Selective enhancement by tumor necrosis factor-alpha of vascular permeability of new blood vessels induced with agarose hydrogel-entrapped Meth-A fibrosarcoma cells.
We have previously developed a simple and quantitative method for assessment of in vivo tumor cell-induced angiogenesis by means of microencapsulation of tumor cells in agarose hydrogel and mouse hemoglobin ELISA (mHb-ELISA). In this article, we report that the new blood vessels induced with agarose-encapsulated tumor cells have the same sensitivity to tumor necrosis factor-alpha (TNF-alpha) as the original solid-tumor vessels. Agarose beads (average diameter = 200 microns), in which Meth-A fibrosarcoma cells were microencapsulated, were subcutaneously implanted in non-syngeneic ddY mice. Ten days later, extensive angiogenesis was observed on the implanted sites of Meth-A agarose heads, whereas no new blood vessels were induced with cell-free agarose heads. The vascular permeability of the new blood vessels induced with agarose-microencapsulated Meth-A cells was selectively and significantly enhanced by the i.v. injection of TNF-alpha, and it reached the maximum level at 2 h after the injection of TNF-alpha. At 4 h after the injection of TNF-alpha, the vascular permeability was reduced to the basal level. This permeability profile in Meth-A agarose beads in ddY mice is very similar to that in Meth-A solid tumor in syngeneic BALB/c mice. On the other hand, TNF-alpha-treatment did not affect the vascular permeability of other normal tissues or inflammatory tissue in ddY mice. These results strongly suggest that the new blood vessels induced with agarose-microencapsulated tumor cells have the specific characteristics of tumor vessels. Our in vivo angiogenesis assay system should be useful not only to screen anti-angiogenetic agents, but also to elucidate the mechanism of tumor angiogenesis.
Okada
N
N
Faculty and Graduate School of Pharmaceutical Sciences, Osaka University.
Kaneda
Y
Y
Miyamoto
H
H
Yamamoto
Y
Y
Mizuguchi
H
H
Tsutsumi
Y
Y
Nakagawa
S
S
Mayumi
T
T
D000818:Animals; D002199:Capillary Permeability; D005260:Female; D005354:Fibrosarcoma / Q000098:blood supply*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D009389:Neovascularization, Pathologic; D011092:Polyethylene Glycols / Q000494:pharmacology; D012685:Sepharose; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*
D014409:Tumor Necrosis Factor-alpha; D011092:Polyethylene Glycols; C028210:monomethoxypolyethylene glycol; D012685:Sepharose