GROWTH-FACTORS AND MYOINTIMAL HYPERPLASIA IN EXPERIMENTAL AORTIC ALLOGRAFTS

Objectives: To analyse the role of growth factors (platelet derived gr owth factor, PDGF; basic fibroblast growth factor, bFGF; interleukin 1 , IL-1) in the genesis of myointimal hyperplasia in arterial allograft s. Materials: Two groups of experiments were performed: isografts and allografts. The isograft group consisted of 15 inbred Lewis rats in wh ich a 1 cm long segment of aorta was inserted as an abdominal aortic i nterposition graft. The aortic segments were obtained from syngenic Le wis rats. The allograft group consisted of 15 inbred Lewis rats, in wh ich a 1 cm long segment of aorta was interposed at the abdominal aorta level. The aortic segments were obtained from allogenic Brown-Norway rats. Chief outcome measures: The animals were killed 4 weeks after su rgery and were analysed by morphometric analysis (n = 3 for each group ). In addition, production of PDGF, bFGF and IL-1 by aortic segments ( n = 12 for each group) in organ culture was assessed. Main results: Al lografts had more myointimal hyperplasia, than isografts (p < 0.05). P DGF and bFGF production, generally considered to be the cause of myoin timal hyperplasia, was not increased in allografts. IL-1 production wa s higher in allografts (p < 0.001). Main conclusions: Myointimal hyper plasia in aortic allografts is dependent of growth factors produced by the graft itself. These growth factors are different from PDGF and bF GF that generally have been implicated in the genesis of naturally occ urring myointimal hyperplasia and atherosclerosis. IL-1 may have a pri ncipal role in the genesis of myointimal hyperplasia in arterial allog rafts.