Indiana University-Purdue University Indianapolis (IUPUI) / Signal Transducers and Activators of Transcription 3 (STAT3), a transcription factor expressed in many cell types, including osteoblasts and osteoclasts, is emerging as a key regulator of bone mass and strength. STAT3 mutations cause a rare human immunodeficiency disease characterized by extremely elevated levels of IgE in serum that have associated craniofacial and skeletal features, such as reduced bone mineral density and recurrent pathological fractures. Our microarray data and immunohistochemical staining using a normal rat model have shown that STAT3 mRNA and protein levels markedly increase in response to mechanical loading. In addition, as indicated by STAT3 phosphorylation in MC3T3-E1 osteoblastic cells, STAT3 activity significantly increases in response to 30 to 90 minutes fluid shear stress. In order to further study the role that STAT3 plays in bone responsiveness to loading, tissue-selective STAT3 knockout (KO) mice, in which inactivation of STAT3 occurs in osteoblasts, were generated by breeding the transgenic mice in which Cre recombinase cDNA was cloned downstream of a 3.6 or 2.3 kb fragment of the rat Col1a1 promoter (Col3.6-Cre and Col2.3-Cre, respectively) with a strain of floxed mice in which the two loxP sites flank exons 18-20 of the STAT3 gene were used. Mice engineered with bone selective inactivation of STAT3 in osteoblasts exhibited significantly lower bone mineral density (7-12%, p<0.05) and reduced ultimate force (21-34%, p<0.01) compared to their age-matched littermate controls. The right ulnae of 16-week-old bone specific STAT3 KO mice and the age-matched control mice were loaded with peak forces of 2.5 N and 2.75 N for female and male mice, respectively, at 2 Hz, 120 cycles/day for 3 consecutive days. Mice with inactivation of STAT3 specific in bone were significantly less responsive to mechanical loading than the control mice as indicated by decreased relative mineralizing surface (rMS/BS, 47-59%, p<0.05) and relative bone formation rate (rBFR/BS, 64-75%, p<0.001). Bone responsiveness was equally decreased in mice in which STAT3 is inactivated either in early osteoblasts (Col3.6-Cre) or in mature osteoblasts (Col2.3-Cre). Accumulating evidence indicates that bone metabolism is significantly affected by activities in mitochondria. For instance, although STAT3 is reported to be involved in bone formation and resorption through regulation of nuclear genes, inactivation of STAT3 is shown to disrupt mitochondrial activities and result in an increased level of reactive oxygen species (ROS). Inactivation of STAT3 suppressed load-driven mitochondrial activity, which led to an elevated level of ROS in cultured primary osteoblasts. Oxidative stress induced by administration of buthionine sulfoximine (BSO) significantly inhibits load-induced bone formation in wild type mice. Taken together, the results support the notion that the loss-of-function mutation of STAT3 in osteoblasts and osteocytes diminishes load-driven bone formation and impairs the regulation of oxidative stress in mitochondria.

Wong Yin-Mei. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 119-135). / Abstracts in English and Chinese. / Abstract (English version) --- p.i / Abstract (Chinese version) --- p.iii / Publications --- p.v / Acknowledgements --- p.vi / Table of contents --- p.viii / List of tables --- p.xi / List of figures --- p.xii / Abbreviations --- p.xiv / Chapter Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Osteoporosis --- p.1 / Chapter 1.1.1 --- Consensus statement --- p.1 / Chapter 1.1.2 --- Epidemiology and outcomes --- p.4 / Chapter 1.1.2.1 --- Hip fractures --- p.4 / Chapter 1.1.2.2 --- Vertebral fractures --- p.5 / Chapter 1.1.2.3 --- Wrist fractures --- p.7 / Chapter 1.1.3 --- Postmenopausal osteoporosis --- p.8 / Chapter 1.1.3.1 --- Pathogenesis --- p.8 / Chapter 1.1.3.1.1 --- Genetics --- p.11 / Chapter 1.1.3.1.2 --- Bone remodeling --- p.14 / Chapter 1.1.3.1.3 --- Calcium homeostasis --- p.21 / Chapter 1.1.3.1.4 --- Life style 一 nutrition and exercise --- p.26 / Chapter 1.1.3.2 --- Current