Cao Zhen, Huang Song, Dou Ce, Xiang Qiang, Dong Shiwu
Department of Biomedical Materials Science, Third Military Medical University, Chongqing, China.
Department of Anatomy, Third Military Medical University, Chongqing, China.
J Cell Physiol. 2018 Mar;233(3):2332-2342. doi: 10.1002/jcp.26105. Epub 2017 Aug 25.
Cartilage is a kind of special connective tissue which does not contain neither blood vessels nor lymphatics and nerves. Therefore, the damage in cartilage is difficult to be repaired spontaneously. Constructing tissue engineered cartilage provides a new technique for cartilage repairing. Mesenchymal stem cells (MSCs) possess a unique capability of self-renew and can differentiate into pre-chondrocytes which are frequently applied as seed cells in tissue engineering. However, in regenerated cartilage the chondrocytes derived from MSCs can hardly maintain homeostasis and preferentially present hypertrophic like phenotype. We investigated the effects of cyanidin, a natural organic compound, on chondrogenic and subsequent hypertrophic differentiation of MSCs in order to seek approaches to inhibit chondrocyte hypertrophy. We evaluated the effects of cyanidin on expression of chondrogenic and hypertrophic marker genes through RT-PCR, Western blot, alcian blue staining, and immunocytochemistry. The results showed that both chondrogenic related genes Sox9, Col2a1, and hypertrophic marker genes Runx2, Col10a1 were inhibited by cyanidin. In addition, we found that cyanidin promoted Nrf2 and p62 expression and suppressed LC3B expression during chondrogenic stage of MSCs. Meanwhile phosphorylation of IκBα and autophagosome related protein LC3B were inactivated by cyanidin during chondrocyte hypertrophic stage. Furthermore, rapamycin, an autophagy activator, abrogated the inhibitory effect of cyanidin on chondrogenic, and hypertrophic differentiation of MSCs. In conclusion, one potential mechanism of cyanidin, by which the chondrogenic and hypertrophic differentiation of MSCs were inhibited, was due to decreased autophagy activity. Our results indicated that cyanidin was a potential therapeutic agent for keeping mature chondrocyte functions.
软骨是一种特殊的结缔组织，既不包含血管、淋巴管，也没有神经。因此，软骨损伤很难自发修复。构建组织工程软骨为软骨修复提供了一种新技术。间充质干细胞（MSCs）具有独特的自我更新能力，可分化为前软骨细胞，常被用作组织工程中的种子细胞。然而，在再生软骨中，源自MSCs的软骨细胞很难维持内环境稳定，且优先呈现肥大样表型。我们研究了天然有机化合物花青素对MSCs软骨形成及随后肥大分化的影响，以寻求抑制软骨细胞肥大的方法。我们通过逆转录聚合酶链反应（RT-PCR）、蛋白质免疫印迹法、阿尔新蓝染色和免疫细胞化学评估了花青素对软骨形成和肥大标记基因表达的影响。结果表明，花青素抑制了软骨形成相关基因Sox9、Col2a1以及肥大标记基因Runx2、Col10a1。此外，我们发现花青素在MSCs软骨形成阶段促进Nrf2和p62表达，并抑制LC3B表达。同时，在软骨细胞肥大阶段，花青素使IκBα的磷酸化和自噬体相关蛋白LC3B失活。此外，自噬激活剂雷帕霉素消除了花青素对MSCs软骨形成和肥大分化的抑制作用。总之，花青素抑制MSCs软骨形成和肥大分化的一个潜在机制是自噬活性降低。我们的结果表明，花青素是维持成熟软骨细胞功能的一种潜在治疗剂。
