Intravital Imaging of Leukocyte-Endothelial Interaction in Hindlimb Ischemia/Reperfusion Injury by Intravital Multiphoton Microscopy.

Ischemia/reperfusion injury in skeletal muscle leads to sterile inflammation and affects structure and function permanently. However, the main understanding of the molecular and cellular mechanisms mainly relies on in vitro and ex vivo investigations. Recent advances in intravital microscopy allow for insights into dynamic processes at the cellular and subcellular level under both physiological and pathophysiological conditions. Real-time intravital imaging by two-photon microscopy (2P-IVM) has emerged as a powerful tool in the evaluation of the cell-cell interaction and molecular biology of leukocytes in live animals. Acute ischemic injury in limbs may occur due to crush syndrome, compartment syndrome, and vascular diseases and injury as in acute peripheral arterial occlusion, caused by a diverse array of pathological conditions. Iatrogenic revascularization and restoration of perfusion results paradoxically in aggravated tissue injury. Furthermore, the effects of IR-injured skeletal muscle in clinical conditions such as compartment syndrome or crush syndrome may induce rhabdomyolysis and are associated with so-called remote injuries as acute kidney dysfunction. Here, we discuss the considerations for and describe a 2P-IVM method designed for visualization of leukocyte-endothelial interaction. This chapter will provide a detailed experimental setup and a step-by-step protocol for the dynamic imaging of leukocyte-endothelial-interaction in an ischemia/reperfusion injury model.