Preservation of human artery function following prolonged cold storage with a new solution

Abstract

Objective: Blood vessels are an important tissue for allogenic vessel replacement surgery, which is needed for example following infection of artificial grafts. For tissue banking, European legislation requires evidence of tissue sterility with assays performed over 1 week. Currently, used cold storage solutions do not protect vascular function longer than 2 days. This does not allow completion of microbiological testing. This discrepancy has almost completely stopped vessel banking in Europe.

Methods: We compared the recently developed storage solution TiProtec (Dr F Köhler Chemie, Bensheim, Germany) with traditionally used histidine-tryptophan-ketoglutarate (HTK) solution, 0.9% NaCl, and phosphate-buffered saline (physiological saline solution [PSS]) solution for extended cold (4°C) storage up to 25 days. Isolated rings of human internal mammary artery were studied with respect to several parameters of vessel function, including vessel tone development, endothelium-dependent and endothelium-independent relaxation, and tissue reductive capacity.

Results: Vessels stored in NaCl or PSS for ≥10 hours failed to develop tone after rewarming. Mammary arteries stored in HTK for 4 hours at 4°C initially showed a well-preserved vessel function with respect to vessel tone development, as well as endothelial and smooth muscle dilatative function. However, following 4 days of cold storage, vessel tone development and dilatative responses were significantly impaired. In contrast, arteries stored in TiProtec showed full preservation of vessel tone as well as endothelial and smooth muscle function after 4 days of cold storage. Even after 10 days of cold storage, endothelium-dependent relaxation was approximately 50% of control, and smooth muscle function was fully preserved. Over 2 weeks, tissue reductive capacity was significantly better maintained after cold storage in TiProtec compared with vessels stored in NaCl.

Conclusions: In contrast to traditional HTK, NaCl, or PSS storage, TiProtec solution offers an excellent potential for prolonged cold storage of human arteries, which may close the existing gap between legal requirements for tissue banking and current cold preservation methods.