Department of Plastic and Hand Surgery, University of Freiburg Medical Centre
Abstract:
Ischemia-reperfusion injury (IRI) has been implicated in a large array of pathological
conditions such as cerebral stroke, myocardial infarction, intestinal ischemia as well as
following transplant and cardiovascular surgery.1 Reperfusion of previously
ischemic tissue, while essential for the prevention of irreversible tissue injury, elicits
excessive inflammation of the affected tissue. Adjacent to the production of reactive
oxygen species, activation of the complement system and increased microvascular
permeability, the activation of leukocytes is one of the principle actors in the
pathological cascade of inflammatory tissue damage during reperfusion.2, 3
Leukocyte activation is a multistep process consisting of rolling, firm adhesion and
transmigration and is mediated by a complex interaction between adhesion molecules in
response to chemoattractants such as complement factors, chemokines, or
platelet-activating factor.4While leukocyte rolling in postcapillary venules is predominantly mediated by the
interaction of selectins5 with their counter ligands, firm adhesion of
leukocytes to the endothelium is selectin-controlled via binding to intercellular adhesion
molecules (ICAM) and vascular cellular adhesion molecules (VCAM).6, 7Gold standard for the in vivo observation of leukocyte-endothelial
interaction is the technique of intravital microscopy, first described in
1968.8Though various models of IRI (ischemia-reperfusion injury) have been described for
various organs, 9-12 only few are suitable for direct visualization of
leukocyte recruitment in the microvascular bed on a high level of image
quality.8We here promote the digital intravital epifluorescence microscopy of the postcapillary
venule in the cremasteric microcirculation of the rat 13 as a convenient method
to qualitatively and quantitatively analyze leukocyte recruitment for IRI-research in
striated muscle tissue and provide a detailed manual for accomplishing the technique. We
further illustrate common pitfalls and provide useful tips which should enable the reader
to truly appreciate, and safely perform the method.In a step by step protocol we depict how to get started with respiration controlled
anesthesia under sufficient monitoring to keep the animal firmly anesthetized for longer
periods of time. We then describe the cremasteric preparation as a thin flat sheet for
outstanding optical resolution and provide a protocol for leukocyte imaging in IRI that
has been well established in our laboratories.Download video file.(88M, mov)