• International Journal of Oral Biology
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• v.33 no.3
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• pp.113-116
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• 2008

Cementum is the mineralized tissue of the tooth. It is similar to bone in several aspects but it differs from bone. Human bone marrow stromal cells (BMSC) and human cementum derived cells (HCDC) (10,000 $cells/cm^2$) were plated in 6 well plates as feeder cells. The next day, mouse bone marrow cells (1.5 million $cells/cm^2$) were added. One group of these plates were incubated in serum-free conditioned medium (SFCM) generated from BMSC or HCDC supplemented with 2% FBS, parathyroid hormone (PTH), 1, 25 dihydroxyvitamin $D_3$ (Vit. $D_3$) and dexamethasone, or plain medium with the same supplements. Another group of plates were cocultured with BMSC or HCDC in plain medium supplemented with 2% FBS, PTH, Vit. $D_3$ and dexamethasone. Plates grown without SFCM or coculture were used as controls. After 10 days, the cells were stained for tartrate-resistant acid phosphatase (TRAP). BMSC were found to support osteoclast formation under normal conditions. This was inhibited however by both SFCM generated from HCDC and also by coculture with HCDC. In addition, HCDC themselves did not support osteoclast formation under any conditions. Our results thus indicate that HCDC do not support osteoclast formation in vitro and that soluble factor (s) from HCDC may inhibit this process. In addition, we show that this inhibition also involves an active mechanism that is independent of osteoprotegerin, a feature that may distinguish cementoblasts from other cells present in periodontium.

• Journal of Periodontal and Implant Science
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• v.25 no.3
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• pp.623-634
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• 1995

Periodontitis is characterized by gingival inflammation and results in periodontal pocket formation with loss of the supporting alveolar bone and connective tissue around the teeth. Therapeutic modalities should therefore aim not only at eliminating the gingival inflammatory process and preventing the progression of periodontal disease but also at reestablishing and regenerating the periodontal tissue previously lost to the disease. To achieve periodontal regeneration, progenitor cells must migrate to the denuded root surface, attach to it, proliferate and mature into an organized and functional fibrous attachment apparatus. Likewise, progenitor bone cells must also migrate, proliferate, and mature in conjunction with the regenerating periodontal ligament. Significant advances have been made during the last decade in understanding the factors controlling the migration, attachment and proliferation of cells. A group of naturally occuring molecules known as polypeptide growth factors in conjunction with certain matrix proteins are key regulators of these biological events. Of these, the fibroblast growth factor(FGF), platelet-derived growth factor(PDGF) , insulin like growth factor(CIGFs), transforming growth factor(TGFs), epidermal growth factor(EGF) and bone morphogenetic growth factor(BMPs) apper to have an important role in periodontal wound healing. The purpose of this study was to determine the effects of BMP on periodontal ligament cells. Human periodontal ligament cells were cultured from extracted tooth for non-periodontal reason. Cultured periodontal ligament cells were treated with BMP. Cellular activities were determined by MTT(3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assay and ALP(alkaline phosphatase) activity. The results were as follows ; Regardless of cultured time, cellular activities were stimulated by BMP. Also, BMP greatly increased alkaline phosphatase(ALP) in periodontal ligament cells. These results suggest that BMP not only have no cytotoxic effect on periodontal ligament cells, but also have osteogenic stimulatory effect on periodontal ligament cells.

• Journal of Periodontal and Implant Science
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• v.35 no.2
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• pp.289-298
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• 2005

Bone morphogenetic protein-7(BMP-7), a member of the transforming growth factor superfamily, stimulates osteoblast differentiation and bone formation. There are lots of evidences supporting a direct participation of periodontal ligament(PDL) cells on periodontal tissue regeneration. The purpose of this study was to evaluate the effect of recombinant human(rh) BMP-7 on primary rat PDL cells in vitro, with special focus on the ability of bone formation. The PDL cells were cultured with rhBMP-7 at the concentration of 0, 10, 25, 50, 100 and 200ng/ml for MTT assay. We evaluated the alkaline phosphatase activity at 3 and 5 days of incubation and the ability to produce mineralized nodules of rat PDL cells at 14 days of cell culture in concentration of 0, 10, 25, 50 and 100ng/ml. The cell activity was not reduced in cells treated with BMP-7 at $10{\sim}100ng/ml$, whereas the cell activity was reduced in the concentration of 200ng/ml than the control at day 1 and 3(p<0.01). At 3 and 5 day, alkaline phosphatase activity was significantly increased in cells treated with BMP-7 at 50ng/ml and 100ng/ml(p<0.05). The area of mineralized bone nodule was greater in cells treated with BMP-7 at 50 and 100 ng/ml than the control(p<0.01). These results suggest that rhBMP-7 stimulate rat PDL cells to differentiate toward osteoblast phenotype and secretion of the extracellular matrix of rat PDL cells.

