Optimizing preservation of umbilical vein segments for use as autologous shunts in neonatal cardiac repair
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INTRODUCTION: The Modified Blalock Taussig (BT) shunt is the most common palliative procedure in neonatal cardiac repair to secure pulmonary blood flow (3-6) despite high mortality and morbidity rates of 4-14% (3,5) and 9-18% (4,5) respectively. The high risk of thrombosis and stenosis associated with the polytetrafluoroethylene (PTFE) material that is currently used for BT shunts significantly contributes to these high mortality and morbidity rates. Thrombosis and stenosis occur in 3-12% of patients (1,5), primarily due to the lack of endothelium of the synthetic PTFE graft. This study hypothesizes that a preserved autologous umbilical vein could be a feasible replacement for the PTFE graft. Experiments were performed to examine and optimize preservation methods of umbilical veins for use as BT shunts. METHODS: Umbilical cords (n=45) were collected from healthy neonates and umbilical vein segments were preserved in either static (n=145) or flow conditions (n=84) for 7 days or 14 days in varying media. Samples of each vein were collected at time of harvest (Day 0) and at the end of culture and compared by burst pressure, histopathology, platelet adhesion and scanning electron microscopy (SEM). RESULTS: Burst pressure strength of veins from Day 0 to up to two weeks of preservation did not significantly differ (431 ± 229 mmHg vs 438 ± 244 mmHg). Overall histology demonstrated an improved morphology in endothelial and medial layers of the segments preserved in flow culture with UW + 5% HPL for 7 days. Platelet adhesion testing demonstrated significantly less platelet attachment in flow samples compared to static, indicating less endothelial injury. SEM showed greater cellular flow-alignment and consistency of the endothelium in flow samples. CONCLUSION: Flow culture utilizing UW plus 5% HPL adequately preserves morphology and function of the endothelium. Preserved autologous umbilical veins stand as a viable option to replace the current PTFE graft used for BT shunts due to the presence of an endothelium.