Development of a Blood-Brain Barrier-on-Chip System to Study Chronic Kidney Disease-Associated Cognitive Impairment

Abstract

Chronic kidney disease (CKD) has a high global prevalence, with incidence rates increasing each year. The disease is characterized by a progressive loss of kidney function and is associated with high mortality, imposing a significant burden on both patients and the healthcare system. A substantial subpopulation of individuals with CKD also experiences cognitive dysfunction as a comorbidity. Recent evidence suggests that blood-brain barrier (BBB) disruption is a major contributor to disease onset and/or progression. However, the underlying mechanisms remain unknown. Metabolic wastes, known as uremic toxins, that accumulate in the blood of patients with kidney dysfunction might play a key role. To accurately describe the behavior of UTs at and their effects on the BBB, advanced in vitro models are necessary. This study seeks to develop a novel BBB-on-chip device that incorporates major cells found in the neurovasculature, namely endothelial cells, pericytes, and astrocytes. A 3D-printing based chip was developed that incorporates hollow-fiber membranes (HFMs) as scaffolds supporting a vascular-like structure. Co-culture media formulation was defined by assessing the metabolic activity of all three cell lines in different media compositions. The seeding characteristics were refined through a novel 12-well plate insert. Rocker-based perfusion was assessed in the system, and the co-culture of human immortalized endothelial cells (hCMEC/D3) and pericytes (HBVP) was optimized. Endothelial cells cultured on the HFMs exhibited proper claudin-5 expression. Moreover, human immortalized astrocytes (HA) cells were cultured in a GeltrexTM matrix, forming robust networks with good dispersion throughout the hydrogel, and will be incorporated on-chip in the near future. However, the chip design and production workflow require optimization to ensure leak-tightness and enable long-term perfusion assays with cells. Future applications of the model include investigations into the effects of uremic toxins on barrier integrity, drug targeting and delivery studies, and potential integration into multi-organ-on-chip platforms for disease modeling.