The Role Of Androgens In Osteoblast Development And Bone Metabolism.
Funder
National Health and Medical Research Council
Funding Amount
$487,500.00
Summary
Maintenance of the skeleton involves the processes of bone formation by cells known as osteoblasts and bone breakdown by cells known as osteoclasts. When these processes become unbalanced, bone loss results, which is the basis of osteoporosis. The reduced bone mass found in osteoporosis leads to an increased susceptibility to bone fracture. 1 in 2 women and 1 in 3 men over the age of 60 will suffer a fracture due to osteoporosis. The increasing incidence of osteoporotic fractures has lead to ren ....Maintenance of the skeleton involves the processes of bone formation by cells known as osteoblasts and bone breakdown by cells known as osteoclasts. When these processes become unbalanced, bone loss results, which is the basis of osteoporosis. The reduced bone mass found in osteoporosis leads to an increased susceptibility to bone fracture. 1 in 2 women and 1 in 3 men over the age of 60 will suffer a fracture due to osteoporosis. The increasing incidence of osteoporotic fractures has lead to renewed efforts to understand the actions of hormones on bone. Androgens, the male sex hormones, have beneficial effects on skeletal growth and bone maintenance in both males and females by stimulating osteoblasts. It is believed that androgens act by binding to a specific protein known as the androgen receptor (AR), which is only found in androgen-responsive cells. Although it is well documented in human and animal models that androgens stimulate osteoblasts to increase the formation of bone, the way in which they act on osteoblasts remains poorly understood. The aim of this project is to investigate the effects of androgens at different stages of the developing osteoblast. This will be achieved by making transgenic mice in which the androgen receptor has been inactivated only in osteoblasts at specific stages of their development. We hypothesise that the inactivation of the androgen receptor will have dramatic effects on the development and function of osteoblasts. This project will help clarify the role androgens play in bone formation and will give fundamental insights into the basic biology of bone in both normal and disease processes. As androgens are one of the few agents that act to increase bone formation, understanding the way in which they act is important for the treatment of osteoporosis in males and females. We believe that this research is of great importance as osteoporosis becomes more prevalent in our aging population.Read moreRead less
Cell Biology Of Stress Fractures: Activation Of Remodelling At Sites Of Non-union
Funder
National Health and Medical Research Council
Funding Amount
$493,817.00
Summary
Stress fractures are debilitating injuries. We characterised a model of stress fractures in rat ulnae, learning that they heal by activated remodelling, that key genes are expressed in a temporal pattern, and that part of the fracture remains un-healed, similar to many clinical cases. Now, we will examine cell localisation of important genes necessary for remodelling, and test the efficacy of different growth factors to activate a healing response in the non-healed section of the fracture.
Molecular And Histopathological Investigation Of Stress Fracture Healing And Effects Of Anti-inflammatory Drugs.
Funder
National Health and Medical Research Council
Funding Amount
$412,652.00
Summary
Stress fractures are debilitating injuries affecting children, adolescents and adults in sport, and army recruits. They also occur in horse and greyhound racing, often resulting in euthanasia of the animals involved. They incur considerable costs in medical expenses, time lost from sport and interruption to military training. But, there is almost no information on the mechanism of healing of these fractures. Non-steroidal anti-inflammatory drugs (NSAIDs) are still the most widely used medication ....Stress fractures are debilitating injuries affecting children, adolescents and adults in sport, and army recruits. They also occur in horse and greyhound racing, often resulting in euthanasia of the animals involved. They incur considerable costs in medical expenses, time lost from sport and interruption to military training. But, there is almost no information on the mechanism of healing of these fractures. Non-steroidal anti-inflammatory drugs (NSAIDs) are still the most widely used medication in management of musculoskeletal injuries, yet their effect on healing of stress fractures is unknown. NSAIDs delay fracture healing, but until recently there has been no standardised way of studying stress fractures. We have created, for the first time, a well-characterised, non-invasive model of stress fractures in the forearm of rats that closely resembles the clinical situation. This provides a novel and unique opportunity to determine the histological and molecular mechanism of stress fracture healing, and to investigate effects of antiinflammatory-analgesic medications on this process. Rats will have an experimental stress fracture produced in one forelimb, and its healing will be examined up to ten weeks using microscopic investigation and analysis of the genes that are turned off or on to initiate the process. Groups of rats will also be treated with antiinflammatory drugs such as ibuprofen, specific COX-2 inhibitors and a new class of drugs that target early immune responses called C5a receptor antagonists. The analgesic Paracetamol will also be investigated as an alternative to the NSAIDs described above. There is widespread use of anti-inflammatory agents in managing stress fractures, so it is vital that their effects on stress fracture healing be examined. This project has enormous significance for optimising approaches for clinical management of stress fractures and for understanding the interaction of anti-inflammatory or analgesic agents in that process.Read moreRead less
Furin: Carving-up Vital Substrates For Bone Remodelling And Homeostasis
Funder
National Health and Medical Research Council
Funding Amount
$815,972.00
Summary
Osteoporosis, or porous bone, is a disease characterized by low bone mass and structural deterioration of bone tissue, leading to bone fragility and an increased susceptibility to fractures. It is caused by an imbalance between the cells that are constantly reabsorbing and reforming bone. The proposed project will address furin as a novel regulator of bone remodelling.
