Poster T16 - Optimizing Red Blood Cell Storage to Improve Quality and Reduce Transfusion-Associated Complications

Introduction: Blood transfusions are one of the most common medical procedures performed in the United States, with over 14 million units transfused each year. The progressive accumulation of biochemical, functional, and metabolic changes while red blood cells (RBCs) are in cold storage is known as the ‘storage lesion’ and may contribute to life-threatening cardiac pathologies. Phthalates are a type of plasticizer that are used to make rigid polyvinyl chloride (PVC) plastic flexible. Di-(2-ethylhexyl) phthalate (DEHP) is the most common phthalate plasticizer used in PVC medical devices, often contributing 40%–80% of the finished weight of blood storage bags. In the past, phthalate leaching was considered beneficial to RBC storage, as plasticizers interact directly with RBC membranes thus imparting resistance to storage hemolysis. Since the 1970s there have been increasing safety concerns surrounding phthalate exposure, especially in young patients. Recent studies have reported associations between phthalate exposure and postoperative complications including arrhythmias, impaired cardiac contractile function, and blood pressure disturbances in neonates and infants undergoing cardiac surgery. As a result of increasing health concerns surrounding phthalate exposure, there has been a push to develop alternative biomaterials for use in RBC storage units that do not negatively affect blood quality by increasing the RBC storage lesion. Additionally, while novel plasticizers are being developed, there is a need for mitigation strategies to reduce DEHP exposure. The aim of this study was to assess the electrophysiologic response to blood stored in DEHP vs an alternative biomaterial and to examine the effectiveness of current mitigation strategies.

Materials and

Methods: Blood products were obtained from the Children’s National Blood Donor Center or the American Red Cross and aged up to 40 days post collection. RBC units were washed with a Sorin Xtra cell saver and DEHP concentrations were quantified using ultra high-pressure liquid chromatography coupled to mass spectrometry. An Axion BioSystems Maestro Edge microelectrode array (MEA) system with human-induced pluripotent stem cell derived cardiomyocytes (hiPSC-CMs; iCell Cardiomyocytes2) was used for all MEA experiments. To mimic pediatric clinical exposure, we isolated the supernatant from blood units and diluted it to 10% in cell culture media.

Results, Conclusions, and Discussions: Our results demonstrate that blood units stored in butyryl trihexyl citrate (BTHC), an alternative biomaterial used in RBC bags, consistently displayed an increased storage lesion. For example, lactate was higher in BTHC units, compared to bags plasticized with DEHP, at every timepoint from day 5 to 40. Furthermore, we observed a dysregulation of the partial pressure of both oxygen and carbon dioxide in units plasticized with BTHC. None of the hiPSC-CMs treated with the supernatant from 40-day old BTHC blood units were responsive to pacing (1.5 Hz). In comparison, cells treated with DEHP were able to be paced, albeit with prolonged electrophysiological parameters (field potential duration +60% vs baseline).

A novel strategy to reduce DEHP exposure in patients receiving blood products is to wash RBC units using a cell saver. Previously, washing blood units has been employed to remove lactate and potassium that accumulate as part of the RBC storage lesion. Our results indicate that washing blood units can reduce DEHP levels by 77% (Figure 1A). When hiPSC-CMs were treated with unwashed blood the field potential duration, a pseudo-QT interval, prolonged by 218.7 ms (p < 0.0001). In comparison, washed RBC units resulted in a minor 17.6 ms prolongation (p < 0.01) of the field potential duration (Figure 1B).

Conclusions of our study suggest that washing blood products in a cell saver removes phthalates, as well as other components of the RBC storage lesion, and produces safer RBC units for use in pediatric cardiac surgery. While the development of alternative biomaterials for use in medical devices is promising, current alternatives, including BTHC, result in an increased RBC storage lesion which can have negative effects on cardiac electrophysiology. In the future, additional work is needed to produce saver alternatives for use in RBC units.

Acknowledgements (Optional): The authors acknowledge University of Colorado School of Medicine Metabolomics Core for help with mass spectrometry experiments.