Bio-Testing of Poly-L-Lactic Acid/Hydroxyapatite Porous Bone Scaffolds

Tissue engineering is a rapidly growing interdisciplinary field which offers a promising new technology to create artificial constructs for regeneration of tissues. One important aspect of bone tissue engineering is to build scaffolds with interconnected 3-D porous structure in order to mimic natural bone architecture. In this work, co-continuous micro-porous scaffolds made of Poly-L-lactic acid (PLLA) with 50% porosity and PLLA/hydroxyapatite (HA) with 40% porosity were prepared by injection molding of an immiscible polymer blend with polystyrene as sacrificial material. The sacrificial material was then removed by solvent leaching with cyclohexane. The porous PLLA/HA matrix supported murine osteoblast (7F2) cell growth for up to 9 days, suggesting that that the introduction and replacement of sacrificial material had no negative effects on cell proliferation. In vitro studies also indicate an increase in mineralization by osteoblasts cultured on the porous structure, as compared to cells cultured on solid scaffold. One month subcutaneous degradation tests showed a mild foreign body reaction and complete fibrous encapsulation. Following surgical implantation of the scaffolds into circular defects in canine tibia, we observed after 12 weeks new bone tissue grew into the porous structures. Taken together our data suggest that interconnected porous structures with good cytocompatibility and increased mineralization in vitro paired with enhanced osteoinductive properties in vivo suggest a great potential of the porous PLLA/HA for inducing and sustaining bone tissue repair.Copyright © 2011 by ASME