Angiogenesis promotion by fixing biotinylated VFGF on endothelial cells

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We have developed an intravascular drug delivery system, in. which a drug injected from a catheter is fixed to the vasculature of the targeted tissue. Cellular protein of viable endothelial cells is first biotinylated directly by biotinylation reagents, and then bound by an avidinated drug or, using avidin as a linker, a biotinylated drug. We hypothesized that if vascular endothelial growth factor (VEGF), which promotes endothelial proliferation and angiogenesis, is biotinylated and given to the endothelium by the above method, its effect will become greater than when the cells are simply exposed to it for very few minutes. In the first experiment, we investigated intracellular locations of the molecule given to the endothelium by the above method. Streptavidht labeled with β-galactosidase was fixed to biotmylated endothelium, and.cells were harvested 0,1,2,3,6,12 hours after. The enzyme was visualized byhistochemical method (x-gal). Electron microscopic study revealed that the enzyme was located at 0 hour in the cytoplasm and reached nuclear membrane. Few were found on the cellular membrane. In the second experiment, biotinylated VEGF was made, and fixed to the biotinylated endothelial cells. Though the activity of the biotinylated VEGF was the same as that of intact VEGF, the fixation of the growth factor on the cells was not so effective for the proliferarion of cultured endothelial cells. We speculate that drugs that influence via the cell membrane receptors are not good candidates for our drug delivery method because the biotinylated drugs enter too fast into the cells without binding to their receptors.