ciPTEC — Human Renal Proximal Tubule Cell Lines for Transporter Assays
Cell4Pharma's ciPTEC cell lines replicate the human proximal tubule in vitro and endogenously express OAT1, OAT3, OCT2 and other key renal drug transporters. Used for nephrotoxicity screening, renal DDI studies and ADME characterisation. Available via SeamlessBio as exclusive DACH distributor.
Human Proximal Tubule Model
Conditionally immortalized cells from a healthy human donor — preserves tubular transporter expression and proximal tubule phenotype.
Endogenous Transporter Expression
OAT1, OAT3, OCT2, P-gp, MRP2, MRP4 and MATE — expressed at functional levels without additional transfection required for the parental line.
10+ Years Validation
Developed in collaboration with AstraZeneca, Roche, Pfizer and GSK — extensive peer-reviewed publication record.
DACH via SeamlessBio
Exclusive DACH distribution partner for Cell4Pharma — EU stock, scientific support, 48h response on technical and regulatory queries.
What is ciPTEC — and when do you need it?
ciPTEC stands for conditionally immortalized proximal tubule epithelial cells — a human renal cell line that replicates the transporter biology of the proximal tubule in vitro.
The proximal tubule is the primary site of active renal drug secretion and the segment most vulnerable to drug-induced nephrotoxicity. Standard cell lines used in DMPK — HEK293, MDCK, LLC-PK1 — do not express the endogenous transporter complement of the proximal tubule at functional levels. ciPTEC does. It is the appropriate model when renal drug handling, transporter-mediated DDI or nephrotoxicity needs to be assessed in a human, proximal-tubule-relevant system.
Renal transporters expressed in ciPTEC
| Transporter | Gene | Direction | Regulatory relevance | Available in |
|---|---|---|---|---|
| OAT1 | SLC22A6 | Basolateral uptake | FDA/EMA DDI — mandatory panel | ciPTEC-OAT1 |
| OAT3 | SLC22A8 | Basolateral uptake | FDA/EMA DDI — mandatory panel | ciPTEC-OAT3 |
| OCT2 | SLC22A2 | Basolateral uptake | FDA/EMA DDI — mandatory panel | ciPTEC 14.4 (endogenous) |
| P-gp (MDR1) | ABCB1 | Apical efflux | FDA/EMA DDI — mandatory panel | ciPTEC 14.4 (endogenous) |
| MRP2 | ABCC2 | Apical efflux | FDA/EMA additional panel | ciPTEC 14.4 (endogenous) |
| MRP4 | ABCC4 | Apical efflux | Renal nucleotide efflux | ciPTEC 14.4 (endogenous) |
| MATE1 / MATE2-K | SLC47A1/A2 | Apical efflux | OCT2/MATE DDI — metformin interactions | ciPTEC 14.4 (endogenous) |
Format and availability
- No transfection required for the parental line. ciPTEC 14.4 endogenously expresses OCT2, P-gp, MRP2, MRP4 and MATE — ready for nephrotoxicity and OCT2 assays without additional engineering.
- Stable OAT expression confirmed. ciPTEC-OAT1 and ciPTEC-OAT3 provide validated uptake activity for regulatory-grade DDI assays.
- Detection-flexible. Compatible with fluorescence, LC-MS/MS and radiolabel readouts depending on substrate and throughput requirements.
- Regulatory publication record. Extensively published in peer-reviewed literature with data from AstraZeneca, Roche, Pfizer and GSK collaborations.
Why ciPTEC matters in DMPK programmes
OAT1 and OAT3 are included in the mandatory transporter panel of the FDA Drug Interaction Guidance (2020) and the EMA Guideline on the Investigation of Drug Interactions. Both agencies require in vitro assessment of new molecular entities as OAT1 and OAT3 substrates and inhibitors as part of standard NDA/MAA DDI submission packages.
Beyond DDI, the proximal tubule is the nephron segment most vulnerable to drug-induced injury due to its high metabolic activity and transporter-mediated drug accumulation. ciPTEC 14.4 supports nephrotoxicity biomarker readouts — KIM-1, NGAL, clusterin — enabling early preclinical safety screening before animal studies.
Unlike HEK293 or MDCK transfectants, ciPTEC provides a physiologically relevant human proximal tubule context in which uptake and efflux transporters interact — enabling more predictive IVIVE for renal PK and toxicity.
Typical applications
- OAT1 / OAT3 substrate and inhibition assays (FDA/EMA)
- OCT2 / MATE1 / MATE2-K interaction studies
- Nephrotoxicity screening — early preclinical safety
- Renal biomarker readouts: KIM-1, NGAL, clusterin
- Transcellular secretion studies (uptake + efflux)
- Drug-induced proximal tubule injury characterisation
- IVIVE — in vitro to in vivo extrapolation for renal PK
Frequently asked questions
What makes ciPTEC different from HEK293 or MDCK cells for renal transporter assays?
