Synergistic inhibition of calcification of porcine aortic root with preincubation in FeCl3 and ?-amino oleic acid in a rat subdermal model

Postimplant calcific degeneration is a frequent cause of clinical failure of glutaraldehyde crosslinked porcine aortic valve bioprostheses. We demonstrated previously in rat subdermal and circulatory implants that alpha-amino oleic acid used as a bioprosthesis pretreatment was highly effective in mitigating aortic valve cusp but not aortic wall calcification. In this study we investigated the feasibility of synergistically applying two proven anticalcification agents (alpha-amino oleic acid and FeCl3) as pretreatments for mitigating both bioprosthetic cusp and aortic wall calcification. alpha-Amino oleic acid is hypothesized to prevent calcification by disrupting calcium phosphate formation kinetics, whereas suppression of alkaline phosphatase activity and ferric-phosphate complexation at a cellular membrane initiation sites may be important factors in ferric ion's inhibition of calcification. In vivo implant studies (21-day rat subdermal model) indicated that individually FeCl3 (0.01 or 0.1 M for 24 h) or alpha-amino oleic acid (saturated solution) treatments were equally effective in mitigating cuspal calcification (tissue calcium levels: 30.2 +/- 10.2, 29.8 +/- 2.7, and 31.6 +/- 7.8 micrograms/mg tissue, respectively). However, sequential application of first alpha-amino oleic acid and then FeCl3 synergistically reduced aortic wall calcification more effectively than either of the agents alone. The benefit of a synergistic application of two anticalcification treatments, alpha-amino oleic acid and FeCl3, was demonstrated. However, the synergistic effect was observed on aortic wall only at a higher FeCl3 concentration. (i.e., 0.1 M).