title: Two-photon imaging within the murine thorax without respiratory and cardiac motion artifact.
abstract: Intravital microscopy has been recognized for its ability to make physiological measurements at cellular and subcellular levels while maintaining the complex natural microenvironment. Two-photon microscopy (TPM), using longer wavelengths than single-photon excitation, has extended intravital imaging deeper into tissues, with minimal phototoxicity. However, due to a relatively slow acquisition rate, TPM is especially sensitive to motion artifact, which presents a challenge when imaging tissues subject to respiratory and cardiac movement. Thoracoabdominal organs that cannot be exteriorized or immobilized during TPM have generally required the use of isolated, pump-perfused preparations. However, this approach entails significant alteration of normal physiology, such as a lack of neural inputs, increased vascular resistance, and leukocyte activation. We adapted techniques of intravital microscopy that permitted TPM of organs maintained within the thoracoabdominal cavity of living, breathing rats or mice. We obtained extended intravital TPM imaging of the intact lung, arguably the organ most susceptible to both respiratory and cardiac motion. Intravital TPM detected the development of lung microvascular endothelial activation manifested as increased leukocyte adhesion and plasma extravasation in response to oxidative stress inducers PMA or soluble cigarette smoke extract. The pulmonary microvasculature and alveoli in the intact animal were imaged with comparable detail and fidelity to those in pump-perfused animals, opening the possibility for TPM of other thoracoabdominal organs under physiological and pathophysiological conditions.
authors.affiliation: Center for Immunobiology, Indiana University, Indianapolis, Indiana, USA. rpresson@iupui.edu
authors.forename: Robert G
authors.initials: RG
authors.lastname: Presson
authors.forename: Mary Beth
authors.initials: MB
authors.lastname: Brown
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Fisher
authors.forename: Ruben M
authors.initials: RM
authors.lastname: Sandoval
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Dunn
authors.forename: Kevin S
authors.initials: KS
authors.lastname: Lorenz
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Delp
authors.forename: Paul
authors.initials: P
authors.lastname: Salama
authors.forename: Bruce A
authors.initials: BA
authors.lastname: Molitoris
authors.forename: Irina
authors.initials: I
authors.lastname: Petrache
mesh_terms: D000818:Animals; D002273:Carcinogens / Q000633:toxicity; D002448:Cell Adhesion; D002465:Cell Movement; D002478:Cells, Cultured; D003952:Diagnostic Imaging; D004730:Endothelium, Vascular / Q000166:cytology / Q000648:ultrastructure*; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D007962:Leukocytes / Q000187:drug effects / Q000378:metabolism; D008168:Lung / Q000166:cytology / Q000648:ultrastructure*; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects; D010477:Perfusion; D017785:Photons; D011650:Pulmonary Alveoli / Q000166:cytology / Q000648:ultrastructure; D051381:Rats; D017207:Rats, Sprague-Dawley; D012907:Smoking / Q000009:adverse effects; D013755:Tetradecanoylphorbol Acetate / Q000633:toxicity; D013909:Thorax / Q000166:cytology / Q000648:ultrastructure*
chemical_list: D002273:Carcinogens; D013755:Tetradecanoylphorbol Acetate