ABSTRACT Extracorporeal therapies (ECT) including cardiopulmonary bypass (CPB) and extracorporeal membrane oxygenation (ECMO) have been refined over the years, yet unfavorable outcomes such as acute kidney injury (AKI) continue to occur and are associated with mortality and prolonged intensive care unit and hospital length of stay. Increased cell-free plasma hemoglobin (PHb) from hemolysis during CPB and ECMO has been identified as playing a central role in such dysfunction and is thus an obvious clinical target. Despite this, there are no clinically available therapies for the selective removal of PHb during ECT. The focus of this proposal is to develop a novel extracorporeal hemoadsorption device to serve as an easily implementable therapy to selectively remove PHb during ECT. The hemoadsorption device will use a bead-based matrix containing immobilized haptoglobin (Hp), a native protein with high-affinity binding for PHb, to selectively remove PHb from whole blood flow. Preliminary work has been conducted to establish the foundational feasibility of the proposed approach. This includes the development of methods to produce Hp-modified beads, confirmation of the ability of these beads to bind PHb, demonstration of the ability of a bead-based column to accommodate whole blood flow, and model-based evidence of the ability for clinically reasonable device flow rates to achieve therapeutic PHb removal. In addition, we have established a rat model of ECT-induced AKI to be used during in vivo assessment of the proposed approach. The two proposed Aims will (i) fabricate functional, scaled-down prototypes and characterize PHb binding kinetics during benchtop studies in whole blood flow and (ii) use a rat model to evaluate the feasibility of device implementation during ECT and its ability to prevent ECT-induced renal injury. Thus, the proposed work involves elements of design and fabrication of extracorporeal blood-contacting devices, porous media fluid dynamics, blood-based mass transfer, hemocompatibility, kidney injury, hemolysis-associated pathology, and clinical implementation of ECT. The research team, led by principal investigators Nahmah Kim-Campbell, MD, MS and William Federspiel, PhD, possesses the unique engineering and clinical expertise necessary to pursue this highly multidisciplinary research. Combined with the rich research environment and resources of the University of Pittsburgh and the McGowan Institute of Regenerative Medicine, this team is well positioned to successfully develop this mechanistically-supported approach to improve adverse outcomes in ECT.

PROJECT NARRATIVE Cell-free plasma hemoglobin (PHb) is now recognized as a common and problematic sequela of extracorporeal therapies (ECT) such as cardiopulmonary bypass (CPB) and extracorporeal membrane oxygenation (ECMO) with contributions to organ injury such as acute kidney injury. The goal of this proposal is to develop a novel and selective extracorporeal hemadsorption device capable of removing PHb during all forms of ECT. A rat model will then be used to evaluate a prototype’s compatibility with ECT, capability to effectively remove PHb, and ability to ameliorate ECT-related kidney injury.