pharmacological treatment --- p.27 / Chapter 1.1.3.2.1 --- Introduction --- p.27 / Chapter 1.1.3.2.2 --- Limitations --- p.31 / Chapter 1.2 --- Traditional Chinese medicine --- p.33 / Chapter 1.2.1 --- The Kidney --- p.33 / Chapter 1.2.2 --- Kidney-tonifying herbs --- p.33 / Chapter 1.3 --- Aim of the studies --- p.36 / Chapter Chapter 2. --- Materials and methods --- p.38 / Chapter 2.1 --- Kidney-tonifying herbs and herbal formula --- p.38 / Chapter 2.1.1 --- Sources --- p.38 / Chapter 2.1.2 --- Herbal extract preparation --- p.38 / Chapter 2.2 --- Animal study --- p.40 / Chapter 2.2.1 --- Reagents --- p.40 / Chapter 2.2.2 --- Animal care --- p.40 / Chapter 2.2.3 --- Herbs and herbal formula preparations for animal studies --- p.41 / Chapter 2.2.4 --- Experimental design --- p.41 / Chapter 2.2.5 --- Gene expression study --- p.44 / Chapter 2.2.5.1 --- Tissue preparation --- p.44 / Chapter 2.2.5.2 --- Isolation of total RNA --- p.45 / Chapter 2.2.5.3 --- Complementary DNA synthesis --- p.47 / Chapter 2.2.5.4 --- Real-time polymerase chain reaction analysis --- p.47 / Chapter 2.3 --- Cell culture study --- p.49 / Chapter 2.3.1 --- Reagents --- p.49 / Chapter 2.3.2 --- Cell lines --- p.49 / Chapter 2.3.2.1 --- "Rat osteosarcoma cell line, UMR-106" --- p.49 / Chapter 2.3.2.2 --- "Human breast cancer cell line, MCF-7" --- p.50 / Chapter 2.3.2.3 --- Cell culture techniques --- p.50 / Chapter 2.3.3 --- Herbs preparations for cell culture --- p.51 / Chapter 2.3.4 --- Cell viability assay --- p.51 / Chapter 2.3.5 --- Cellular alkaline phosphatase activity assay --- p.52 / Chapter 2.3.6 --- Matrix mineralization assay --- p.54 / Chapter 2.3.7 --- Competitive estrogen receptor binding assay --- p.56 / Chapter 2.4 --- Statistical analyses --- p.58 / Chapter Chapter 3. --- Results --- p.59 / Chapter 3.1 --- Extraction yields of Kidney-tonifying herbs and herbal formula --- p.59 / Chapter 3.2 --- Effects of Kidney-tonifying herbs and herbal formula on the gene expressions of calcium absorption and reabsorption related genes --- p.61 / Chapter 3.2.1 --- Gene expression of 25-hydroxyvitamin D3-1 alpha-hydroxylasein the kidney --- p.62 / Chapter 3.2.2 --- Gene expression of vitamin D receptor in the duodenum --- p.65 / Chapter 3.2.3 --- Gene expression of calbindin D9K in the duodenum --- p.67 / Chapter 3.2.4 --- Gene expression of vitamin D receptor in the kidney --- p.69 / Chapter 3.2.5 --- Gene expression of calbindin D28K in the kidney --- p.71 / Chapter 3.3 --- Effects of Kidney-tonifying herbs on osteoblastic UMR-106 cell line --- p.73 / Chapter 3.3.1 --- Effects of Kidney-tonifying herbs on the cell viability of UMR-106 cells --- p.73 / Chapter 3.3.2 --- Effects of Kidney-tonifying herbs on the osteoblastic differentiation of UMR-106 cells --- p.76 / Chapter 3.3.2.1 --- Cellular alkaline phosphatase activity --- p.76 / Chapter 3.3.2.2 --- Degree of matrix mineralization --- p.80 / Chapter 3.4 --- Estrogen receptor binding activities of Kidney-tonifying herbs --- p.85 / Chapter Chapter 4. --- Discussion --- p.89 / Chapter 4.1 --- Safety of Kidney-tonifying herbs and herbal formula --- p.89 / Chapter 4.2 --- Kidney-tonifying herbs and herbal formula preserve bone mineral density --- p.93 / Chapter 4.3 --- Kidney-tonifying herbs and herbal formula modulate calcium homeostasis --- p.97 / Chapter 4.3.1 --- "Roles in renal synthesis of the hormonally active form of vitamin D: 1,25-dihydroxyvitamin D3" --- p.97 / Chapter 4.3.2 --- Roles in calcium absorption in the duodenum --- p.99 / Chapter 4.3.3 --- Roles in calcium reabsorption in the kidney --- p.102 / Chapter 4.3.4 --- Summary --- p.104 / Chapter 4.4 --- Kidney-tonifying herbs modulate bone formation --- p.106 / Chapter 4.4.1 --- Effects on osteoblast proliferation --- p.106 / Chapter 4.4.2 --- Effects on osteoblastic differentiation --- p.107 / Chapter 4.4.3 --- Summary --- p.108 / Chapter 4.5 --- Kidney-tonifying herbs interact with estrogen receptor --- p.110 / Chapter 4.6 --- Active ingredients of Kidney-tonifying herbs --- p.111 / Chapter 4.7 --- Limitations of the present studies --- p.115 / Chapter 4.8 --- Conclusion and future prospect --- p.117 / References --- p.119

