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Dorsal air sac model

Dorsal air sac model

The dorsal air sac model is used to examine the in vivo effect(s) of substances against the angiogenic response triggered by cancer cells . Briefly, both sides of a Millipore ring are covered with filters (0.45 µm pore size) and the resultant chamber carefully filled with a tumour cell suspension; this is then implanted into the preformed dorsal air sac of an anaesthetized mouse. Following treatment with the compound of interest, the chamber is carefully removed and rings of the same diameter placed directly upon the sites that were exposed to a direct contact with the chamber. The angiogenic response can then be assessed by counting the number of newly formed blood vessels that lie within the area marked by the ring, using a dissecting microscope.

This assay is relatively simple to perform, although care must be taken not to irritate the surface upon which the chamber is placed, as this may itself induce angiogenesis and hence mask those blood vessels formed due to the presence of the tumour cells.

Chamber assays

The in vivo study of chronic angiogenesis has been greatly advanced by the development of several types of transparent chamber, such as the rabbit ear chamber, dorsal skinfold chamber and cranial window chamber. In these systems, a piece of skin (ear and skinfold chambers) or part of the skull (cranial window chamber) is removed from an anaesthetized animal. Tumour cells, or a gel containing angiogenic factors, is then placed on the exposed surface and covered by glass, which is then secured in place; once the animals have recovered, these models allow for the continuous measurement of various parameters in living animals, including gene expression, angiogenesis, pH and blood flow and hence aid the study of the effect of tissue microenvironment on angiogenesis.