Test systems in GLP studies include in vivo (live animals) and in vitro (cell cultures, microorganisms, or subcellular systems) models used to evaluate the safety of test items. The OECD GLP Principles require that test systems be maintained under controlled conditions appropriate for the species or system type. Proper management of test systems ensures the validity and reproducibility of study results.

In Vivo Test Systems

For in vivo studies, test facility conditions must include appropriate housing, feeding, bedding, and environmental controls such as temperature, humidity, and light cycles. Animals must be acclimatized to the facility before study initiation, and their health status must be monitored throughout the study. Identification of individual animals through ear tags, microchips, or other methods ensures traceability of data.

In Vitro Test Systems

In vitro test systems require controlled culture conditions including temperature, atmosphere composition, and sterile technique. Cell lines must be characterized, monitored for contamination, and used within defined passage limits. Media, sera, and reagents must be tested for suitability and recorded with lot numbers and expiration dates.

Environmental Controls

All test system environments must be monitored and documented at intervals specified in the study plan or Standard Operating Procedures (SOPs) . Environmental monitoring equipment must be calibrated and deviations recorded with corrective actions. For in vivo systems, veterinary care and humane endpoint criteria must be established in advance.

Test System Records

Comprehensive records must be maintained for each test system, including source, receipt date, condition upon arrival, and any treatments or observations during the study. For in vivo studies, records include body weights, food consumption, clinical observations, and necropsy findings. For in vitro studies, records include passage history, contamination testing, and quality control results.

Conclusion

The integrity of test systems directly impacts the reliability of GLP study data. Rigorous environmental control, health monitoring, and record-keeping are essential for both in vivo and in vitro models. Facilities must establish robust systems for test system management that meet both GLP requirements and animal welfare standards.