Mapping of the functional microcirculation in vital organs using contrast-enhanced in vivo video microscopy.
A functional microcirculation is vital to the survival of mammalian tissues. In vivo video microscopy is often used in animal models to assess microvascular function, providing real-time observation of blood flow in normal and diseased tissues. To extend the capabilities of in vivo video microscopy, we have developed a contrast-enhanced system with postprocessing video analysis tools that permit quantitative assessment of microvascular geometry and function in vital organs and tissues. FITC-labeled dextran (250 kDa) was injected intravenously into anesthetized mice to provide intravascular fluorescence contrast with darker red blood cell (RBC) motion. Digitized video images of microcirculation in a variety of internal organs (e.g., lung, liver, ovary, and kidney) were processed using computer-based motion correction to remove background respiratory and cardiac movement. Stabilized videos were analyzed to generate a series of functional images revealing microhemodynamic parameters, such as plasma perfusion, RBC perfusion, and RBC supply rate. Fluorescence contrast revealed characteristic microvascular arrangements within different organs, and images generated from video sequences of liver metastases showed a marked reduction in the proportion of tumor vessels that were functional. Analysis of processed video sequences showed large reductions in vessel volume, length, and branch-point density, with a near doubling in vessel segment length. This study demonstrates that postprocessing of fluorescence contrast video sequences of the microcirculation can provide quantitative images useful for studies in a wide range of model systems.
Varghese
Hemanth J
HJ
Department of Medical Biophysics, University of Western Ontario, London, Ontario, Canada N6A 5C1.
MacKenzie
Lisa T
LT
Groom
Alan C
AC
Ellis
Christopher G
CG
Chambers
Ann F
AF
MacDonald
Ian C
IC
D000818:Animals; D001783:Blood Flow Velocity; D003287:Contrast Media; D003911:Dextrans; D004912:Erythrocytes; D005260:Female; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives*; D007089:Image Enhancement; D007091:Image Processing, Computer-Assisted; D008102:Liver Circulation; D008113:Liver Neoplasms / Q000098:blood supply / Q000556:secondary; D051379:Mice; D008815:Mice, Inbred Strains; D008833:Microcirculation; D008856:Microscopy, Fluorescence; D018715:Microscopy, Video; D010053:Ovary / Q000098:blood supply*; D011652:Pulmonary Circulation; D012079:Renal Circulation
D003287:Contrast Media; D003911:Dextrans; C015219:fluorescein isothiocyanate dextran; D016650:Fluorescein-5-isothiocyanate