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Senile Osteoporosis: The Involvement of Differentiation and Senescence of Bone Marrow Stromal Cells. Int J Mol Sci 2020; 21:ijms21010349. [PMID: 31948061 PMCID: PMC6981793 DOI: 10.3390/ijms21010349] [Citation(s) in RCA: 125] [Impact Index Per Article: 31.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 12/26/2019] [Accepted: 12/31/2019] [Indexed: 12/12/2022] Open
Abstract
Senile osteoporosis has become a worldwide bone disease with the aging of the world population. It increases the risk of bone fracture and seriously affects human health. Unlike postmenopausal osteoporosis which is linked to menopause in women, senile osteoporosis is due to aging, hence, affecting both men and women. It is commonly found in people with more than their 70s. Evidence has shown that with age increase, bone marrow stromal cells (BMSCs) differentiate into more adipocytes rather than osteoblasts and undergo senescence, which leads to decreased bone formation and contributes to senile osteoporosis. Therefore, it is necessary to uncover the molecular mechanisms underlying the functional changes of BMSCs. It will benefit not only for understanding the senile osteoporosis development, but also for finding new therapies to treat senile osteoporosis. Here, we review the recent advances of the functional alterations of BMSCs and the related mechanisms during senile osteoporosis development. Moreover, the treatment of senile osteoporosis by aiming at BMSCs is introduced.
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Rogina A, Antunović M, Pribolšan L, Caput Mihalić K, Vukasović A, Ivković A, Marijanović I, Gallego Ferrer G, Ivanković M, Ivanković H. Human Mesenchymal Stem Cells Differentiation Regulated by Hydroxyapatite Content within Chitosan-Based Scaffolds under Perfusion Conditions. Polymers (Basel) 2017; 9:E387. [PMID: 30965692 PMCID: PMC6418638 DOI: 10.3390/polym9090387] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 08/18/2017] [Accepted: 08/21/2017] [Indexed: 11/24/2022] Open
Abstract
The extensive need for hard tissue substituent greatly motivates development of suitable allogeneic grafts for therapeutic recreation. Different calcium phosphate phases have been accepted as scaffold's components with positive influence on osteoinduction and differentiation of human mesenchymal stem cells, in terms of their higher fraction within the graft. Nevertheless, the creation of unlimited nutrients diffusion through newly formed grafts is of great importance. The media flow accomplished by perfusion forces can provide physicochemical, and also, biomechanical stimuli for three-dimensional bone-construct growth. In the present study, the influence of a different scaffold's composition on the human mesenchymal stem cells (hMSCs) differentiation performed in a U-CUP bioreactor under perfusion conditioning was investigated. The histological and immunohistochemical analysis of cultured bony tissues, and the evaluation of osteogenic genes' expression indicate that the lower fraction of in situ formed hydroxyapatite in the range of 10⁻30% within chitosan scaffold could be preferable for bone-construct development.
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Affiliation(s)
- Anamarija Rogina
- Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, p.p.177, 10001 Zagreb, Croatia.
| | - Maja Antunović
- Faculty of Science, University of Zagreb, Horvatovac102a, 10001 Zagreb, Croatia.
| | - Lidija Pribolšan
- Faculty of Science, University of Zagreb, Horvatovac102a, 10001 Zagreb, Croatia.
| | | | - Andreja Vukasović
- Department of Histology and Embryology, School of Medicine, University of Zagreb, Šalata 3, 10001 Zagreb, Croatia.
| | - Alan Ivković
- Department of Histology and Embryology, School of Medicine, University of Zagreb, Šalata 3, 10001 Zagreb, Croatia.
- Department of Orthopaedic Surgery, University Hospital, Sveti Duh, 10001 Zagreb, Croatia.
| | - Inga Marijanović
- Faculty of Science, University of Zagreb, Horvatovac102a, 10001 Zagreb, Croatia.
| | - Gloria Gallego Ferrer
- Centro de Biomateriales e Ingeniería Tisular, Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain.
- Biomedical Research Networking centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Mariano Esquillor s/n, 50018 Zaragoza, Spain.
| | - Marica Ivanković
- Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, p.p.177, 10001 Zagreb, Croatia.
| | - Hrvoje Ivanković
- Faculty of Chemical Engineering and Technology, University of Zagreb, Marulićev trg 19, p.p.177, 10001 Zagreb, Croatia.
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Jakus AE, Rutz AL, Jordan SW, Kannan A, Mitchell SM, Yun C, Koube KD, Yoo SC, Whiteley HE, Richter CP, Galiano RD, Hsu WK, Stock SR, Hsu EL, Shah RN. Hyperelastic “bone”: A highly versatile, growth factor–free, osteoregenerative, scalable, and surgically friendly biomaterial. Sci Transl Med 2016; 8:358ra127. [DOI: 10.1126/scitranslmed.aaf7704] [Citation(s) in RCA: 251] [Impact Index Per Article: 31.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Accepted: 08/16/2016] [Indexed: 12/22/2022]
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Analysis of the Influence of Hormone Replacement Therapy on Osteocalcin Gene Expression in Postmenopausal Women. BIOMED RESEARCH INTERNATIONAL 2015; 2015:416929. [PMID: 26357654 PMCID: PMC4556843 DOI: 10.1155/2015/416929] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 06/15/2014] [Revised: 08/23/2014] [Accepted: 09/09/2014] [Indexed: 12/16/2022]
Abstract
Background. Osteocalcin (OC) contributes to the process of bone mineralization. Present study was designed to investigate the changes in OC gene expression of postmenopausal women treated with hormone replacement therapy (HRT). Study was also designed to evaluate OC gene expression in cells which are not part of connective tissue. Material and Methods. Research was carried out on 30 postmenopausal women not treated and 30 treated with HRT. Examination of OC gene expression was conducted on peripheral blood lymphocytes (PBL) and buccal epithelial lining (BEL). Densitometry was conducted on femur and mandible. Results. Tests revealed OC gene expression in BEL and PBL. BMD was higher in groups treated with HRT. Assessment of correlation between the OC gene expression in BEL and BMD of mandible revealed significant positive relation. Conclusions. OC gene expression can be stated BEL and PBL. Analysis of correlation between OC gene expression in oral cavity and mandible BMD showed significant correlation between local OC expression and local bone metabolism. The relation between OC gene expression and bone metabolism is complex and further research is needed to clear all of the uncertainties.
