Microcavitary Alginate Hydrogel Reverses Chondrocyte Dedifferentiation via Temporal Modulation of the p53 Pathway.

The dedifferentiation of chondrocytes significantly restricts their functional performance and practical applications. In our previous research, an easily preparable microcavitary alginate hydrogel (MCG) was shown to effectively promote the redifferentiation of dedifferentiated chondrocytes. Building on this, the present study further investigates the transcriptomic changes during chondrocyte dedifferentiation, utilizing high-throughput RNA sequencing to explore how MCG regulates passage-four dedifferentiated porcine chondrocytes over a 28-day period. Integrated analysis of transcriptomic profiling data across multiple time points identified the p53 signaling pathway as a potentially central regulatory node. Key findings validated by quantitative real-time polymerase chain reaction, Western blot, and Cell Counting Kit-8 assays demonstrated the following: (1) MCG arrested the progression of dedifferentiation, downregulated fibrosis/degeneration markers (COL1A1, WNT5A/B), and partially restored chondrogenic gene expression relative to P4; (2) Time-series analysis revealed MCG's influence on cell cycle regulation, extracellular matrix organization, DNA repair, and differentiation processes; (3) Crucially, MCG dynamically regulated the p53 pathway: early activation (TP53, p-p53 Ser15, MDM2) promoted DNA repair (RRM2B) and suppressed excessive inflammation/apoptosis (IL6/8, PMAIP1/CASP3), while subsequent attenuation of the pathway correlated with enhanced late-stage proliferation. In conclusion, the growth factor-free MCG microenvironment alleviates chondrocyte dedifferentiation and facilitates partial redifferentiation by orchestrating cellular behaviors through dynamic regulation of the p53 pathway-particularly via enhanced DNA repair-thereby offering a promising strategy for cell-based therapeutic approaches.