Cell Line Characterization Services
Generating master and working cell banks in compliance with GMP requires specialized expertise in manufacturing, biosafety, and characterization testing to ensure a robust, safe supply of cells for manufacturing processes.
Sartorius provides comprehensive services to characterize mammalian cell banks in line with ICH guidelines. All testing follows global pharmacopeial standards and is conducted in facilities accredited by the U.S. FDA, EMA, and MHRA.
Ready-to-use quality control plans support testing and release of:
- Research cell banks (RCBs)
- Master cell banks (MCBs)
- Working cell banks (WCBs)
- End-of-production cell banks (EoPCBs)
Integrated cGMP biosafety and cell characterization services
Sartorius has extensive experience in the characterization of cell banks used to produce biologic drugs, including protein-based and viral-based therapies. Our quality control testing plans meet requirements for mammalian cell bank release and are designed to align with ICH Q5A regulations, using assays validated to GMP standards. Ready-to-use testing schemes may be added to existing drug development risk strategies or customized to meet the needs of specific programs.
Biosafety testing and cell characterization packages
Stringent cGMP biosafety testing is required for all cell banks to confirm the absence of contaminants, including bacteria, mycoplasma, and viruses.
Cell bank testing regulations can be extensive. Sartorius has developed cGMP platform methods for cell bank testing that align with ICH Q5 guidelines.
Research cell bank testing
The process of cell banking begins with a research cell bank (RCB), which is used to generate a master cell bank (MCB).
Before this step, the RCB must be certified, at a minimum, as sterile, mycoplasma-free, and identity-assured. The manufacturer may also request a broad-spectrum cell-based in vitro test for potential viral contaminants.
To expedite RCB release, options include rapid testing by polymerase chain reaction (PCR), interim-read in vitro strategies, and identity testing by DNA barcoding.
Master cell bank testing
The master cell bank (MCB) is the primary, well‑characterized cell source from which all working cell banks (WCBs) are derived. It is generated from a single, clonally derived cell line, expanded under controlled conditions, aliquoted, and stored (e.g., in the vapor phase of liquid nitrogen) to support consistent manufacturing over the product lifecycle. Extensive testing is performed on the MCB, typically including:
Genetic identity and stability
- Assessment of the transgene and integration profile (e.g., Southern blotting, mRNA sequencing, and | or transgene copy number).
- Confirmation of identity (e.g., DNA barcoding or equivalent methods).
The extensive qualification of the MCB supports reduced, risk‑based testing of derived WCBs.
Microbial and adventitious agent safety
- Testing for bacteria, fungi, mycoplasma, and mycobacteria (e.g., sterility, mycoplasma, and mycobacterium assays).
- Comprehensive virus safety testing in line with the cell line’s risk profile and regulatory expectations.
Working cell bank testing
Working cell banks (WCBs) are prepared from the MCB. Biosafety testing requirements for the WCB depend on the level of testing conducted on the MCB.
Where extensive characterization has already been completed on the MCB, minimal testing is required on the WCB. Depending on the regulatory authority, this is typically limited to assessment of identity, stability, and microbial contamination. Virus testing is recommended only where a recognized risk occurs.
To characterize genetic stability, the transgene is assessed using techniques such as Southern blotting, mRNA sequencing, and | or transgene copy number. Identity can be measured using DNA barcoding. The presence of microbes is determined using sterility, mycoplasma, and mycobacterium assays.
Test methodologies used to characterize working cell banks originating from different species include:
- Sterility testing
- Mycoplasma testing
- In vitro assays
Genetic stability assays may be requested using these methods:
- Nucleic acid sequencing
- Southern blotting
- Identity testing
- Gene copy number
End-of-production cell bank testing
An end-of-production cell bank (EoPCB) is sometimes referred to as a post-production cell bank (PPCB) or as cells at the limit of in vitro cultivation. These cells are tested to validate the production system to ensure cell stability and identify any contamination issues.
The timing of EoPCB sampling will vary by product and is performed on a case-by-case basis.
For cell lines used in the manufacture of protein-based therapies, testing typically covers two areas: stability and contamination (biosafety). Testing schemes for cell lines used in viral vaccines or viral vectors may not require the same genetic stability assessments, depending on the MCB generation process.
Requirements for the EoPCB are very similar to those of the MCB. The EoPCB requires genetic stability testing and direct comparison with the MCB. Tests used include genetic analysis of the transgene using techniques such as Southern blotting, mRNA sequencing, or transgene copy number. A number of methods are used to test for potential contaminants, including those for microbes (sterility and mycoplasma), adventitious viruses (in vitro and in vivo tests and transmission electron microscopy), and specific virus tests, as determined by the process.
