Tumour Vasculature Targeting and Pre-clinical Experience

The corneal pocket assay and the window preparations are designed to measure vessel formation after addition of stimulators. These assays can for instance be used for the study of angiogenic potential of human tumours. These models are also suitable for pre-clinical testing of angiogenesis inhibitors. 

Implantation of polymer matrices that contain angiogenic factors requires quantification of the extent of vessel ingrowth. This can either be analysed immunohistochemically or by haemoglobin/red blood cell count in the tissue. These models generally do not allow analysis of the time course of vascularization since this would require the sacrifice of animals. Application in a dorsal skin fold chamber circumvents this experimental problem, as it provides the opportunity to monitor vessel formation at various time points during the experiment. 

In vivo assays however, also have a munber of disadvantages. For example, the pharmacokinetics, necessary for correct interpretation of results, are often unknown, and in addition the host might respond nonspecifically to the implantation. For a review on in vivo angiogenesis models and their potentials and problems, the reader is referred to reference [67]. 

In general, endothelial-specific markers can be grouped into three major categories  

A number of molecules in groups 2 and 3 have been identified by the differential homing capacity of phage display libraries and combination peptide libraries [71]. Biochemical strategies such as the application of 2D gel electrophoresis on protein extracts from endothelial cell surfaces have also proven useful in this respect [72]. 

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