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Vascular anatomy and in particular angiogenesis and antiangiogenesis are in focus of modern medicine. In
consideration of animal welfare the establishment of in vitro models of angiogenesis plays a decisive role.
Most models comprise the simulation of just one step of the angiogenic cascade, i.e. either migration or
proliferation or formation of tubular structures by endothelial cells. In these models endothelial cells are
always cultured on collagen-coated dishes or in Matrigel®. Currently, the method published by our group,
allows investigation and quantitation of all steps of the angiogenic cascade including the development of
capillary-like structures and secretion of basal lamina components in one assay. Quantitation of
angiogenesis is carried out by division of the phases of the angiogenic cascade into eight defined stages and
time-dependent ascertainment of these stages within 60 days. In order to standardise our method we used
four different endothelial cultures derived from heart, lung, adult and neonatal foreskin. Collagen-free
cultivation showed that only two of these cultures (heart, neonatal foreskin) run through all stages of
angiogenesis. In the other foreskin derived culture cells remained at stage 1 and 2. In endothelial cells of the
lung angiogenesis reached stage 3, paused and regressed from day 30 of investigation on.
Immunolocalisation of endothelial expression of collagen type IV, an essential component of the basal
lamina, showed a continuous expression in the ?angiogenic? heart and neonatal foreskin derived cultures. In
opposite, in the ?non angiogenic? cultures of lung and adult foreskin collagen type IV was expressed only
moderately resulting in a fragmentary collagenous network. Collagen type IV consists of 6 distinct alphachains
(alpha-1-6). PCR from cDNA showed that in angiogenic cells alpha-1, -2 and -5, whereas in nonangiogenic
only alpha-1 and -2 were expressed. Our results show that only particular microvascular
endothelial cells can be stimulated to run through all stages of angiogenesis in vitro. Therefore only specific
cultures should be used for the establishment of realistic in vitro models of angiogenesis. One potential
reason for this may be the ability of the cells to express collagen type IV and in particular its alpha-5-chain.