• International Neurourology Journal
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• v.22 no.4
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• pp.260-267
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• 2018

Purpose: A major question remaining in approaches to tissue engineering and organ replacement is the role of native mobilized native cells in the regeneration process of damaged tissues and organs. The goal of this study was to compare the cell mobilizing effects of the chemokine CXCL12 and cell therapy on the urinary sphincter of nonhuman primates (NHP) with chronic intrinsic urinary sphincter dysfunction. Methods: Either autologous lenti-M-cherry labeled skeletal muscle precursor cells (skMPCs) or CXCL12 were injected directly into the sphincter complex of female NHPs with or without surgery-induced chronic urinary sphincter dysfunction (n=4/treatment condition). All monkeys had partial bone marrow transplantation with autologous lenti-green fluorescent protein (GFP) bone marrow cells prior to treatment. Labeled cells were identified, characterized and quantified using computer-assisted immunohistochemistry 6 months posttreatment. Results: GFP-labeled bone marrow cells (BMCs) were identified in the bone marrow and both BMCs and skMPCs were found in the urinary sphincter at 6-month postinjection. BMCs and skMPCs were present in the striated muscle, smooth muscle, and lamina propria/urothelium of the sphincter tissue. Sphincter injury increased the sphincter content of BMCs when analyzed 6-month postinjection. CXCL12 treatment, but not skMPCs, increased the number of BMCs in all layers of the sphincter complex (P<0.05). CXCL12 only modestly (P=0.15) increased the number of skMPCs in the sphincter complex. Conclusions: This dual labeling methodology now provides us with the tools to measure the relative number of locally injected cells versus bone marrow transplanted cells. The results of this study suggest that CXCL12 promotes mobilization of cells to the sphincter, which may contribute more to sphincter regeneration than injected cells.

• International Journal of Oral Biology
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• v.42 no.4
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• pp.163-168
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• 2017

Osteoporosis is a metabolic bone disease that is characterized by low bone mass resulting from an increase in bone resorption relative to bone formation. The most current therapies for osteoporosis have focused on inhibiting bone resorption by osteoclasts. The purpose of this study is to develop new anabolic agents for treatment of osteoporosis that have fewer risks compared to conventional therapies. We searched the natural products that were derived from the traditional Asian medicines which have been used for treatment of bone related diseases. Icaritin is a flavonoid glycoside derived from the herb Epimedium which has beneficial effects on bone formation. To determine the effect of icaritin on bone formation, we examined the effect of icaritin on MC3T3-E1 cell proliferation and differentiation. For determining the effects of icaritin on proliferation, we performed the MTT assay using MC3T3-E1 cells. To evaluate whether icaritin could promote the osteogenic differentiation of MC3T3-E1 cells, alkaline phosphatase (ALP) activity and mRNA expressions of Runx2, osteocalcin (OCN), RANKL, and osteoprotegerin (OPG) were determined. Icaritin increased MC3T3-E1 cell proliferation. Icaritin increased the ALP activity of MC3T3-E1 cells on 72 hour culture in osteogenic media. mRNA expression of Runx2 was increased after 24 hour culture with icaritin. mRNA expression of osteocalcin was increased after 72 hour culture with icaritin. In addition, icaritin increased the mRNA expressions of OPG and RANKL. However, icaritin increased the mRNA expression of OPG much more than that of RANKL, and then, it increased the OPG/RANKL ratio. These results suggest that icaritin promotes osteogenic differentiation of osteoblasts and decreases osteoclast formation regulated by osteoblasts.

• Journal of Biomedical Engineering Research
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• v.28 no.3
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• pp.377-386
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• 2007

Mechanical loading to bone cells using simple sine wave or constant wave fluid flow has been widely used for in vitro experiments. Human gait is characterized by a complex loading to bones of lower extremities which results from a series of events consisting of heel strike, foot flat and push-off during the stance phase of the gait cycle. Telemetric force analyses have shown that human femora are subject to multiphasic loading. Therefore, it would be ideal if the physiologic loading conditions during human walking can be used for in vitro mechanotransduction studies. Here, for a mechanotransduction study, we develop it fluid flow system (FFS) in order to simulate human physiologic mechanicalloading on bone cells. The development methods of the FFS including the COR (Center for Orthopedic Research), monitor program are presented. The FFS could generate various multiphasic loading conditions of human gaits with output flow. Wall shear distribution was very uniform, with 81 % of the effective loading area of the culture on a glass slide. Our results demonstrated that the FFS, provide a new translational approach for unveiling molecular mechanotransduction pathways in bone cells.

