Effect of Zn and Mg in tricalcium phosphate and in culture medium on apoptosis and actin ring formation of mature osteoclasts

Abstract

This study investigated the resorptive activity of osteoclasts on tricalcium phosphate (TCP), zinc-containing tricalcium phosphate (ZnTCP) and magnesium-containing tricalcium phosphate (MgTCP) ceramics in different Zn- or Mg-containing culture media. On the TCP ceramic, an increase in Zn ions in the culture medium within the range between 0.3 and 6.8 ppm significantly induced an increase in osteoclast apoptosis and a decrease in actin ring formation. However, even a high level of Mg ions up to 100 ppm in the culture medium was unlikely to induce an increase in osteoclast apoptosis. Mg ions in the MgTCP ceramics have no effect on osteoclast apoptosis and actin ring formation. There was almost no significant difference in osteoclast apoptosis and actin ring formation between ZnTCP and MgTCP ceramics which have the same solubility and dissolution rates. It is indicated that only an increase in Zn level outside resorption lacuna has an inhibitory effect on osteoclast resorption and that an increase in Zn level inside resorption lacuna could not influence the osteoclast activity.

Sinomenine induces apoptosis in RAW 264.7 cell-derived osteoclasts in vitro via caspase-3 activation

“…Osteoclast survival and bone resorption depend upon the actin cytoskeleton [19] . A previous report has shown that changes in the actin cytoskeleton were related to apoptotic osteoclast death [20] . Therefore, SIN might suppress the survival of mature osteoclasts by inducing apoptosis.…”

Bioinorganics and biomaterials: Bone repair

“…The addition of zinc to brushite-forming b-TCP cement showed a positive effect on adhesion, proliferation, ALP activity and Col-I secretion of the MC3T3-E1 osteblastic cell line, an effect which was even more pronounced when both strontium and zinc were present in the cement [168]. The presence of zinc in b-TCP (up to 0.6 wt.%) has been shown to have a dose-dependent negative effect on the resorptive activity of primary mature rabbit osteoclasts, as indicated by an increase in the number of apopoptic osteoclasts and a decrease in actin ring formation [169,170]. Incorporation of zinc into thin apatite films also led to the decreased resorption by primary osteoclasts, whereas no effect was found on the initial attachment of cells [171].…”

Improving the bone forming ability of synthetic bone substitutes using trace element additions

“…For example, fluoride stimulates the proliferation and osteogenic differentiation of osteoblastic cells in vitro [64][65][66][67][68][69][70] and silicon enhances the proliferation, metabolic activity and the synthesis of collagen type I in osteoblastlike cells [71,72]. Moreover, zinc [73][74][75][76][77][78] and strontium [40,79] were found to have dual effects that they favour osteogenesis while suppressing osteoclastic activity, indicating their potential in modulating bone growth. These findings indicate that the application of trace elements in the orthopaedic field has enormous potential.…”

“…As mentioned previously, many trace elements such as silicon, zinc, fluorine, magnesium and strontium can regulate cellular activities of bone cells [64][65][66][67][68][69][70][71][72][73][74][75][76][77][78]40,79]. In view of this, there are growing interests to incorporate various trace elements in orthopaedic materials, aiming to achieve a release of these ions from the materials and thus enhance their bone forming ability.…”

“…It has been shown that zinc can influence the behavior of (pre)osteoblast [73][74][75] and osteoclast [76][77][78], indicating zinc plays an important role in bone metabolism. Thereafter, zinc has been introduced in various calcium phosphates ceramics in expectation that the release of zinc may promote the bone forming ability of synthetic materials.…”