In Vitro effects of zinc on markers of bone formation

Abstract

Zinc deficiency is associated with a reduced rate of bone formation that can be corrected by supplementation of the deficient diet with adequate amounts of zinc. This study was conducted to examine the effects of zinc on bone cell parameters associated with bone formation. Tibiae were removed from 19-d-old chicken embryos and incubated for 48 h in Dulbecco's modified Eagle's medium supplemented with antibiotics, bovine serum albumin, and HEPES. The addition of zinc (25-200 g/dL) to tibial cultures resulted in a concentration-dependent increase in alkaline phosphatase activity, an increase in the incorporation of proline into bone protein and an increase in the post-translational oxidation of proline to peptidyl hydroxyproline. These effects of zinc were all diminished by the addition of 2,6-pyridine dicarboxylic acid, a chelator of zinc. The addition of either cycloheximide (10(-5)M), dactinomycin (10(-8)M), or hydroxyurea (10(-3)M) to tibial cultures also attenuated the effects of zinc. The effect of zinc on bone cell DNA synthesis was measured by following the incorporation of 3H-thymidine into DNA and by fluorometric measurement of cellular DNA content. These methods revealed that the addition of zinc to cultured tibiae resulted in a concentration-dependent increase in tibial DNA content and synthesis rate. The magnitude of the zinc-induced DNA increase was similar to the magnitude of the zinc-induced increases in alkaline phosphatase activity, proline incorporation, and hydroxyproline synthesis. Normalization of these latter responses to tibial DNA content yield data indicating that the effect of zinc on bone formation results from a zinc-induced increase in bone cell proliferation.

Role of zinc in cellular zinc trafficking and mineralization in a murine osteoblast-like cell line

“…Anderson et al [27] concluded that the early phase of mineralization was closely associated with tissue non-specific alkaline phosphatase. According to a previous report [28], addition of Zn to bone culture resulted in a concentrationdependent increase in alkaline phosphatase activity. Although we did not evaluate the alkaline phosphatase activity in our study, we hypothesize that the differences in mineralization of osteoblasts with Zn exposure during the early phase may partly be due to cellular alkaline phosphatase activity.…”

The Important Role of Osteoblasts and Citrate Production in Bone Formation: “Osteoblast Citration” as a New Concept for an Old Relationship

“…Recent reported studies of osteoblast intermediary energy metabolism [such as 25–30] have not included any involvement of the specialized metabolic relationships of citrate and/or zinc in osteoblasts. Chen et al in their 1999 report of zinc effects on bone formation [31] emphasized that “ Studies of bone in tissue culture typically do not include addition of zinc specifically… Interpretation of data from such studies should take this variable (zinc) into account. ” The important relationship of zinc accumulation on cellular citrate metabolism as described above (Fig.…”

Bio-composite scaffolds containing chitosan/nano-hydroxyapatite/nano-copper–zinc for bone tissue engineering

“…Zn inhibits osteoclast differentiation and promotes osteoblast activity and promotes bone formation [15,16], and it is also an important trace element found in bone. Zn is also involved increasing biomineralization both in vivo and in vitro [17,18].…”