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Mahmoudi T, Karimi K, Arkani M, Farahani H, Nobakht H, Dabiri R, Asadi A, Vahedi M, Zali MR. Lack of associations between Vitamin D metabolism-related gene variants and risk of colorectal cancer. Asian Pac J Cancer Prev 2014; 15:957-61. [PMID: 24568525 DOI: 10.7314/apjcp.2014.15.2.957] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
PURPOSE With regard to the protective effect of vitamin D against colorectal cancer (CRC), we evaluated genetic variants that might influence vitamin D metabolism: vitamin D receptor (VDR), vitamin D binding protein (GC), vitamin D 25-hydroxylase (CYP2R1), and vitamin D 25-hydroxy 1-alpha hydroxylase (CYP27B1). MATERIALS AND METHODS A total of 657 subjects, including 303 cases with CRC and 354 controls were enrolled in this case-control study. All 657 were genotyped for the four gene variants using PCR-RFLP methods. RESULTS In this study, no significant difference was observed for VDR (rs2238136), GC (rs4588), CYP2R1 (rs12794714), and CYP27B1 (rs3782130) gene variants in either genotype or allele frequencies between the cases with CRC and the controls and this lack of difference remained even after adjustment for age, BMI, sex, smoking status, NSAID use, and family history of CRC. Furthermore, no evidence for effect modification of the variants and CRC by BMI, sex, or tumor site was observed. CONCLUSIONS Our findings do not support a role for VDR, GC, and CYP27B1 genes in CRC risk in our Iranian population. Another interesting finding, which to our knowledge has not been reported previously, was the lack of association with the CYP2R1 gene polymorphism. Nonetheless, our findings require confirmation and possible roles of vitamin D metabolism-related genes in carcinogenesis need to be further investigated.
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Affiliation(s)
- Touraj Mahmoudi
- Gastroenterology and Liver Diseases Research Center, Shahid Beheshti University of Medical Sciences, Tehran, Iran E-mail :
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Keller J, Schinke T. The role of the gastrointestinal tract in calcium homeostasis and bone remodeling. Osteoporos Int 2013; 24:2737-48. [PMID: 23536255 DOI: 10.1007/s00198-013-2335-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2012] [Accepted: 02/25/2013] [Indexed: 12/11/2022]
Abstract
While skeletal biology was approached in a rather isolated fashion in the past, an increasing understanding of the interplay between extraskeletal organs and bone remodeling has been obtained in recent years. This review will discuss recent advances in the field that have shed light on how the gastrointestinal tract and bone relate to each other. In particular, the importance of the GI tract in maintaining calcium homeostasis and skeletal integrity will be reviewed as impaired gastric acid production represents a major public health problem with possible implications for sufficient calcium absorption. Osteoporosis, the most prevalent bone disease worldwide, is caused not only by intrinsic defects affecting bone cell differentiation and function but also by a large set of extrinsic factors including hormonal disturbances, malnutrition, and iatrogenic drug application. Given the skeletal requirements of calcium, amino acids, and energy for bone turnover and renewal, it is not surprising that the gastrointestinal (GI) tract is of major importance for skeletal integrity.
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Affiliation(s)
- J Keller
- Department of Osteology and Biomechanics, University Medical Center Hamburg-Eppendorf, Martinistr. 52, 20246, Hamburg, Germany
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Osteoinduction of calcium phosphate biomaterials in small animals. MATERIALS SCIENCE & ENGINEERING. C, MATERIALS FOR BIOLOGICAL APPLICATIONS 2013; 33:1254-60. [DOI: 10.1016/j.msec.2012.12.023] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2012] [Revised: 10/05/2012] [Accepted: 12/03/2012] [Indexed: 11/20/2022]
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Lie KK, Moren M. Retinoic acid induces two osteocalcin isoforms and inhibits markers of osteoclast activity in Atlantic cod (Gadus morhua) ex vivo cultured craniofacial tissues. Comp Biochem Physiol A Mol Integr Physiol 2011; 161:174-84. [PMID: 22075542 DOI: 10.1016/j.cbpa.2011.10.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2011] [Revised: 10/24/2011] [Accepted: 10/24/2011] [Indexed: 11/19/2022]
Abstract
Nutritional status including vitamin A could explain some of the developmental deformities observed in cultivated teleosts, including Atlantic cod (Gadus morhua). In the present study we aimed to investigate the transcriptional effect of retinoic acid (RA) on bone related genes using Atlantic cod craniofacial explants tissue cultures. Two different osteoblast specific osteocalcin/bone gla protein isoforms were discovered in cod. Transcription of both isoforms was up-regulated following RA treatment of 65 dph cod lower jaw explants. In contrast, transcripts coding for genes related to bone resorption and osteoclast activity, matrix metalloproteinase 9 and cathepsin K were down-regulated following RA treatment. This could be linked to the decreased transcriptional ratio between receptor activator of nuclear factor kappa-B ligand rankl and osteoprotegerin observed in the same tissue samples. RA treatment of juvenile explants had no effect on runt-related transcription factor 2 and osterix mRNA levels. However, osterix was significantly down-regulated in 25 dph cod head explants following RA treatment. In situ hybridizations revealed differential spatial distribution of the two isoforms and the predominant expression of cathepsin K in bone surrounding tissues. The present study indicates that RA causes a shift in the balance between osteoclast activity and osteoblast activity in favor of the latter.
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Affiliation(s)
- Kai Kristoffer Lie
- National Institute of Nutrition and Seafood Research, Nordnesboder 1-2, N-5005 Bergen, Norway.
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Teven CM, Liu X, Hu N, Tang N, Kim SH, Huang E, Yang K, Li M, Gao JL, Liu H, Natale RB, Luther G, Luo Q, Wang L, Rames R, Bi Y, Luo J, Luu HH, Haydon RC, Reid RR, He TC. Epigenetic regulation of mesenchymal stem cells: a focus on osteogenic and adipogenic differentiation. Stem Cells Int 2011; 2011:201371. [PMID: 21772852 PMCID: PMC3137957 DOI: 10.4061/2011/201371] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Accepted: 04/27/2011] [Indexed: 12/20/2022] Open
Abstract
Stem cells are characterized by their capability to self-renew and terminally differentiate into multiple cell types. Somatic or adult stem cells have a finite self-renewal capacity and are lineage-restricted. The use of adult stem cells for therapeutic purposes has been a topic of recent interest given the ethical considerations associated with embryonic stem (ES) cells. Mesenchymal stem cells (MSCs) are adult stem cells that can differentiate into osteogenic, adipogenic, chondrogenic, or myogenic lineages. Owing to their ease of isolation and unique characteristics, MSCs have been widely regarded as potential candidates for tissue engineering and repair. While various signaling molecules important to MSC differentiation have been identified, our complete understanding of this process is lacking. Recent investigations focused on the role of epigenetic regulation in lineage-specific differentiation of MSCs have shown that unique patterns of DNA methylation and histone modifications play an important role in the induction of MSC differentiation toward specific lineages. Nevertheless, MSC epigenetic profiles reflect a more restricted differentiation potential as compared to ES cells. Here we review the effect of epigenetic modifications on MSC multipotency and differentiation, with a focus on osteogenic and adipogenic differentiation. We also highlight clinical applications of MSC epigenetics and nuclear reprogramming.
