Cryopreservation of coronary endothelium and endothelial-mediated responses

Limited availability of functionally viable biological tissues for graft transplantation and scientific research necessitates the development of an effective storage method for preserving existing tissue samples. In this report we briefly reviewed recent attempts in the cryopreservation of coronary endothelium and endothelial-mediated vasoregulatory function. In contrast to partial preservation of vascular smooth muscle cell function, cryostorage of coronary arteries in dimethyl sulfoxide and fetal calf serum resulted in a near complete preservation of the endothelium and its vasoregulatory function. This protection was observed in both animal and human epicardial conduit coronary arteries, as well as in dog intramyocardial resistance arteries. The apparent better preservation of the latter resistance arteries, with a luminal diameter less than 50 microns, is consistent with earlier findings that cryopreservation efficacy improves with fewer and less packing of cells. To further investigate the cryopreservation of endothelial function, we cryostored canine cardiac valves and evaluated the vasorelaxant effects of valvular endothelium-derived vasoactive factors using a bioassay system. As was observed with intact coronary arteries, a near complete preservation of valvular endothelium and its production of vasoactive factors was noted following the freeze and thaw procedures. Thus, these results demonstrate that cryopreservation may provide a useful and efficient storage method for the conservation of limited supplies of biological vascular tissues for graft transplantation and scientific research.