BME Colloquium Series: Xinping Zhang, MD, PhD

Periosteum in Repair and Regeneration

Assistant Professor, Department of Orthopaedics Center for Musculoskeletal Research, University of Rochester

Abstract

Periosteum is a microvascularized connective tissue membrane that covers the outer surface of the cortical bone. Periosteum contains abundant mesenchymal progenitors that can be activated by mechanical stimuli, trauma, and infection. The lack of a defined phenotype and cellular markers for mesenchymal progenitor cells significantly hampers the efforts to track cell fate and further understand the molecular pathways underlying the expansion and differentiation of periosteal progenitor cells during repair processes. Using a segmental bone graft transplantation model in mice we tracked the periosteal cell fate and examined the unique periosteum tissue morphogenesis during bone graft healing. We demonstrated that the expansion and further differentiation of the periosteal progenitor cells drive the initiation of osteogenesis and angiogenesis of donor bone graft healing. Removal of periosteum from live bone graft significantly impairs healing whereas engraftment of mesenchymal precursors on devitalized bone allograft markedly improves healing and graft incorporation.

These studies provide a rationale for MSCs-based therapeutic strategies for enhancing bone graft repair and reconstruction. The success of such an approach will depend on further understanding of the molecular signals that control inflammation, cellular recruitment as well as mesenchymal stem cell differentiation and expansion during the early phase of the repair process. It will also depend on multidisciplinary collaborations between biologists, material scientist and bioengineers to address issues of material selection and modification, biological and biomechanical parameters for functional evaluation of bone healing. I will present our recent progress towards defining molecular signals/pathways that are essential for periosteum-mediated healing. An electrospun nano- and microfiber-mediated tissue engineering approach for repair and regeneration will also be discussed.