Deans

Linda C. Niessen, D.M.D., M.P.H., M.P.P. – College of Dental Medicine

Award Date

1-1-2020

Abstract

Reconstruction of craniofacial bone defects caused by tumor and trauma as well as such congenital malformation as cleft palate presents clinical challenge. The purposes for the reconstruction of bone defect in cranio-and maxillofacial region is essential to restore the facial appearance, improve the masticatory function and the reduce the speech abnormalities. Especially, to sustain the huge force generated at mastication, the regenerated bone must be constantly remodeled to reinforce the structure by sufficient blood supply. The long-term goal of the proposed study is to engineer a stem cell therapy that can regenerate the functional bone, which has sufficient vasculature for the continuous auto-remodeling. Indeed, bone modeling is characterized by a balanced coupling between steogenesis and angiogenesis. Stem cell based bone augmentation procedures offer a promising alternative for the repair of critical size defects. However, clinical application of stem cell-based therapies is limited by the insufficient vascularization, which, in turn, leads to poor graft integration and failure of engineered bone in the recipient body. Herein, we intend to develop a novel strategy of simultaneous transplanting of ex vivo programmed two types of gingival mesenchymal stem cells (GMSCs), i.e, angiogenic GMSCs and osteogenic GMSCs. Especially, we utilize the unique property of GMSCs that produce Semaphorin 4D (Sema4D), a molecule with angiogenic and anti-osteogenic functions, which is not produced by commonly used bone marrow derived MSCs. Our hypothesis holds that temporally controlled on-and-off of Sema4D functions by monoclonal antibody (mAb)-based neutralization in transplanted GMSCs would sufficiently regenerate vascularized bone. Using PRG mechanism, we propose to carry out the in vitro proof of concept experiments. The programmed angiogenic GMSCs and osteogenic GMSCs will be first co-cultured in vitro in the absence of mAb so that angiogenesis is progressed, owing to the Sema4D produced by GMSCs, while osteogenesis is withheld. After completion of angiogenesis, Sema4D will be neutralized by anti- Sema4D mAb to enhance osteogenesis of GMSCs. The angiogenesis and osteogenesis events in the co-culture will be monitored by the detections of osteogenic marker gene and protein expressions, while the cellular organizations of vascular endothelial cells and osteoblasts will be analyzed by fluorescent microscopy. Accomplishments of this novel study will pave a way to develop novel stem cell therapy for the restoring of bone defects in the patients with craniofacial defects such as cleft palate.

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