Extracellular pH modulates the activity of cultured human osteoblasts

Abstract

The effect of medium pH on the activity of cultured human osteoblasts was investigated in this study. Osteoblasts derived from explants of human trabecular bone were grown to confluence and subcultured. The first-pass cells were incubated in Hepes-buffered media at initial pHs adjusted from 7.0 to 7.8. Osteoblast function was evaluated by measuring lactate production, alkaline phosphatase activity, proline hydroxylation, DNA content, and thymidine incorporation. Changes in medium pH were determined from media pHs recorded at the beginning and end of the final 48 h incubation period. As medium pH increased through pH 7.6, collagen synthesis, alkaline phosphatase activity, and thymidine incorporation increased. DNA content increased from pH 7.0 to 7.2, plateaued from pH 7.2 to 7.6, and increased again from pH 7.6 to 7.8. The changes in the medium pH were greatest at pHs 7.0 and 7.8, modest at pHs 7.4 and 7.6, and did not change at 7.2, suggesting that the pHs are migrating towards pH 7.2. Lactate production increased at pH 7.0 but remained constant from 7.2 to 7.8. These results suggest that in the pH range from 7.0-7.6 the activity of human osteoblasts increases with increasing pH, that this increase in activity does not require an increase in glycolytic activity, and that pH 7.2 may be the optimal pH for these cells.

Variation of pH in lysed platelet concentrates influence proliferation and alkaline phosphatase activity in human osteoblast-like cells

“…Acidification down to pH 7.0 decrease proliferation, collagen synthesis, and ALP activity in comparison with pH 7.4 (28,29). We observed that LPB preparations at pH 4.4 contributed to a significant acidification of the culture media, which was not compensated by the media buffering capacity.…”

“…(Direct effects of low pH on osteoblasts in vitro have previously been reported (28,29,30). Acidification down to pH 7.0 decrease proliferation, collagen synthesis, and ALP activity in comparison with pH 7.4 (28,29).…”

Biocompatible glass–ceramic materials for bone substitution

“…It is known that osteoblasts prefer a slightly alkaline medium (7.8) [14,15], but it is also known that severe changes in pH can inhibit osteoblast activity and cause cell necrosis or apoptosis [16][17][18].…”

Morphology and Dissolution Rate of Wear Debris from Silicon Nitride Coatings

“…The observed pH increase, starting only after a few days, cannot be an effect of the dissolution of the particles alone, as it was observed also for the controls not containing particles. The absence of a verifiable pH increase in comparison to the control is positive for an eventual clinical application, since it has been found that at pH 7.8 and higher, osteoblastic activity decreases 43 . The dissolution rate seen in this study was higher than what was reported by Zhmud et.…”