Selective laser sintered Ca-P/PHBV nanocomposite scaffolds with sustained release of rhBMP-2 for bone tissue engineering

Ca-P/PHBV nanocomposite scaffolds for bone tissue engineering were fabricated via selective laser sintering. The surface modification of Ca-P/PHBV scaffolds was conducted firstly by physical entrapment of gelatin. Heparin was then immobilized on gelatin-modified scaffolds through covalent conjugation. Human umbilical cord derived mesenchymal stem cells (hUC-MSCs) were seeded onto the scaffolds. Compared to non-modified scaffolds, heparin-immobilized scaffolds exhibited higher cell proliferation at the early stage of cell culture. hUC-MSCs became confluent after 21 day culture on scaffolds and covered the whole scaffold surface, strongly adhering to the scaffolds. Recombinant human bone morphogenetic protein (rhBMP)-2 was loaded onto scaffolds with or without surface modification and its in vitro release behavior was studied. An initial burst release of rhBMP-2 was observed for both types of scaffolds. However, the immobilization of heparin on the surface of Ca-P/PHBV scaffolds not only provided a means to protect the rhBMP-2 but also improved its sustained release. Surface modified scaffolds loaded with rhBMP-2 promoted significantly higher ALP activity of hUC-MSCs than the scaffolds with simple adsorption of rhBMP-2. The strategy of combining advanced scaffold fabrication technology, nanocomposite and growth factor delivery is promising for bone tissue regeneration.