Primary Isolation, Culture, and Phenotypic Verification of Rat Knee Articular Chondrocytes

Cartilage damage resulting from trauma, aging, or inflammatory conditions remains a significant clinical challenge due to the tissue's inherently limited regenerative capacity. Chondrocytes, being the sole cellular component of cartilage, are responsible for maintaining extracellular matrix structure and function, making them essential for understanding cartilage physiology, pathology, and regeneration. The current study presents a comprehensive and standardized protocol for the isolation, culture, and phenotypic verification of primary rat articular chondrocytes from the knee joint. The procedure utilizes young, suckling rats to ensure maximal cell viability and employs sequential enzymatic digestion with trypsin and collagenase type II for efficient cell extraction. The chondrocyte phenotype is verified through type II collagen immunofluorescence, flow cytometric analysis, and Interleukin (IL)-1β stimulation assays to confirm cellular identity and inflammatory responsiveness. This optimized and reproducible workflow enables the generation of high-purity chondrocyte cultures suitable for drug screening, mechanistic investigations, and tissue engineering applications, advancing cartilage biology research.