IN-VIVO GENE-TRANSFER - PREVENTION OF NEOINTIMA FORMATION BY INHIBITION OF MITOGEN-ACTIVATED PROTEIN-KINASE KINASE

Background The mitogen-activated protein kinase kinase (MAPKK) is a pr otein downstream ras which is rapidly activated in cells stimulated wi th various extracellular signals. These proteins are believed to play a pivotal role in integrating and transmitting transmembrane signals r equired for cell growth. Methods and Results To study the effect of in hibition of MAPKK on smooth muscle cell (SMC) proliferation in vivo af ter vascular injury, we performed experimental balloon angioplasty usi ng the standard Clowes technique in male Wistar rats 14-weeks old. The animals did not receive any treatment after vascular injury (N = 6) o r were randomly assigned to receive, after balloon injury, a 30 % (w/v ) pluronic gel solution applied to the injured carotid artery, contain ing respectively: 1) no plasmid DNA (n = 10); 2) RSV-lacZ (encoding th e p-galactosidase gene) as control gene without effects on SMC prolife ration (n = 10); 3) Tg-CAT (encoding cloramphenicol acetyl-transferase gene under the control of thyreoglobulin promoter) as an additional c ontrol gene without effects on SMC proliferation (n = 7); 4) a negativ e mutant of mitogen-activated Protein Kinase Kinase (MAPKK(-)) (n = 13 ), Fourteen days after vascular injury, carotid arteries were removed and cross sections were cut and stained with hematoxylin/eosin. Morpho metric analysis demonstrated, in the MAPKK(-)-treated rats. a signific ant reduction of both neointima (0.096 +/- 0.018 mm(2) vs. 0.184 +/- 0 .019 mm(2), p < 0.01) and neointima/media ratio (0.603 +/- 0.103 vs. 1 .471 +/- 0.161, p < 0.01) compared to control DNA. Conclusions The inh ibition of MAPKK. by a dominant inhibitor mutant gene, prevents the SM C proliferation after vascular injury in vivo.