Test methodology used to characterize EoPCBs originating from different species include:
- Sterility testing
- Mycoplasma testing
- In vivo testing
- In vitro testing
- Retrovirus testing
- Bovine and porcine assays
- Electron microscopy
- Species-specific assays
Genetic stability assays provided by Sartorius include the following:
- Nucleic acid sequencing
- Southern blotting
- Identity testing
- Gene copy number
Regulatory requirements for cell line characterization
With a safety profile established over 20 years, CHO cells are by far the most widely used production cell lines in the pharmaceutical industry. Sartorius has performed biosafety and characterization testing on more than 200 CHO cell banks. Our scientists have extensive experience to advise on the most appropriate and cost-effective testing strategy to meet regulatory requirements. This recommendation takes into consideration both the history of the cell line and the raw materials used during the cell bank manufacturing. Below is a standard QC testing plan for CHO cell line characterization. While this plan may be modified for cells of human and simian origin, the basic principles apply.
| Biosafety testing | |
|---|---|
| Microbiological safety |
|
| Viral safety |
|
| Characterization | |
|---|---|
| Genetic analysis | Transgene confirmation (gene copy number and sequencing) |
| Identity | DNA barcoding |
With a well-established safety profile, HEK cells are widely used as host cell lines in biopharmaceutical research and production, particularly for viral vectors and recombinant proteins. Sartorius has extensive experience performing biosafety and characterization testing on HEK cell banks and can recommend appropriate, cost-effective testing strategies to meet regulatory expectations, considering both cell line history and raw materials used. The table below provides an overview of a standard QC testing package for HEK cell line characterization.
| Biosafety testing | |
|---|---|
| Microbiological safety |
|
| Viral safety |
|
| Characterization | |
|---|---|
| Genetic analysis | Sequencing and gene copy number (custom development) |
| Identity | Morphology (if adherent) and DNA barcoding |
With a well-established safety profile, MDCK cells are widely used as host cell lines in biopharmaceutical research and vaccine production, particularly for influenza virus manufacturing. Sartorius has extensive experience performing biosafety and characterization testing on MDCK cell banks and can recommend appropriate, cost-effective testing strategies to meet regulatory expectations, considering both cell line history and raw materials used. The table below provides an overview of a standard QC testing package for MDCK cell line characterization.
| Biosafety testing | |
|---|---|
| Microbiological safety |
|
| Viral safety |
|
| Characterization | |
|---|---|
| Genetic analysis | Transgene confirmation (gene copy number and Southern blot) |
| Appearance and identity | Morphology (if adherent) and DNA barcoding |
With a well-established use in advanced therapies, stem and immune cells are increasingly used as starting materials for cell and gene therapy products. Sartorius has extensive experience performing biosafety and characterization testing on stem and immune cell banks and can recommend appropriate testing strategies to meet regulatory expectations, considering both cell source | history and raw materials used. The table below provides an overview of a standard QC testing package for stem and immune cell bank characterization.
| Biosafety testing (standard package) | |
|---|---|
| Microbiological safety |
|
| Viral safety |
|
| Identity |
|
| Additional testing (based on product risk assessment) | |
|---|---|
| Additional adventitious viruses | Next-generation sequencing |
| Species-specific viruses | Simian virus panel, bovine and porcine viruses, sexually transmitted disease (STD) panel by PCR or next-generation sequencing |
| Replication competency | Replication-competent retrovirus (if retroviral vectors were used to induce gene editing) |
| Impurities | Residual plasmids and viruses (for induced pluripotent stem cells induced using plasmid or viral vectors); custom testing design |
| Tumorigenicity | Not required for continuous cell lines or irradiated cells. For highly expanded cells, testing may be considered in specific circumstances, as described by FDA guidance |
| Other species | As required |
Learn more about cell line characterization
Related Assets
Frequently Asked Questions
Cell characterization is a critical step in biopharmaceutical manufacturing that ensures the safety, purity, and efficacy of protein-based biologics, biosimilars, and viral vaccines. Because biologics are produced from living organisms (such as mammalian cell lines), there is an inherent risk of microbial and viral contamination. Testing should align with ICH Q5D guidelines, confirming the identity, purity, genetic stability, and freedom from adventitious agents of the MCB, WCB, and EoPCB. Regulatory bodies, including the FDA and EMA, require this testing before clinical or commercial manufacturing to help ensure the product is safe for human use before it reaches the market.
- Research cell bank (RCB): An early, often less‑controlled stock of cells used for exploratory or preclinical research, not intended for direct manufacturing of clinical | commercial products.
Master cell bank (MCB): The primary, well‑characterized, GMP-produced cell stock derived from a single cell line, from which all subsequent production cell banks are generated.
Working cell bank (WCB): A set of cell vials expanded from the MCB and used routinely to start production bioreactor runs for clinical or commercial manufacturing.
End-of-production cell bank (EoPCB): Cells taken from the production process at (or near) the end of their manufacturing lifetime, stored to allow later testing for genetic stability and consistency of the production cell line over time.
A master cell bank (MCB) is the original, extensively characterized GMP cell stock that serves as the long‑term reference source for a production cell line. A working cell bank (WCB) is derived from the MCB and is the routinely used source of cells to start manufacturing batches.
Our GMP cell bank manufacturing services combine single-use technologies with relevant technical and regulatory expertise to provide a closed, semi-automated process designed to mitigate risks from manual handling, contamination, shear stress, and cytotoxicity caused by overexposure to cryoprotectants. Integrated testing services provide tested and QP-released master cell banks in < 5 months and working cell banks in < 3 months.