhesion kinase on Y(397) and responded to rhBMP-2 by activating Smad pathway. Thus, pRGD PCL may be used to favour bone cell cytoskeletal organization and response to rhBMP-2.