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Affiliation(s)
- Chad M Teven
- Molecular Oncology Laboratory, Department of Surgery, The University of Chicago Medical Center, 5841 South Maryland Avenue, Chicago, IL 60637, USA
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Yang Q, Jian J, Abramson SB, Huang X. Inhibitory effects of iron on bone morphogenetic protein 2-induced osteoblastogenesis. J Bone Miner Res 2011; 26:1188-96. [PMID: 21308772 DOI: 10.1002/jbmr.337] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Postmenopausal osteoporosis is characterized by an imbalance of bone resorption exceeding bone formation, resulting in a net loss of bone mineral density (BMD). Estrogen deficiency is known to promote bone resorption. However, the causative factors that impair bone formation have not been identified. Women after menopause experience not only estrogen deficiency but also iron accumulation as a result of cessation of menstruation. In this study we investigated whether increased iron plays a role in osteoporosis. By growing primary mouse osteoclast and osteoblast progenitor cells as well as immortalized cell lines in the presence of iron, we found that increased iron had minimal effects on osteoclast cell differentiation. Interestingly, iron, particularly in its inorganic form, and to a lesser extent ferritin and transferrin all suppressed alkaline phosphatase (ALP) activities in osteoblasts. Moreover, iron downregulated mRNA levels of several other osteoblastogenic markers such as Runx2, osterix, osteopontin, and osteocalcin. To further show that this in vitro finding is relevant to the in vivo condition, we demonstrated that iron-accumulated mice with intact ovaries exhibited a significant decrease in BMD. Although iron inhibited preosteoblast cell differentiation, it did enhance preosteoblast cell proliferation, as evidenced by increased cell growth and expression of cell cycle regulator genes such as CDK4, CDK6, cyclin D1, and cyclin D3 and G(2) /M phase cell population. Taken together, our results suggest that increased iron could be a factor that slows down bone formation in postmenopausal women.
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Affiliation(s)
- Qing Yang
- Department of Environmental Medicine, New York University, School of Medicine, New York, NY 10016, USA
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Zhu MH, Dong WB, Dong GY, Zhang P, Chen YJ, Wu BL, Han H. Disturbed tooth germ development in the absence of MINT in the cultured mouse mandibular explants. Mol Biol Rep 2011; 38:777-84. [PMID: 20393883 DOI: 10.1007/s11033-010-0166-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2009] [Accepted: 03/30/2010] [Indexed: 10/19/2022]
Abstract
The Msx2-interacting nuclear target protein (MINT) is a nuclear matrix protein that regulates the development of many tissues. However, little is known regarding the role of MINT in tooth development. In this study, we prepared polyclonal antibodies against MINT, and found that that MINT was expressed in different cells at each stage of tooth germ development by immunohistochemistry. The role of MINT in tooth development was further illustrated by the misshapen and severely hypoplastic tooth organ in the cultured mandibular explants of MINT deficient mice. From the initiation to cap stage, the differences between mutants and wild-type molars were more and more distinguished histologically. In the MINT-deficient mandibular explants, the tooth germ was reduced in the overall size and lacked enamel knot, with abnormal dental lamina and collapsed stellate reticulum. Furthermore, the BrdU incorporation experiment showed that the proliferation activity was significantly reduced in MINT-deficient dental epithelium. Our results suggest that MINT plays an important role in tooth development, in particular, epithelial morphogenesis.
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Affiliation(s)
- Ming-Hui Zhu
- Department of General and Emergency Dentistry, College of Stomatology, Xian, China
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Mahmoudi T, Karimi K, Mohebbi SR, Fatemi SR, Zali MR. Start codon FokI and intron 8 BsmI variants in the vitamin D receptor gene and susceptibility to colorectal cancer. Mol Biol Rep 2010; 38:4765-70. [PMID: 21132374 DOI: 10.1007/s11033-010-0613-1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2010] [Accepted: 11/25/2010] [Indexed: 10/18/2022]
Abstract
Epidemiological evidence suggests the protective effect of vitamin D against colorectal cancer (CRC) and the polymorphisms in vitamin D receptor (VDR) gene may influence the development of CRC. In this study the possible association of VDR FokI and BsmI gene polymorphisms with CRC risk was examined. A total of 904 subjects, including 452 cases with CRC and 452 controls were enrolled in this study. All 904 subjects were genotyped for VDR FokI and BsmI gene polymorphisms by PCR-RFLP method. We observed no significant difference in genotype and allele frequencies between the cases with CRC and controls for the both FokI and BsmI polymorphisms either before or after adjustment for confounding factors including age, BMI, sex, and smoking status. Furthermore, no evidence for effect modification of the association VDR gene FokI and BsmI variants and CRC by BMI, sex, or tumor site was observed. In addition, there was no significant difference in genotype and allele frequencies between the normal weight (BMI <25 kg/m(2)) cases with CRC and overweight/obese (BMI ≥25 kg/m(2)) cases with CRC for the two SNPs. Our results do not lend support to the hypothesis that VDR gene FokI and BsmI polymorphisms are associated with the risk of CRC. However, further studies are required to confirm this finding.
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Affiliation(s)
- Touraj Mahmoudi
- Department of Cancer, Research Center for Gastroenterology and Liver Diseases (RCGLD), Shahid Beheshti University of Medical Sciences, Velenjak, Shahid Chamran Highway, 1985711151 Tehran, Iran.
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Foresta C, De Toni L, Selice R, Garolla A, Di Mambro A. Increased osteocalcin-positive endothelial progenitor cells in hypogonadal male patients. J Endocrinol Invest 2010; 33:439-42. [PMID: 20671406 DOI: 10.1007/bf03346620] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVE Endothelial dysfunction is considered a key factor in the development of cardiovascular diseases. Endothelial regeneration is necessary for the maintenance of endothelial function and circulating endothelial progenitor cells (EPC) participate of it in both direct and indirect manner. The molecular phenotype of EPC is not univocally defined and recent studies identified an osteocalcin (OCN)-positive (EPC-OCN+) subpopulation of EPC highly correlated with atherosclerosis progression. AIM Considering that hypogonadism is a risk factor for cardiovascular diseases and atherosclerosis, we investigated the circulating levels of EPC-OCN+ in hypogonadal patients. SUBJECTS AND METHODS Ten hypogonadotropic hypogonadal (HH) male patients and 30 healthy eugonadal men were evaluated for clinical status and hormonal levels. Circulating levels of CD34+/CD133+/kinase insert domain-receptor+ EPC and EPC-OCN+ were also determined by flow cytometry. RESULTS Compared to controls, HH patients displayed lower FSH, LH, estradiol, testosterone, and EPC levels. On the contrary, EPC-OCN+ were significantly increased. CONCLUSIONS The observed association of low levels of circulating EPC and increased values of EPC-OCN+ sub-population in hypogonadal men strengthens the significance of hypogonadism as cardiovascular risk factor.
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Affiliation(s)
- C Foresta
- Department of Histology, Microbiology and Medical Biotechnologies, Section of Clinical Pathology and Centre for Male Gamete Cryopreservation, University of Padua, Via Gabelli 63, 35121 Padua, Italy.
