Solid tumors depend on angiogenesis for growth and metastasis, It has been
shown that blood vessel density, as determined by counting the number of ca
pillaries in clustered bursts, is a significant prognostic factor in carcin
omas. It is unclear, however, whether vessel density is a prognostic factor
in sarcomas, In this study, we examined angiogenesis in sarcomas of variou
s grades and compared their vascular patterns to those of carcinomas. Micro
vessels were identified by von Willebrand factor staining. The matrix of mu
ltiple sarcoma and breast carcinoma specimens were extracted and subjected
to Western analysis of various angiogenic factors and inhibitors. Metallopr
oteinase inhibitor presence was also determined by in situ hybridization, I
n breast carcinomas, capillaries were clustered in bursts within the stroma
of the tumor, whereas the sarcoma capillaries were homogeneously distribut
ed in the tumor stroma, Random blood vessel density per high power field in
sarcomas did not correlate with patient prognosis. The matrix of sarcomas
and carcinomas contained both angiogenic stimulators and inhibitors. Tissue
inhibitor of metalloproteinase-l was found predominantly in fibroblasts an
d myofibroblasts in the matrix of carcinoma specimens, The difference in th
e pattern of angiogenesis in sarcomas and carcinomas may be attributable to
the presence of fibroblasts and myofibroblasts in carcinomas, resulting in
the compartmentalization of bursts of angiogenic factors. The homogeneous
appearance of vessel density in sarcomas observed in the present study woul
d be the consequence of the influence of a single compartment.