Novel three Dimensional Biodegradable Scaffolds for Bone Tissue Engineering

We have constructed osteogenic scaffolds using solid freeform fabrication techniques. Blends of biodegradable polymers, polycaprolactone and poly(D,L-lactic-co-glycolic acid), have been examined as scaffolds for applications in bone tissue engineering. Hydroxyapatite granules were incorporated into the blends and porous discs were prepared. Mechanical properties and degradation rates of the composites were determined. The discs were seeded with rabbit bone marrow or cultured bone marrow stromal cells and in vitro studies were conducted. Electron microscopy and histological analysis revealed an osteogenic composite that supports bone cell growth not only on the surface but throughout the 1 mm thick scaffold as well. Seeded and unseeded discs were mechanically assembled in layers and implanted in a rabbit rectus abdominis muscle. Bone growth was evident after eight weeks in vivo. Electron microscopy and histological analyses indicate vascularization and primitive bone formation throughout the seeded composite, and also a “fusion” of the layers to form a single, solid construct. Finally, we have begun to incorporate the growth factor IGF-I into the scaffold to enhance osteogenicity and/or as an alternative to cell seeding.