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Bahar H, Yaffe A, Boskey A, Binderman I. Influence of bone-derived matrices on generation of bone in an ectopic rat model. J Orthop Res 2010; 28:664-70. [PMID: 19918912 DOI: 10.1002/jor.21017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Most bone regeneration experimental models that test bone-derived matrices take place in conjunction with the native bone. Here, we compared the relative effectiveness of bone matrix components on bone-marrow-directed osteogenesis in an ectopic model. Cortical bone cylinders consisted of diaphysis of DA rat femurs. They were either demineralized (DBM), deproteinized (HABM), or nontreated (MBM). Fresh bone marrow was placed into cylinders and implanted at subcutaneous thoracic sites of 2-month-old DA rats. At designated times the cylinders were surgically removed from the animals. Microradiographs of DBM and histology of DBM and MBM cylinders demonstrated progressive increase in mineralized bone volume and its trabecular configuration. Bone filled the inner volume of DBM and MBM cylinders within 4 weeks, while in HABM cylinders mostly granulation tissue developed. In the DBM cylinders cartilage deposited within 10 days, while in the MBM cylinders bone was directly deposited. As early as day 3 after marrow transplantation, marrow cells interacting with DBM increased significantly the genes that express the cartilage and the bone phenotype. In conclusion, organic components of bone are needed for marrow-directed osteogenesis.
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Affiliation(s)
- H Bahar
- Department of Oral Biology, The Maurice and Gabriela Goldschleger, School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel
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Chesnutt BM, Yuan Y, Buddington K, Haggard WO, Bumgardner JD. Composite chitosan/nano-hydroxyapatite scaffolds induce osteocalcin production by osteoblasts in vitro and support bone formation in vivo. Tissue Eng Part A 2009; 15:2571-9. [PMID: 19309240 DOI: 10.1089/ten.tea.2008.0054] [Citation(s) in RCA: 92] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
There is a significant clinical need to develop alternatives to autografts and allografts for bone grafting procedures. Porous, biodegradable scaffolds based on the biopolymer chitosan have been investigated as bone graft substitutes, and the addition of calcium phosphate to these scaffolds has been shown to improve the mechanical properties of the scaffold and may increase osteoconductivity. In this study, in vitro mineralization was examined for osteoblasts seeded in a porous scaffold composed of fused chitosan/nano-hydroxyapatite microspheres. Human fetal osteoblasts were cultured on composite and chitosan scaffolds for 21 days. On days 1, 4, 7, 14, and 21, total dsDNA, alkaline phosphatase, type I collagen, and osteocalcin production were measured. Total cellularity (measured by dsDNA), alkaline phosphatase, and type I collagen production were similar between the two scaffold groups. However, osteocalcin production occurred significantly earlier (day 7 vs. day 21) and was more than three times greater (0.0022 vs. 0.0068 ng/mL/ng DNA) on day 21 when osteoblasts were cultured on composite scaffolds. Osteocalcin is a marker of late osteoblastic differentiation and mineralized bone matrix formation. Therefore, the increase in osteocalcin production seen when cells were cultured on composite scaffolds may indicate that these scaffolds were superior to chitosan-only scaffolds in facilitating osteoblast mineralization. Composite scaffolds were also shown to be biocompatible and osteoconductive in a preliminary critical size rat calvarial defect study. These results demonstrate the potential of composite chitosan/nano-hydroxyapatite scaffolds to be used in bone tissue engineering.
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Affiliation(s)
- Betsy M Chesnutt
- Department of Biomedical Engineering, University of Memphis, Memphis, Tennessee 38152, USA
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Reichert JC, Heymer A, Berner A, Eulert J, Nöth U. Fabrication of polycaprolactone collagen hydrogel constructs seeded with mesenchymal stem cells for bone regeneration. Biomed Mater 2009; 4:065001. [DOI: 10.1088/1748-6041/4/6/065001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Yin D, Wang Z, Gao Q, Sundaresan R, Parrish C, Yang Q, Krebsbach PH, Lichtler AC, Rowe DW, Hock J, Liu P. Determination of the fate and contribution of ex vivo expanded human bone marrow stem and progenitor cells for bone formation by 2.3ColGFP. Mol Ther 2009; 17:1967-78. [PMID: 19603005 DOI: 10.1038/mt.2009.151] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Bone marrow transplantation can provide an effective cell-based strategy to enhance bone repair. However, the fate of implanted cells and the extent of their contribution to bone osteoinduction remain uncertain. To define the fate of bone marrow-derived cells and their contribution in vivo, we used a bone-specific collagen I promoter (2.3Col) driving green fluorescent protein (GFP) (2.3ColGFP) within a lentiviral vector. Prior to in vivo cell fate determination, we verified a high efficiency of lentiviral transduction in human bone marrow stromal cells (hBMSCs), without altering the proliferation or differentiation potential of these cells. We showed that the 2.3ColGFP marker responded to endogenous transcriptional regulation signals. In a mouse ossicle model, we demonstrated that the 2.3ColGFP marker is able to specifically define human bone marrow-derived stem cells that enter the osteoblast lineage in vivo. In addition, cells labeled with 2.3ColGFP with the donor origin, directly make a major contribution to bone formation. Furthermore, we also demonstrated in a calvarial defect model that a mixture of human bone marrow-derived populations, have stronger bone regenerative potential than that of hBMSCs, and an optimal dose is required for bone regeneration by the mixed populations.
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Affiliation(s)
- Dezhong Yin
- Aastrom Biosciences Inc., Ann Arbor, Michigan 48105, USA
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Wu M, Hesse E, Morvan F, Zhang JP, Correa D, Rowe GC, Kiviranta R, Neff L, Philbrick WM, Horne WC, Baron R. Zfp521 antagonizes Runx2, delays osteoblast differentiation in vitro, and promotes bone formation in vivo. Bone 2009; 44:528-36. [PMID: 19095088 PMCID: PMC2746087 DOI: 10.1016/j.bone.2008.11.011] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/25/2008] [Revised: 11/04/2008] [Accepted: 11/05/2008] [Indexed: 01/23/2023]
Abstract
Zfp521, a 30 C2H2 Kruppel-like zinc finger protein, is expressed at high levels at the periphery of early mesenchymal condensations prefiguring skeletal elements and in all developing bones in the perichondrium and periosteum, in osteoblast precursors and osteocytes, and in chondroblast precursors and growth plate prehypertrophic chondrocytes. Zfp521 expression in cultured mesenchymal cells is decreased by BMP-2 and increased by PTHrP, which promote and antagonize osteoblast differentiation, respectively. In vitro, Zfp521 overexpression reduces the expression of several downstream osteoblast marker genes and antagonizes osteoblast differentiation. Zfp521 binds Runx2 and represses its transcriptional activity, and Runx2 dose-dependently rescues Zfp521's inhibition of osteoblast differentiation. In contrast, osteocalcin promoter-targeted overexpression of Zfp521 in osteoblasts in vivo results in increased bone formation and bone mass. We propose that Zfp521 regulates the rate of osteoblast differentiation and bone formation during development and in the mature skeleton, in part by antagonizing Runx2.
