Peptide Discovery for Osteogenesis - PROJECT SUMMARY In treating a patient with large craniofacial bone defects, the greatest challenge for craniofacial bone regeneration is achieving full bone healing spanning the defect. The long-term goal of this project is to create an off-the-shelf biomaterial that will regenerate a craniofacial bone defect of any shape or size and avoid the need for costly growth factors or exogenous cells. Success in achieving an osteogenic biomaterial resides in peptides, which can be reproducibly synthesized and conjugated to biomaterials to guide the differentiation of endogenous bone marrow-derived mesenchymal stem cells (BMSCs). There is a lack of rigorous, systematic, and reproducible methods to identify new peptides for bone regeneration. In this void, we leverage a peptide discovery strategy that is uncommon to regenerative medicine. Our approach employs peptide microarrays, which are less labor intensive, less costly, and faster than traditional methods (e.g., phage display) to quickly iterate vast numbers of peptides. In our preliminary studies, we examined bone morphogenetic protein (BMP)-9 with the peptide microarray approach, and we are pleased to report that a unique peptide was discovered that led to remarkable upregulation of osteogenic gene expression in human BMSCs. We have the exciting opportunity to expand the technology to other osteogenic growth factors, osteo-related ECM proteins, and lesser studied proteins that have previously demonstrated osteogenic potential. The objective of this proposal is therefore to evaluate the osteoinductivity of our recently identified peptide alongside promising new peptides identified from osteogenic growth factors, osteo-related extracellular matrix proteins, and lesser studied proteins via the peptide microarray approach, and then to evaluate leading peptides in a 3D hydrogel for BMSC osteogenesis and finally to regenerate critical size calvarial defects. The chief hypothesis is that osteoinductive peptides will outperform BMP-2 in calvarial bone regeneration, to be tested by the following specific aims: 1) Discover new osteogenic peptide sequences from peptide microarrays, 2) Screen and select peptides based on osteoinductivity in vitro, and 3) Evaluate peptides for bone regeneration in a rat calvarial defect model. Successful completion of this project fills a gap in current knowledge regarding biomaterials capable of adequately regenerating critical size defects without the need for costly growth factors or prior cell harvest. In addition to our already discovered peptide from BMP-9, we have the exciting opportunity to identify additional osteogenic peptides using our peptide microarray approach. Although the identification of new peptides is not a requirement for the project to proceed successfully, the identification of new peptides would add great value for method validation and future follow-on grant applications. Future avenues to explore using our microarray method to enhance the regenerative power of biomaterials for bone regeneration would include applying the method to the areas of angiogenesis and immunology, whereby developing a holistic biomaterial capable of orchestrating multiple paradigms of bone regeneration simultaneously.
