Multiphoton microscopy opens up unprecedented possibilities for visualizing biological processes in vivo. With its low phototoxicity and in-depth tissue imaging, multiphoton microscopy is a powerful tool to elucidate temporal dynamics of cell behaviors, thereby transforming our understanding of cardiovascular pathologies.

To understand and ultimately improve cardiovascular pathologies, we aim to visualize and manipulate the cells associated with the cardiovascular system in living animals using the multiphoton microscope. In most in vivo biological studies, different animals are sacrificed at fixed time points, generating snapshots of events over time. By contrast, multiphoton microscopy allows appreciating the dynamics and complexity of a biological phenomenon in the same animal over time. This way, by tracking individual cells labeled with fluorescent reporters, a complete vascular pathological event can be evaluated. High-resolution imaging permits precise identification of any potential therapeutic mechanism and its impact on vessel functionality (hemodynamics, perfusion and leakage). Another crucial point is cellular plasticity: various reports identified a switch in cell lineage in pathological microenvironments such as highly inflammatory areas. Together with genetic tools using specific promoters that direct expression of fluorescent reporter proteins, multiphoton imaging allows tracking every desired cell type in the selected pathology and following their behavior over time.