Reprogramming Dedifferentiation Regulatory Networks Preserves Human Chondrocyte Phenotypes.

Area of Science:

• Regenerative Medicine
• Cell Biology
• Biotechnology

Background:

• Autologous chondrocyte implantation (ACI) is a cell-based strategy for cartilage repair.
• In vitro expansion of chondrocytes is necessary to achieve sufficient cell numbers for ACI.
• Chondrocyte expansion leads to dedifferentiation, reducing matrix formation and impacting repair efficacy.

Purpose of the Study:

• To investigate the molecular mechanisms of human chondrocyte dedifferentiation during in vitro expansion.
• To identify regulatory pathways and potential therapeutic targets to maintain chondrocyte identity and function.

Main Methods:

• Single-nucleus multiome profiling (snRNA-Seq and snATAC-Seq) was employed to analyze transcriptional and chromatin accessibility changes.
• Integration of multiome data across cell passages identified dedifferentiation trajectories.
• Small-molecule inhibitors were screened to identify compounds preserving chondrocyte phenotype.

Main Results:

• Chondrocyte dedifferentiation followed a continuous trajectory characterized by coordinated gene expression and chromatin accessibility remodeling.
• Chromatin destabilization was identified as an early event in chondrocyte phenotype loss.
• Fludarabine treatment suppressed STAT1 programs, stabilized the chromatin landscape, enhanced matrix formation, and increased protein synthesis.

Conclusions:

• Chromatin stability is a critical determinant of chondrocyte dedifferentiation during expansion.
• Fludarabine represents a potential pharmacologic strategy to maintain chondrocyte potency for cell manufacturing in cartilage repair.