Bioactive glass coatings affect the behavior of osteoblast-like cells.

Functionally graded coatings (FGCs) of bioactive glass on titanium alloy (Ti6Al4V) were fabricated by the enameling technique. These innovative coatings may be an alternative to plasma-sprayed, hydroxyapatite-coated implants. Previously we determined that a preconditioning treatment in simulated body fluid (SBF) helped to stabilize FGCs [Foppiano S et al. Acta Biomater 2006;2(2):133-42]. The primary goal of this work was to assess the in vitro cytocompatibility of preconditioned FGCs with MC3T3-E1.4 mouse pre-osteoblastic cells. We evaluated cell adhesion, proliferation and mineralization on FGCs in comparison to uncoated Ti6Al4V and tissue culture polystyrene (TCPS). No difference in cell adhesion was identified, whereas proliferation was significantly different on all materials, being highest on FGCs followed by TCPS and Ti6Al4V. Qualitative and quantitative mineralization assays indicated that mineralization occurred on all materials. The amount of inorganic phosphate released by the mineralizing layers was significantly different, being highest on TCPS, followed by FGC and uncoated Ti6Al4V. The secondary objective of this work was to assess the ability of the FGCs to affect gene expression, indirectly, by means of their dissolution products, which was assessed by real-time reverse-transcription polymerase chain reaction. The FGC dissolution products induced a 2-fold increase in the expression of Runx-2, and a 20% decrease in the expression of collagen type 1 with respect to TCPS extract. These genes are regulators of osteoblast differentiation and mineralization, respectively. The findings of this study indicate that preconditioned FGCs are cytocompatible and suggest that future work may allow composition changes to induce preferred gene expression.

[1]  C. V. van Blitterswijk,et al.  Biomimetic calcium phosphate coatings on Ti6AI4V: a crystal growth study of octacalcium phosphate and inhibition by Mg2+ and HCO3-. , 1999, Bone.

[2]  T. Kokubo,et al.  REVIEW Bioactive metals: preparation and properties , 2004, Journal of materials science. Materials in medicine.

[3]  Silvia Panzavolta,et al.  Nanocrystalline hydroxyapatite coatings on titanium: a new fast biomimetic method. , 2005, Biomaterials.

[4]  R. Bloebaum,et al.  Osteolysis from a press-fit hydroxyapatite-coated implant. A case study. , 1993, The Journal of arthroplasty.

[5]  S. Radin,et al.  In vitro transformation of bioactive glass granules into Ca-P shells. , 2000, Journal of biomedical materials research.

[6]  P. Layrolle,et al.  Nucleation of biomimetic Ca-P coatings on ti6A14V from a SBF x 5 solution: influence of magnesium. , 2002, Biomaterials.

[7]  R. Lahti,et al.  A new and convenient colorimetric determination of inorganic orthophosphate and its application to the assay of inorganic pyrophosphatase. , 1981, Analytical biochemistry.

[8]  G. Karsenty.  The genetic transformation of bone biology. , 1999, Genes & development.

[9]  E. Saiz,et al.  Glass-based coatings for titanium implant alloys. , 1999, Journal of biomedical materials research.

[10]  J. Polak,et al.  Ionic products of bioactive glass dissolution increase proliferation of human osteoblasts and induce insulin-like growth factor II mRNA expression and protein synthesis. , 2000, Biochemical and biophysical research communications.

[11]  G. Jell,et al.  Gene activation by bioactive glasses , 2006, Journal of materials science. Materials in medicine.

[12]  G. Stein,et al.  Progressive development of the rat osteoblast phenotype in vitro: Reciprocal relationships in expression of genes associated with osteoblast proliferation and differentiation during formation of the bone extracellular matrix , 1990, Journal of cellular physiology.

[13]  Larry L Hench,et al.  Third-Generation Biomedical Materials , 2002, Science.

[14]  P. Bianco,et al.  Stem cells in tissue engineering , 2001, Nature.

[15]  J. B. Park,et al.  Biomechanical and morphometric analysis of hydroxyapatite-coated implants with varying crystallinity. , 1999, Journal of oral and maxillofacial surgery : official journal of the American Association of Oral and Maxillofacial Surgeons.

[16]  G W Marshall,et al.  Bioactive glass coatings with hydroxyapatite and Bioglass particles on Ti-based implants. 1. Processing. , 2000, Biomaterials.

[17]  Makoto Sato,et al.  Targeted Disruption of Cbfa1 Results in a Complete Lack of Bone Formation owing to Maturational Arrest of Osteoblasts , 1997, Cell.

[18]  Eduardo Saiz,et al.  Functionally graded bioactive coatings: reproducibility and stability of the coating under cell culture conditions. , 2006, Acta biomaterialia.

[19]  L L Hench,et al.  Gene-expression profiling of human osteoblasts following treatment with the ionic products of Bioglass 45S5 dissolution. , 2001, Journal of biomedical materials research.

[20]  J. Polak,et al.  Characterization of human fetal osteoblasts by microarray analysis following stimulation with 58S bioactive gel-glass ionic dissolution products. , 2006, Journal of biomedical materials research. Part B, Applied biomaterials.

[21]  L L Hench,et al.  In vitro dissolution of melt-derived 45S5 and sol-gel derived 58S bioactive glasses. , 2002, Journal of biomedical materials research.

[22]  S. Radin,et al.  The effect of in vitro modeling conditions on the surface reactions of bioactive glass. , 1997, Journal of biomedical materials research.

[23]  K. Bachus,et al.  Postmortem comparative analysis of titanium and hydroxyapatite porous-coated femoral implants retrieved from the same patient. A case study. , 1993, The Journal of arthroplasty.