Lectin Intravital Perfusion Studies in Tumor-bearing Mice: Micrometer-resolution, Wide-area Mapping of Microvascular Labeling, Distinguishing Efficiently and Inefficiently Perfused Microregions in the Tumor

Abstract

Intravital lectin perfusion was combined with computer-guided scanning digital microscopy to map the perfused elements of the vasculature in tumor-bearing mice. High-precision composite images (spatial precision 1.3 micron and optical resolution 1.5 micron) were generated to permit exact positioning, reconstruction, analysis, and mapping of entire tumor cross-sections (c. 1 cm in diameter). Collation of these mosaics with nuclear magnetic resonance maps in the same tumor plane identified sites of rapid contrast medium uptake as tumor blood vessels. Digitized imaging after intravital double labeling allowed polychromatic visualization of two different types of mismatched staining. First, simultaneous application of two lectins, each bearing a different fluorochrome, revealed organ-specific differential processing in the microvascular wall. Second, sequential application of two boluses of one lectin, bearing different fluorochromes successively, distinguished between double-labeled microvessels, representing efficiently perfused vascular segments, and single-labeled microvessels, with inefficient or intermittent perfusion. Intravital lectin perfusion images of blood vessels in the vital functional state thus highlighted biologically significant differences in vessel function and served as high-resolution adjuncts to MR imaging.

Use of labeled tomato lectin for imaging vasculature structures

“…Several different lectins have been used experimentally by several groups of investigators (Simionescu et al 1982;Nag 1985;Alroy et al 1987;Debbage et al 1998;Jilani et al 2003). Differences in results from different lectins were reported, but overall, the tomato lectin appears to provide consistently strong labeling.…”

“…Differences in results from different lectins were reported, but overall, the tomato lectin appears to provide consistently strong labeling. Further, tomato lectin appears to be the best candidate for studies of central nervous system (CNS) vasculature, as use of other lectins reportedly produces poor labeling of CNS vasculature (Debbage et al 1998).…”

“…Interestingly, Debbage et al (1998) report that CNS labeling is not achieved from use of other lectins, suggesting that the tomato lectin may be particularly advantageous in studies of CNS vasculature (Mazzetti et al 2004).…”

“…Lectins can be tagged fluorescently or with biotin, and have been used to label vascular elements in fixed tissue sections, through their binding to carbohydrate components of the endothelial plasmalemma (Nag 1985;Jilani et al 2003;Baratta et al 2009). Others have used intravascular injections of one or more of several different lectins to label certain vascular elements (Alroy et al 1987;Debbage et al 1998;Hashizume et al 2000; Lee et al 2002;Gee et al 2003;Lokmic and Mitchell 2011). Results reported thus far indicate wide variation in the efficacy of vascular labeling of different lectins, and that tomato lectin may provide the best labeling of central nervous system vasculature (Alroy et al 1987;Debbage et al 1998;Jilani et al 2003;Lokmic and Mitchell 2011;Smolkova et al 2001).…”

“…Others have used intravascular injections of one or more of several different lectins to label certain vascular elements (Alroy et al 1987;Debbage et al 1998;Hashizume et al 2000; Lee et al 2002;Gee et al 2003;Lokmic and Mitchell 2011). Results reported thus far indicate wide variation in the efficacy of vascular labeling of different lectins, and that tomato lectin may provide the best labeling of central nervous system vasculature (Alroy et al 1987;Debbage et al 1998;Jilani et al 2003;Lokmic and Mitchell 2011;Smolkova et al 2001). The purpose of this project was to test the utility of intravenous injection of tomato lectin (Nachbar et al 1980) to visualize elements of the vascular system in several different organs.…”