Modifying fragility fracture healing using a gradient-based mechanotransduction fixation approach - PROJECT SUMMARY Candidate: Dr. Hast received his bachelor's degree in mechanical engineering with a focus on thermodynamics and a Ph.D. in mechanical engineering with a focus on computational biomechanics. His long-term goal is to become an independent researcher focused on improving patient outcomes following fragility fractures. This proposal uses an interdisciplinary research framework using a small animal model to identify mechanisms that govern fracture healing in healthy and diseased bone. The objective of this proposal is to have Dr. Hast acquire the training necessary in small animal models, cellular assays, and molecular laboratory techniques to fully define the mechanisms that govern callus formation and bone remodeling in the milieu of osteoporosis. This will equip him with the tools necessary to become a thought leader in the field of fragility fracture repair. Mentoring Committee and Training Plan: Dr. Mauck will serve as primary mentor and provide structured mentoring in tissue engineering, laboratory techniques, and provide career development training. Drs. Boerckel and Qin will serve as co-mentors and provide hands-on training in small animal surgeries, histology, immunohistochemistry, and molecular profiling. Dr. Hast will also have advisory committees (technical: Drs. Liu, Ahn, Mehta, Manogharan; career: Drs. Soslowsky, Arbogast, Elliott) to guide his development. Dr. Hast will participate regularly in faculty meetings, seminars, workshops, and coursework to make him a complete and independent researcher. He will present his research at national conferences and in peer-reviewed journals. Environment: The University of Pennsylvania is home to the McKay Orthopaedic Research Laboratory and Penn Center for Musculoskeletal Disorders (PCMD), a 22,00 ft2 research space that is well-equipped for the proposed training and research plan. The PCMD and hosts several NIH supported core services focused on musculoskeletal research, which include histology, biomechanics, and imaging. Both the PCMD and Penn host weekly/monthly seminars in cellular and molecular biology, medical imaging, bioengineering, and professional development. Research: This proposed work will challenge the current clinical paradigms that use metal implants to heal fractures. The central hypothesis is that properly timed gradual (gradient-based) increases in loading will lead to improved repair of simulated fractures. To test this novel hypothesis, a rat model will be used in 2 aims. Aim 1 will establish the effects of gradual introduction of mechanotransduction on fracture repair in healthy bone. Aim 2 will determine what changes in mechanotransduction are required to improve fracture repair in compromised bone. Testing these aims will generate critical preliminary data for a follow-up R01 that includes a larger animal model, along with pharmacological interventions that may accelerate and improve repair. Institutional Commitment to Candidate: Dr. Hast is an Assistant Research Professor and has been provided start-up funds, laboratory space, and research personnel needed to perform the proposed work.