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Affiliation(s)
- Meilin Wu
- Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | - Eric Hesse
- Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Harvard School of Dental Medicine and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Frederic Morvan
- Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | - Jian-Ping Zhang
- Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | - Diego Correa
- Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Harvard School of Dental Medicine and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Glenn C. Rowe
- Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Harvard School of Dental Medicine and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Riku Kiviranta
- Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Harvard School of Dental Medicine and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Lynn Neff
- Yale University School of Medicine, New Haven, Connecticut 06510, USA
| | | | - William C. Horne
- Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Harvard School of Dental Medicine and Harvard Medical School, Boston, Massachusetts 02115, USA
| | - Roland Baron
- Yale University School of Medicine, New Haven, Connecticut 06510, USA
- Harvard School of Dental Medicine and Harvard Medical School, Boston, Massachusetts 02115, USA
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19
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Ahlström M, Pekkinen M, Lamberg-Allardt C. Dexamethasone downregulates the expression of parathyroid hormone-related protein (PTHrP) in mesenchymal stem cells. Steroids 2009; 74:277-82. [PMID: 19121329 DOI: 10.1016/j.steroids.2008.12.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2008] [Revised: 10/28/2008] [Accepted: 12/04/2008] [Indexed: 11/26/2022]
Abstract
Parathyroid hormone-related protein (PTHrP) has been shown to have anabolic effects in women with postmenopausal osteoporosis. PTHrP promotes the recruitment of osteogenic cells and prevents apoptotic death of osteoblasts and osteocytes. The receptor responsible for the effects of PTHrP is the common PTH/PTHrP receptor (PTH1R). Glucocorticoids (GC) are commonly used as drugs to treat inflammatory diseases. Long-term GC treatments are often associated with bone loss which can lead to GC-induced osteoporosis. The aim of this work was to study the effects of the glucocorticoid dexamethasone (Dex) on the expression of PTHrP and PTH1R in adult human mesenchymal stem cells, the progenitor cells of osteoblasts. Adult human mesenchymal stem cells (hMSC) were cultured and differentiated by standard methods. The expression of PTHrP and PTH1R mRNA was assayed by real-time qPCR. The PTHrP release into the culture media was measured by an immunoradiometric assay. Treatment with Dex (10 nM) resulted in an 80% drop in the PTHrP release within 6 h. A 24 h Dex treatment also reduced the expression of PTHrP mRNA by up to 90%. The expression of PTH1R receptor mRNA was simultaneously increased up to 20-fold by 10 nM Dex. The effects of Dex on PTHrP and PTH1R were dose-dependent and experiments with the GC-receptor antagonist mifepristone showed an involvement of GC-receptors in these effects. In addition to the Dex-induced effects on PTHrP and PTH1R, Dex also increased mineralization and the expression of the osteoblast markers Runx2 and alkaline phosphatase. In our studies, we show that dexamethasone decreases the expression of PTHrP and increases the expression of the PTH1R receptor. This could have an impact on PTHrP-mediated anabolic actions on bone and could also affect the responsiveness of circulating PTH. The results indicate that glucocorticoids affect the signalling pathway of PTHrP by regulating both PTHrP and PTH1R expression and these mechanisms could be involved in glucocorticoid-induced osteoporosis.
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Affiliation(s)
- Mikael Ahlström
- Calcium Research Unit, Department of Applied Chemistry and Microbiology, P.O. Box 66, 00014 University of Helsinki, Finland.
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20
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Benayahu D, Shefer G, Shur I. Insights into the transcriptional and chromatin regulation of mesenchymal stem cells in musculo-skeletal tissues. Ann Anat 2008; 191:2-12. [PMID: 18926677 DOI: 10.1016/j.aanat.2008.07.008] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Revised: 07/23/2008] [Accepted: 07/23/2008] [Indexed: 11/18/2022]
Abstract
Utilizing adult stem cells for regenerative medicine of skeletal tissues requires the development of molecular and biochemical tools that will allow isolation of these cells and direction of their differentiation towards a desired lineage and tissue formation. Stem cell commitment and fate decision into specialized functional cells involve coordinated activation and silencing of lineage-specific genes. Transcription factors and chromatin-remodeling proteins are key players in the control process of lineage commitment and differentiation during embryogenesis and adulthood. Transcription factors act in cooperation with co-regulator proteins to generate tissue-specific responses that elicits the tissue specific gene expression. Consequently, one of the main challenges of today's research is to characterize molecular pathways that coordinate the lineage-specific differentiation. Epigenetic regulation includes chromatin remodeling that control structural changes of DNA required for the binding of transcription factors to promoter regions. Revealing the mechanisms of action of such factors will provide understanding of how transcription and chromatin regulatory factors function together to regulate stem cell lineage fate decision.
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Affiliation(s)
- Dafna Benayahu
- Department of Cell and Developmental Biology, Sackler School of Medicine, Tel-Aviv University, Tel-Aviv 69978, Israel.
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21
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Yu S, Franceschi RT, Luo M, Zhang X, Jiang D, Lai Y, Jiang Y, Zhang J, Xiao G. Parathyroid hormone increases activating transcription factor 4 expression and activity in osteoblasts: requirement for osteocalcin gene expression. Endocrinology 2008; 149:1960-8. [PMID: 18187540 PMCID: PMC2276723 DOI: 10.1210/en.2007-1573] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
PTH is an important peptide hormone regulator of calcium homeostasis and osteoblast function. However, its mechanism of action in osteoblasts is poorly understood. Our previous study demonstrated that PTH activates mouse osteocalcin (Ocn) gene 2 promoter through the osteoblast-specific element 1 site, a recently identified activating transcription factor-4 (ATF4) -binding element. In the present study, we examined effects of PTH on ATF4 expression and activity as well as the requirement for ATF4 in the regulation of Ocn by PTH. Results show that PTH elevated levels of ATF4 mRNA and protein in a dose- and time-dependent manner. This PTH regulation requires transcriptional activity but not de novo protein synthesis. PTH also increased binding of nuclear extracts to osteoblast-specific element 1 DNA. PTH stimulated ATF4-dependent transcriptional activity mainly through protein kinase A with a lesser requirement for protein kinase C and MAPK/ERK pathways. Lastly, PTH stimulation of Ocn expression was lost by small interfering RNA down-regulation of ATF4 in MC-4 cells and Atf4(-/-) bone marrow stromal cells. Collectively, these studies for the first time demonstrate that PTH increases ATF4 expression and activity and that ATF4 is required for PTH induction of Ocn expression in osteoblasts.
