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Short answer
The Caco-2 cell line (ATCC HTB-37, Cellosaurus CVCL_0025) is a human colorectal adenocarcinoma line, derived from the colon of a 72-year-old male donor, that grows as an adherent, epithelial-like monolayer and shows enterocytic differentiation once confluent. The same line is described with different doubling times and STR values in different reference records, so a lab should cite the exact source and authenticate its own stock.
What is a cell line, and what Caco-2 is
Cell line definition
A cell line is a population of cells that can be grown and propagated repeatedly in culture, so that many experiments can start from the same lineage of cells rather than from fresh tissue each time. A continuous line is described by its species, tissue, disease state, donor details and the repository record it came from. Cell lines are different from biospecimens, which are the original samples taken from a donor.
Caco-2 in one paragraph
The ATCC record lists Caco-2 as Homo sapiens, large intestine (colon), colorectal adenocarcinoma, epithelial-like morphology, adherent growth. ATCC notes that on reaching confluence the cells show enterocytic differentiation. That property is why the line is widely used as an in vitro model of the intestinal epithelium; the permeability workflow built on it is covered separately in our guide to the Caco-2 permeability assay, so this page stays on the cell line itself.
Origin and identity records
Two public records are the usual anchors for Caco-2:
- ATCC HTB-37: donor 72 years old, male; tissue large intestine, colon; disease colorectal adenocarcinoma.
- Cellosaurus CVCL_0025: human, male, 72 years at sampling, colon adenocarcinoma, derived in situ from the colon. It cross-references ATCC HTB-37 and DSMZ ACC-169 and lists synonyms such as Caco-2/ATCC and Caco-II.
The Cellosaurus accession (CVCL_0025) is the unambiguous identifier to cite in a methods section, because it resolves to one entry however a paper spells the name.
How the line is maintained (supplier’s record)
The following are the conditions ATCC publishes for HTB-37, stated here as the supplier’s record and not as a protocol. Always follow the documentation that shipped with your own vial.
- Growth mode: adherent; cells show enterocytic differentiation upon confluence.
- Medium listed by ATCC: ATCC-formulated Eagle’s Minimum Essential Medium (ATCC 30-2003) with fetal bovine serum to a final concentration of 20%.
- Atmosphere and temperature: 37 °C, 95% air and 5% CO₂.
- Subculture: when cells are about 80% confluent; recommended subcultivation ratio 1:4 to 1:6; medium renewed 1 to 2 times per week.
- Doubling time on the ATCC product page: about 62 hours.
Many published protocols use a different base medium or serum percentage from the one ATCC lists. A supplier’s specification is the reference point for that vial; a change of medium or serum is a methods detail worth reporting, not an invisible default. Routine culture hygiene, including contamination checks, is covered in our guide to cell culture contamination.
Sublines and where the records disagree
Cellosaurus lists dozens of derived cell lines under Caco-2, including the named variants C2BBe1, Caco-2/15 and Caco-2/TC-7 as well as gene-edited and reporter lines. A paper that says only “Caco-2” may therefore mean the parental line or a subline, which is one reason the name alone is not a sufficient identifier.
The reference records also differ on basic characteristics of the parental line. The comparison below uses only values printed on the ATCC product page and the Cellosaurus entry.
| Characteristic | Value and source in the record |
|---|---|
| Doubling time | About 62 hours (ATCC product page); 3-4 days (ATCC, as quoted by Cellosaurus); 51.41 hours (PubMed, as quoted by Cellosaurus); about 60-70 hours (CLS); about 80 hours (DSMZ); about 32 hours (PBCF) |
| STR locus D8S1179 | 12 (DSMZ); 12,14 (ATCC), per Cellosaurus |
| STR locus D21S11 | 30 (DSMZ); 30,32 (ATCC), per Cellosaurus; the ATCC product page lists 30,32 |
| Other STR loci | Penta D and D7S820 also differ between sources in Cellosaurus |
The gain from reading these records side by side is practical: a growth rate or a short tandem repeat (STR) profile that looks “wrong” for your stock may simply reflect which source was used as the reference. Name the reference when you compare.
Where it matters for labs: a reporting checklist
These items are suggested reporting fields drawn from what the records above show varies. They are not a mandated standard.
- Identifier: name plus Cellosaurus accession CVCL_0025, and the ATCC or DSMZ catalogue number if that is the source.
- Parental line or subline: say whether it is Caco-2 or, for example, C2BBe1, Caco-2/15 or Caco-2/TC-7.
- Source and passage: supplier or collaborator, and the passage number used in the experiment.
- Medium and serum: base medium and serum percentage, with the supplier’s specification if you departed from it.
- Authentication: the STR profile and the named reference database or record it was compared against. See our dictionary entry on authentication of key resources for the funder-facing context.
Supplier biosafety designations should be confirmed with the supplier and your institutional biosafety committee before work starts.
Common misunderstandings
- “All colon cancer lines behave the same.” They do not. Sibling lines such as HT-29 are separate lines with their own records; check each entry instead of transferring conditions between them.
- “There is one Caco-2 doubling time.” The records above give values from about 32 hours to about 80 hours, plus ATCC’s 3-4 days.
- “Caco-2 is the assay.” Caco-2 is the cell line; the permeability assay is a method that uses it. Vendor descriptions of the assay, such as Sygnature Discovery’s, describe 21 days of differentiation on Transwell inserts and report apparent permeability (Papp) and efflux ratio.
- “A cancer-derived line is a stand-in for a person.” It is a model system derived from one donor’s tumour, with the limits that implies.
FAQ
What is a cell line?
A cell line is a population of cells that can be propagated repeatedly in culture from a common origin, documented by species, tissue, disease and donor details in a repository record.
What is the definition of a cell line, and is the Caco-2 line the same as a cell line from another repository?
The definition is the same for any line, but a name does not guarantee identical stock. ATCC HTB-37 and DSMZ ACC-169 are cross-referenced to the same Cellosaurus entry, yet the entry shows differing doubling-time and STR values by source.
Are all cell lines the same?
No. Each line has its own tissue of origin, donor, growth behaviour and culture conditions, and each should be cited by its own identifier.
Where can I read about the Caco-2 assay?
See the Caco-2 permeability assay guide.
Sources
- ATCC, Caco-2 (HTB-37) product page, atcc.org/products/htb-37, checked 2026-10-29.
- Cellosaurus, Caco-2 (CVCL_0025), cellosaurus.org/CVCL_0025, checked 2026-10-29.
- Sygnature Discovery, Caco-2 permeability assay description, sygnaturediscovery.com, checked 2026-10-29 (vendor description, cited only for assay use).
