Biological Efficacy of Modified Structure of Polymer Surfaces for Bone Substitute

Hydroxyapatite (HA) coatings were introduced onto Poly L-lactic Acid (PLLA) polymer in a controlled manner by immobilized urease method with a shortened precipitation time. Osteoblastic-like cellular responses to the composite were examined in terms of cell proliferation, differentiation and cell morphology, as well as the expression of bone-associated genes. The cells exhibited higher cellular proliferation at 2 and 4 days on the HA/PLLA composite compared to PLLA scaffold, while no significant difference was observed later at 6 days. The alkaline phosphatase (ALP) activity by cells at 7 days was statistically higher on HA/PLLA scaffold than on PLLA. Moreover, the gene expression of ALP and osteocalcin (OC) was up regulated on HA/PLLA composite by RT-PCR analysis. The preliminary study suggested that the use of the controlled modification of hydroxyapatite coating on PLLA scaffold to produce HA/PLLA composite might enhance cellular activity, indicating the potential use for bone substitute in tissue engineering.