“Variable induction of experimental abdominal aortic aneurysms with different preparations of porcine pancreatic elastase”☆
Article Outline
To the Editors:
Many experimental studies on the pathogenesis of abdominal aortic aneurysms have used the elastase-induced rodent model first described in 1990 by Anidjar et al.1 We wish to make the readership aware of an important, recently recognized problem with this model that is not apparent from the published literature.
Nearly every report that uses the Anidjar model describes the use of type I porcine pancreatic elastase purchased from Sigma Chemical Company (catalog no. E-1250, St Louis, Mo). In February 1997, Sigma introduced a new assay system to measure the elastase activity of these preparations. Despite considerable experience with the Anidjar model and the use of a conversion factor to calculate the amount of elastase activity necessitated, we subsequently found that aortic perfusion with E-1250 elastase no longer induced the process of aneurysmal degeneration. We later learned that the company also had introduced a modification in the purification of pancreatic elastase that results in a preparation with fewer contaminating proteases (Harry Dapron, Sigma Chemical Company, personal communication). Indeed, our own studies also revealed a considerable difference between the “old” and “new” preparations of E-1250 elastase by protein gel electrophoresis (Fig. 1).
Fig. 1.
Sodium dodecylsulfate-polyacrylamide gel electrophoresis of “old” and “new” preparations of Sigma E-1250 type I porcine pancreatic elastase, run under nondenaturing conditions and stained for total protein (2 μL per lane). Elastase is expected to migrate at approximately 30 kD (*). Several of the proteins removed during the “enhanced” preparation of E-1250 are indicated by arrows. Although the “old” preparation is effective in the induction of experimental abdominal aortic aneurysms, the “new” preparation is not. Mr, Molecular weight markers; AAA, abdominal aortic aneurysms.
Although the old formulation of E-1250 is no longer available for purchase, Sigma has generously provided us with the remaining lots of the previous E-1250 elastase. This preparation continues to be effective for the induction of aneurysms in the rat, and we are presently attempting to identify the critical substances that were removed during the additional purification of pancreatic elastase. Nonetheless, we are aware of at least three other laboratories that have been unable to establish or reproduce the Anidjar model during the past year with the commercially available E-1250 elastase preparation. Therefore, it is important that other investigators be made aware of this problem before planning studies with the elastase-induced model of aortic aneurysm in rats.
