An In Vitro Multi-Modality Evaluation of a Standardized Experimental System Utilizing Recombinant α1-Microglobulin

<title>Abstract</title> <p> Evaluating the membrane transport of large middle molecules like α ₁ -microglobulin (α ₁ -MG) remains a challenge due to native protein scarcity and a lack of versatile <italic>in vitro</italic> systems. This study systematically evaluated the utility, versatility, and fidelity of a newly established <italic>in vitro</italic> experimental system utilizing a recombinant α ₁ -MG as a test solute in three modalities of treatment: hemodialysis (HD), pre-dilution online hemodiafiltration (HDF), and post-dilution online HDF. The blood flow rate ( <italic>Q</italic> _B ) and temperature were strictly maintained at 250 mL/min and 37°C. Results demonstrated that cumulative albumin leakage and α ₁ -MG removal kinetics were highly consistent with clinical benchmarks. In HD mode, trans-membrane albumin leakage was severely restricted due to pure diffusive limitations. Conversely, both HDF configurations yielded significantly higher but comparable total albumin loss through enhanced convective driving forces. Crucially, the transport trade-off dependency between cumulative albumin leakage and the α ₁ -MG reduction rate converged into a single, unified distribution curve across all three modalities. These findings validate that the developed experimental system and recombinant solute serve as a highly reliable, standardized alternative platform for the multi-modality benchmarking of advanced extracorporeal blood purification devices. </p>