Background and aim of the study: Substantial heart valve research relies on the isolation of valvular interstitial cells (VICs). While a wide variety of conditions have been reported for VIC isolation, the effectiveness of these methods has rarely been compared. It is also likely that valve donor age will influence these valvular tissue dissociation conditions. The study aim was to increase the efficiency and cost-effectiveness of VIC isolation, while taking into account possible differences due to valve donor age.
Methods: Aortic valves were obtained from six-month-old (n = 24) and six-week-old (suckling) pigs (n = 45) within 24 h of death. After removal of endothelial cells, the tissues were minced and subjected to a variety of enzymatic digestions for variable lengths of time.

Results: The optimal concentration of collagenase III was determined as 1 mg/ml for six-week-old pigs, and 2 mg/ml for six-month-old pigs. The optimal duration of digestion was 4 h for both ages. The addition of neutral protease (2 mg/ml) further increased yield, while additional DNAse and hyaluronidase had no effect. Yield was not influenced by the volume of enzyme solution, nor the use of previously frozen enzyme solution.
Conclusion: These findings provide age-specific conditions for improving the yield of VIC isolation, which should be of value in experimental studies of valvular cell biology and tissue engineering investigations.

The Journal of Heart Valve Disease 2007;16:175-183