HEK293 and MDCK require stable transfection of individual transporters in isolation — eliminating the functional crosstalk between uptake and efflux transporters that characterises the real proximal tubule. ciPTEC is a human proximal tubule cell line that expresses OAT1 (ciPTEC-OAT1), OAT3 (ciPTEC-OAT3), OCT2, P-gp, MRP2, MRP4 and MATE at physiologically relevant levels — enabling a more predictive model of renal drug handling, particularly for compounds that interact with multiple transporters simultaneously.
Are OAT1 and OAT3 assays in ciPTEC accepted by FDA and EMA for DDI submissions?
OAT1 and OAT3 are both included in the mandatory transporter panel for DDI assessment in the FDA Drug Interaction Guidance (2020) and the EMA Guideline on the Investigation of Drug Interactions. Both agencies require in vitro assessment of new molecular entities as OAT1 and OAT3 substrates and inhibitors as part of the standard NDA/MAA submission package. ciPTEC-OAT1 and ciPTEC-OAT3 provide a validated human cell-based format for these assays with an extensive peer-reviewed publication record.
What is the difference between ciPTEC-OAT1 and ciPTEC-OAT3?
OAT1 (SLC22A6) and OAT3 (SLC22A8) share substantial substrate overlap but differ in selectivity — OAT3 preferentially transports sulphate conjugates and larger organic anions; OAT1 is more active with smaller polar anions. FDA and EMA treat them as separate assessment requirements. Most DDI programmes run both in parallel. Probe substrates: ciPTEC-OAT1 uses fluorescein or PAH; ciPTEC-OAT3 uses estrone-3-sulfate (E1S).
Can ciPTEC be used for nephrotoxicity studies, not just DDI?
Yes — nephrotoxicity screening is one of the primary applications of ciPTEC 14.4. The proximal tubule is the most nephrotoxin-sensitive segment of the nephron due to its high metabolic activity and transporter-mediated drug accumulation. ciPTEC 14.4 supports cell viability readouts (MTT, WST8), ROS production, and validated renal toxicity biomarker panels including KIM-1, NGAL and clusterin — enabling early preclinical safety screening before animal studies.
Do I need ciPTEC if I already use ABC transporter vesicle kits?
ABC transporter vesicle kits (P-gp, BCRP, BSEP, MRP) cover efflux transporter inhibition — the regulatory default for hepatic and intestinal efflux characterisation. ciPTEC fills a different gap: renal uptake transporter assessment (OAT1, OAT3, OCT2) and nephrotoxicity, for which isolated vesicles are not the appropriate model. A complete DMPK transporter package for drug development typically requires both.
When should I use the ciPTEC assay service instead of buying the cell lines?
The ciPTEC assay service is for groups that need transporter data without establishing cell culture in-house — one-time regulatory submissions, limited capacity, or when a CRO-quality study report is needed. Buying the cell lines directly is the right approach for groups running transporter assays routinely as part of an ongoing DMPK programme.
What documentation is available for ciPTEC assays for regulatory submissions?
Cell4Pharma provides lot-specific characterisation data, transporter expression confirmation and assay validation documentation for all ciPTEC cell lines. For regulatory submission support — study reports, GLP compliance documentation, or specific data packages for IND/NDA/MAA dossiers — contact us with the regulatory context and we will scope what is available.
Three ciPTEC Cell Lines — Which One Fits Your Study?
Cell4Pharma offers three ciPTEC variants covering general nephrotoxicity screening through to specific OAT1 and OAT3 transporter assays for regulatory DDI submissions.
ciPTEC 14.4
The parental cell line. Endogenously expresses OCT2, P-gp, MRP2, MRP4 and MATE — baseline model for nephrotoxicity screening, OCT2/MATE DDI and general renal pharmacology. Supports cell viability, ROS, biomarker and CRISPR-based applications.
Learn more →ciPTEC-OAT1
Stably transfected with OAT1 (SLC22A6) — primary basolateral uptake transporter for organic anions, antivirals and nephrotoxins. FDA/EMA mandatory DDI panel. Validated with AstraZeneca. Probe substrate: fluorescein, PAH.
Learn more →ciPTEC-OAT3
Stably transfected with OAT3 (SLC22A8) — selective for sulphate conjugates and larger organic anions. FDA/EMA mandatory DDI panel. Complements ciPTEC-OAT1 for full OAT coverage. Probe substrate: estrone-3-sulfate (E1S).
Learn more →Need ciPTEC cell lines or a full renal transporter assay?
Contact our team for cell line availability, pricing and technical documentation — or to scope a ciPTEC assay study if you need regulatory-ready data without in-house cell culture.
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