Migration and proliferation of human plaque cells in vitro: effect of Dipyridamole?

Abstract

Migration and proliferation of smooth muscle cells (SMC) from the media into the subendothelial space have been recognized as essential steps in the development of atherosclerotic plaques. Plaque material of primary stenosing and restenosing lesions from 26 patients was removed by atherectomy from peripheral arteries (Prof. Höfling, Dr. Bauriedel, Klinikum Großhadern, Munich). Plaque cells were isolated by enzymatic disaggregation with elastase/collagenase. Isolated cells were identified as SMC by positive reaction with monoclonal antibodies against smooth muscle α-actin. Dipyridamole (DPD) was added to the cultures at concentrations ranging from 10⁻⁹ mol/l to 10⁻³ mol/l.

Migration: Confluent cultures were cut with a blade in order to obtain a cell-free area. Immediately after cutting, Dipyridamole (DPD) was added to the cultures at concentrations from 10⁻⁸ mol/l to 10⁻³ mol/l. After 48 hours 111 ± 27 cells (x ± SD) had migrated into the cell-free area. The migration rate was 18 ± 3 ¼m/hour (x ± SD). At clinical concentrations DPD had no effect on the migration of SMC.

Proliferation: Cell number was analysed in a cell counter (Casy I, Schärfe System). Population doubings per day (PD/day) of plaque cells from restenosing lesions were significantly increased in comparison to plaque cells from primary stenosing lesions. DPD at concentrations ranging from 10⁻⁹ mol/l to 10⁻⁴ mol/l was added to the cultures one day after seeding. At each change of medium DPD was renewed as well. After 5 days cell number was analysed. There was no effect to DPD to proliferation of plaque cells within therapeutical concentrations.

Conclusion: Highly increased growth rates of plaque cells from restenosing lesions might be an in vitro equivalent to the rapid progression of restenosing events after angioplasty in vivo. Within therapeutical concentrations migration and proliferation of plaque cells in vitro was not affected by DPD.

Zusammenfassung

Interventionelle Techniken werden in immer größerem Umfang zur symptomatischen Behandlung von Folgeerscheinungen der Atherosklerose eingesetzt. Auf zellulärer Ebene scheint beim Restenosierungsprozeß nach Angioplastie der Migration und Proliferation von glatten Muskelzellen (SMC) aus der Media in den subendothelialen Raum eine besondere Bedeutung zuzukommen [7]. In der folgenden Untersuchung wurden Zellen aus atherosklerotischem Plaquematerial isoliert und ihre migratorische und proliferative Aktivität in vitro analysiert. Da Dipyridamol (DPD) in verschiedenen Zentren zur Vor- und Nachbehandlung bei Angioplastien und Bypass-Operationen eingesetzt wird [1, 9], wurde in vitro der Einfluß dieser Substanz auf das Migrations- und Proliferationsverhalten von SMC aus atherosklerotischem Plaquematerial geprüft.