Regulating Skeletal Stem Cell and Neutrophil Dynamics for Improved Cleft Palate Bone Regeneration by Newly Designed Surrogate Bone Morphogenetic Protein-2 - Cleft Lip and Palate (CLP) is one of the most frequent birth anomalies, currently treated with autografts from the iliac crest. This approach involves multiple invasive surgeries and suffers from graft failures and high donor site complications. Currently, the only other viable treatment option is Bone Morphogenetic Protein-2 (BMP-2) based bone regeneration, which offers a less invasive alternative by eliminating the need for autografts. Yet, FDA approval of BMP-2 is currently limitted by two issues: variability in its bone regenerative effectiveness— particularly, clinical meta-analyses indicate a lower efficacy in palatal bone compared to mandibular bone—and its propensity to induce significant tissue inflammation via interaction with immune cells. Thus, there is a critical need to solve significant knowledge gaps on (1) the mechanism behind the varied success of BMP-2 in palatal versus mandibular bone repair and (2) the dynamics between BMP-2 and immune cells to improve the BMP-2 based palate bone repair. As BMP-2 is known to enhance bone repair by activating endogenous skeletal stem cell (SSCs), investigating the palatal bone regeneration from SSC point of view is critical. Dr. Takematsu’s preliminary data suggest that differences in the subpopulations and BMP receptor (BMPR) usage between palatal and mandibular SSCs contribute to variations in bone regeneration. Thus, she will identify how BMP-2 based palatal and mandibular bone regeneration is regulated by SSCs at the cellular and receptor level (Aim1). She will employ single-cell RNA sequencing (scRNAseq) to identify if the differences in SSC subpopulations are responsible for the varied regenerative capacities. To understand how different BMPR utilizations by SSCs lead to diverse regenerative results, she has engineered a surrogate BMP-2 made of a bispecific nanobody. This innovative tool will pair the specific BMPRs, allowing the investigation of their interactions and bone regenerative capacity of SSCs. Building on her preliminary data that indicate neutrophils (NPs) contribute to inflammation, she will identify the interactions between NPs and SSCs in the palatal bone regenerative interface and develop safe bone regeneration strategies using the surrogate BMP-2 (Aim2). She will examine the genetic interplay between NPs and SSCs in palatal bone defects repaired by BMP-2 using scRNAseq and will develop strategies to mitigate NP-induced inflammation. By leveraging the differential BMPR expression between NPs and SSCs, she can also create the surrogate BMP-2 to selectively activate SSCs and avoid NP- induced inflammation. This project will advance Dr. Takematsu’s career goal of becoming an investigator specializing in craniofacial SSC biology with an emphasis on osteoimmunology, aiming to control the complex immune interactions and improve the protein therapeutics for craniofacial bone repair. With the mentorship and a research-enriching environment at Stanford University, she will be well-equipped for applying to an independent faculty position. The K99/R00 research will yield robust data to support a R01 proposal, focused on developing safe and effective bone regeneration strategies to repair various craniofacial bone defects.
