Structural assessment of a tissue engineered scaffold for bone repair

The limitations of current grafting materials have driven the search for synthetic alternatives to cancellous bone. A variety of biodegradable polymer foams composed of poly(lactide-co-glycolide) [PLAGA] have been evaluated for such uses. However, structural limitations may restrict the clinical use of these scaffolds. We have developed a sintered microsphere scaffold composed of 85:15 poly(lactide-co-glycolide) with a biomimetic pore system equivalent to the structure of cancellous bone. Analysis of the structural data, indicated that the microsphere matrix sintered at a temperature of 160°C with a microsphere diameter of 355-425 μm resulted in a optimal, biomimetic structure with an approximate pore diameter of 75 to 275 μm, 35% porosity, and a compressive modulus of 272 MPa. The in vitro evaluation of human osteoblasts on the sintered matrix indicated that the structure was capable of supporting the attachment and proliferation of the cells throughout its pore system. Immunofluorescent staining of actin showed that the cells were proliferating 3-dimensionally through the pore system. The stain for osteocalcin showed that the cells had maintained the phenotypic expression for this bone specific protein. Through this work, it was shown that an osteoconductive PLAGA scaffold with a pore system equivalent to the structure of cancellous bone could be fabricated through the sintered microsphere method.