Metal Substrates Influence the Release of Glycosaminoglycan and Transforming Growth Factor β by Human Bone Cells

Abstract

Bone cells derived from human jaw were isolated from explants and grown in vitro. Subcultures were cultured on plastic (control) and metal substrates for 24 and 48 hours in medium containing 3H-glucosamine and labeled glycosaminoglycan (GAG) accumulation was measured. In bone cells cultured on metal substrates there was an evident reduction in the synthesis and secretion of radiolabeled macromolecules compared to bone cells cultured on plastic. Moreover, the accumulation of single GAG classes was specific for each substrate tested. The results showed that titanium was the only metal substrate studied in which the percentage of individual GAG classes remained the same as control cultures. GAG reduction was due to a decreased synthesis and not to an increased degradation as shown by the decrement of exoglycosidase activity. The metals also reduced the activity of transforming growth factor beta (TGF beta), measured using interleukin-1 assay method, a factor involved in the various phases of bone remodeling; in this case, too, cells grown on titanium showed the highest TGF beta activity compared to the other metal substrates studied. The results indicate that the substrate to which the cells adhere do exhibit specific differences in GAG composition and TGF beta activity. The differences observed may be important during in vivo events such as guided tissue regeneration and bone deposition.

Phenotype expression of human bone cells cultured on implant substrates

“…In a previous study, in which some metal substrates used in oral implantology were tested, titanium seemed to be the most suitable in promoting bone cell growth. 24 The present results suggest that TPS is more suitable than titanium or THA in favouring cell proliferation, in increasing both synthesis and degradation of GAG and furthermore in facilitating their accumulation in the ECM. Since GAG are able to concentrate various growth factors, protect them from enzymatic degradation and facilitate their binding with the membrane receptors, 25Y26 the high accumulation of these macromolecules in the ECM may favour osseo-integrative processes.…”

Biocompatibility of alloys used in orthodontics evaluated by cell culture tests

“…Some of these ions, such as Cr +6 , Ni ++ , and Cu ++ are known to be cytotoxic for the cells. 4,[24][25][26] Certain authors consider Ag + and Pd ++ to be cytotoxic, 11,27 while others consider them to be nontoxic. 26,28 Studies on 3 H-thymidine incorporation have demonstrated that metal ions influence cell proliferation in different ways.…”

“…At the same time the cells synthesize and secrete local growth factors and macromolecules that make up the extracellular matrix (ECM). [10][11][12][13] The ECM, in turn, controls numerous biological processes, such as cell proliferation, differentiation, and tissue regeneration; therefore, any variation in the ECM composition can influence the tissue's state of health. [14][15][16][17] Previous studies have provided information regarding cellular response to implant materials by evaluating ECM component neosynthesis and degradation and TGF ␤ activity by human bone cells in vitro.…”

In vitro cytotoxic effects of orthodontic appliances

“…In the oral environment, the orthodontic appliances undergo corrosion processes with the release of metal ions that are known to be cytotoxic for the cells, as shown by our and other studies and confirmed by the effects of enriched MEM, 7,[13][14][15]26,27 We, therefore, tested the effects of Ag ϩ , Pd ϩϩ , Cu ϩϩ , Cr ϩ6 , and Ni ϩϩ , which are the major components of the stainless steel and of the brazing alloy. The concentrations chosen were those released by one orthodontic appliance immersed for 28 days in de-ionized, distilled water at pH 5.5.…”