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Affiliation(s)
- Shibing Yu
- Division of Hematology/Oncology, Department of Medicine, University of Pittsburgh, Pittsburgh, PA 15240, USA
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22
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Yu S, Jiang Y, Galson DL, Luo M, Lai Y, Lu Y, Ouyang HJ, Zhang J, Xiao G. General transcription factor IIA-gamma increases osteoblast-specific osteocalcin gene expression via activating transcription factor 4 and runt-related transcription factor 2. J Biol Chem 2008; 283:5542-53. [PMID: 18171674 DOI: 10.1074/jbc.m705653200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
ATF4 (activating transcription factor 4) is an osteoblast-enriched transcription factor that regulates terminal osteoblast differentiation and bone formation. ATF4 knock-out mice have reduced bone mass (severe osteoporosis) throughout life. Runx2 (runt-related transcription factor 2) is a runt domain-containing transcription factor that is essential for bone formation during embryogenesis and postnatal life. In this study, we identified general transcription factor IIA gamma (TFIIA gamma) as a Runx2-interacting factor in a yeast two-hybrid screen. Immunoprecipitation assays confirmed that TFIIA gamma interacts with Runx2 in osteoblasts and when coexpressed in COS-7 cells or using purified glutathione S-transferase fusion proteins. Chromatin immunoprecipitation assay of MC3T3-E1 (clone MC-4) preosteoblast cells showed that in intact cells TFIIA gamma is recruited to the region of the osteocalcin promoter previously shown to bind Runx2 and ATF4. A small region of Runx2 (amino acids 258-286) was found to be required for TFIIA gamma binding. Although TFIIA gamma interacts with Runx2, it does not activate Runx2. Instead, TFIIA gamma binds to and activates ATF4. Furthermore, TFIIA gamma together with ATF4 and Runx2 stimulates osteocalcin promoter activity and endogenous mRNA expression. Small interfering RNA silencing of TFIIA gamma markedly reduces levels of endogenous ATF4 protein and Ocn mRNA in osteoblastic cells. Overexpression of TFIIA gamma increases levels of ATF4 protein. Finally, TFIIA gamma significantly prevents ATF4 degradation. This study shows that a general transcription factor, TFIIA gamma, facilitates osteoblast-specific gene expression through interactions with two important bone transcription factors ATF4 and Runx2.
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Affiliation(s)
- Shibing Yu
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania 15240, USA
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23
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Lallier TE, Spencer A, Fowler MM. Transcript Profiling of Periodontal Fibroblasts and Osteoblasts. J Periodontol 2005; 76:1044-55. [PMID: 16018745 DOI: 10.1902/jop.2005.76.7.1044] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND Fibroblasts are critical to the establishment and maintenance of the periodontal attachment apparatus (cementum, periodontal ligament [PDL], and bone). In order to characterize the cellular changes that accompany periodontal regeneration, better tools are necessary to distinguish periodontal ligament fibroblasts (PDLF), gingival fibroblasts, and osteoblasts. Our goal is to identify gene markers to better characterize and identify these cell types. METHODS We chose to examine and compare the expression of numerous gene transcripts by semiquantitative reverse transcriptase-polymerase chain reaction using primers specific for 44 different gene transcripts in order to better characterize the identity of these cells. RESULTS Several transcripts were cell-type specific. Specifically, fibromodulin was expressed only in PDL fibroblasts, while osteopontin was expressed only in dermal fibroblasts. In addition, lumican was expressed by all three types of fibroblasts (PDL, gingival, and dermal), while alkaline phosphatase was expressed by osteoblasts as well as PDL and gingival fibroblasts. CONCLUSIONS Our results indicate that PDL fibroblasts are distinct from either gingival or dermal fibroblasts or osteoblasts. In general, PDL and gingival fibroblasts displayed greater similarity to each other than either displayed toward dermal fibroblasts. Furthermore, both gingival and PDL fibroblasts displayed greater similarity to osteoblasts than to dermal fibroblasts, possibly reflecting their common origin (the neural crest).
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Affiliation(s)
- Thomas E Lallier
- Center of Excellence in Oral and Craniofacial Biology, Department of Cell Biology and Anatomy, School of Dentistry, Louisiana State University Health Sciences Center, 1100 Florida Avenue, New Orleans, LA 70119, USA.
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24
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Wiesmann HP, Nazer N, Klatt C, Szuwart T, Meyer U. Bone tissue engineering by primary osteoblast-like cells in a monolayer system and 3-dimensional collagen gel. J Oral Maxillofac Surg 2004; 61:1455-62. [PMID: 14663811 DOI: 10.1016/j.joms.2003.05.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To engineer living bone tissue in vitro, bone cells must be multiplied and differentiated in cell culture. Osteoblasts are known to be the crucial cells responsible for the bone modeling process. Periosteal-derived osteoblasts were therefore cultured for up to 3 weeks in Petri dishes as well as in a 3-dimensional collagen gel. METHODS Proliferation, migration, and differentiation of cells as well as the synthesis of extracellular matrix proteins were monitored during the culture period by histology, electron microscopy, and immunohistochemistry. Mineral formation was investigated by electron diffraction studies and element analysis. RESULTS Osteoblasts proliferated and migrated in Petri dishes as well as in the collagen gel without loss of viability during the whole experimental period. They demonstrated a mature osteoblast phenotype as indicated by the synthesis of a bone-like extracellular matrix. They formed an extracellular matrix containing osteocalcin, osteonectin, and newly synthesized collagen type I in both environments. Mineral formation was seen in colocalization with the bone-like extracellular matrix proteins in Petri dishes. Microanalytical investigations revealed a matrix vesicle-mediated mineral formation at early stages of culture. CONCLUSIONS Our cell culture confirmed the ability to multiplicate differentiated and viable osteoblast-like cells in 2- and 3-dimensional space. Additionally, bone-like mineralization can be induced by primary osteoblasts in monolayer culture. The data suggest that this approach can be used as a tool in bone tissue engineering.
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Affiliation(s)
- Hans Peter Wiesmann
- Klinik and Poliklinik für Mund und Kiefer-Gesichtschirurgie, Universitäatklinikum Münster, Germany.
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25
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Reddi AH, Roodman D, Freeman C, Mohla S. Mechanisms of tumor metastasis to the bone: challenges and opportunities. J Bone Miner Res 2003; 18:190-4. [PMID: 12568395 DOI: 10.1359/jbmr.2003.18.2.190] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In human cancers, bone is a common site for metastasis. It is well known that metastasis is the cause of morbidity and mortality in patients with cancer. Both breast and prostate carcinomas have a propensity to metastasize to bone. In general, metastatic breast cancers result in osteolytic lesions. On the other hand, prostate cancer metastases are osteoblastic and result in osteosclerosis. Thus, bone formation and bone resorption are at the crux of the cancer metastasis problem. For example, in the prostate, there is a vicious cycle of metastasis to bone (Fig. 1). Metastases to bone causes excruciating bone pain, pathological fractures, and eventually death, and therefore is a serious challenge to both bone biologists and cancer cell biologists. The stromal-epithelial interactions in breast and prostate are critical in initiation of carcinogenesis and the progression of the metastatic cascade to bone (Fig. 2). Over a hundred years ago, Stephen Paget enunciated the seed and soil hypothesis in which seeds of metastatic cancer cells of breast preferentially settle in the soil of bone matrix. Thus, the prostate/breast cancer bone interface and continuum has continuously presented challenges and opportunities and were discussed at a recent workshop.
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Affiliation(s)
- A Hari Reddi
- Center for Tissue Regeneration and Repair, University of California, School of Medicine, Sacramento, California 95817, USA.
