A Matrigel-Free 3D Chondrocytic Spheroid Model for Rheumatoid Arthritis-Associated Synoviocytes Invasion Studies.

BACKGROUND

The primary pathology of rheumatoid arthritis (RA) involves the invasion of the extracellular matrix (ECM) of articular cartilage by inflammation-activated fibroblast-like synoviocytes (FLS), a process targeted by most RA therapeutic drugs. However, the absence of an efficient in vitro model for evaluating FLS invasion hinders relevant drug screening and mechanism research. To address this, a novel three-dimensional (3D) chondrocytic spheroid model that mimics cartilage ECM has been developed, along with corresponding indices to quantify synoviocytes invasion.

METHODS

The matrigel-free 3D chondrocytic spheroid model was developed using an ultra-low attachment plate. The model was characterized using transcriptome sequencing, immunofluorescent staining. To explore the feasibility of this 3D chondrocytic spheroid model for evaluating the invasive capacity of synoviocytes, multi-interference strategies, including gene overexpression, inflammatory cytokine stimulation, and anti-inflammatory drug (Etanercept) treatment were involved. Additionally, specific indices-Invasion Depth Ratio (IDR), Invasion Counts (IC), Invasion Ratio (IR), and Invasion Area Ratio (IAR)-were designed to quantify synoviocytes invasion.

RESULTS

The 3D culture environment is more suitable for cartilage ECM synthesis by increasing cartilage anabolism-related gene () and reducing catabolism-related genes () expression. Moreover, the optimal conditions for developing the 3D chondrocytic spheroid model were identified. This model was sensitive to gene, inflammation and drug interference. Increased IDR, IC, IR and IAR was observed in overexpressed- and IL-1β-treated chondrocytic spheroid. Further, Etanercept could inhibit TNF-α induced synoviocytes invasion of chondrocytic spheroid.

CONCLUSION

This matrigel-free 3D chondrocytic spheroid model offers an ideal platform for innovative drug screening and pathogenesis studies focused on synoviocytes invasion of cartilage.