A direct bone tendon junction consists of four zones: tendon, uncalcified fibrocartilage, calcified fibrocartilage, and bone. The uncalcified and calcified fibrocartilage together forms the transition zone. This organization ensures a gradual transition in stiffness and material properties, and protects the junction from failure. Transition zone regeneration during bone tendon junction healing is important to restore this unique protective mechanism. / Bone tendon junction repair is involved in many orthopaedic reconstructive procedures. Healing is observed to be slow. The junction often heals by fibrous tissue formation. Previous attempts to enhance bone tendon junction healing have resulted in increased bone formation. However, fibrocartilage transition zone is not restored. / This thesis describes a series of studies on transition zone regeneration in bone tendon junction healing using two partial patellectomy animal models. The healing process inside a bone trough was first studied and characterized. Little transition zone regeneration was observed except near the articular cartilage cut surface. The possibility of using articular cartilage to stimulate transition zone regeneration was explored. Both articular cartilage autograft and allogeneic cultured chondrocyte pellet implantations resulted in significantly increased fibrocartilage transition zone regeneration. Cell tracking indicated that the regenerated tissue likely originated from host cells. To elucidate the mechanism of stimulation by allogeneic cultured chondrocyte pellet, the role of cellular and matrix component needed to be differentiated. Freezing and rapid freeze thaw cycles permanently devitalized the allogeneic cultured chondrocyte pellet, but retained its structural integrity and matrix contents. Preliminary results indicated that implantation of the devitalized allogeneic cultured chondrocyte pellet could still increase fibrocartilage transition zone regeneration. Cellular activity seemed not to be essential for the stimulatory effect. / With further research and development, it is envisioned that a cartilage-based stimulation method for fibrocartilage transition zone regeneration in bone tendon junction healing will be developed for clinical application. / Wong Wan Nar, Margaret. / Source: Dissertation Abstracts International, Volume: 70-06, Section: B, page: 3423. / Thesis (M.D.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 216-231). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Bone is a composite material consisting of hydroxyapatite crystals deposited in an oriented manner on a collagen backbone. The arrangement of the mineral and organic phases provides bone tissue with the appropriate strength, stiffness, and fracture resistance properties required to protect vital internal organs and maintain the shape of the body. A remarkable feature of bone is the ability to alter its properties and geometry in response to changes in the mechanical environment. However, in cases of metabolic bone diseases or aging, bone can no longer successfully adapt to its environment, increasing its fragility. To elucidate the mechanisms of bone microdamage, this research project developed a specimen-specific approach that integrated 3D imaging, histological damage labeling, image registration, and image-based finite element analysis to correlate microdamage events with microstructural stresses and strains under compressive loading conditions. By applying this novel method to different ages of bovine and human bone, we have shown that the local mechanical environment at microdamage initiation is altered with age. We have also shown that formation of microdamage is time-dependent and may have implications in age-related microdamage progression with cyclic and/or sustained static loading. The work presented in this dissertation is significant because it improved our understanding of trabecular bone microdamage initiation and unlocked exciting future research directions that may contribute to the development of therapies for fragility diseases such as osteoporosis.

