Modeling hyperosmotic blood–brain barrier opening within human tissue-engineered in vitro brain microvessels

Abstract

As the majority of therapeutic agents do not cross the blood–brain barrier (BBB), transient BBB opening (BBBO) is one strategy to enable delivery into the brain for effective treatment of CNS disease. Intra-arterial infusion of the hyperosmotic agent mannitol reversibly opens the BBB; however, widespread clinical use has been limited due to the variability in outcomes. The current model for mannitol-induced BBBO assumes a transient but homogeneous increase in permeability; however, the details are poorly understood. To elucidate the mechanism of hyperosmotic opening at the cellular level, we developed a tissue-engineered microvessel model using stem cell-derived human brain microvascular endothelial cells (BMECs) perturbed with clinically relevant mannitol doses. This model recapitulates physiological shear stress, barrier function, microvessel geometry, and cell-matrix interactions. Using live-cell imaging, we show that mannitol results in dose-dependent and spatially heterogeneous increases in paracellular permeability through the formation of transient focal leaks. Additionally, we find that the degree of BBB opening and subsequent recovery is modulated by treatment with basic fibroblast growth factor. These results show that tissue-engineered BBB models can provide insight into the mechanisms of BBBO and hence improve the reproducibility of hyperosmotic therapies for treatment of CNS disease.

Vascularized Microfluidics and the Blood–Endothelium Interface

“…Others expanded on the use of perfusable microfluidics to study the BBB, focusing on the role of plasma in electrolyte balance and in particular the use of hyperosmotic therapies for the treatment of central nervous system disease. Linville et al [56], using stem cell-derived brain Once the microchannels are created using these top-down approaches they are then endothelialized. In order to accomplish this an ECM protein, such as collagen, fibronectin or laminin is infused and allowed to adsorb to the channels inner surface [46][47][48].…”

“…Others expanded on the use of perfusable microfluidics to study the BBB, focusing on the role of plasma in electrolyte balance and in particular the use of hyperosmotic therapies for the treatment of central nervous system disease. Linville et al [56], using stem cell-derived brain microvascular ECs in a PDMS-based model, demonstrated that mannitol, an osmotic diuretic used clinically to treat elevated intracranial pressure, resulted in a dose-dependent, spatially heterogenous increase in paracellular permeability by forming transient focal leaks in the vascular endothelium. In addition, using bFGF before treatment with mannitol, they were able to demonstrate its direct role in the modulation of the degree of BBB opening and subsequent recovery.…”

Update of inflammasome activation in microglia/macrophage in aging and aging‐related disease

“…Cleaved‐IL1β and cleaved‐IL18 released from inflammasome‐forming cells induce production of proinflammatory factors by neighbor cells, including IFNγ, TNFα, and ROS . The proinflammatory factors further impair blood‐brain barrier (BBB) and attract peripheral leukocytes . Besides, pyroptosis induced by inflammasome activation gives rise to DAMPs, which activate inflammasome and exacerbate the inflammatory status.…”

“…21 The proinflammatory factors further impair blood-brain barrier (BBB) and attract peripheral leukocytes. 22,23 Besides, pyroptosis induced by inflammasome activation gives rise to DAMPs, which activate inflammasome and exacerbate the inflammatory status. Neural inflammation plays a key role in multiple aging-related neurological diseases.…”

Three-dimensional induced pluripotent stem-cell models of human brain angiogenesis

“…Importantly, our hierarchical model allows probing of how BBB phenotype changes across the vascular tree. Recently, we demonstrated use of BBB microvessels for studying hyperosmotic BBB disruption [71], but do not know if capillaries are more susceptibility to opening. Figure 1 dhBMECs were differentiated from the WTC iPSC line with a fluorescently-tagged plasma membrane (Fig.…”