Purity testing is performed in accordance with regulatory guidelines to determine whether cell banks and biological products are contaminated with unwanted microorganisms.
For CHO cells and CHO-derived products, purity testing primarily focuses on the detection of microbial contamination. Common microbial contaminants include:
Mycoplasma
Bacteria
Fungi
Mycobacteria
According to regulatory requirements, sterility testing of cell banks is typically performed using the direct inoculation method.
A representative portion of the cell bank is tested, generally using 1% of the cell bank and no fewer than two vials, in accordance with applicable pharmacopoeial requirements and the recommendations of ICH Q5D.
Testing should be conducted in a validated isolator system or an ISO Class 5 environment.
Appropriate culture media and incubation conditions are used to detect a broad range of potential microbial contaminants, including:
Fungi
Anaerobic bacteria
Aerobic bacteria
This testing helps confirm the microbiological purity of the cell bank before its use in subsequent manufacturing processes.
Mycoplasma testing is conducted in accordance with applicable pharmacopoeial requirements.
Conventional mycoplasma detection methods include:
Solid culture methods
Semi-solid culture methods
Indicator cell culture assays
In addition to conventional culture-based methods, quantitative PCR (qPCR) can be used for rapid mycoplasma detection.
PCR-based methods can significantly shorten testing timelines compared with traditional culture-based approaches. The European Pharmacopoeia has also established specific requirements for the validation of nucleic acid amplification techniques when they are used for mycoplasma detection.
Mycobacteria testing can be performed with reference to the Chinese Pharmacopoeia 2020 Edition, Volume III, as well as relevant European Pharmacopoeia requirements.
By using appropriate positive and negative controls and conducting extended culture for up to 56 days, potential mycobacterial contamination can be detected.
In addition to conventional culture-based testing, PCR-based methods can also be used for rapid detection of mycobacteria.
BRC Biotech has developed a rapid mycobacteria detection kit based on molecular detection technology, providing a faster testing option to support accelerated product release and manufacturing timelines.
Microbial contamination can be introduced through cell substrates, raw materials, culture processes, manufacturing environments, or other stages of biopharmaceutical production.
Therefore, purity testing is an essential component of cell bank characterization and biological product quality control.
By combining conventional compendial methods with rapid molecular detection technologies, an appropriate testing strategy can help ensure compliance with regulatory requirements while improving testing efficiency and turnaround time.
BRC Biotech (Shanghai) Co., Ltd. was established in 2022 and is located in the FTZ No. 1 Life Sciences Industrial Park within the Shanghai Pilot Free Trade Zone.
BRC Biotech operates approximately 6,000 m² of testing laboratories, business facilities, and training centers designed to meet cGMP and Biosafety Level 2 (BSL-2) standards.
We are committed to providing professional and compliant services across fields including:
Cell and gene therapy
Therapeutic antibodies
Vaccines
Nucleic acid therapeutics
Our capabilities include biosafety testing, analytical method development, target validation and evaluation, as well as related testing reagent products.
As your biosafety testing partner, BRC Biotech provides internationally aligned, high-quality local services to support the safety, quality, and regulatory development of biopharmaceutical products.
GMP cell banking and cell bank characterization
Drug substance and drug product testing services
Customized product testing and analytical method development
GMP-grade biological sample storage services
Product quality and regulatory compliance consulting
In our next article, we will continue exploring biosafety testing strategies for CHO cells.
