In Vitro Permeability Assay on Human Gut Tissue.
Measure apparent permeability and BCS class on RepliGut® Planar, a human intestinal epithelium grown from donor stem cells. Start with absorption, then extend the same human tissue into transport and metabolism.
Design your studyExplore RepliGut® PlanarWhy permeability decides whether a drug is absorbed
An in vitro permeability assay is the first read on whether an oral drug will be absorbed. It measures how fast a compound crosses the intestinal epithelium, from the apical gut side to the basal blood side.
Caco-2 is the established permeability screen, and for ranking passive permeability it works well. It was also standardized decades ago, for small molecules, well before today's new modalities. And because it comes from a single colon tumor, it cannot speak to human mucus, regional biology, metabolism, or donor variability. Regulators now also favor human-relevant alternative testing methods.
A permeability assay built on human tissue
For passive permeability, Caco-2 is a capable screen. RepliGut® Planar measures the same endpoint on human intestinal tissue, then lets you extend into the biology a tumor line cannot reach.
| Feature | Caco-2 | RepliGut® Planar |
|---|---|---|
| Passive permeability | Reliable ranking, the established standard. | Reliable ranking on human intestinal tissue, benchmarked to Caco-2. |
| Tissue origin | One colon tumor cell line, single donor genetics. | Human small intestinal donor stem cells, from many donors. |
| Beyond permeability | Limited metabolism and transporter fidelity. | Adds Phase I and II metabolism, P-gp and BCRP, and regional range. |
| Mucus layer | None. | MUC2 goblet cells and a real mucus layer. |
How the in vitro permeability assay runs
Human jejunum stem cells differentiate on semipermeable transwell inserts in a 96-well plate. That opens both the apical and basal sides. We dose one compartment, sample the other, and quantify by accurate mass LC/MS to calculate Papp.
Apparent permeability
Bidirectional A to B and B to A transport, measured by LC/MS and reported as a Papp coefficient.
BCS permeability class
Classify high versus low permeability against ICH M9 criteria, with atenolol and propranolol as controls.
TEER integrity check
Automated TEER before and after dosing confirms a tight, intact monolayer for every well.
Region and donor options
Run jejunum by default, or compare permeability across gut regions and multiple donors.
The assay works across a 14-compound panel, and it correlates with Caco-2 head-to-head on the same drugs.
Tracks human absorption
We ran 14 compounds against ICH M9 criteria on RepliGut® Planar Jejunum. Papp cleanly separates high and low permeability drugs, and it follows the known human fraction absorbed.
Correlates with Caco-2 head-to-head
On the same 14 drugs, RepliGut® Planar apparent permeability correlates with Caco-2 at R² 0.83. The read is human-relevant, and you can extend the same tissue into metabolism and transport. See the method in our publications.
Active transport and efflux, when you need it
Passive permeability is the starting point. When a compound is an efflux substrate, RepliGut® Planar also measures active transport. P-gp and BCRP are functional, and inhibitors like tariquidar and Ko143 confirm the mechanism. See the full workflow on our drug transporter assay page.
Built to reflect the human gut
Human small intestine
Grown from human adult donor stem cells of the small intestine, not a colon tumor line.
Benchmarked to Caco-2
Apparent permeability correlates with Caco-2 at R squared 0.83 across 14 compounds.
Apical and basal access
The planar transwell format opens both surfaces for bidirectional dosing and sampling.
One system, more biology
Extend the same human tissue into metabolism, transport, regions, and donors.
Run it in your lab or have us run it
RepliGut® Kits
Run the permeability assay in your own lab. Kits ship in 12-well and 96-well formats, complete with cells, plates, media, and technical support.
Explore kitsFull-service permeability
Have our scientists run it. We deliver Papp, efflux ratios, and TEER data, ready to drop into your model.
Explore servicesPart of a broader program? Explore the full RepliGut® platform or our in vitro DMPK and ADME capabilities.
Ready to run a permeability assay on human tissue?
Send us your compounds. We will design an in vitro permeability assay on RepliGut® Planar and deliver Papp you can trust.
Design your study