Biomimetic and Injectable Highly Porous Nanofiber Microsphere-based Platform for Alveolar Bone Regeneration

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PROJECT SUMMARY Alveolar bone is a critical tissue for tooth and dental implant retention. Increasing alveolar bone mass in patients who lose this tissue as a result of periodontal disease or trauma is crucial for successful dental implant therapy (e.g., loss of bone around a tooth extraction site prior to implant placement). Currently, bone grafts (e.g., iliac or mandibular bone) or artificial bone grafts are commonly used for alveolar bone regeneration therapy. However, most of these therapies require extensive surgical procedures, which present risks of many complications, particularly in aged patients. Therefore, the development of new alveolar bone regeneration techniques that do not require surgical procedures is urgently needed. Herein, in this proposed study, we aim to develop an injectable and biomimetic highly porous nanofiber microsphere-based therapy for healing critical- sized alveolar bone defects. We recently developed an exciting approach for the fabrication of biomimetic nanofiber microspheres consisting of short electrospun nanofiber segments without limitation to certain compositions. Cells can attach and proliferate on the surface of such nanofiber microspheres. Working with Dr. Reinhardt (Co-I), we also demonstrated that mineralized short nanofibers incorporated with E7-BMP-2 peptides showed promise for healing a critical-sized socket defect model created in rat maxillae, following extraction of the first molar teeth. In addition, our most recent study revealed that BMP-2/QK peptides conjugated nanofiber microspheres can significantly enhance osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) and tubular network formation of human umbilical vein endothelial cells (HUVECs). Based on these findings, it is hypothesized that the injectable highly porous nanofiber microspheres in combination with biomimetic delivery of signaling molecules and/or incorporation of BMSCs could greatly promote alveolar bone regeneration after minimally invasive administration to critical-sized alveolar bone defects in rats. To test the hypothesis and accomplish the primary objective, our strategy is three-fold: i) Demonstrate the fabrication of porous nanofiber microspheres with controlled composition, structure, and coupling of signaling molecules; ii) Examine the effect of engineered porous nanofiber microspheres with biomimetic delivery of signaling molecules on cellular response; and iii) Determine the bone regenerative capacity of injectable porous nanofiber microspheres in combination with biomimetic delivery of signaling molecules and/or BMSCs for healing alveolar bone defects in rats. We expect to identify the critical factors of biomimetic and injectable highly porous nanofiber microsphere-based therapy that contribute to alveolar bone regeneration. Also, we expect successful completion of these aims to lay the foundation for developing injectable bone grafts that could greatly accelerate healing of alveolar bone defects without invasive surgical procedures.