EFFECT OF POLYLACTIC ACID ON OSTEOINDUCTION OF DEMINERALIZED BONE - PRELIMINARY-STUDY OF THE USEFULNESS OF POLYLACTIC ACID AS A CARRIER OF BONE MORPHOGENETIC PROTEIN

To evaluate the usefulness of polylactic acid (PLA), a bioabsorbable a nd plastic polymer, as a carrier of bone morphogenetic protein (BMP), a preliminary study has been carried out to investigate any negative e ffect of PLA on osteoinduction of demineralized bone (DB). PLA (10,600 mol. wt) was mixed with DB particles (1-1.5 mm square) prepared from rat femurs and laid subcutaneously on the intercostal muscle of 4-week -old Wistar rats. The PLA/DB pellets were harvested at 2, 4, 8 and 24 weeks after the operation, and prepared for light microscopic examinat ion. Histological examination revealed cartilage formation at 2 weeks and new bone formation at 4 weeks. Extensive bone and marrow formation were observed at 24 weeks. PLA was gradually absorbed and completely disappeared at 24 weeks to be replaced by connective tissue. These res ults demonstrate that PLA does not have a negative influence on the os teoinductive activity and that PLA could well be a promising bioabsorb able carrier of BMP.