Delayed bone healing can be a considerable problem in both children and adults. Up to 10% of fractures fail to heal properly. An advanced understanding of the cellular responses in bone repair and their manipulation could improve the lives of many patients with orthopaedic problems. These studies will advance out knowledge of interventions to promote bone healing which could be translated rapidly into clinical care.
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
Relationships Between Human Osteoblasts And Haemopoietic Cells In Bone Remodelling
Funder
National Health and Medical Research Council
Funding Amount
$436,450.00
Summary
Bone diseases, such as osteoporosis and osteoarthritis, currently afflict more than 4 million Australians. These diseases are characterised by abnormal bone remodelling, which can result in a net loss of bone (for example, in osteoporosis) or abnormal bone structure (for example, in osteoarthritis). We are seeking to better understand the factors that regulate bone remodelling, and particularly the cells involved in this process. Physiological bone remodelling results from the intimate collabora ....Bone diseases, such as osteoporosis and osteoarthritis, currently afflict more than 4 million Australians. These diseases are characterised by abnormal bone remodelling, which can result in a net loss of bone (for example, in osteoporosis) or abnormal bone structure (for example, in osteoarthritis). We are seeking to better understand the factors that regulate bone remodelling, and particularly the cells involved in this process. Physiological bone remodelling results from the intimate collaboration between osteoblasts and osteoclasts. Osteoblasts stimulate the formation of osteoclasts and also produce new bone at resporption sites. However, the way that the same type of cell can perform both these tasks, is not clear. Our studies are designed to increase our understanding of the development of human osteoblasts and of the factors that cause them to be sequentially pro-osteoclastic and then pro-osteogenic. We believe that an important factor in this process is vitamin D and we will test the hypothesis that this molecule is produced in bone and acts locally to regulate bone turnover.Read moreRead less
Molecular Determinants Of Bone Remodelling In The Bone Microenvironment
Funder
National Health and Medical Research Council
Funding Amount
$317,640.00
Summary
There is little information regarding the expression of specific molecules in human bone tissue or their role in skeletal disease. The process of bone remodelling is fundamental for the maintenance of skeletal integrity. Our understanding of the molecular signalling involved in activating bone remodelling is principally derived from tissue culture and animal experiments. We will study human cancellous bone samples donated by patients undergoing surgery, and with the consent of the next-of-kin, t ....There is little information regarding the expression of specific molecules in human bone tissue or their role in skeletal disease. The process of bone remodelling is fundamental for the maintenance of skeletal integrity. Our understanding of the molecular signalling involved in activating bone remodelling is principally derived from tissue culture and animal experiments. We will study human cancellous bone samples donated by patients undergoing surgery, and with the consent of the next-of-kin, taken at autopsy. These molecular and histomorphometric studies will determine whether the understanding derived from tissue culture and animal experiments is consistent with associations demonstrable in the human cancellous bone microenvironment. The elucidation of the molecular signalling in the human bone microenvironment is essential for the effective diagnosis and treatment of bone disease. Recently reported studies have shown very persuasively that fatigue microdamage accumulates in the skeleton and is targeted for repair by remodelling. Our preliminary data shows that microcrack length is positively correlated with IL-11 mRNA gene expression. We will further investigate mRNA gene expression of a number of cytokines involved in bone cell signalling and their association with the level of microdamage in the bone. Using a animal model of controlled bone microdamage induction we will seek to determine the bone remodelling causal relationship between microdamage and cytokine signalling. Furthermore, the cellular and molecular mechanisms that lead to trabecular structures are not well understood. These studies will provide new insight into the processes that determine trabecular structures. This project will investigate these mechanisms and increase our understanding of bone cell function, essential for diagnosis and design of rational treatment for bone diseases.Read moreRead less