Skeletal fragility is characterized by low bone mass, negative changes in bone microarchitecture, and compromised tissue matrix properties, including accumulation of microdamage. Microdamage accumulates in vivo from daily physiological loading and is targeted for repair through a normal remodeling process, thus preventing microcrack growth and potential fracture. However, impaired remodeling is associated with aging and osteoporosis, resulting in an increased accumulation of microdamage which contributes to reduced bone mechanical properties. The current clinical method for assessing increased risk of fracture involves measuring bone mineral density (BMD) of the hip and spine, locations of trabecular bone where high rates of remodeling occur. The bisphosphonate alendronate (ALN) reduces clinical risk for fracture by significantly increasing BMD, but studies have shown a concomitant reduction in intrinsic properties that may be the underlying cause for recent reports of spontaneous fractures with long-term alendronate use. Another anti-resorptive agent called raloxifene (RAL) is a selective estrogen receptor modulator (SERM) and has been shown to modestly improve BMD while decreasing fracture risk to a similar degree as alendronate. The combination of RAL and ALN as a treatment for osteoporosis may provide the benefits of each drug without the negative effects of ALN. Therefore, the overall goal of this thesis was to address the effects of aging and anti-resorptive agents on the properties of bone through the formation of microdamage. Assessment of age-related effects on bone was conducted through quantification of microdamage progression. It was found that old bone results in greater incidences of microdamage progression, reflecting a compromised tissue matrix with reduced resistance to crack growth. Effects of combination treatment with RAL and ALN were evaluated through biomechanical testing, micro-CT imaging, and microdamage quantification. Results showed improved trabecular bone volume and ultimate load with positive effects on trabecular architecture. Combination treatment reduced the proportion of microdamage that may lead to catastrophic fracture, indicating an improvement in the local tissue matrix properties.

Excavated osteological material has been very valuable tool to reconstitute the more precise and objective view of the horses farmed in the past, to follow the evolution of the Lithuanian horse. The data that enabled to estimate the height, constitution and age of the horse is very rare. The metacarpal, metatarsal bones and scull or at least the lower jaw (mandibule) with teeth could be pointed out as the most valuable material. Teeth belong to the best preserved elements of excavations’ material. Such factors as dentition or wear allow determining the animal age. However solitary molars (as they found frequently) do not able to provide this kind of information. Therefore, the methods allowing determining the horse age according to the tooth height and number of cementum rings are very valuable.

The purpose of this paper is the development of a model to investigate possible causal relationships among some of the commonly reported risk factors for the development of osteoporosis and consequential hip fracture. Comparison of hip fracture incidence between women of primarily European descent, referred to in the literature as Caucasians, and Japanese women is made. Studies report the incidence of hip fractures among Japanese women is lower than among Caucasian women. Numerous factors related to the development of osteoporosis are significantly different between Japan and the United States. The model helps explain the interrelationships among the variables involved in this observed geographical variation in hip fracture incidence. / Department of Anthropology

[Truncated abstract] Bone remodeling is an important process to maintain mechanical integrity. It is accomplished by two important steps, bone resorption followed by new bone formation. Osteoclasts and osteoblasts are the principal cells in bone resorption and bone formation, respectively. A multitude of local and systemic factors regulates this process by controlling the cellular activities in bone remodeling compartments (BRC). An imbalance of osteoblastic bone formation and osteoclastic bone destruction will result in the development of skeletal diseases. Recent studies suggested that angiogenesis is closely associated with bone remodeling. The vasculature in bone is important for skeletal development, growth and repair. During endochondral ossification, cartilage is invaded by blood vessels which bring in osteoblast and osteoclast precursor cells, nutrients, growth factors and differentiation factors. During fracture repair, it has been demonstrated that mature osteoclasts produce heparanase which can degrade heparin sulfate proteoglycans, a major component in extracellular matrix (ECM). The process leads to the release of heparin-binding growth factors including vascular endothelial growth factor (VEGF), a potent angiogenic factor which contributes largely to local angiogenesis. In recent studies, endothelial cells have been found to produce bone morphogenetic protein (BMP)-2 and BMP-4 when they are subjected to mechanical stimuli, or a hypoxia environment. Conversely, inhibition of angiogenesis has been shown to prevent fracture healing. In a distraction osteogenesis model, either inhibition of angiogenesis or disruption of the mechanical environment prevents normal osteogenesis and results in fibrous nonunion. .... A total of 42 mice from F1 and F2 generations were genotyped as transgene positive. Preliminary analysis using radiography did not reveal any difference between the gross structures of transgenic and wild type mice. Interestingly, the preliminary histology revealed a decrease in trabecular bone and an increase of lipid space in metaphysis of transgenic mice overexpressing EGFL6. However, further studies will need to be carried out to investigate the role of EGFL6 in angiogenesis and adipogenesis using a transgenic mice model. This will be a prime focus of future work. Collectively, the results presented in this thesis have identified EGFL6, a member of the EGF-like family, as a potential angiogenic factor which may play an important role in bone remodeling. EGFL6 has been found to be expressed highly in calvarial osteoblasts and upregulated during primary murine osteoblast differentiation. EGFL6 has been 8 characterized to be a secreted homomeric complex. More importantly, EGFL6 has been shown to induce angiogenic activity in endothelial cell migration, tube formation and in vivo chick embryo chorioallantoic membrane assay. Furthermore, conditioned medium containing the EGFL6 recombinant protein was shown to induce phosphorylation of ERK in endothelial cells. Inhibition of ERK impaired EGFL6-induced ERK activation and endothelial cell migration. Taken together these studies raise the possibility that EGFL6 has a potential role in angiogenesis, and mediates a paracrine mechanism of cross-talk between vascular endothelial cells and osteoblasts during osteogenesis. An understanding of this process offers the potential to facilitate the development of therapeutic treatments for bone disease.

