Comparison of osteogenesis in poly(L-lactic acid)-coated and non-coated porous hydroxyapatite scaffolds

To improve the biocompatibility and mechanical strength of porous hydroxyapatite (HA) scaffolds that have high osteoconduction, we coated them with 1, 5, or 10 wt% poly(L-lactic acid) (PLLA). In the 5 and 10 wt% PLLA-coated groups, osteoblast proliferation rates were higher than those in non-coated and 1 wt% PLLA-coated groups. The alkaline phosphatase (ALP) activity was highest in the 5 wt% PLLA-coated group. In addition, the porosity was highest in the non-coated HA group (82 %), whereas it was 72, and 41 % in the 5, and 10 wt% PLLA-coated groups, respectively. Scaffold strength increased in proportion to the concentration of PLLA coating. Overall, the 5 wt% PLLA scaffold had best characteristics when considering osteoblast proliferation, ALP activity, porosity, and compressive strength. We next tested this scaffold in an in vivo alveolar defect rabbit model. Multi-detector row computed tomography showed that non-coated and 5 wt% PLLA-coated HA groups had a similar high density. Adequate osteogenesis was observed by histological analysis in the non-coated HA and 5 wt% PLLA-coated HA groups. In addition, sufficient mineralization was observed in the coated scaffolds by X-ray fluorescence spectroscopy without significant adverse effects. Therefore, based on our findings, a PLLA-coated porous HA scaffold may be a suitable bone substitute for the correction of bone defects.