Chondral Differentiation of Induced Pluripotent Stem Cells Without Progression Into the Endochondral Pathway
Chondral Differentiation of Induced Pluripotent Stem Cells Without Progression Into the Endochondral Pathway
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DOI：
10.3389/fcell.2019.00270
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发表时间：
2019-11-01
影响因子：
5.5
通讯作者：
Richter, Wiltrud
中科院分区：
文献类型：
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作者：
Diederichs, Solvig;Klampfleuthner, Felicia A. M.;Richter, Wiltrud
体外干细胞衍生软骨细胞的一个主要问题是不希望的肥厚变性，关节软骨细胞（ACs）对其有抵抗力。作为所有成体组织的祖细胞，诱导多能干细胞（iPSCs）理论上能够形成稳定的关节软骨。到目前为止，iPSCs在体外分化为具有ac表型和肥厚抗性的软骨细胞尚未得到证实。在这里，我们提出了一种新的方案，成功地从人类多能干细胞中获得软骨细胞，而不使用促肥厚骨形态发生蛋白。ipsc -软骨细胞具有较高的软骨形成能力，每个细胞沉积的蛋白聚糖比成人ac多两倍。重要的是，ipsc -软骨细胞工程化的软骨具有与ACs软骨相似的增生性标志物（COL10A1, PTH1R， IBSP, ALPL mrna）的边缘表达。在ipsc软骨中几乎检测不到X胶原，比间充质间质细胞（MSCs）衍生的肥大软骨低30倍。此外，碱性磷酸酶（ALP）活性在整个iPSC软骨形成过程中保持在基础ac样水平，与肥厚性MSCs中众所周知的显著上调形成对比。结果表明，体外矿化条件下ipsc软骨几乎没有矿化，而msc衍生的肥大软骨矿化强烈。ACs中印度hedgehog (IHH) like的低表达，而MSCs中BMP7 like的表达升高，表明表型稳定性与hedgehog而非骨形态发生蛋白（BMP）途径相关。综上所述，现在可以在体外从人多能干细胞中产生无量的ac样软骨细胞，其蛋白多糖产量高，使人想起幼年软骨细胞，并具有肥厚和矿化的抗性。这为软骨再生、疾病建模和药理研究开辟了新的策略。
A major problem with chondrocytes derived in vitro from stem cells is undesired hypertrophic degeneration, to which articular chondrocytes (ACs) are resistant. As progenitors of all adult tissues, induced pluripotent stem cells (iPSCs) are in theory able to form stable articular cartilage. In vitro differentiation of iPSCs into chondrocytes with an AC-phenotype and resistance to hypertrophy has not been demonstrated so far. Here, we present a novel protocol that succeeded in deriving chondrocytes from human iPSCs without using pro-hypertrophic bone-morphogenetic-proteins. IPSC-chondrocytes had a high cartilage formation capacity and deposited two-fold more proteoglycans per cell than adult ACs. Importantly, cartilage engineered from iPSC-chondrocytes had similar marginal expression of hypertrophic markers (COL10A1, PTH1R, IBSP, ALPL mRNAs) like cartilage from ACs. Collagen X was barely detectable in iPSC-cartilage and 30-fold lower than in hypertrophic cartilage derived from mesenchymal stromal cells (MSCs). Moreover, alkaline phosphatase (ALP) activity remained at basal AC-like levels throughout iPSC chondrogenesis, in contrast to a well-known significant upregulation in hypertrophic MSCs. In line, iPSC-cartilage subjected to mineralizing conditions in vitro showed barely any mineralization, while MSC-derived hypertrophic cartilage mineralized strongly. Low expression of Indian hedgehog (IHH) like in ACs but rising BMP7 expression like in MSCs suggested that phenotype stability was linked to the hedgehog rather than the bone morphogenetic protein (BMP) pathway. Taken together, unlimited amounts of AC-like chondrocytes with a high proteoglycan production reminiscent of juvenile chondrocytes and resistance to hypertrophy and mineralization can now be produced from human iPSCs in vitro. This opens new strategies for cartilage regeneration, disease modeling and pharmacological studies.