Immunology of bovine heart valves. II. Reaction with connective tissue components

Polyphenol-stabilized tubular elastin scaffolds for tissue engineered vascular grafts

Tissue-engineered vascular grafts require elastic, acellular porous scaffolds with controlled biodegradability and properties matching those of natural arteries. Elastin would be a desirable component for such applications, but elastin does not easily regenerate experimentally. Our approach is to develop tubular elastin scaffolds using decellularization and removal of collagen from porcine carotid arteries ( approximately 5 mm diameter) using alkaline extraction. Because elastin is susceptible to rapid degeneration after implantation, scaffolds were further treated with penta-galloyl glucose (PGG), an established polyphenolic elastin-stabilizing agent. Scaffolds were compared in vitro with detergent-decellularized arteries for structure, composition, resistance to degradation, mechanical properties, and cytotoxicity and in vivo for cell infiltration and remodeling potential. Results showed effective decellularization and almost complete collagen removal by alkaline extraction. PGG-treated elastin scaffolds proved to be resistant to elastase digestion in vitro, maintained their cylindrical shapes, showed high resistance to burst pressures, and supported growth of endothelial cells and fibroblasts. In vivo results showed that PGG treatment reduced the rate of elastin biodegradation and controlled cell infiltration but did not hamper new collagen and proteoglycan deposition and secretion of matrix-degrading proteases. Alkali-purified, PGG-treated tubular arterial elastin scaffolds exhibit many desirable properties to be recommended for clinical applications as vascular grafts.

Effect of valvular surgery on antibody to the group A streptococcal carbohydrate

Because previous studies revealed that high levels of antibody to the group A streptococcal carbohydrate (A-antibody) persist in the serum of patients with chronic rheumatic valvular disease, the effect of valvular surgery on the level of this antibody was examined in the present study. Streptococcal antibody titers (ASO, anti-DNAse B, and A-antibody) were determined on 73 patients admitted for cardiac surgery: 36 with chronic rheumatic valvular disease and 37 with nonrheumatic cardiac or coronary disease. While the ASO and anti-DNAse B presurgical titers were similar in rheumatic and nonrheumatic individuals, the levels of A-antibody were significantly higher in rheumatic patients. The effect of blood perfusion during cardiac surgery was reflected by reversion of antibody titers towards the mean value for a normal population. A trend toward a rise in all antibodies was seen in all patients two to seven weeks after surgery. However, after an interval of eight weeks or more following surgery, a significant decline in the A-antibody occurred in rheumatic patients who had undergone excision and replacement of the affected valve, but not in those who had experienced a simple commissurotomy. These findings provide additional evidence to support a relationship between valvular disease and A-antibody level in rheumatic patients.