title: Potential pitfalls of radiolabel adsorption to ceramic biomaterials.
abstract: The use of radiolabeled precursor molecules for the metabolic analysis of cell functions is commonplace. Tritiated thymidine, in particular, has been used to quantitate cellular proliferation in numerous cells, including osteoblasts, when cultured on various biomaterials. Our aim was to assess cellular protein synthesis and proliferation, on a range of fluoride ion-substituted hydroxyapatites. Initially, we used a classical metabolic analysis strategy with radiolabeled tracer molecules. Our results suggested that these materials supported enhanced protein synthesis and proliferation of SaOS-2 human osteoblast-like cells. However, control samples also revealed enhanced adsorption of the radiolabeled tracer. We have shown that this arises because partially fluoride ion-substituted hydroxyapatite exhibits enhanced adsorptive characteristics of radiolabeled leucine and thymidine over tissue culture plastic, hydroxyapatite, and fluoroapatite. Moreover, manual cell count data obtained through SEM analysis showed no significant difference in cell proliferation between any of the materials, further indicating that our initial results were artifacts. These results highlight the use and reporting of appropriate cell-free controls are critical in bioassays examining functional responses of cells to biomaterials, and if absent, may confound accurate data interpretation. Our findings have general implications for investigations of cell function on other novel ceramic biomaterials.
authors.affiliation: Tissue BioRegeneration Domain, Institute of Health and Biomedical Innovation and the School of Life Sciences, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia. a0.parker@student.qut.edu.au
authors.forename: Tony
authors.initials: T
authors.lastname: Parker
authors.forename: Zee
authors.initials: Z
authors.lastname: Upton
authors.forename: Douwe
authors.initials: D
authors.lastname: Vellinga
authors.forename: Mei
authors.initials: M
authors.lastname: Wei
authors.forename: David
authors.initials: D
authors.lastname: Leavesley
mesh_terms: D000327:Adsorption; D001672:Biocompatible Materials / Q000737:chemistry*; D002460:Cell Line; D049109:Cell Proliferation; D002516:Ceramics / Q000737:chemistry*; D005459:Fluorides; D006801:Humans; D006882:Hydroxyapatites / Q000737:chemistry; D007553:Isotope Labeling / Q000592:standards*; D007930:Leucine / Q000737:chemistry; D010006:Osteoblasts / Q000166:cytology*; D014176:Protein Biosynthesis; D011849:Radioactive Tracers; D012106:Research / Q000592:standards; D013941:Thymine / Q000737:chemistry; D014316:Tritium / Q000737:chemistry
chemical_list: D001672:Biocompatible Materials; D006882:Hydroxyapatites; D011849:Radioactive Tracers; D014316:Tritium; D007930:Leucine; D005459:Fluorides; D013941:Thymine