Stimulation by 1,25-dihydroxyvitamin D3 of in vitro mineralization induced by osteoblast-like MC3T3-E1 cells
- Fourth Department of Internal Medicine, University of Tokyo School of Medicine (Japan)
Although vitamin D is essential for mineralization of bone, it is as yet unclear whether vitamin D has a direct stimulatory effect on the bone mineralization process. In the present study, the effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) on in vitro mineralization mediated by osteoblast-like MC3T3-E1 cells was examined. MC3T3-E1 cells continued to grow after they reached confluency, and DNA content and alkaline phosphatase activity increased linearly until about 16 days of culture, whereas 45Ca accumulation into cell and matrix layer remained low. After this period, DNA content plateaued, and 45Ca accumulation increased sharply. Histological examination by von Kossa staining revealed that calcium was accumulated into extracellular matrix. In addition, needle-shaped mineral crystals similar to hydroxyapatite crystals could be demonstrated in between collagen fibrils by electron microscopy. Thus, MC3T3-E1 cells differentiate in vitro into cells with osteoblastic phenotype and exhibit mineralization. When MC3T3-E1 cells were treated with 1,25(OH)2D3 at this stage of culture, there was a dose-dependent stimulation of 45Ca accumulation by 1,25(OH)2D3, and a significant stimulation of 45Ca accumulation was observed with 3 x 10(-10) M 1,25(OH)2D3. Although 1,25(OH)2D3 enhanced alkaline phosphatase activity and collagen synthesis at the early phase of culture, it did not affect any of these parameters at the late phase when 1,25(OH)2D3 stimulated mineralization. Neither 24,25-dihydroxyvitamin D3 nor human PTH(1-34) affected mineralization in the presence or absence of 1,25(OH)2D3. These results demonstrate that 1,25(OH)2D3 stimulates matrix mineralization induced by osteoblastic MC3T3-E1 cells, and are consistent with the possibility that 1,25(OH)2D3 has a direct stimulatory effect on bone mineralization process.
- OSTI ID:
- 5464141
- Journal Information:
- Bone; (United States), Vol. 12:1; ISSN 8756-3282
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALKALINE PHOSPHATASE
ENZYME ACTIVITY
BONE CELLS
MINERALIZATION
COLLAGEN
BIOSYNTHESIS
VITAMIN D
BIOLOGICAL EFFECTS
CALCIUM 45
DNA
DOSE-RESPONSE RELATIONSHIPS
ELECTRON MICROSCOPY
PHENOTYPE
TRACER TECHNIQUES
ALKALINE EARTH ISOTOPES
ANIMAL CELLS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CALCIUM ISOTOPES
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
ENZYMES
ESTERASES
EVEN-ODD NUCLEI
HYDROLASES
INTERMEDIATE MASS NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
MICROSCOPY
NUCLEI
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PHOSPHATASES
PROTEINS
RADIOISOTOPES
SCLEROPROTEINS
SOMATIC CELLS
SYNTHESIS
VITAMINS
550201* - Biochemistry- Tracer Techniques