VASCULAR ENDOTHELIAL GROWTH FACTOR PROMOTES PROLIFERATION AND MIGRATION OF CAVERNOUS SMOOTH MUSCLE CELLS

Abstract

We investigated whether cavernous smooth muscle cells secrete vascular endothelial growth factor (VEGF), how they respond to VEGF and how age affects their ability to secrete and respond to VEGF. Corpus cavernous tissues were isolated from rats of various ages and grown as monolayer cell cultures. Smooth muscle identity was determined by immunofluorescence staining. Secreted VEGF was measured with a VEGF enzyme-linked immunosorbent assay kit. Cell proliferation was assayed with a cell titer kit. Cell migration was measured with Transwell chambers. VEGF receptor (VEGFR) messenger RNA and proteins were identified by reverse transcription-polymerase chain reaction and immunoblotting, respectively. Cavernous smooth muscle cells from young (age 1 week) and old (age 28 months) rats secreted the least amounts of VEGF and those from 16-week-old rats secreted the most. VEGF stimulated the growth of cavernous smooth muscle cells at an optimal concentration of 12.5 ng./ml. At this concentration cavernous smooth muscle cells from 11-week-old and 28-month-old rats showed the highest and lowest growth rates, respectively. The optimal VEGF concentration for cavernous smooth muscle cell migration was 10 ng./ml. At this concentration cells from 4-week-old and 28-month-old rats showed the highest and lowest migratory rates, respectively. The expression of VEGFR-1 appeared to parallel the VEGF regulated growth rates of these cells. VEGFR-2 was undetectable in cavernous smooth muscle cells. Cavernous smooth muscle cells from rats of different ages secreted different amounts of VEGF and showed different abilities to respond to VEGF. Cavernous smooth muscle cells responded to VEGF in terms of cell proliferation and migration. Cavernous smooth muscle cells from rats of different ages expressed different levels of VEGFR-1 but did not express VEGFR-2.