The Effect of Extracellular Calcium Ion on Gene Expression of Bone-related Proteins in Human Pulp Cells

Abstract

Calcium hydroxide is often used for induction of reparative dentin formation in endodontic treatment. However, little is known about the mechanism by which calcium hydroxide works. The calcium ion (Ca2+) is an important regulator of cell functions. In this study, we examined the effect of extracellular Ca2+ on gene expression of bone-related proteins in human cultured pulp cells in serum-free conditions. A Ca2+ level elevated by 0.7 mM induced an increase in mRNA expression of osteopontin and bone morphogenetic protein (BMP)-2. However, mRNA levels of BMP-4 and alkaline phosphatase decreased under the elevated Ca2+ culture condition. The same concentration of additional magnesium ions had little effect on expressions of the examined bone-related protein mRNAs. These findings suggest that Ca2+ in Ca(OH)2 specifically modulates osteopontin and BMP-2 levels during calcification in pulp.

Morphohistological Change and Expression of HSP70, Osteopontin and Osteocalcin mRNAs in Rat Dental Pulp Cells with Orthodontic Tooth Movement

“…In this study, osteopontin and osteocalcin mRNA expression was higher in the experimental groups than in the control group. Osteopontin and osteocalcin are wellknown markers of bone-related cell differentiation [14][15][16]21) . In particular, osteopontin is a marker of osteoblast or odontoblast differentiation 21) .…”

“…Osteopontin and osteocalcin are wellknown markers of bone-related cell differentiation [14][15][16]21) . In particular, osteopontin is a marker of osteoblast or odontoblast differentiation 21) . Rashid et al suggests that, with orthodontic tooth movement, disturbance of blood flow in the dental pulp incurs hypoxic conditions, which causes pulpal calcification, formation of denticles and differentiation of pulp cells into odontoblasts 21) .…”

“…In particular, osteopontin is a marker of osteoblast or odontoblast differentiation 21) . Rashid et al suggests that, with orthodontic tooth movement, disturbance of blood flow in the dental pulp incurs hypoxic conditions, which causes pulpal calcification, formation of denticles and differentiation of pulp cells into odontoblasts 21) . In this study, although no pulpal calcification was observed, mRNA expression-related calcification increased.…”

“…The formation of dentin or osteodentin in the dental pulp is known to be one of the reactions of homeostasis. Bone-related protein is related to the calcification of pulp 21) , and hard tissue formation is regulated by the activity of pulp cells 1,28) . Heat shock protein 70 (HSP70), which serves as a molecular chaperone to maintain homeostasis, is expressed physiologically in response to stimulation 24) .…”

The citotoxicity of calcium hydroxide intracanal dressing by MTT assay

“…Some in vitro studies on calcium hydroxide, one of studies done by Rashid et al 21 has proved that by adding CaCl 2 4 mM in human pulp cell which has been measured, resulting the increase of alkaline phosphatase (ALPase) activity so pulp cell proliferation would occur, however by adding 0.7 mM decreasing alkaline phosphatase (ALPase) activity in pulp cell would cause decreasing the number of pulp cell. Collagen synthetisis and alkaline phosphatase would increase simultaneously with the increase of pH medium until 8.…”