TISSUE ENGINEERED BONE-REGENERATION USING DEGRADABLE POLYMERS - THE FORMATION OF MINERALIZED MATRICES

In the development of 3-dimensional cell-polymer matrices for tissue e ngineering, the ability of osteoblast cells to maintain their phenotyp ic properties and form. a mineralized matrix while seeded on the polym er surface is very important. Osteoblast cell differentiation and bone formation using rat calvaria cells were studied on the surface of a p orous poly(lactide/glycolide)/hydroxyapatite (PLAGA/HA) 3-dimensional polymer matrix. Cell adhesion and proliferation were determined at 24 hr, 3, 7, 14, and 21 days. Cell attachment and proliferation were obse rved to increase throughout the first two weeks of the study, followed by a period of gradual plateauing of cell numbers. Environmental scan ning electron microscopy demonstrated that cells grown on the surface of the 3-dimensional porous PLAGA/HA matrix retained their characteris tic morphology and grew in a multi-layer fashion. Light microscopy obs ervations of experiment cultures revealed active osteoblastic cells fo rming a characteristic mineralized matrix in the presence of 13-glycer ophosphate as a phosphate donor. Mineralization did not occurred in me dia either not supplemented with 13-glycerophosphate or when the matri x without cells was incubated with the reagents, indicating that the m ineralization was due to the cells and not the HA in the matrix. These results suggest that the 3-dimensional PLAGA/HA matrix could provide a matrix for bone cell differentiation and mineralization in vitro and , therefore, may be a candidate as a synthetic implant for bone regene ration.