Indiana University-Purdue University Indianapolis (IUPUI) / The Cre/loxP system is a tool for targeted recombination of DNA. For applying Cre recombinase-mediated genome modifications, there is a requirement for reliable, high-fidelity, and specific transgenic expression of the Cre recombinase. This study focuses on the reliability of different bone cell specific Cre models in the Cre/loxP system. In this study, DMP1-Cre transgenic mouse which has a transgene driven by DMP1 promotor that allows Cre-expression only in late stage osteoblasts and osteocytes was used. Ctsk-Cre mouse with a driven by Ctsk promoter was used so that only osteoclasts would undergo Cre-mediated recombination. E2A-Cre mouse where the Cre recombinase is driven by a global promoter E2A was also included in this study as a control line to test the Cre reporter line Ai9. Dmp1-Cre, Ctsk-Cre and E2A-Cre mice were crossed to the fluorescent Cre-reporter line—Ai9, which harbors a floxed stop codon, followed by the fluorophoremTomato, inserted into the Rosa26 locus. This construct is expected to give red fluorescence when it recombines with Cre-expressing mouse cells and no fluorescence in non-recombinant mouse cells. Double positive (Ai9+/Cre+) offspring selected by PCR were perfused, and 5mu-m thick section of bone and soft tissues were examined for red fluorescent expression. Cre positive cells were quantitated using ‘ImageJ’ software program. The DMP1-vi Cre mouse results showed significant expression in the targeted osteocytes and osteoblasts. In addition, skeletal muscle tissue also showed significant Cre- expression. Ctsk-Cre mice showed significant expression in targeted osteoclasts. But brain tissue was positive in Cre-expression. Bone-Cre mouse models are expected to express Cre recombinase only in their respective bone cells and they have been used for gene deletion studies in bone cells. However, this study has revealed that the bone cell specific Cre mouse models DMP1-Cre and Ctsk-Cre have unexpected expression in muscle and brain respectively. In order to use these models for targeted gene deletion in bone cells, further testing and studies have to be conducted.

Indiana University-Purdue University Indianapolis (IUPUI) / Mechanical loading associated with exercise is known to benefit bone health; however, most studies explore exercise benefits on bone mass independent of bone structure and strength. The purpose of this dissertation is to explore the response of the skeleton to exercise across the translational divide between animal- and human-based studies, with a particular emphasis on exercise-induced changes in bone structure and estimated strength. To explore the skeletal benefits of exercise, models were used wherein loading is introduced unilaterally to one extremity. Unilateral exercise enables the contralateral, non-exercised extremity to be used as an internal control site for the influences of systemic factors, such as genetics and circulating hormones. In study 1, a dose response between load magnitude and tibial midshaft cortical bone adaptation was observed in mice that had their right tibia loaded in axial compression at one of three load magnitudes for 3 d/wk over 4 weeks. In study 2, the ability of peripheral quantitative computed tomography to provide very good prediction of midshaft humerus mechanical properties with good short-term precision in human subjects was demonstrated. In study 3, collegiate-level jumping (long and/or high jump) athletes were shown to have larger side-to-side differences in tibial midshaft structure and estimated strength between their jump and lead legs than observed in non-jumping athletes. In study 4, prepubertal baseball players followed for 12 months were shown to gain more bone mass, structure and estimated strength in their throwing arm relative to their nonthrowing arm over the course of 12 months. These cumulative data using a combination of experimental models ranging from animal to cross-sectional and longitudinal human models demonstrate the ability of the skeleton to adapt its structure and estimated strength to the mechanical loading associated with exercise. Study of these models in future work may aid in optimizing skeletal responses to exercise.