Investigation Of COX-2 Regulation Of Bone Turnover And Mechanically Induced Bone Formation By Genetic Overexpression.
Funder
National Health and Medical Research Council
Funding Amount
$440,750.00
Summary
This project is important because it uses novel experimental models to advance our knowledge of prostaglandin biology in normal and pathological bone remodelling, and the response of the skeleton to increased physical activity. We expect that a genetic modification in mice to increase the normal production of key prostaglandin enzymes, cyclooxygenase-2 (COX-2), in bone cells will increase the number of cells that remove bone (osteoclasts), and increase bone loss and the rate of bone turnover whe ....This project is important because it uses novel experimental models to advance our knowledge of prostaglandin biology in normal and pathological bone remodelling, and the response of the skeleton to increased physical activity. We expect that a genetic modification in mice to increase the normal production of key prostaglandin enzymes, cyclooxygenase-2 (COX-2), in bone cells will increase the number of cells that remove bone (osteoclasts), and increase bone loss and the rate of bone turnover when compared to normal mice. We believe this will occur via the effect of prostaglandins on expression of genes that control osteoclast formation. This will be tested by examining the structure of the skeleton, and the expression of certain genes, in transgenic mice at different ages from 2-8 months. These effects may be exacerbated in conditions of increased bone turnover, such as postmenopausal bone loss. This will be tested by examining the bone structure and gene expression in adult mice following removal of their ovaries. Due to the role of COX-2 in adaptation of bone to mechanical loading, we also expect the load-bearing skeleton to be more sensitive to increased weight-bearing activity. We will investigate this hypothesis by applying mechanical loads to the tibiae of mice in a controlled manner and then analysing the bone structure. Knowledge of specific pathways by which bone formation can be stimulated is important for developing novel approaches to induction and augmentation of osteogenesis in skeletal diseases associated with ageing or disability, or for maintenance of new bone around implants. The discovery that COX-2 is a key enzyme in mechanotransduction and osteoclastogenesis in bone, and a pharmacological target for modulating inflammation, has considerable clinical significance. Exploiting this knowledge requires precise knowledge of the role of this enzyme in bone remodelling and adaptation and our experiments will contribute significantly to that knowledgeRead moreRead less
Osteal Macrophages: Novel Regulators Of Osteoblast Function And The Endosteal Stem Cell Niche
Funder
National Health and Medical Research Council
Funding Amount
$406,125.00
Summary
Bone diseases are a major health problem and current treatments are inadequate. We are investigating a novel role for macrophages (cells important in tissue maintenance and immune responses) in bone growth, repair and disease. Greater understanding of this will provide new ways to treat bone disease. We will also determine if these macrophages help support stem cells that reside near bone surfaces, which may provide new treatment strategies to improve bone marrow transplantation in cancer.
Chondrocyte Hypertrophy In Development And Disease
Funder
National Health and Medical Research Council
Funding Amount
$360,018.00
Summary
Whereas chondrocyte hypertrophy is a normal feature of skeletal growth, in adult chondrocytes it is associated with osteoarthritis (OA). We propose that collagen II fragments provide signals for hypertrophy in cartilage. The lack of collagen II fragments in our collagenase-resistant mouse provides a unique opportunity to address the role of collagen II fragments in driving cellular hypertrophy. We will identify bioactive collagen II fragments that represent novel targets for OA therapies
Novel Strategies For The Treatment Of Bone Disease By Nutrient Activators Of Calcium-sensing Receptors
Funder
National Health and Medical Research Council
Funding Amount
$467,432.00
Summary
Osteoporosis is a major health problem in the Australian community and will worsen with an ageing population. This work aims to develop new strategies for the treatment of osteoporosis and associated fractures based on the nutritional and/or pharmacological activation of calcium-sensing receptors.
Identification Of Novel PTH Anabolic Targets In Osteoblasts
Funder
National Health and Medical Research Council
Funding Amount
$547,216.00
Summary
Osteoporosis is a major disease affecting Australians. Whilst there are a number of drugs available that will reduce bone loss, there are few drugs available that build new bone, and little is known of the action of these drugs. New targets have been identified that modulate bone formation, and this project aims to validate these in appropriate models and determine their mechanism of action.
Trabecular Architecture During Growth - Does It Determine Metaphyseal Peak Bone Strength In Adulthood?
Funder
National Health and Medical Research Council
Funding Amount
$165,339.00
Summary
Skeletal fragility is common is elderly people but has its origin in childhood. Strong bone established during growth will provide more protection against occurrence of fragility fracture in old age. Identifying individuals during childhood who are at high risk of skeletal fragility, and early intervention is a strategic approach managing the burden of skeletal fragility on the ageing population.
