Mammalian bone has the capacity throughout life to regenerate in response to fracture injury. However, there is a ceiling for this regenerative potential, with hurdles to regeneration after a major trauma like limb amputation.Thishasasignificantsocioeconomicimpact,asitisestimatedthatatleastoneintwoAmericans over age 50 is expected to have or be at risk of bone disease, and every year an estimated 1.5 million individualssufferafractureduetobonedisease.Recently,wehavedevelopedimagingmethodstostudyhow osteoblasts drive bone regeneration in zebrafish, which display robust regeneration after major injury to bony structures like their fins, scales, and jaws. Our goal is to exploit this regenerative capacity, new imaging platformswehavecreated,andthemoleculargeneticapproachesavailableinzebrafishtoimproveourability tounderstandandmanipulatetheregenerativecapacityofbone.Thegoalofthisproposalistogenerateanin totomapofthecellularandsignalingeventsthatregeneratepatternedskeletalbone.Ourexperimentswilltest the hypothesis that correct patterning of regenerating bone requires dynamic signaling events that control osteoblast behaviors at individual and population levels. 1) We will use long-term live imaging, labeling with photo-convertible proteins, and computational analysis to generate a detailed map of how cell proliferation, hypertrophy and cellular flows, and interactions with neighboring tissues drive bone regeneration. 2) We will use cutting edge biosensors, live imaging, computational approaches, and mathematical modeling to dissect how traveling waves of chemical signals stimulate the growth of a regenerating osteoblast population. 3) We willusetranscriptomeprofilingapproachestoderivefurtherinsightsonthedynamicsofgrowthfactorsignaling, including single-cell sequencing-based approaches to link gene expression programs with osteoblast behaviors. These experiments will define a novel quantitative framework for understanding how osteoblast behaviorsorchestrateboneregeneration.
Together, our experiments will define individual and collective behaviors of osteoblasts during bone regeneration, and they will reveal new molecular mechanisms responsible for key behaviors. Our experiments will uncover general principles of regeneration and will reveal processes that are potentially importantforstimulatingboneregenerationinclinicalsettings.