Bone destruction is a theme central to many bone-related conditions such as osteoporosis, osteonecrosis of the jaw, stress fractures and osteolysis. Understanding the response of bone at the cellular level to mechanical loading is critical to eradicating these conditions, as well as improving fracture healing and distraction osteogenesis outcomes, developing bone substitutes for tissue engineering, and improving implant designs. Current mechanotransduction research models are ill-equipped to study the basic science mechanisms by which bone cells sense and coordinate a response to mechanical stimulation and improved mechanotransduction models are essential. Microsystems technology offers a major improvement over existing mechanotransduction models by enabling multicellular and intercellular interactions to be studied in small cell populations while removing temporal and spatial limitations. With a Microsystems approach models may be developed that enable critical cellular activity to be physiologically simulated. This study utilizes this technology to develop a model of osteocyte microdamage induced by mechanical overload. Specifically, the currently purported theory that mechanical damage is sensed by the osteocyte which then coordinates bone remodeling activity is tested. Using a recently developed, novel microloading platform, osteocytes will be subjected to damage-inducing level of mechanical strain. Osteocyte damage as a function of dendritic process destruction versus cell viability will be assessed and soluble activity resulting from the strain will be collected and quantified for sclerostin and Dickkopf-1. n addition, the conditioned medium will be generated from these damage-inducing strain levels and used to investigate mechanisms of damage signal transmission. That is, using microchannel techniques, osteocytes in communication-intact and -deficient environments will be subjected to conditioned medium from mechanically-damaged osteocytes in a concentration-dependent manner and the effects of direct soluble activity versus indirect cellular communication in damage signal transmission will be investigated. Given the novel nature of Microsystems in the bone research field, this work will bring together two laboratories specializing in Mechanotransduction and Microsystems. Both laboratories are eligible for AREA (R15) support. This project is appropriate for consideration of AREA funding as it meets many of the intended goals, including 'pilot study and feasibility research', 'development and testing of new research techniques'and a 'discrete project demonstrating research capability'. The short-term goals of this research are to utilize a novel microloading platform to investigate the basic science mechanisms by which localized, mechanical overload of osteocytes provide the impetus for site-specific bone remodeling and to demonstrate the power and potential of Microsystems in bone research. The long-term goals are to expand these platforms with increasing biomimicry capabilities to address a wide range of clinical applications relevant to the bone field including lab-on-a-chip systems for bone disease diagnostics and detection.
This research is aimed at understanding the mechanisms and pathways by which bone remodels in response to mechanical damage. Specifically, this research investigates the role the osteocyte bone cells play in sensing mechanical damage and locally transmitting this signal to bring about bone resorption/formation. Understanding the mechanisms by which bone remodels enables exploitation of this knowledge to develop novel osteoporosis and osteonecrosis treatments;improve fracture healing and fixation of orthopedic and craniofacial implants;develop bioreactors to aid in functional tissue engineering of bone substitutes;and, develop new laboratory models and 'lab-on-a-chip'sensors in metabolic bone disease detection and treatment efficacy.