Intravital optoacoustic ultrasound bio-microscopy reveals radiation-inhibited skull angiogenesis

Angiogenesis is critical in bone development and growth. Dense, large-scale, and multi-layered vascular networks formed by thin-walled sinusoidal vessels perfuse the plate bones and play an important role in bone repair. Yet, the intricate functional morphology of skull microvasculature remains poorly understood as it is difficult to visualize using existing intravital microscopy techniques. Here we introduced an intravital fully-transcranial imaging approach based on hybrid optoacoustic and ultrasound bio-microscopy, allowing for large-scale observations and quantitative analysis of the vascular morphology, angiogenesis, vessel remodeling, and subsurface roughness in murine skulls. Our approach also enabled high-throughput physiological studies to understand radiation-inhibited angiogenesis in the skull bone. We observed previously undocumented sinusoidal vascular networks spanning the entire skullcap, thus opening new vistas for studying the complex interactions between calvarian, pial, and cortical vascular systems.