In vitro growth of human adult bone-derived cells on hydroxyapatite plasma-sprayed coatings.

The growth of adult human bone-derived cells on hydroxyapatite (HA) plasma-sprayed coatings was investigated. Such cells were difficult to grow on original plasma-sprayed coatings, even following rinsing and rubbing down. We obtained cell growth only on samples previously immersed 15 or 22 days in complete culture medium. We describe a dissolution/precipitation phenomenon on the HA coating surface assessed by modifications of Ca and P concentrations in the culture medium, by the transformation of the HA coating into carbonated HA (X-ray diffraction and infrared spectrometry and by the presence demonstrated by scanning electron microscopy of spherocrystallites on the HA after 15 days of immersion. Our results show that adult human bone-derived cells are apparently particularly sensitive to the changes in the coating surface induced by liquid immersion. We raise the question of the limits of in vitro investigations on bioactive ceramics such as HA plasma-sprayed coatings susceptible to modification by simple immersion in aqueous solutions such as cell culture medium or physiologic saline.