Design of Implantable Microfluidic Device Based on Polyacryamide Hydrogel for Kidney Replacement

M. Tamer, M. Bassil, M. Bechelany, S. Balme, Ph. Miele, M. El Tahchi
Montpellier University,
France

Keywords: hydrogel, kidney, filtration, microfluics

Summary:

Organs-on-a-chip technology has shown strong promise in organ replication. This approach combined bioengineering and microfluidic technologies in order to closely mimic the complexity of the natural organ [1,2]. A kidney-on-a-chip can mimic the structural, mechanical and physiological properties of the human kidney. It has emerged as a novel strategy for the improvement of kidney filtration function allowing to address the growing kidney donor deficiency in the case of kidney disease treatment [3]. Inspired by the natural organ and the dialysis system, we present in this study the design of a new bioartificial kidney. The device is composed of several filtration units. Each “filtration unit” encapsulates a Polyacrylamide (PAAM) hydrogel matrix that is considered as the functional unit of the device and acts as an exchange membrane. Several hydrogel matrices are prepared and their physicochemical properties are tailored as desired in order to monitor the filtration ability and efficiency of the “filtration unit”. The effect of the hydrogel structural properties (pore size, mechanical properties, degree of ionization) on the filtration ability is tested. Results show that the size selectivity and the molecular weight cutoff of the matrix are controlled by changing the pore size, while the speed of solute diffusion across the matrix is controlled by varying the pores number. Bovine serum albumin 66 kDa and Fluorescein isothiocyanate–dextran (FITC-Dextran, MW: 40, 70, 150 kDa) were used to test the molecular weight cutoff of PAAM membrane as they mimic the blood proteins. The results show a restriction of proteins passage having a molecular weight above 66 kDa through the membrane. The ion selectivity of the membrane was tested using (Na+, K+, Cl-, PO43-) to verify the stability of a normal body fluid composition. The future bioartificial kidney would be an assembly of several filtration units working in parallel each having a specific function and imitating a specific renal activity. 1. Zheng, F. et al. Organ-on-a-Chip Systems: Microengineering to Biomimic Living Systems. Small 12, 2253–2282 (2016). 2. Ashammakhi, N., Wesseling-Perry, K., Hasan, A., Elkhammas, E. & Zhang, Y. S. Kidney-on-a-chip: untapped opportunities. Kidney Int. 94, 1073–1086 (2018). 3. Wilmer, M. J. et al. Kidney-on-a-Chip Technology for Drug-Induced Nephrotoxicity Screening. Trends Biotechnol. 34, 156–170 (2016).