Human fibroblast-like synoviocyte isolation matter: a comparison between cell isolation from synovial tissue and synovial fluid from patients with rheumatoid arthritis

OBJECTIVE: Cell culture technology has become a popular method in the field of cell biology, pharmacology, and medical researches. Primary cells represent the normal physiological condition of human cells. Fibroblasts are the most common native cells of connective tissue that play a crucial role in the entire pathogenesis of various disorders, such as rheumatoid arthritis (RA). Fibroblast-like synoviocytes (FLSs), which overlie the loose connective tissue of the synovial sublining, are known to be the central mediators of joint damage. The most routine approach for the isolation of FLS is an enzymatic digestion of synovial tissue. This experimental study is designed to introduce an easy, fast, and high-throughput method compared with enzymatic digestion for isolation of FLS. METHODS: The synovial tissue and synovial fluid (SF) samples were collected from eight patients with RA who underwent routine knee replacement surgery. Synovial tissue was incubated with collagenase VIII enzyme, while SF was washed with a similar volume of phosphatebuffered saline. The cells were further subcultured and stored based on the standard protocols. The purity of isolated synoviocytes was confirmed using flow cytometry analysis. RESULTS: Isolation of FLS from SF was more successful with a faster rate, 3-5 days after culture. The morphological assessment and flow cytometry analysis confirmed the purity of SF-derived cells in passage 4. CONCLUSIONS: SF could be a more accessible source of FLS than synovial tissue. Obtaining primary FLS from SF is a simple, fast, and cost-effective way to have a large-scale cell during a short time.