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

Abstract

Abstract:To determine the role of physicochemical characteristics of the surface of dense ceramics on osteoconduction, we studied the proliferation and differentiation of human trabecular (HT) osteoblastic cells, extracellular collagenous matrix production, and biologic apatite formation on stoichiometric hydroxyapatite (HA) and type A carbonate apatite (CA). The surface physicochemical 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 both HA and CA substrates, HT cells attached, proliferated, and differentiated. Cell proliferation did not differ on HA and CA. However, the initial cell attachment and spreading of HT cells were much lower on CA compared to HA. Physicochemical and biologic analyses showed that collagenous synthesis by HT cells after 6 weeks of culture also was lower on CA than on HA. Quantitative histologic analysis confirmed that the collagenous matrix production was lower on CA than on HA. Measurement of wettability showed that the polar interaction energy with water was significantly lower on CA than on HA. The lower cell attachment and collagen production on CA compared to HA clearly 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 the 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, osteoconduction.

Growth substrate induced functional changes elucidated by FTIR and Raman spectroscopy in in–vitro cultured human keratinocytes

“…Recently it has been demonstrated in the literature that these effects can be expressed in the cell at the level of genomic regulation, thus contributing to very fundamental changes in cellular physiology, ultimately resulting in unknown adjustments to cellular proliferation, motility and, in some cases, phenotype [17][18][19][20][21][22][23]. In this work we have demonstrated that measurements of cellular proliferation and viability on coated spectroscopic substrates can be correlated with spectral changes induced by adjustments to cell physiology when cultured on the different coatings.…”

“…This ultimately results in increasing proliferation and motility, which is also dependent on the charge distribution presented by the ECM coating molecule to the adhering cell [18][19][20][21][22][23]25]. Ultimately the reaction of the cell to such influences are complex, being the cumulative effect of the increased or decreased regulation of a number of stimulatory pathways in the cell, with the end physiological change in any given cell being dependent on the cell and substrate ECM [50,51].…”

“…It has been demonstrated that surfaces and scaffolds for cell culture can induce changes in cellular adhesion and motility [17,18], in their proliferation and differentiation [16,19], and in gene expression [20], ultimately influencing the fate of the cell [21]. Much of the interaction of adherent cells with their culture substrates is dependent on the surface chemistry [18,22] and surface energy [23]. When substrates are coated with biocompatible molecules to effect or enhance cellular proliferation, the conformation of the molecule has also been shown to produce changes in the level of response [19].…”

Improved Wettability Increases Osteoblastic Adhesion on Hydroxyapatite

“…Thus, the improved wettability of the HA surfaces resulted from other factors. The modification of surface wettability on HA was reportedly achieved by A-type carbonate apatite, corresponding to the location of carbonate ions on monovalent anionic OH -sites 3 and by fluoridated HA, incorporating fluorine in HA 4 . However, the improvement of HA surface wettability by polarization did not affect structural transformation.…”

“…The former subject, surface characteristics, including the topography, constituent elements, functional group, and wettability of biomaterials affect osteoblast attachment and adhesion 2 . The surface characteristics were reportedly affected by surface roughness, surface crystallinity 2 , the constituent elements at the surface, and the incorporation of ions such as carbonate or fluorine 3,4 . In addition, electron-induced surface energy modifications such as photoluminescence and surface photovoltage spectroscopy were also effective in the improvement of the surface characteristics 5 .…”