<p>Human-induced pluripotent stem cells (hiPSCs) represent a promising cell source for cartilage regeneration because of their self-renewal capacity and chondrogenic potential. However, the propensity of hiPSC-derived chondrocytes to undergo hypertrophic maturation remains a major obstacle to generating stable articular cartilage. Here, we identified core binding factor β (CBFβ) as a critical regulator of early chondrogenic identity and a suppressor of hypertrophic transition during hiPSC-derived cartilage organoid formation. CBFβ expression was markedly diminished in degenerative articular cartilage from both human osteoarthritis (OA) specimens and mouse OA models, and cartilage-specific ablation of <i>Cbfβ</i> accelerated cartilage structural deterioration and matrix loss. Notably, CBFβ was secreted by non-mineralizing cells, including chondrocytes and vascular smooth muscle cells, suggesting an autocrine/paracrine regulatory role. Pharmacological inhibition with Brefeldin A reduced extracellular CBFβ levels, whereas blockade of exosome release by GW4869 had minimal effect, indicating a secretion-associated mechanism independent of exosomes. Recombinant human CBFβ (rhCBFβ) treatment enhanced the chondrocyte phenotype by upregulating early chondrogenic markers (SOX9, COL2A1) while suppressing hypertrophic and catabolic markers ( RUNX2, MMP13). In hiPSC-derived cartilage organoids, rhCBFβ enhanced matrix deposition and increased COL2A1 and SOX9 expression. Transcriptomic profiling and qRT-PCR validation further demonstrated that rhCBFβ activated cartilage matrix-associated and anti-hypertrophic transcriptional programs, including upregulation of <i>PTHRP</i>, <i>HIF1α</i>, HDAC4, <i>MGP</i>, <i>CILP</i>, and <i>ALK5</i>, together with suppression of RUNX2.</p><p><?noindent??>Collectively, these findings establish CBFβ as a key regulator of articular cartilage homeostasis and highlights its therapeutic potential for cartilage regeneration in OA. The ability of rhCBFβ to preserve early chondrogenic identity while preventing hypertrophic maturation offers a promising strategy for cartilage tissue engineering. Further preclinical studies are warranted to evaluate its efficacy and accelerate clinical translation for OA therapy.</p>

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Core binding factor β preserves early chondrogenic identity and prevents hypertrophic transition in cartilage organoids formation

  • Xiangguo Che,
  • Xian Jin,
  • Dong-Kyo Lee,
  • Eun-Jung Heo,
  • Min Park,
  • Jinyoung Oh,
  • Hee-June Kim,
  • Hyun-Ju Kim,
  • Hyung-Ryong Kim,
  • Je-Yong Choi

摘要

Human-induced pluripotent stem cells (hiPSCs) represent a promising cell source for cartilage regeneration because of their self-renewal capacity and chondrogenic potential. However, the propensity of hiPSC-derived chondrocytes to undergo hypertrophic maturation remains a major obstacle to generating stable articular cartilage. Here, we identified core binding factor β (CBFβ) as a critical regulator of early chondrogenic identity and a suppressor of hypertrophic transition during hiPSC-derived cartilage organoid formation. CBFβ expression was markedly diminished in degenerative articular cartilage from both human osteoarthritis (OA) specimens and mouse OA models, and cartilage-specific ablation of Cbfβ accelerated cartilage structural deterioration and matrix loss. Notably, CBFβ was secreted by non-mineralizing cells, including chondrocytes and vascular smooth muscle cells, suggesting an autocrine/paracrine regulatory role. Pharmacological inhibition with Brefeldin A reduced extracellular CBFβ levels, whereas blockade of exosome release by GW4869 had minimal effect, indicating a secretion-associated mechanism independent of exosomes. Recombinant human CBFβ (rhCBFβ) treatment enhanced the chondrocyte phenotype by upregulating early chondrogenic markers (SOX9, COL2A1) while suppressing hypertrophic and catabolic markers ( RUNX2, MMP13). In hiPSC-derived cartilage organoids, rhCBFβ enhanced matrix deposition and increased COL2A1 and SOX9 expression. Transcriptomic profiling and qRT-PCR validation further demonstrated that rhCBFβ activated cartilage matrix-associated and anti-hypertrophic transcriptional programs, including upregulation of PTHRP, HIF1α, HDAC4, MGP, CILP, and ALK5, together with suppression of RUNX2.

Collectively, these findings establish CBFβ as a key regulator of articular cartilage homeostasis and highlights its therapeutic potential for cartilage regeneration in OA. The ability of rhCBFβ to preserve early chondrogenic identity while preventing hypertrophic maturation offers a promising strategy for cartilage tissue engineering. Further preclinical studies are warranted to evaluate its efficacy and accelerate clinical translation for OA therapy.