Chapter 8. Noninvasive imaging of blood vessels

Angiogenesis is a key component in several major clinical conditions including cancer, diabetic retinopathy, rheumatoid arthritis, endometriosis and psoriasis. All these diseases could be managed much more effectively if their angiogenic capacities were somehow curtailed. Hence there is great interest in developing a fuller understanding of angiogenesis and designing agents to suppress, guide, and normalize this process. Although much has been learned from in vitro methods, the perspective is limited because angiogenesis depends on active blood flow and a variety of circulating precursor cells provided by the intact host. Therefore, noninvasive in vivo methods that provide information over days and weeks are needed. Accordingly, the rodent dorsal skinfold tissue window chamber facilitates the imaging of new vessels around implanted cells, around an injury, or around a simple device impregnated with growth factors. Tissue oxygen levels can be measured during the course of angiogenesis using a window chamber that is also fitted with a miniature multiple electrode sensor. The present review describes window chamber methods and hardware, the measurement of oxygen, and the introduction into the chamber of tumors, growth factors, and organs to induce angiogenesis. The application of multiphoton microscopy to intravital imaging is discussed, along with a description of how to modify a standard brightfield or fluorescence microscope for multiphoton imaging of window chamber microvessels.