ELASTIN DEGRADATION PRODUCTS INDUCE ADVENTITIAL ANGIOGENESIS IN THE ANIDJAR DOBRIN RAT ANEURYSM MODEL/

Background. Infusion of the abdominal aorta with pancreatic elastase i nduces aneurysms in a rat model (Anidjar/Dobrin). Because elastolysis liberates elastin degradation products (EDPs), the present experiment was carried out to test the hypothesis that an EDP alone could induce features of aneurysm disease. Methods. The EDP val/gly/val/ala/pro/gly (VGVAPG), elastase, or saline solution was infused into infrarenal ao rta (n = 4/group). After 1 week aortic diameters were measured, and th e tissues were prepared for histologic examination. Adventitial capill aries (vessel per high-power field) were counted over a standardized p reparation of aorta. Wall thickness was measured by means of computer- aided planimetry. Results. There was an increase of greater than 100-f old in mean vessels per high-power field in aortas receiving VGVAPG or elastase versus saline controls (4.10 +/- 0.68 SEM or 4.48 +/- 0.49 S EM versus 0.03 +/- 0.03 SEM, respectively, p < 0.05). The VGVAPG-perfu sed group had a 26% +/- 4% SEM increase in diameter from baseline that was statistically significant (p < 0.01), but the aortas did not reac h aneurysmal dimensions. Conclusions. Although no aneurysms occurred a t 1 week after the infusion of EDP, the results demonstrate that the E DP VGVAPG can induce a characteristic feature of aneurysm disease. The model permits study of the earliest stages of experimental aneurysm f ormation and raises interesting questions regarding the role of the va sa vasorum in this pathologic process.