COMPARISON OF THE RELEASE OF GROWTH-HORMONE FROM HYDROXYAPATITE, HEAT-TREATED HYDROXYAPATITE, AND FLUOROAPATITE COATINGS ON TITANIUM

Hydroxyapatite (HA), heat-treated hydroxyapatite (HAH), and fluorapati te (FA) coatings on titanium were loaded with human growth hormone (GH ), and the subsequent release was monitored in vitro. The amount of GH released was significantly increased from the HA coating that had rec eived a post-plasma-spraying heat treatment prior to incorporation of the growth hormone. Scanning electron microscopy was used to assess th e surfaces of the ceramic coatings prior and postincubation with GH. S urface changes were observed on the HA and HAH coatings but not on the FA coatings after incubation with GH. Osteoblast-like cells were grow n on the coatings and maintained in culture. Scanning electron microsc opy was used to study the morphology of the cells and the interaction of the cells with the ceramic coatings. We used thymidine uptake and D NA content to determine the relative rates of cell division on the dif ferent coatings; the optimum rate of cell proliferation was observed o n the HAH coating loaded with 0.1 IU/mL GH. (C) 1995 John Wiley & Sons , Inc.