A Quasi-Physiological Microfluidic Blood-Brain Barrier Model for Brain Permeability Studies

Abstract

Microfluidics-based organ-on-a-chip technology allows for developing a new class of in-vitro blood-brain barrier (BBB) models that recapitulate many hemodynamic and architectural features of the brain microvasculature not attainable with conventional two-dimensional platforms. Herein, we describe and validate a novel microfluidic BBB model that closely mimics the one in situ. Induced pluripotent stem cell (iPSC)-derived brain microvascular endothelial cells (BMECs) were juxtaposed with primary human pericytes and astrocytes in a co-culture to enable BBB-specific characteristics, such as low paracellular permeability, efflux activity, and osmotic responses. The permeability coefficients of [13C12] sucrose and [13C6] mannitol were assessed using a highly sensitive LC-MS/MS procedure. The resulting BBB displayed continuous tight-junction patterns, low permeability to mannitol and sucrose, and quasi-physiological responses to hyperosmolar opening and p-glycoprotein inhibitor treatment, as demonstrated by decreased BBB integrity and increased permeability of rhodamine 123, respectively. Astrocytes and pericytes on the abluminal side of the vascular channel provided the environmental cues necessary to form a tight barrier and extend the model’s long-term viability for time-course studies. In conclusion, our novel multi-culture microfluidic platform showcased the ability to replicate a quasi-physiological brain microvascular, thus enabling the development of a highly predictive and translationally relevant BBB model.

The Effects of Propofol on a Human in vitro Blood-Brain Barrier Model

“…The validity of iPSC-derived BBB models have been questioned due to a mixed endothelial: epithelial transcriptional profile ( Lu et al, 2021 ); yet, these iPSC-derived like BMECs exhibit near in vivo barrier function, an essential component of a BBB model ( Workman and Svendsen, 2020 ). More recently, iPSC-derived BMECs have been utilized to enhance tissue engineering models, replicate pathological conditions, and unveil novel therapeutic approaches in the BBB ( Li et al, 2021 ; Neal et al, 2021 ; Noorani et al, 2021 ; Raut et al, 2021 ; Wellens et al, 2021 ; Wu et al, 2021 ). Three common anesthetics, propofol, isoflurane, and sevoflurane, have independently demonstrated a degree of BBB damage ( Sharma et al, 2014 ; Zhao et al, 2014 ; Acharya et al, 2015 ).…”

Vascularizing the brain in vitro

“…Several vascular permeability markers have been used, including fluorescently labeled FITC-dextran ( Bischel et al., 2016 ; Marino et al., 2018 ; Salman et al., 2020 ), sodium fluorescein ( Maeda et al., 2021 ; Xu et al., 2016 ; Zhang et al., 2021 ), lucifer yellow ( Sitia et al., 2019 ), and the active permeability of P-glycoprotein (P-gp) substrate rhodamine 123 ( Lippmann et al., 2014 ; Noorani et al., 2021 ).…”

Induced pluripotent stem cell-based organ-on-a-chip as personalized drug screening tools: A focus on neurodegenerative disorders

“… 108 Importantly, results suggests that TfR triggers nanoparticles transcytosis, highlighting the advantages in using iPSCs derived endothelial cells. 108 A commercially available brain-on-a-chip (Emulate, Boston, MA, USA) was used with iPSC-derived BMECs (iBMECs) 109 and [ 13 C 12 ] sucrose and [ 13 C 6 ] mannitol permeability were measured in presence or absence of primary human brain astrocytes and pericytes. Results suggest that the presence of astrocytes and pericytes enhanced barrier properties bringing them nearly to physiology, characterized also by a high TEER value (1000–3000 Ω·cm 2 ).…”

“…Moreover, barrier permeability has been shown to be modulated by osmotic opening; the functionality of efflux pumps was assessed given the increased permeability to rhodamine123, but not sucrose, in presence of the P-gp inhibitor cyclosporine A. 109 In another work, a pumpless BBB-on-chip model was developed 104 ( Figure 2(a) ), it is composed by iBMECs and rat primary astrocytes respectively seeded on two sides of the semipermeable membrane. The systems allow maintenance of high TEER value (2000 Ω·cm 2 ) up to 10 days, and evaluation of barrier permeability to caffein (a small lipophilic molecule), cimetidine (histamine H2-receptor antagonist, with moderate permeability), doxorubicin (antineoplastic agent characterized by poor permeability) and different molecular weight FITC-dextran, resulted in very low values comparable to in vivo measurement.…”