Alternative preservation strategies of DCD hearts: Effect of cold ischemia time before normothermic machine perfusion

Donation after circulatory death (DCD) offers a promising strategy to expand the donor pool by 20-30%. However, DCD heart grafts suffer from warm ischemia injury, making effective graft viability assessment before transplantation prudent. Current methods for assessing DCD hearts are impacted either by ethical concerns and regional limitations (thoracoabdominal normothermic regional perfusion - taNRP) or by the need for significant resources, expertise, and equipment, with limitations in functional assessment (direct procurement and reperfusion - DPP, via the Organ Care System (OCS) by TransMedics). This study explores an alternative approach to DCD heart preservation, using controlled hypothermia at 6-8 degrees Celsius for up to 7 hours, followed by reanimation using normothermic machine perfusion. DCD grafts were procured from porcine donors after 19 mins of functional warm ischemia, stored via controlled cold static preservation for up to 7 hours and evaluated via a novel method of ex vivo cardiac loading. No functional, biochemical or proteomic differences were observed between DCD cardiac grafts stored via controlled hypothermia for up to 7 hours and DCD grafts reperfused immediately after procurement. These results suggest that controlled hypothermia may be a viable alternative to current DCD preservation methods, eliminating ethical concerns of taNRP and reducing logistical complexity and costs associated with DPP. These findings provide a foundation for a potential shift in DCD heart preservation practices, offering a more effective and cost-efficient approach to expand the donor pool and improve transplantation outcomes.