GSE193743
A High-Resolution Route Map Reveals Distinct Stages of Chondrocyte Dedifferentiation (ATAC-Seq)
Objectives: Articular cartilage damage has become a universal health burden. Despite the recent progresses in cell-based cartilage regeneration, chondrocyte dedifferentiation has compromised the clinical outcomes, which is frequently seen in chondrocyte expansion and osteoarthritis, involving functional phenotype loss. However, its concept remains elusive with unknown intermediate process and mechanisms. Here we demonstrated a time-lapse atlas of chondrocyte dedifferentiation, to provide molecular details and informative biomarkers for clinical chondrocyte evaluation. Methods:  Single-cell RNA sequencing (scRNA-seq) was employed to dissect the chondrocyte dedifferentiation and identify distinct cellular subpopulations. To validate the findings, live-cell metabolic assay, high-resolution imaging and ¡°assay for transposase-accessible chromatin with high throughput sequencing¡± (ATAC-seq) were conducted. Using a chemical inhibitor BTB06584 affecting on mitochondrial F1F0ATPase, we revealed the recovery potential of early and late dedifferentiated chondrocytes. Results:Our findings shape a biphasic model consist of early and late dedifferentiation stages. Early dedifferentiated chondrocytes uniquely obtained a transient glycolytic phenotype with an activation of metabolic and anti-oxidant genes; late dedifferentiated chondrocytes exhibited ultrastructural changes including mitochondrion damages and stress-associated chromatin remodeling. Using a chemical inhibitor BTB06584, we revealed that early and late dedifferentiated chondrocytes possessed distinguished recovery potential from functional phenotype loss. BTB06584 treatment ameliorated early phenotype loss through inhibiting MAPK pathway. Notably, this two-stage transition was validated in human chondrocyte culture. An image-based approach was established for clinical utilization, to efficiently predict chondrocytes plasticity with stage-specific biomarkers. Conclusion: Thus this study lays a foundation for future clinical chondrocyte quality regulation and provides insights for deeper understanding of chondrocyte dedifferentiation. Overall design: We employed ATAC-seq of serial-passaged murine chondrocytes (P0 and 8) to reconstruct a time-lapse atlas of chondrocyte dedifferentiation.