Osteoblastic differentiation markers

Once stem cells are committed to the osteoblast lineage, proliferating osteoprogenitors become preosteoblasts, cell growth declines, and there is a progressive expression of differentiation markers by osteoblasts (Stein et al. 1996). Osteoblastic differentiation is characterized by the sequential expression of alkaline phosphatase (ALP), an early marker of osteoblastic phenotype, followed by the synthesis and deposition of collagen type I, bone matrix proteins, and glycosaminoglycans and an increased expression of os-... 

They also reported that lycopene had a stimulatory effect on ALP activity, a marker of osteoblastic differentiation in more mature cells, but depending on the time of addition, it had an inhibitory or no effect on younger SaOS-Dex cells (Figure 14). These findings constituted the first report on the effect of lycopene on human osteoblasts. In another study by Park et al. (1997), the effect of lycopene on MC3T3 cells (the osteoblastic cells of mice) was contrary to the findings of Kim et al. (2003). Park demonstrated that lycopene had an inhibitory effect on cell proliferation. Both studies, however, reported that ALP activity was stimulated. The discrepancy in the effect of lycopene on cell proliferation could be a result of species differences or experimental conditions. More studies are required to clarify the role of lycopene in osteoblasts. 

Human osteoblasts like cells osteosarcoma SaOS-2 cells were cultured for 24 hours, after which varying doses of a water dispersible microemulsion preparation of lycopene or vehicle of the same dilution were added. The cells were further cultured for 24 to 144 h and the cell numbers were counted. Lycopene at 10 and 10 M had significant stimulatory effects on cell numbers, compared with the corresponding vehicle treatment, at all time points from 24 h to 144 h. The effects of lycopene on activity of the differentiation marker alkaline phosphatase activity in the absence or presence of dexamethasone were shown to be dependent on osteoblasts of human origin [79]. 

Antiosteonectin (M) BioDesign 1 100 MWER Sensitive marker of possible osteoblastic differentiation... 

Antiosteocalcin (M) Biogenesis 1 100 MWER Specific marker of osteoblastic differentiation... 

In support of this possibility, resveratrol shows estrogenlike effect by stimulating proliferation and differentiation of osteoblasts. Mizutani et al. ° reported that resveratrol increased alkaline phosphatase activity, an osteoblast-specific marker, and DNA synthesis in mouse osteoblastic MC3T3-C1 cells in a dose-dependent fashion. Instead of accelerating bone loss like tamoxifen, resveratrol not only prevented bone loss but also stimulated osteoblast formation. Thus, resveratrol may serve as a beneficial agent in the prevention of and therapy for osteoporosis in postmenopausal women. It is also suggested that resveratrol has cardioprotective effect in isolated ischemic/reperfused rat heart model by its free-radical-scavenging effect. ... 

The determination of alkaline phosphatase activity is an excellent hio-marker to assess the osteoblastic differentiation on a material and also was significantly higher after 10 days of cultivation. In vivo tests on a rat model having a calvaria defect (diameter 5 mm) have been performed and bone regeneration has been studied. In contrast to the chitosan, the hybrid material (without any additional precultured cells) induced complete healing of the bone, while being completely resorbed after a period of 3 weeks. 

MC3T3-E1, one of the available mouse osteoblastic cell lines, has been proved to be a model system suitable for analysis of the stimulatory effects of ascorbic acid on osteoblastic differentiation (Sudo et aL, 1983 Quarles et al., 1992), since MC3T3-E1 expresses osteoblast marker proteins and forms a mineralized extracellular matrix in response to ascorbic acid (Franceschi and Iyer, 1992 Torii et ai, 1994). Without ascorbic acid in the medium, the expression of alkaline phosphatase and osteocalcin mRNAs is totally repressed for a ten-day culture period (Fig. 2). On culturing with ascorbic acid, expression of alkaline phosphatase mRNA as well as enzyme activity begins to increase on day five, reaches a maximum level on day ten, and then decreases to the same level as that on day five. Similarly, osteocalcin is markedly induced only on culturing with ascorbic acid and reaches a maximum... 

Casting the polymer films from water miscible tetrahydrofuran (THE), as opposed to the chloroform and benzene used in previous studies, reduces the toxicity of the solvent system to cells. Porous polymers with average pore diameters 10, 6, and 3.5 rm have been produced in this manner and the murine osteoblast cell line MC3T3-E1 was cultured on the materials. When compared to a non-porous PCL control film, the honeycomb patterned polymers were seen to promote the adhesion of cells to the polymer, cell spreading, and proliferation. In addition, gene expression of the bone-specific differentiation markers ALP, collagen type I, OCN, and OPN was... 

The EST has continued to be a popular test subject to further optimization, especially through the addition of alternative pathways of differentiation and the addition of molecular markers of effects. Besides cardiac muscle differentiation, other cell types such as neurons (29-31), osteoblasts (32), adipocytes (33), and hepato-cytes (34) have been generated in dedicated differentiation protocols, providing additional opportunities for testing the interference of differentiation pathways with chemical exposures. The addition of transcriptomics approaches to measure differential gene expression, both as influenced by the differentiation process as well as due to chemical exposure, has proven informative and may enhance the predictability of EST assays (35). The extension of this concept to human embryonic stem cell lines is still in its infancy, but has opened a new realm of options that bypasses the need for interspecies extrapolation (36). 

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