Local Delivery of Platelet-Derived Growth Factor Receptor–Specific Tyrphostin Inhibits Neointimal Formation in Rats

Abstract

Abstract-Signal transduction through the platelet-derived growth factor (PDGF)/PDGF receptor (PDGFR) system is involved in the process of postangioplasty restenosis. Tyrphostins are low molecular weight inhibitors of protein tyrosine kinases. We assessed the antiproliferative effects of PDGFR␤-specific tyrphostin AG-1295 in vitro and in vivo. AG-1295 significantly inhibited rat smooth muscle cell growth stimulated by PDGF-BB or FCS. This antiproliferative effect was paralleled by reversible reduction of the total phosphotyrosine level and the degree of PDGFR␤ phosphorylation by the drug in vitro. Local sustained delivery of the drug from perivascularly implanted polymeric matrices resulted in focal AG-1295 levels of 711 and 29.1 ng/mg of dry arterial tissue 1 and 14 days after implantation in rats. AG-1295 delivered from polymeric matrices resulted in a 35% reduction of neointimal formation on day 14 after balloon injury in the rat carotid model. Tyrosine phosphorylation of certain transduction proteins in arterial tissue extracts was significantly upregulated by balloon injury on day 3 but was essentially returned to or below basal levels 14 days after injury. Tyrphostin treatment decreased tyrosine phosphorylation at both time points below the basal levels. Moreover, the enhancement of PDGFR␤ expression 3 and 14 days after arterial injury was strongly inhibited by AG-1295 treatment. It can be concluded that AG-1295 reduces neointimal formation by inhibiting PDGF␤-triggered tyrosine phosphorylation.

Liposomal Simvastatin Attenuates Neointimal Hyperplasia in Rats

“…The section with the greatest luminal narrowing by neointima was analyzed as previously described (49). The residual lumen, the area bounded by the internal elastic lamina (original lumen), and the area circumscribed by the external elastic lamina (total arterial area) were measured directly.…”

The cell cycle: A critical therapeutic target to prevent vascular proliferative disease

“…In vitro experiments have shown that the tyrphostin AGL-2043, as well as the related tyrphostin AG-1295, selectively inhibit PDGF receptors and selectively inhibit SMC proliferation in culture (163). Local delivery of AG-1295 by a perivascular polymeric matrix or intraluminally with nanoparticules inhibited intimal hyperplasia in a rat carotid injury model (164,165). AGL-2043 DESs with a biodegradable, polymeric coating (162) led to a reduction of in-stent neointima formation in a pig coronary injury model.…”

Novel PDGFβR antisense encapsulated in polymeric nanospheres for the treatment of restenosis

“…Rat smooth muscle cells (SMCs) were isolated and cultured from thoracic aortas of either Sabra male rats or Sprague-Dawley female rats weighing 200-300 g by the explant method. 12 Freshly dissected blood vessels from animals killed less than 5 min previously were placed in cold media. The vessels were aseptically cleaned by removing the fat and connective tissue (adventitia) and were cut longitudinally.…”

“…10,36 The procedures were adapted 12,13,28 with some modifications and adjustment for antisense delivery. Animals were obtained from Harlan Laboratories, Israel, and housed in the animal facilities of the Faculty of Medicine, The Hebrew University of Jerusalem, conforming to the standards for care and use of laboratory animals of The Hebrew University of Jerusalem and NIH.…”

“…A sustained inhibition of this pathway is a promising strategy, which has gained considerable research attention. [12][13][14][15][16][17][18][19] AS-ODNs have been utilized in an attempt to inhibit growth regulatory or cell-cycle genes (c-myb, c-myc, PCNA, cdc2, and cdk2) of SMC. 16,20 However, all the ASODNs used were fully phosphorothioated analogs.…”