A Novel Dynamic Neonatal Blood-Brain Barrier on a Chip

Abstract

Studies of neonatal neural pathologies and development of appropriate therapeutics are hampered by a lack of relevant in vitro models of neonatal blood-brain barrier (BBB). To establish such a model, we have developed a novel blood-brain barrier on a chip (B3C) that comprises a tissue compartment and vascular channels placed side-by-side mimicking the three-dimensional morphology, size and flow characteristics of microvessels in vivo. Rat brain endothelial cells (RBEC) isolated from neonatal rats were seeded in the vascular channels of B3C and maintained under shear flow conditions, while neonatal rat astrocytes were cultured under static conditions in the tissue compartment of the B3C. RBEC formed continuous endothelial lining with a central lumen along the length of the vascular channels of B3C and exhibited tight junction formation, as measured by the expression of zonula occludens-1 (ZO-1). ZO-1 expression significantly increased with shear flow in the vascular channels and with the presence of astrocyte conditioned medium (ACM) or astrocytes cultured in the tissue compartment. Consistent with in vivo BBB, B3C allowed endfeet-like astrocyte-endothelial cell interactions through a porous interface that separates the tissue compartment containing cultured astrocytes from the cultured RBEC in the vascular channels. The permeability of fluorescent 40 kDa dextran from vascular channel to the tissue compartment significantly decreased when RBEC were cultured in the presence of astrocytes or ACM (from 41.0±0.9 x 10−6 cm/s to 2.9±1.0 x 10−6 cm/s or 1.1±0.4 x 10−6 cm/s, respectively). Measurement of electrical resistance in B3C further supports that the addition of ACM significantly improves the barrier function in neonatal RBEC. Moreover, B3C exhibits significantly improved barrier characteristics compared to the transwell model and B3C permeability was not significantly different from the in vivo BBB permeability in neonatal rats. In summary, we developed a first dynamic in vitro neonatal BBB on a chip (B3C) that closely mimics the in vivo microenvironment, offers the flexibility of real time analysis, and is suitable for studies of BBB function as well as screening of novel therapeutics.

Permeability across a novel microfluidic blood-tumor barrier model

“…Briefly in this model, endothelial cells are seeded in the outer compartments, while astrocytes (BBB) or brain seeding breast cancer cells (BTB) are seeded in the central compartment. The porous architecture between the two compartments allows for cellular crosstalk and biochemical exchanges, while shear stress from perfusate flow facilitates development of endothelial morphology [19]. Confocal brightfield images show the differences in morphology between endothelial cells with and without flow (Fig.…”

“…Second, because the cells are grown in a static media, there is no shear stress (or flow) forced on the endothelial cells, which may contribute to the low passive permeability measurements which can be as low as ~74 Ω cm 2 [47], compared to in vivo values of ~2000 Ω cm 2 [48]. While a few other in vitro models and microfluidic devices have a flow component [27–31], this microfluidic device is the first commercially available blood-tumor barrier using a microfluidic model seeded with brain-seeking cells and with shear stress similar to that observed in vivo [19] in addition to real-time visualization and quantitation.…”

Microphysiological Human Brain and Neural Systems-on-a-Chip: Potential Alternatives to Small Animal Models and Emerging Platforms for Drug Discovery and Personalized Medicine

“…39 Deosarkar et al also showed that endothelial cells exhibited tight junction formation, as measured by the expression of ZO-1 in microfluidic BBB models, and allowed endfeet-like neonatal astrocyte-endothelial cell interactions through a porous interface. 59 Although beyond the scope of this review, we note that microfluidic tissue chips have been applied toward a number of organ systems. 18,19,60 As a result, the microfluidic-based tissue chip design is commonly referred to as an organ-on-a-chip; however, we caution the reader that the ‘organ-on-a-chip’ concept does not strictly apply to microfluidic designs as alternative design and manufacturing approaches now exist for constructing tissue chips ( e.g.…”

Three‐Dimensional Models of the Human Brain Development and Diseases

“…[94] In two subsequent studies, Prabhakarpandian and Deosarkar et al reconstituted a BBB-on-chip constructed of two-compartments chamber with a microvascular channels cultured with rat brain endothelial cells under shear flow and a tissue compartment seeded with rat astrocytes under static flow as a 3D in vitro model to study neonatal neural pathology (Figure 4C). [95,96] Overall, current in vitro BBB models could not yet be fully applied to assess the mechanism pathways underlying human brain diseases. However, they are increasingly useful for assessing the toxicity of drugs for neurological diseases, together with in vitro 2D and in vivo models.…”