Cartilage is a resilient and smooth connective tissue that is found throughout the body. Among the three major types of cartilage, namely hyaline cartilage, elastic cartilage, and fibrocartilage, hyaline cartilage is the most widespread type of cartilage predominantly located in the joint surfaces (articular cartilage, AC). It remains a huge challenge for orthopedic surgeons to deal with AC damage since it has limited capacity for self-repair. Xiphoid cartilage (XC) is a vestigial cartilage located in the distal end of the sternum. XC-derived chondrocytes exhibit strong chondrogenic differentiation capacity. Thus, XC could become a potential donor site of chondrocytes for cartilage repair and regeneration. However, the underlying gene expression patterns between AC and XC are still largely unknown. In the present study, we used state-of-the-art RNA-seq technology combined with validation method to investigate the gene expression patterns between AC and XC, and identified a series of differentially expressed genes (DEGs) involved in chondrocyte commitment and differentiation including growth factors, transcription factors, and extracellular matrices. We demonstrated that the majority of significantly up-regulated DEGs (XC vs. AC) in XC were involved in regulating cartilage regeneration and repair, whereas the majority of significantly up-regulated DEGs (XC vs. AC) in AC were involved in regulating chondrocyte differentiation and maturation. This study has increased our knowledge of transcriptional networks in hyaline cartilage and elastic cartilage. It also supports the use of XC-derived chondrocytes as a potential cell resource for cartilage regeneration and repair.

软骨是一种有弹性且光滑的结缔组织，遍布全身。在三种主要类型的软骨，即透明软骨、弹性软骨和纤维软骨中，透明软骨是主要位于关节表面（关节软骨，AC）的最普遍的软骨类型。由于 AC 损伤的自我修复能力有限，对于骨科医生来说，处理 AC 损伤仍然是一个巨大的挑战。剑突软骨 (XC) 是位于胸骨远端的残留软骨。XC 衍生的软骨细胞表现出很强的软骨分化能力。因此，XC 可能成为软骨细胞修复和再生的潜在供体位点。然而，AC 和 XC 之间的潜在基因表达模式仍然很大程度上未知。在目前的研究中，我们使用最先进的 RNA-seq 技术结合验证方法来研究 AC 和 XC 之间的基因表达模式，并确定了一系列参与软骨细胞定型和分化的差异表达基因 (DEG)，包括生长因子、转录因子和细胞外基质。我们证明了 XC 中大多数显着上调的 DEG（XC 与 AC）参与调节软骨再生和修复，而 AC 中大多数显着上调的 DEG（XC 与 AC）参与调节软骨细胞分化和成熟。这项研究增加了我们对透明软骨和弹性软骨转录网络的了解。