Experimental freeze-dried microarterial allografts in rabbits.

Arterial allografts, 3.5 cm in length, were freeze-dried and placed into the femoral arteries of 20 female rabbits (16 experimental subjects and four controls). Immediate patency was 100%. Subjects were surgically explored after two months of observation. Overall patency at this time was 31% (5/16). A patency rate of 50% (5/10) was achieved with size-matched femoral grafts. However, all of the smaller diameter brachial grafts were unsuccessful. Analysis by light microscopy as well as transmission and scanning electron microscopy demonstrated intimal hyperplasia, which was more prominent in nonpatent grafts. There was no evidence of a cellular immune response to the freeze-dried grafts by the host. The use of size-matched grafts and postoperative anticoagulants in future studies may improve patency rates and the potential clinical applicability of this promising microvascular technique.