Hypothermic preservation of endothelialized gas-exchange membranes

Endothelialization of the blood contacting surfaces of blood-contacting medical devices, such as cardiovascular prostheses or biohybrid oxygenators, represents a plausible strategy for increasing their hemocompatibility. Nevertheless, isolation and expansion of autologous endothelial cells (ECs) usually requires multiple processing steps and time to obtain sufficient cell numbers. This excludes endothelialization from application in acute situations. Off-the-shelf availability of cell-seeded biohybrid devices could be potentially facilitated by hypothermic storage. In this study, the survival of cord-blood-derived endothelial colony forming cells (ECFCs) that were seeded onto polymethylpentene (PMP) gas-exchange membranes and stored for up to 2 weeks in different commercially available and commonly used preservation media was measured. While storage at 4°C in normal growth medium (EGM-2) for 3 days resulted in massive disruption of the ECFC monolayer and a significant decline in viability, ECFC monolayers preserved in Chillprotec could recover after up to 14 days with negligible effects on their integrity and viability. ECFC monolayers preserved in Celsior, HTS-FRS, or Rokepie medium showed a significant decrease in viability after 7 days or longer periods. These results demonstrated the feasibility of hypothermic preservation of ECFC monolayers on gas-exchange membranes for up to 2 weeks, with potential application on the preservation of pre-endothelialized oxygenators and further biohybrid cardiovascular devices.