THREE SOURCES

Where the cells come from

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Primary cells

Taken straight from tissue. Realistic, but scarce and variable from one preparation to the next

♾️

Immortalized lines

Such as hCMEC/D3. Easy and cheap to grow, but they tend to form a leaky barrier

🌱

Stem-cell derived

Grown from induced pluripotent stem cells (iPSCs), which can be turned into brain-like endothelial cells

Each source trades realism against convenience.

THE iPSC ROUTE

From a skin cell to a barrier cell

An adult cell is reprogrammed into an induced pluripotent stem cell, a discovery by Shinya Yamanaka, and then guided with signals and growth factors to become a cell that behaves like a brain endothelial cell.

The same donor's cells can become endothelium, astrocytes, and neurons.

WHY IT'S ATTRACTIVE

Human, scalable, personal

Human They carry human transporters, receptors, and pumps

Supply One stem-cell line can supply many experiments

Personal Cells can come from a patient with a particular disease

Caution Protocols vary, and some resulting cells show mixed identity, so checking is essential

Promising, but not yet standardized.

THE SUPPORTING CAST

Adding the neighbors

⭐

Astrocytes

Send signals that tighten the barrier and keep it mature

🤝

Pericytes

Add stability and signals along the vessel wall

⚡

Neurons and microglia

Added in more advanced models to include activity and immune responses

More cell types means a richer model and a harder experiment.

QUALITY CHECKS

Prove the cells are what you think

🔬

Stain

Look for claudin-5, ZO-1, and GLUT1 in the expected places

⚡

Measure

Track TEER and tracer leak, as in Unit 8

💊

Function

Test transporters and efflux pumps with known substrates

A barrier model is only as good as its checks.

UNIT 14 STUDY COMPLETE

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Ready for the Fab Challenge?

You've compared the cell sources for a barrier chip and how researchers check their quality.