Experimental Comparison of Primary and hiPS-Based In Vitro Blood–Brain Barrier Models for Pharmacological Research

Abstract

In vitro model systems of the blood–brain barrier (BBB) play an essential role in pharmacological research, specifically during the development and preclinical evaluation of new drug candidates. Within the past decade, the trend in research and further development has moved away from models based on primary cells of animal origin towards differentiated models derived from human induced pluripotent stem cells (hiPSs). However, this logical progression towards human model systems from renewable cell sources opens up questions about the transferability of results generated in the primary cell models. In this study, we have evaluated both models with identical experimental parameters and achieved a directly comparable characterisation showing no significant differences in protein expression or permeability even though the achieved transendothelial electrical resistance (TEER) values showed significant differences. In the course of this investigation, we also determined a significant deviation of both model systems from the in vivo BBB circumstances, specifically concerning the presence or absence of serum proteins in the culture media. Thus, we have further evaluated both systems when confronted with an in vivo-like distribution of serum and found a notable improvement in the differential permeability of hydrophilic and lipophilic compounds in the hiPS-derived BBB model. We then transferred this model into a microfluidic setup while maintaining the differential serum distribution and evaluated the permeability coefficients, which showed good comparability with values in the literature. Therefore, we have developed a microfluidic hiPS-based BBB model with characteristics comparable to the established primary cell-based model.

Electrospun Scaffolds as Cell Culture Substrates for the Cultivation of an In Vitro Blood–Brain Barrier Model Using Human Induced Pluripotent Stem Cells

“…The differentiation of human induced pluripotent stem (hiPS) cell-derived brain capillary endothelial-like cells (BCECs) was carried out according to Danz et al [17]. The hiPS cell line Ukki011-A was seeded with a density of 5 × 10 3 cells/cm 2 on Matrigel ®coated 6-well plates and cultivated for 3 days in mTeSR1 medium before differentiation.…”

“…However, the isolated primary cells show considerable variability and further exhibit interspecies discrepancies regarding physiology on a cellular level, limiting their use in predictive in vitro models [14,15]. Overcoming these drawbacks, human induced pluripotent stem cells (hiPSCs) have emerged as a promising source of reproducible human-derived biological material, showing great potential for the development of robust BBB in vitro models [15][16][17]. In comparison to primary cells, hiPSCs are able to proliferate indifferently and further differentiate into specialized human brain capillary endothelial cells, which are requisite for forming a functional BBB.…”

“…Differing from the conditions provided by the native ECM, commercial cell culture inserts comprise a membrane made of synthetic polymers, such as polycarbonate, polytetrafluoroethylene, or polyethylene terephthalate, preventing dynamic interaction with cells. Therefore, cells that have been cultivated on top of these stiff membranes cannot restructure their surroundings and tend to form abnormal cell-cell interactions compared to in vivo tissues, leading to artificial intracellular functions and polarity [17,18]. Furthermore, compared to the basement membrane, these inserts are thicker, less porous, mechanically stiffer, lack surface roughness, and the nanoporous, three-dimensional structure of collagen fibrils found in the native tissue [19].…”

Evaluation of the Transport and Binding of Dopamine-Loaded PLGA Nanoparticles for the Treatment of Parkinson’s Disease Using In Vitro Model Systems

“…The human brain capillary endothelial cells (hBCECs) used in the transport studies were differentiated from human induced pluripotent stem cells (hiPSCs) as described by Stebbins et al [32] and with modifications as indicated elsewhere [33]. In short, hiPSCs of the stem cell line Ukki011-A were seeded at a density of 5 × 10 3 cells cm −2 on day -3 on Matrigel-coated (Corning, Amsterdam, The Netherlands) 6-well plates and cultivated in mTeSR1 medium (Stem Cell Technologies, Vancouver, BC, Canada) until day 0, and then the medium was changed to unconditioned medium (DMEM/F12 with 20% knockout serum replacement, 1% non-essential amino acids, 0.5% GlutaMAX and 0.1 µM 2mercaptoethanol) from day 0 until day 5.…”

Bioactive nanoscaffolds for controlled drug delivery and tissue engineering

“…Moreover, the cultivation of primary cells or hiPSCs on these hydrophobic substrates is often impeded due to the artificial hydrophobicity of the inserts. To overcome this hindrance, a substrate coating consisting of proteins such as collagen or fibronectin is mandatory to resemble the native extracellular matrix [103,104]. Summarizing the disadvantages of Transwell® based models, the cell substrate is thicker, less porous and lacks surface roughness compared to the collagen fibrils of the human basement membrane [105].…”