SIMILARITY IN BEHAVIOR OF POLYTETRAFLUOROETHYLENE (EPTFE) PROSTHESES IMPLANTED INTO DIFFERENT INTERFACES

The biomaterial ePTFE is widely used in the clinical environment for v ascular replacement or bypass, as well as in the repair of tissue defe cts, especially those involving the abdominal wall. The objective of t his study was to evaluate the healing response to ePTFE prostheses imp lanted into a circulatory interface and a tissue interface, each in a different animal species. For vascular implants, the Sprague-Dawley ra t (n = 60) was used, while the New Zealand white rabbit (n = 20) was u sed in the tissue replacement model. In the former, a vascular micropr osthesis measuring 5 mm in length and 1 mm in internal diameter, havin g a porosity of 30 mu m, was implanted into the common iliac artery. I n the rabbit, a 7 x 5-cm fragment of ePTFE (Soft-Tissue Patch) was imp lanted into a defect in anterior abdominal wall that involved all the tissue layers. In this case, the prosthesis was left touching the inte stinal loops. The implants were studied between 14 and 90 days of post implantation by means of light micros copy, scanning electron microsco py, and immunohistochemistry. The latter involved the use of anti-rat (MAC-341) and anti-rabbit (RAM-11) macrophage-specific monoclonal anti bodies. The behavior of the ePTFE in the different interfaces (vascula r and abdominal wall) was similar with respect to the following aspect s: the prosthesis presented a process of encapsulation which was more intense on the outer surface; colonization of the implant was limited to the outermost two thirds, with minimal invasion of the middle porti on; colonization was absent on the edges of the prosthesis; collageniz ation of the interstice of the mesh occurred late; the foreign body re action taking place on the outer surface was similar in both interface s, with formation of a barrier consisting of macrophages and giant cel ls that did not penetrate the prosthesis; and, finally, in neither of the two models was vascular colonization of the PTFE prosthesis observ ed; rather, the angiogenic process was limited to the periprosthetic z ones. The integration of the implant made of ePTFE is similar despite the differences in interfaces and the use of different animal species. The macrophage response does not determine the success or failure of the implant. (C) 1996 John Wiley & Sons, Inc.