The Role Of TWIST Family Basic Helix-Loop-Helix Transcription Factors In Bone Cell Commitment, Function And Repair
Funder
National Health and Medical Research Council
Funding Amount
$485,928.00
Summary
In developed countries, projected estimates predict an alarming trend of a two to three fold increase in the number of fractures that require surgical intervention and rehabilitation therapy in the coming decades as a consequence of an aging population. Fracture healing is a complex physiological process that involves the coordinated participation of different bone marrow cells, immune cells and skeletal progenitor cells. Multiple factors regulate interactions between these cell types that influ ....In developed countries, projected estimates predict an alarming trend of a two to three fold increase in the number of fractures that require surgical intervention and rehabilitation therapy in the coming decades as a consequence of an aging population. Fracture healing is a complex physiological process that involves the coordinated participation of different bone marrow cells, immune cells and skeletal progenitor cells. Multiple factors regulate interactions between these cell types that influence the capacity of bone cell progenitors to develop into functional bone forming cells known as osteoblasts. An understanding of the fracture healing is critical for the future advancement of fracture treatment, and for identifying the mechanisms of skeletal growth and repair as well as the causes of aging and disease. This proposal seeks to identify critical regulatory molecules that act to mediate bone cell progenitor recruitment and development during bone fracture repair.Read moreRead less
Osteoclasts (OC) are large multinucleated cells present in bone that are responsible for bone resorption. The renewal of bone and bone growth are regulated by the opposing actions of OCs and osteoblasts, cells that form new bone. Together, with other accessory cells in the bone marrow, these constitute 'bone-forming units' (BFU). Excess production or over-activation of OCs in the BFU leads to common bone conditions such as osteoporosis, Paget's disease and the bone lysis caused by bone cancers. ....Osteoclasts (OC) are large multinucleated cells present in bone that are responsible for bone resorption. The renewal of bone and bone growth are regulated by the opposing actions of OCs and osteoblasts, cells that form new bone. Together, with other accessory cells in the bone marrow, these constitute 'bone-forming units' (BFU). Excess production or over-activation of OCs in the BFU leads to common bone conditions such as osteoporosis, Paget's disease and the bone lysis caused by bone cancers. Osteoporosis causes a great deal of pain and disability and it alone costs the Australian taxpayers more than $400 million per year. OCs are formed from white blood cells that are present in the bone marrow and the blood. The recent discovery of a family of new factors that control the formation of OCs has enabled the generation of human OCs in the laboratory so now we can investigate the genes that control the process of conversion of white blood cells to OCs. An important advance in this project involves the use of cord blood that contains stem cells. These very na ve cells will enable us to study the very earliest genes that control differentiation of precursors to OC. We have found a number of genes that are regulated by these new bone-forming factors. In white blood cells the activation of particular genes can regulate OC formation. One example is vitamin D-upregulated gene, VDUP. This gene is of particular interest as it causes inhibition of the mechanism that leads to OC formation in the bone. Obviously, the ability to control a 'switch' that regulates OC formation may enable us to control the progress of bone loss in diseases such as osteoporosis. In this project, we intend to investigate how and why the genes that lead to OC formation are regulated and what influence the various bone cell factors have on the formation of bone-resorbing OCs. These studies will lead to the development of treatments for osteoporosis and other bone diseases.Read moreRead less
Understanding Skeletal Development: A Non-proteolytic Mechanism Of Aggrecan Resorption In The Growth Plate
Funder
National Health and Medical Research Council
Funding Amount
$563,044.00
Summary
Bone formation requires resorption of a cartilage template. We challenge the dogma that cartilage resorption is only by PROTEASES, and propose instead that GLYCOSIDASES might also be involved. Aims: Demonstrate that chondrocytes release glycosidases that are important for bone formation. Significance: New information for the design of reconstructive therapies for people with congenital and acquired limb deficiencies or inherited disorders such as arthritis and chondrodysplasias may be gained.
Roles Of Injury-induced Inflammatory Response In Regulating Bony Repair At Injured Growth Plate Cartilage
Funder
National Health and Medical Research Council
Funding Amount
$366,301.00
Summary
Children's growth plate cartilage is responsible for bone lengthening. Due to popularity of sports and play, trauma-induced growth plate damage and subsequently bone growth defects are common in children, with up to 30% of growth plate injury cases resulting in growth abnormality, for which the present surgical correction is highly invasive and not fully effective. Although we know that the growth plate injury-induced bone growth defects result from bony repair of the injured growth cartilage, w ....Children's growth plate cartilage is responsible for bone lengthening. Due to popularity of sports and play, trauma-induced growth plate damage and subsequently bone growth defects are common in children, with up to 30% of growth plate injury cases resulting in growth abnormality, for which the present surgical correction is highly invasive and not fully effective. Although we know that the growth plate injury-induced bone growth defects result from bony repair of the injured growth cartilage, we largely don't understand why and how this bony repair occurs. Understanding mechanisms for this faulty bony repair of injured growth plate will be critical prior to effective biological treatments can be developed. Recently, using an injury model in young rats, we found that bony tissue formation at injured growth plate is preceded sequentially by inflammatory, fibrogenic, chondrogenic and osteogenic responses. The inflammatory response is an initial event and our recent studies suggest that inflammatory response recruits inflammatory cells and produces important molecules that could significantly influence subsequent fibrogenic, chondrogenic and osteogenic events leading to the bony repair of the injured growth plate cartilage. The current proposal further addresses roles of the inflammatory response and the molecular pathways of this response in regulating downstream bony repair events. This project will generate novel understanding on the faulty bony repair of injured growth plate, and will provide valuable information for developing cost-effective and simple therapeutic intervention that aims to prevent bony repair and to enhance cartilage regeneration of the injured growth plate in children.Read moreRead less