Engineering the human blood-brain barrier at the capillary scale using a double-templating technique

Area of Science:

• Neuroscience
• Biomedical Engineering
• Cell Biology

Background:

• In vitro blood-brain barrier (BBB) models are crucial for studying neurovascular processes like immune cell trafficking and drug delivery.
• Current models lack the hierarchical structure found in capillaries, hindering research into cerebrovascular diseases.
• Understanding capillary-scale BBB function is essential for advancing neurological disease mechanisms and therapeutic strategies.

Purpose of the Study:

• To engineer a hierarchical in vitro blood-brain barrier (BBB) model at the capillary scale.
• To incorporate physiological barrier function into the engineered BBB model.
• To enable the study of immune cell interactions and disease processes at the human BBB capillary level.

Main Methods:

• Developed a novel double-templating technique to create hierarchical vascular networks.
• Utilized human umbilical vein endothelial cells for initial vascular network formation.
• Characterized barrier function using induced pluripotent stem cell-derived brain microvascular endothelial-like cells (iBMECs).
• Assessed immune cell adhesion and transmigration under inflammatory conditions (TNF-alpha perfusion).

Main Results:

• Successfully engineered hierarchical vascular networks mimicking capillary structures.
• Demonstrated physiological barrier function in the iBMEC-based BBB model.
• Replicated capillary-scale immune cell behaviors, including leukocyte plugging, observed in vivo.
• Validated the model's ability to recapitulate human BBB responses to inflammatory stimuli.

Conclusions:

• The double-templated hierarchical BBB model provides a robust platform for capillary-scale research.
• This model overcomes limitations of existing in vitro BBB systems.
• It facilitates the investigation of immune cell trafficking, drug delivery, and disease mechanisms at the human BBB.