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26
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Steinbrech DS, Mehrara BJ, Rowe NM, Dudziak ME, Luchs JS, Saadeh PB, Gittes GK, Longaker MT. Gene expression of TGF-beta, TGF-beta receptor, and extracellular matrix proteins during membranous bone healing in rats. Plast Reconstr Surg 2000; 105:2028-38. [PMID: 10839400 DOI: 10.1097/00006534-200005000-00018] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Poorly healing mandibular fractures and osteotomies can be troublesome complications of craniomaxillofacial trauma and reconstructive surgery. Gene therapy may offer ways of enhancing bone formation by altering the expression of desired growth factors and extracellular matrix molecules. The elucidation of suitable candidate genes for therapeutic intervention necessitates investigation of the endogenously expressed patterns of growth factors during normal (i.e., successful) fracture repair. Transforming growth factor beta1 (TGF-beta1), its receptor (Tbeta-RII), and the extracellular matrix proteins osteocalcin and type I collagen are thought to be important in long-bone (endochondral) formation, fracture healing, and osteoblast proliferation. However, the spatial and temporal expression patterns of these molecules during membranous bone repair remain unknown. In this study, 24 adult rats underwent mandibular osteotomy with rigid external fixation. In addition, four identically treated rats that underwent sham operation (i.e., no osteotomy) were used as controls. Four experimental animals were then killed at each time point (3, 5, 7, 9, 23, and 37 days after the procedure) to examine gene expression of TGF-beta1 and Tbeta-RII, osteocalcin, and type I collagen. Northern blot analysis was used to compare gene expression of these molecules in experimental animals with that in control animals (i.e., nonosteotomized; n = 4). In addition, TGF-beta1 and T-RII proteins were immunolocalized in an additional group of nine animals killed on postoperative days 3, 7, and 37. The results of Northern blot analysis demonstrated a moderate increase (1.7 times) in TGF-beta1 expression 7 days postoperatively; TGF-beta1 expression returned thereafter to near baseline levels. Tbeta-RII mRNA expression was downregulated shortly after osteotomy but then increased, reaching a peak of 1.8 times the baseline level on postoperative day 9. Osteocalcin mRNA expression was dramatically downregulated shortly after osteotomy and remained low during the early phases of fracture repair. Osteocalcin expression trended slowly upward as healing continued, reaching peak expression by day 37 (1.7 times the control level). In contrast, collagen type IalphaI mRNA expression was acutely downregulated shortly after osteotomy, peaked on postoperative days 5, and then decreased at later time points. Histologic samples from animals killed 3 days after osteotomy demonstrated TGF-beta1 protein localized to inflammatory cells and extracellular matrix within the fracture gap, periosteum, and peripheral soft tissues. On postoperative day 7, TGF-beta1 staining was predominantly localized to the osteotomized bone edges, periosteum, surrounding soft tissues, and residual inflammatory cells. By postoperative day 37, complete bony healing was observed, and TGF-beta1 staining was localized to the newly formed bone matrix and areas of remodeling. On postoperative day 3, Tbeta-RII immunostaining localized to inflammatory cells within the fracture gap, periosteal cells, and surrounding soft tissues. By day 7, Tbeta-RII staining localized to osteoblasts of the fracture gap but was most intense within osteoblasts and mesenchymal cells of the osteotomized bone edges. On postoperative day 37, Tbeta-RII protein was seen in osteocytes, osteoblasts, and the newly formed periosteum in the remodeling bone. These observations agree with those of previous in vivo studies of endochondral bone formation, growth, and healing. In addition, these results implicate TGF-beta1 biological activity in the regulation of osteoblast migration, differentiation, and proliferation during mandibular fracture repair. Furthermore, comparison of these data with gene expression during mandibular distraction osteogenesis may provide useful insights into the treatment of poorly healing fractures because distraction osteogenesis has been shown to be effective in the management of these difficult clinical cases.
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Affiliation(s)
- D S Steinbrech
- Institute of Reconstructive Plastic Surgery, and the Department of Surgery, New York University Medical Center, NY 10016, USA
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27
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Christiansen M, Kveiborg M, Kassem M, Clark BF, Rattan SI. CBFA1 and topoisomerase I mRNA levels decline during cellular aging of human trabecular osteoblasts. J Gerontol A Biol Sci Med Sci 2000; 55:B194-200. [PMID: 10811146 DOI: 10.1093/gerona/55.4.b194] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In order to understand the reasons for age-related impairment of the function of bone forming osteoblasts, we have examined the steady-state mRNA levels of the transcription factor CBFA1 and topoisomerase I during cellular aging of normal human trabecular osteoblasts, by the use of semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR). There is a progressive and significant reduction of the CBFA1 steady-state mRNA level down to 50% during cellular aging of human osteoblasts. In comparison to the normal cells, human osteosarcoma cell lines SaOS-2 and KHOS/NP, and the SV40-transformed human lung fibroblast cell line MRC5V2 have 20 to 40% higher levels of CBFA1 mRNA. Similar levels of CBFA1 mRNA are detectable in normal human skin fibroblasts, and these cells also exhibit an age-related decline to the same extent. In addition, the expression of topoisomerase I is reduced by 40% in senescent osteoblasts, and the mRNA levels are significantly higher (40-70%) in transformed osteoblasts and fibroblasts. These changes in gene expression may be among the causes of impaired osteoblast functions, resulting in reduced bone formation during aging.
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Affiliation(s)
- M Christiansen
- Danish Centre for Molecular Gerontology, Department of Molecular and Structural Biology, University of Aarhus, Denmark
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28
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Afroze T, Husain M. c-Myb-binding sites mediate G(1)/S-associated repression of the plasma membrane Ca(2+)-ATPase-1 promoter. J Biol Chem 2000; 275:9062-9. [PMID: 10722757 DOI: 10.1074/jbc.275.12.9062] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
We demonstrate that two Myb-binding sites of the mouse plasma membrane Ca(2+)-ATPase-1 (PMCA1) promoter are required for G(1)/S cell cycle stage-associated repression of PMCA1 promoter activity. Nuclear run-on experiments revealed G(1)/S-associated repression of PMCA1 transcription. Ribonuclease protection assays revealed two transcription initiation sites between two Myb-binding sites in the PMCA1 promoter. Gel shift assays showed that c-Myb can bind to wild-type but not point mutated Myb binding sequences of the PMCA1 promoter. Transient transfection assays using cell cycle-synchronized vascular smooth muscle cells (VSMC) and PMCA1 promoter-luciferase constructs showed a 2-fold decrease in reporter activity at G(1)/S as compared with G(0). Overexpression of wild-type c-Myb severely repressed PMCA1 promoter activity at both G(0) and G(1)/S while co-transfection of a dominant negative c-Myb, or a construct encoding an anti-c-Myb neutralizing antibody, completely abolished the repression seen at G(1)/S. Single nucleotide substitutions in the first, second, or both Myb-binding sites alleviated the G(1)/S-associated repression of PMCA1 promoter activity in transformed rat VSMC and primary mouse VSMC cultures. We conclude that c-Myb mediates G(1)/S-associated transcriptional repression of the PMCA1 Ca(2+) pump in rodent VSMC by direct binding to the PMCA1 promoter.
