The interactions between myeloid and stromal cells during bone healing under compromising conditions will be visualised by Hauser and Niesner. Myeloid cells can integrate various types of signals such as interactions with hematopoietic and stromal cells, as well as metabolic conditions, and mechanical stimuli in order to differentiate during bone regeneration. Combining the development of state-of-the-art technology for functional, longitudinal intravital imaging with expertise in immunology and bone biology while using genetic and pharmacological tools will allow to dissect the signals acting on myeloid cell differentiation at the site of injury in fracture models. Analysing the spatio-temporal heterogeneity of myeloid cells and their microenvironment during the course of bone healing, followed by intravital investigation of the correlation between myeloid cell functions and cellular metabolism and an investigation of the molecular mechanisms underlying mechanosensing in myeloid cells will be used to analyse the impact of the microenvironment on myeloid cell phenotype and functions during the phases of bone healing via cellular interactions, local metabolic conditions and mechanical cues.