Transforming growth factor-β in graft vessels: histology and immunohistochemistry

OBJECTIVES: The biological functions of transforming growth factor-β signaling that involves Smad proteins have not been previously investigated with respect to coronary artery bypass grafts. The aim of the present study was to observe the immunostaining of proteins that are related to this signaling pathway. METHODS: Fifteen remnants of coronary artery bypass grafts, including nine saphenous veins, three radial arteries and three mammary arteries, were collected from 12 patients who were undergoing coronary artery bypass. Hematoxylin and eosin, Masson's trichrome, and immunohistochemical staining of transforming growth factor-β1, type I receptor of transforming growth factor-β, Smad2/3, Smad4, and Smad7 were performed. RESULTS: The saphenous veins showed more severe intimal degeneration, more severe smooth muscle cell proliferation and more collagen deposition than the arterial grafts, as evidenced by hematoxylin and eosin and Masson's trichrome stainings. Immunohistochemical assays demonstrated that the majority of the transforming growth factor-β1 signaling cytokines were primarily localized in the cytoplasm in the medial layers of all three types of grafts, whereas ectopic transforming growth factor-β1, type I receptor of transforming growth factor-β, and Smad7 overexpressions in the interstices were observed particularly in the saphenous vein and radial arterial grafts. CONCLUSION: Enhanced transforming growth factor-β1 signal transduction with medial smooth muscle cell proliferation and ectopic transforming growth factor-β1, the presence of the type I receptor of transforming growth factor-β, and Smad7 overexpressions in the extracellular matrix may provide primary evidence for early or late graft failure.

Producción comparativa de prostaciclina en arteria epigástrica inferior, arteria mamaria interna y vena safena: implicancias en el pronóstico de la revascularización miocárdica / Prostacycline production by the inferior epigastric artery, compared to the internal mammary artery and the saphenous vein

Se usó un sistema in vitro para medir la producción de PG12 en anillos aislados de la arteria mamaria interna, la arteria epigástrica inferior y la vena safena obtenidos en 5 pacientes durante cirugía de revascularización. La muestras fueron incubadas en solución Krebs'Ringer a pH 7.4. Por radioinmuoensayo (Amersham) se midió el 6-keto-PGF la, metabolito de PG12 en alicuotas del sobrenadante. La producción de arterias epigástrica fue 12,5 2,0 ng/mg/30 min, la de arteria mamaria interna 9,3 1,7 y la de vena safena5,1 0,7 (p 0,01). Por lo tanto, la arteria epigástrica inferior produce PG12 en cantidades similares a las de la arteria mamaria interna y considerablemente mayores que las de la vena safena. Ello podría traducirse en un mejor pronóstico de los puentes coronarios efectuados con arteria epigástrica comparados con las de la vena safena