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Affiliation(s)
- T Afroze
- Centre for Cardiovascular Research, Toronto General Hospital, Toronto, Ontario, Canada
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29
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Javed A, Gutierrez S, Montecino M, van Wijnen AJ, Stein JL, Stein GS, Lian JB. Multiple Cbfa/AML sites in the rat osteocalcin promoter are required for basal and vitamin D-responsive transcription and contribute to chromatin organization. Mol Cell Biol 1999; 19:7491-500. [PMID: 10523637 PMCID: PMC84749 DOI: 10.1128/mcb.19.11.7491] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Three Cbfa motifs are strategically positioned in the bone-specific rat osteocalcin (rOC) promoter. Sites A and B flank the vitamin D response element in the distal promoter and sites B and C flank a positioned nucleosome in the proximal promoter. The functional significance of each Cbfa element was addressed by mutating individual or multiple Cbfa sites within the context of the -1.1-kb rOC promoter fused to a chloramphenicol acetyltransferase reporter gene. Promoter activity was assayed following transient transfection and after stable genomic integration in ROS 17/2.8 osteoblastic cell lines. We show that all three Cbfa sites are required for maximal basal expression of the rOC promoter. However, the distal sites A and B each contribute significantly more (P < 0.001) to promoter activity than site C. In a genomic context, sites A and B can largely compensate for a mutation at the proximal site C, and paired mutations involving site A (mAB or mAC) result in a far greater loss of activity than the mBC mutation. Strikingly, mutation of the three Cbfa sites leads to abrogation of responsiveness to vitamin D. Vitamin D-enhanced activity is also not observed when sites A and B are mutated. Significantly, related to these losses in transcriptional activity, mutation of the three Cbfa sites results in altered chromatin structure as reflected by loss of DNase I-hypersensitive sites at the vitamin D response element and over the proximal tissue-specific basal promoter. These findings strongly support a multifunctional role for Cbfa factors in regulating gene expression, not only as simple transcriptional transactivators but also by facilitating modifications in promoter architecture and chromatin organization.
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Affiliation(s)
- A Javed
- Department of Cell Biology, University of Massachusetts Medical School, Worcester, Massachusetts 01655-0106, USA
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30
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Camacho NP, Rinnerthaler S, Paschalis EP, Mendelsohn R, Boskey AL, Fratzl P. Complementary information on bone ultrastructure from scanning small angle X-ray scattering and Fourier-transform infrared microspectroscopy. Bone 1999; 25:287-93. [PMID: 10495132 DOI: 10.1016/s8756-3282(99)00165-9] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Scanning small angle X-ray scattering (scanning SAXS) and Fourier-transform infrared microspectroscopy (FT-IRM) have previously been utilized independently to characterize the structural properties of bone in an anatomical position-resolved fashion. Whereas SAXS provides a direct measure of the physical characteristics of apatitic crystals, FT-IRM assesses structure of both mineral and organic matrix at the molecular level. In the present study both methods were applied to examine the same developing bone tissue from the L-4 vertebra of a 14-month-old (accidental death). A 200-microm-thick section was processed for examination by scanning electron microscopy and SAXS. Spectra were collected at 200 microm spatial resolution at specific locations in cortical and cancellous bone. Parameters determined included total SAXS intensity, crystal thickness (T), and degree and direction of predominant crystal orientation. For FT-IRM analysis, a section 4 microm thick was cut longitudinally from the top of the sample. Spectra of regions 100 x 100 microm2 were acquired from the same locations as the SAXS spectra. Integrated areas of the phosphate nu(1,3) collagen amide I, and carbonate nu2 absorbances, were calculated to obtain mineral: matrix and carbonate:mineral ratios. The relative quantities of types A, B, and labile carbonate (substituted for apatite hydroxyl, phosphate, and surface positions, respectively) were also evaluated. Polarized FT-IRM data were collected to determine molecular orientation of the apatite and collagen components. The results of this study show that the information obtained from the two techniques is complementary. Both SAXS and FT-IRM data revealed that the crystals were significantly larger in the cancellous region compared with the cortical region, that mineralization was greater in the cortex, and that the crystals were oriented to a larger degree in the cancellous compared with the cortical bone. The scanning SAXS measure of crystal thickness was significantly correlated to the FT-IRM measures of crystallinity, type A carbonate substitution, and crystal orientation. In conclusion, it was found that the combined use of SAXS and FT-IRM provides valuable, unique information on structural changes in bone at both the microstructural and ultrastructural level. Although each method can be used individually, the combination of techniques provides additional insights into the mechanism of bone crystal maturation.
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Affiliation(s)
- N P Camacho
- Hospital for Special Surgery, Research Division, New York, NY, USA
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31
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Davie JR, Samuel SK, Spencer VA, Holth LT, Chadee DN, Peltier CP, Sun JM, Chen HY, Wright JA. Organization of chromatin in cancer cells: role of signalling pathways. Biochem Cell Biol 1999. [DOI: 10.1139/o99-044] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The role of mechanical and chemical signalling pathways in the organization and function of chromatin is the subject of this review. The mechanical signalling pathway consists of the tissue matrix system that links together the three-dimensional skeletal networks, the extracellular matrix, cytoskeleton, and nuclear matrix. Intermediate filament proteins are associated with nuclear DNA, suggesting that intermediate filaments may have a role in the organization of chromatin. In human hormone-dependent breast cancer cells, the interaction between cytokeratins and chromatin is regulated by estrogens. Transcription factors, histone acetyltransferases, and histone deacetylases, which are associated with the nuclear matrix, are components of the mechanical signalling pathway. Recently, we reported that nuclear matrix-bound human and chicken histone deacetylase 1 is associated with nuclear DNA in situ, suggesting that histone deacetylase has a role in the organization of nuclear DNA. Chemical signalling pathways such as the Ras/mitogen-activated protein kinase (Ras/MAPK) pathway stimulate the activity of kinases that modify transcription factors, nonhistone chromosomal proteins, and histones. The levels of phosphorylated histones are increased in mouse fibroblasts transformed with oncogenes, the products of which stimulate the Ras/MAPK pathway. Histone phosphorylation may lead to decondensation of chromatin, resulting in aberrant gene expression.Key words: histone acetylation, histone phosphorylation, nuclear matrix, cytoskeleton, histone deacetylase, cancer.
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Affiliation(s)
- T J Barrett
- Department of Biochemistry and Molecular Biology, Mayo Clinic, Rochester, Minnesota 55905, USA
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Abstract
Recent advances highlight the involvement of histone acetyltransferases in transcriptional activation and histone deacetylases in transcriptional repression. Transcription factors loaded onto regulatory DNA elements may recruit either coactivators with histone acetyltransferase activity or corepressors associated with histone deacetylases. The recruited enzymes may either acetylate or deacetylate proximal nucleosomal histones or nonhistone chromosomal proteins.
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Affiliation(s)
- J R Davie
- Department of Biochemistry and Molecular Biology, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
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