A human arterial organ culture model of postangioplasty restenosis: results up to 56 days after ballooning

Background: Restenosis is a reparative process that is activated in respons e to injury induced by angioplasty. Despite numerous experimental models of restenosis the number of human arterial organ culture systems is very limi ted and long-term experiences do not exist. Methods and results: During rou tine nephrectomies parts of the renal arteries of 88 patients were extracte d, 47 were suitable for organ culture preparations. Sections were made at 3 mm intervals perpendicular to the vessel wall axis. The arterial segments were treated with 3 mm standard balloon-catheters (Medtronic 14K2030E) for 60 s with 3, 6, 9, and 12 bar. After angioplasty, the organ segments were c ultured in a mixture of Waymouth's MB 752/1 and Ham F-12, supplemented with 15% fetal calf serum. After 0, 4, 14, 21, 28, and 56 days the organ cultur es were fixed in 4% para-formaldehyde and embedded in paraffin. After stain ing with a modified elastica-van Gieson technique the intimal wall thickeni ng was analyzed with a computerized morphometric system. For the identifica tion of smooth muscle cells (SMC) a monoclonal antibody against smooth musc le alpha-actin was used. Endothelial cells were identified using an anti-hu man von Willebrand factor. To determine the number of cells undergoing DNA synthesis, bromodeoxyuridine (BrdU), a thymidine analogue, was added to the culture media 18 h prior to fixation. BrdU was detected with a monoclonal antibody, as secondary antibody a biotinylated horse-anti-mouse antibody wa s used. After 14, 21, and 28 days in culture BrdU-positive cells were detec ted in the neointima of the organ cultures, indicating mitotic activity in this area. After 28 and 56 days in culture a clear increase of neointimal t hickening was found in the morphometric analysis. By positive reaction with antibodies against smooth muscle alpha-actin these cells were partly ident ified as SMC. Conclusions: The organ culture model offers opportunities for in vitro investigations of postangioplasty restenosis. The data emphasize the importance of a relatively late proliferative response of SMC ill the h uman arterial organ culture model. (C) 1999 Elsevier Science Ireland Ltd. A ll rights reserved.