Simultaneous imaging of astrocyte behavior and hemodynamic activities using a near-infrared fluorescent protein based photoacoustic microscopy

Astrocytes have the important ability to delivery oxygen and glucose from intravascular sources to neurons, due to its interposed location between the neurons and the micro-vessels in the brain. As the primary cellular component of the blood-brain barrier, concurrently capturing astrocytes activity and brain functional indicator of blood-oxygen change could provide insights into neurological disorders. Yet there remains a lack of effective tools to monitor both astrocyte behavior and cerebral vascular oxygen dynamics in vivo simultaneously. We developed a novel emiRFP-based photoacoustic microscopy (PAM) mouse system to address this gap. Our cellular identity staining confirmed that astrocytes could be labeled by near-infrared fluorescent protein emiRFP. Furthermore, this emiRFP expression was compatible with existing tissue clearing technique and provided excellent signal-to-noise ratio. Above all, we have shown SpO ₂ changes in ischemia brain, and astrocytes were exhibited as particles with cellular resolution tightly around cerebral vascular by using emiRFP-based PAM. This research introduces an advanced tool for studying astrocytic responses during cerebrovascular dynamics simultaneously at cellular level, offering valuable insights into cell deep imaging and microcirculation function changes, especially the oxygen.