Experimental basis for autograft growth and viability.

An experimental model has been designed to evaluate the potential of growth of aortic vascular autografts and homografts. In 25 young rabbits a graft interposition was performed at the level of the infrarenal aorta, with micro-surgical techniques. Different groups included fresh autografts, fresh and cryopreserved homografts and controls. Animals were allowed to grow normally and were sacrificed when adult, at the mean weight of 2.99 kg. We studied for each case the growth of the native aorta and that of the graft, and calculated the growth-ratio (growth of the graft/growth of native vessel). Grafts and adjacent aorta were histologically studied. The growth in terms of increase in diameter of the native aorta was identical between the four groups (from 1.97 +/- 0.14 mm to 2.86 +/- 0.23 mm). Growth of the graft was normal (mean growth ratio 1.08 +/- 0.21) for autografts. Growth was absent (mean ratio 0.12 +/- 0.15) for fresh and cryopreserved homografts (p = 0.001). Histologic study showed normal optical microscopic aspects (endothelial layer, intima and media thickness and cellularity) when growth had been normal and, when growth had been absent, aspects compatible with rejection including mainly intima hyperplasia and media attenuation. In conclusion, normal growth of the arterial autografts was confirmed, the histologic features of these grafts were normal, but homologous aortic grafts, fresh or cryopreserved, never showed any growth potential.