Behavior of human osteoblastic cells on stoichiometric hydroxyapatite and type A carbonate apatite: Role of surface energy

To determine the role of physicochemical characteristics of the surface of dense ceramics on osteoconduction, we studied the proliferation and differe ntiation of human trabecular (HT) osteoblastic cells, extracellular collage nous matrix production, and biologic apatite formation on stoichiometric hy droxyapatite (HA) and type A carbonate apatite (CA). The surface physicoche mical characteristics (composition, roughness) of HA and CA carefully were determined by Fourier-transformed infrared, X-ray photoelectron, and Raman spectroscopies, and by FTIR microscopy, before and after cell culture. On b oth HA and CA substrates, HT cells attached, proliferated, and differentiat ed. Cell proliferation did not differ on HA and CA. However, the initial ce ll attachment and spreading of HT cells were much lower on CA compared to H A. Physicochemical and biologic analyses showed that collagenous synthesis by HT cells after 6 weeks of culture also was lower on CA than on HA. Quant itative histologic analysis confirmed that the collagenous matrix productio n was lower on CA than on HA. Measurement of wettability showed that the po lar interaction energy with water was significantly lower on CA than on HA. The lower cell attachment and collagen production on CA compared to HA cle arly were related to the low affinity of HT cells for the CA surface. This study shows that the surface energy of the biomaterial greatly influences t he initial cell attachment and spreading of human osteoblastic cells at the surface and affects collagenous matrix deposition on the biomaterial. This suggests that the enhancement of polar components of the surface of dense biomaterials may improve osteoblastic cell attachment and, thereby, osteoco nduction. (C) 2000 John Wiley & Sons, Inc.