Checa and Petersen will investigate in a combined in vitro and in silico approach how outer-vascular mechanics as an age-dependent regulator of sprouting steers angiogenesis and vessel patterning. They will explore how stromal cells that surround nascent vessels guide sprout formation and vascular patterning through their own structural organisation, through the mechanical communication with vessel-resident endothelial cells and through the secretion of extracellular matrix. Checa and Petersen hypothesise that outervascular cells actively contribute to sprout formation by mechanical tension deposited in the cell‐extracellular matrix (ECM) network surrounding the vascular structures. As aging compromises the intrinsic capacity of stromal cells to sense, convert and respond to mechanical signals, this mechanical support of sprout formation is expected to be age-dependent. The ultimate goal is to understand how the alignment, tensional state and remodelling of extracellular matrix fibres modulate the process of angiogenic sprouting with relevance for bone defect healing.