Introduction: The purpose of this study was to investigate the biological responses of human osteoblstes on plasma sprayed HA coating (HAC), and the effects of surface roughness. In addition, the biological responses of human osteoblstes on HACs that pre-treated in the similar body fluid (SBF) were also investigated.

Methods: In this study, the HACs with 50mm thickness were made by atmosphere plasma spray (APS). The human osteoblasts derived from loose bone during the hip surgery were cultured in D-MEM with 4% FBS on polished HA coating (HACp), plasma sprayed HA coating (HAC) and polystyrene (PS) (as control). Part 1: The three specimens mentioned before were dipped in the SBF three days for pre-treatment (named t-PS, t-HACp, t-HAC). The cell adhesion and growth of pre-treated specimens were compared with non-treated specimens at the early phase (3, 12, 24 hours). Part 2: The cell growths (1, 3, 5, 10, 15 days) were evaluated by counting the cell number on the surface of PS, HAC and HACp. The biological functions of human osteoblasts were evaluated by the alkaline phosphatase activity (3, 5, 10, 15 days) and TGF-b concentration (5–15 days).

Results: Part 1: At the early phase of cell culture (< 1day), osteoblasts on pre-treated specimens surface showed the better attachment and growth than those culture on non-treated specimens. This result was due to the protein in the SBF provided the nutrient to cell, therefore, shortened the time of cell attachment and promoted the cell growth. Part 2: The cell morphology under SEM showed that cells on smooth PS and HACp surfaces had the better attachment than those on rough HAC surface. On cell growth and cell number (1, 3, 5, 10, 15 days), the PS was the best and HACp was better than HAC. It is due to the easy attachment and better growth on smooth surface than rough one. On alkaline phosphatase activity (APA), HAC showed better APA than HACp, the PS was the worst. On TGF-b concentration, the TGF-b secreted from human osteoblasts on rough HAC had higher concentration than smooth HACp and PS. The results mentioned above showed that the rough surface material promote the biological activity of human osteoblasts in late phase (5–15 days).

Conclusion: 1. The HACs after pre-treatment in the SBF would promote the cell attachment on coating surface and speed the cell growth. 2. The results from this study showed that rough HAC expressed better biocompatibility than the smooth one and smooth HAC show early superiority of cell growth than rough one.