• Journal of Veterinary Clinics
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• v.7 no.2
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• pp.451-469
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• 1990

The present study was carried out to investigate whether the aloe had a radioprotective effect in mice exposed to cobalt-60 gamma radiation or not. The survival ratio of mice for 30 days, hematopoiesis of blood-forming stem cells by spleen colony assay, chromosomal aberration frequency of bone marrow cells and histopathological findings of bone marrow were investigated. The survival ratios of aloe administered groups with concentration of 250, 500, 1,000 and 1,500mg for 3 days before irradiation and control group in cobalt-60 gamma irradiated mice(700rads whole body irradiation, dose rate of 50rads/min.) were 77.4, 79.3, 80.6, 90.0 and 53.1％, respectively. The survival ratios of pre-irradiation aloe administered groups were superior to those of post-irradiation aloe groups and control group. In spleen colony assay, Aloe vera administration before irradiation enhanced the recoveries of numbers of blood-forming stem cells of bone marrow of irradiated mice. There were decreased chromosomal aberrations of bone marrow cells at the first day after irradiation in aloe administered groups compared to that of control group. Histopathological findings in the bone marrow of irradiated mice were hypocellularity due to the depletion of myelocytes, abundant of fat vacuoles and these changes were weakened in aloe administered groups compared to that of control group.

• International Journal of Oral Biology
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• v.31 no.4
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• pp.119-125
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• 2006

The importance of phytoestrogens to human health is currently being actively investigated. Hesperidin, abundantly found in citrus fruits, is known to possess antioxidant, anticancer, and anti-inflammatory effects. Recently, it has been reported that hesperidin inhibits bone loss and decreases serum and hepatic lipids in ovariectomized mice. In our study, to determine the possible role of hesperidin in the regulation of bone metabolism, we observed the effects of hesperidin on the proliferation and activity of osteoblasts, as well as the effects of hesperidin on osteoclast generation and activity. We observed that, when treated with hesperidin, the number and viability of osteoblastic cells increased, alkaline phosphatase (ALP) activity of osteoblastic cells increased, and osteoprotegerin (OPG) secretion from MG63 cells decreased. Hesperidin treatment had no effect on the osteoclast generation and activity in the bone marrow cell culture, but decreased the number and resorptive activity of osteoclasts generated from RAW/264.7 cells. Taken together, these results indicate that hesperidin increases the proliferation and activity of osteoblasts, while inhibiting generation and activity of osteoclasts. Although the precise role of hesperidin remains to be elucidated, our study suggests that it is one of the important modulators of bone metabolism.

• International Journal of Oral Biology
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• v.31 no.2
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• pp.67-72
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• 2006

Nitric oxide(NO) is a labile, uncharged, reactive radical that functions as a sensitive mediator of intercellular communication in diverse tissues. It has been reported that NO is produced by osteoblast and these results may suggest that NO is integrally involved in the regulation of osteoclast formation and osteoclast resorption activity by osteoblastic cells. We examined the effect of cytokines on NO release by mouse bone marrow cell. We also examined the effects of cytokines and sodium nitroprusside(SNP) on the formation of osteoclast-like cell from mouse bone marrow cells in culture. Cytokines stimulated NO production of mouse bone marrow cells, and N-nitro-L-arginine methyl ester, a specific inhibitor of NO synthase, suppressed the cytokine-induced NO production. SNP showed dual action in the generation of osteoclasts. The addition of $30{\mu}M$ SNP inhibited the formation of tartrate resistant acid phosphatase(TRAP)(+) multinucleated cell, whereas lower concentration($3{\mu}M$) of SNP enhanced it. Although the precise action of NO remains to be elucidated in detail, the action of NO in osteoclast generation in our studies seems to be associated, at least in part, with bone metabolism and bone pathophysiology.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2001.04a
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• pp.103-112
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• 2001

Bone homeostasis is maintained by a balance between activities of osteoblasts(bone forming cells) and osteoclasts (bone resorbing cells). The activities of these cells are closely regulated by multiple factors including hormones and cytokines. The cessation of estrogen at menopause disrupts the balanced regulation and is the main cause of osteoporosis in postmenopausal women. Recent molecular biological studies led to a discovery of tumor necrosis factor(TNF) and TNF receptor families genes that play critical roles in the regulation of osteoclast formation and function. RANKL (receptor activator of nuclear factor kappa B ligand; also called ODF, TRANCE, and OPGL) expressed on cells supporting osteoclast is essential for osteoclast differentiation, activation, and survival. RANK, the counter-receptor for RANKL, is expressed on progenitor and mature osteoclasts. The interaction between RANKL and RANK is requlated by a soluble decoy receptor OPG (osteoprotegerin). Gene knock out studies of these molecules showed profound effects on bone. These results prompted development of new strategies for treatment of bone diseases. Inhibition of osteoclast activity by blocking the RANKL-RANK interaction using OPG is being attempted. Research on the signaling pathways of RANK is also actively carried out. Screening natural products that inhibit the RANKL-RANK interaction or the activity of obteoclasts would be another effective means to a new drug target for bone resorbing diseases.