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Tissue Engineering

Tissue Engineering - Poster Session E

Poster BB8 - Hemodialytic Optimization of an Ex Vivo Perfusion Machine for Tumor-Bearing Organs

Saturday, October 26, 2024
10:00 AM - 11:00 AM EST
Location: Exhibit Hall E, F & G

Introduction:  The Perfusitech Ex-Vivo Research Machine is a modular perfusion system that can prolong and maintain organ viability at physiological conditions in order to facilitate scientific interrogation. Hemodialysis is a crucial component of the Perfusitech system that is responsible for removing metabolic waste from circulation and stabilizing blood chemistries to physiological specifications. The current system employs a clinically designated AN69 Continuous Renal Replacement Therapy (CRRT) membrane for hemodialysis; however, its use introduces significant monetary expenses, design constraints, and operational complexity. Here, we demonstrate the advantages, experimental performance, and proposed implementation of laboratory-grade regenerated cellulose tubing in an alternative hemodialysis configuration.

Materials and

Methods:  The experimental dialysis circuit consisted of regenerated cellulose dialysis tubing (12-14 kDa pore size), vinyl tubing (1/4" ID), a single rotary pump, silk surgical ties, and two volumetrically annotated receptacles. The dialysate and perfusate fluids were modeled by a 300 mL solution of plain saline and a 200 mL solution of 300 mg/dL (D) Glucose and 4g/dL BSA in saline, respectively. Glucose served as a model dialyzable solute, whereas non-dialyzable albumin osmotically dominated the system and helped imitate the oncotic pressure exerted by whole blood.

During setup, the cellulose membrane was cut to fit, wetted, and subsequently secured on either end to similarly sized pieces of ¼" vinyl tubing. Both ¼" tubing arms were fed into a receptacle containing the dialysate. One of the two tubing arms was routed through a rotary pump during this process. The cellulose membrane was submerged in a receptacle containing perfusate. The system was allowed to run at steady state. Samples of each solution were taken directly from their respective reservoir on a half-hourly basis and analyzed using a Stat Profile Prime Plus Analyzer. This experimental approach was refined after several attempts involving different solution formulations and dialysate flow parameters. Results were analyzed via Excel and graphed with Prism 10. System diagrams were composed using BioRender.

Results, Conclusions, and Discussions: Experimental results showed a 50% reduction in perfusate glucose concentration in under four hours despite recycling the dialysate to maintain a closed system. After normalizing mass exchange per unit area, the cellulose membrane demonstrated comparable glucose flux to that of the AN69 membrane. However, unlike the AN69 membrane housed in a rigid plastic cassette, the cellulose tubing is supplied as a pliable roll. Therefore, our findings suggest that the cellulose membrane can both preserve filtration performance and offer greater flexibility in scaling dialysis to system needs. Furthermore, the accessible form factor of loose tubing could altogether eliminate the side circuit that is currently demanded by the AN69 membrane. This change would both streamline the overall system design and reduce hemolytic stress associated with an unnecessary blood pump. The proposed hemodialysis redesign would involve continuous pumping of physiologically normative dialysate through a submerged coil of cellulose tubing directly inside the Perfusitech’s bulk blood reservoir. Cellulose membrane material is also considerably cheaper per unit surface area than its clinical grade counterpart, costing a mere $20/m2 to $60/m2 compared with the $410/ m2 expense of a single Prismaflex kit.

Acknowledgements (Optional):  Thank you to the many patients whose tissue donations serve as the foundation and future of The Perfusitech system.