The in vitro growth and activity of sheep osteoblasts on three-dimensional scaffolds from poly(L/DL-lactide) 80/20%

Critical-size bone defects usually require the use of autogenous bone grafts to heal. Harvesting of bone is traumatic, and results in high morbidity of donor site. A potential alternative to bone graft may be a bone substitute with adequate biocompatibility and biological properties produced from ceramics and/or bioresorbable or biodegradable polymers. In the present study, sheep osteoblasts isolated from cancellous bone chips were seeded and cultured for 1, 2, and 3 weeks on porous poly(L/DL-lactide) 80/20% scaffolds. The cell morphology was assessed from rhodamine staining and scanning electron microscopy, cell growth, and activity from the measurements of DNA, alkaline phosphatase activity, and total protein amount in the cell lysate, and mineral deposits from EDAX and van Kossa staining. The cells attached firmly to the scaffold walls, grew deeply into the pores, and exhibited morphology typical of osteoblasts. Mineralized noduli with a Ca/P ratio of 1.4 to 1.8 found in the scaffold indicated that the cells had maintained their osteoblastic phenotype. The amount of DNA, alkaline phosphatase activity, and the total amount of proteins increased with time of culturing, although at 3 weeks the cells did not yet reach the contact inhibition. These results demonstrate that three-dimensional porous poly(L/DL-lactide) 80/20% scaffolds provide a suitable substrate for the attachment and growth of primary osteoblasts, and might potentially be used as bone defect fillers and in the design of tissue-engineered bone substitutes.