Human Stem Cell Blood-Brain Barrier Model with Retinoic Acid
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Solution Overview
Problem
Current in vitro blood-brain barrier (BBB) models, particularly those derived from animal sources, are limited in their ability to accurately represent human BBB properties, hindering the development of robust and accessible human BBB models for drug screening and neurological research.
Innovation Solution
A fully-human BBB model is created by differentiating human pluripotent stem cells into brain microvascular endothelial cells and neural cells, which are then co-cultured with pericytes or differentiated neural progenitor cells to achieve high transendothelial electrical resistance (TEER) values, exceeding 5000 Ω×cm2, using retinoic acid enhancement and optimized media conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If primary human BMECs are used to create BBB models, then the model accurately represents human BBB properties, but the availability and yield are extremely low and cannot be scaled for large library screens
Solution Approach 1:
The patent uses induced pluripotent stem cells (iPSCs) to generate copies of human brain microvascular endothelial cells. Instead of directly using scarce primary human BMECs, the invention creates a renewable source by reprogramming somatic cells into iPSCs and differentiating them into BMECs, thereby copying the desired cell type with unlimited potential while maintaining human-specific BBB properties.
Solution Approach 2:
The patent employs retinoic acid treatment to modify the differentiation parameters of iPSCs, directing them toward the endothelial cell lineage with high efficiency. This chemical parameter change (addition of retinoic acid) transforms the differentiation outcome to preferentially generate BMECs over other cell types, thereby increasing yield and scalability.
2Productivity
If immortalized BMEC cell lines are used to create BBB models, then prodigious growth from clonal population is achieved, but barrier properties are poor and not optimal for screening therapeutics
Solution Approach 1:
The patent creates fresh copies of primary human BMECs through iPSC differentiation rather than using established immortalized cell lines. This approach regenerates cells with authentic primary-like barrier properties while maintaining renewable supply, avoiding the compromise of using cells that have accumulated genetic modifications during immortalization.
Solution Approach 2:
The patent uses retinoic acid and optimized differentiation conditions to induce proper endothelial maturation and barrier function formation. By controlling differentiation parameters, the generated BMECs achieve high TEER values and authentic barrier properties that immortalized cell lines fail to maintain.
3Ease of manufacture
If animal-derived BMECs are used to create BBB models, then the models are useful for studying developmental and regulatory mechanisms, but species differences prevent accurate screening of therapeutics for human BBB traversal
Solution Approach 1:
The patent generates human-specific BMECs by differentiating human iPSCs, creating authentic human cellular models rather than relying on animal cells. This copying approach using human-derived cells eliminates species differences while maintaining the accessibility and scalability of cell culture models.
Solution Approach 2:
The patent uses retinoic acid treatment and optimized culture conditions to enhance the maturation and functional properties of human-derived BMECs, ensuring they exhibit adult-like barrier characteristics that accurately reflect the human BBB, unlike immature or species-specific models.
4Reliability
If retinoic acid is used to enhance BBB model properties, then TEER values exceeding 5000 Ω×cm2 are achieved comparable to in vivo barriers, but additional culture optimization steps are required
Solution Approach 1:
The patent incorporates retinoic acid treatment during the early differentiation stage of iPSCs, before BMEC maturation. This preliminary action primes the cells to develop robust barrier properties, reducing the need for extensive later optimization and simplifying the overall protocol while achieving high TEER values.
Solution Approach 2:
The patent uses retinoic acid as a key differentiation parameter to drive efficient BMEC generation with high barrier function. By optimizing this single chemical parameter and its timing, the protocol achieves superior TEER values without requiring complex multi-factor optimization, balancing effectiveness with procedural simplicity.
Data Source
AI summary
In one embodiment, the present invention is a method of creating a fully-human blood-brain barrier (BBB) model, comprising the steps of (a) obtaining a mixture of neural cells and brain microvascular endothelial cells (BMECs), wherein the neural cells and BMECs that comprise the mixture were produced from the differentiation of human pluripotent stem cells (hPSCs); (b) purifying BMECs from the mixture of neural cells and BMECs of step (a); and (c) co-culturing the purified BMECs with a cell type selected from the group consisting of pericytes, astrocytes and differentiated neural progenitor cells (NPCs), wherein a blood brain barrier model is created.