Grants We Funded

Abstract
Critical bony defects are those that can't heal spontaneously due to their large size. They arise from trauma, both military and civilian, from non-union following a fracture or osteotomy, or may be secondary to ablative surgery for cancer. These defects may be repaired using vascularized autograft harvested from elsewhere in the body. However, there may be inadequate bone available, and autograft harvest carries significant donor site morbidity. The primary alternative material available to reconstructive surgeons is processed cadaveric bone, or allograft. Allograft is particularly useful for repair of large, load-bearing defects; however it is limited by a lack of vascularity. Without a blood supply allograft bone fails to grow or remodel in vivo, leading to weakening of the graft and ultimately fracture, with failure rates near 50% after 10 years. Laboratory-based bone tissue engineering strategies have made great strides but have not yet been successful for clinical applications due to an inability to produce adequate volumes of bone and to become integrated into the host's vascular network. Our goal is to engineer large volumes of vascularized bone, ultimately providing a new standard for repair of critical bone defects. Our preliminary data suggest that this is possible. We previously applied basic principles of bone tissue engineering to create large volume, well-vascularized bone in vivo, using allograft as a scaffold. This process is called allograft revitalization. This proposal will investigate the mechanism of allograft revitalization using our established hemi-mandible porcine model, and adapt our model for repair of critical porcine tibial defects. The ability of revitalized allograft to repair a critical defect will be directly compared to the current clinical standards, allograft and autograft. Repair of critical defects using allograft revitalization represents a potentially dramatic improvement over these modalities for reconstructive surgeons.

Biography
Dr. Runyan was raised in Indianapolis, IN and completed his undergraduate studies in Microbiology at Brigham Young University. He then joined the Medical Scientist Training Program at the University of Cincinnati where he studied Molecular and Developmental Biology with Dr. Christopher Wylie. His doctoral dissertation was entitled ‘The importance of cell death in germ cell migration’, and helped explain the occurrence of extragonadal germ cell tumors. Upon return to medical school he was drawn to Plastic and Reconstructive Surgery in part because of the many opportunities for translational research. While completing medical school, he conducted a preliminary study under the direction of Dr. Jesse Taylor, engineering vascularized bone in a large animal model. He remained in Cincinnati for residency training in Plastic Surgery, where he continues to pursue research interests in bone tissue engineering and craniofacial development. Upon completion, he hopes to pursue an academic career in craniofacial plastic surgery.