Angiogenesis has been recognised as a precursor of fibrosis in several
pathologic conditions. Its participation has been demonstrated in
schistosomiasis, both during periovular granuloma formation and in the
genesis of schistosomal periportal fibrosis. Paradoxically,
proliferation of new blood vessels, accompanied by production of
vascular-endothelial growth factor, appeared prominent during fibrosis
regression months after curative treatment of schistosomiasis. Thus,
angiogenesis in schistosomiasis seems to have a two-way mode of action,
participating both in fibrogenesis and in fibrosis degradation.
Morphological observations presented here are in keeping with the
possibility that, in the first case, angiogenesis allows pericytes to
come in great numbers to the site of lesions and be detached from
capillary walls and transformed into myofibroblasts, which are
important extra-cellular matrix forming cells. During post-curative
fibrosis regression, actin-containing pericytes appeared at various
foci of tissue remodelling, especially at sites of repair of vascular
lesions. The molecular and cell factors involved in both situations
seem to be important subjects in need of further investigations and the
schistosomiasis model certainly will be of great avail in this regard