Stanford and San Francisco, Calif. From the Hagey Pediatric Regenerative Research Laboratory, Department of Surgery, Division of Plastic and Reconstructive Surgery, Stanford University School of Medicine, and the University of California, San Francisco, School of Medicine.
Plast Reconstr Surg. 2010 May;125(5):1352-1361. doi: 10.1097/PRS.0b013e3181d62980.
In utero retinoid exposure results in numerous craniofacial malformations, including craniosynostosis. Although many malformations associated with retinoic acid syndrome are associated with neural crest defects, the specific mechanisms of retinoid-induced craniosynostosis remain unclear. The authors used the culture of mouse cranial suture-derived mesenchymal cells to probe the potential cellular mechanisms of this teratogen to better elucidate mechanisms of retinoid-induced suture fusion.
Genes associated with retinoid signaling were assayed in fusing (posterofrontal) and patent (sagittal, coronal) sutures by quantitative real-time polymerase chain reaction. Cultures of mouse suture-derived mesenchymal cells from the posterofrontal suture were established from 4-day-old mice. Cells were cultured with all-trans retinoic acid (1 and 5 muM). Proliferation, osteogenic differentiation, and specific gene expression were assessed.
Mouse sutures were found to express genes necessary for retinoic acid synthesis, binding, and signal transduction, demonstrated by quantitative real-time polymerase chain reaction (Raldh1, Raldh2, Raldh3, and Rbp4). These genes were not found to be differentially expressed in fusing as compared with patent cranial sutures in vivo. Addition of retinoic acid enhanced the osteogenic differentiation of suture-derived mesenchymal cells in vitro, including up-regulation of alkaline phosphatase activity and Runx2 expression. Contemporaneously, cellular proliferation was repressed, as shown by proliferative cell nuclear antigen expression. The pro-osteogenic effect of retinoic acid was accompanied by increased gene expression of several hedgehog and bone morphogenetic protein ligands.
Retinoic acid represses proliferation and enhances osteogenic differentiation of suture-derived mesenchymal cells. These in vitro data suggest that retinoid exposure may lead to premature cranial suture fusion by means of enhanced osteogenesis and hedgehog and bone morphogenetic protein signaling.
子宫内视黄酸暴露会导致多种颅面畸形，包括颅缝早闭。虽然许多与维甲酸综合征相关的畸形都与神经嵴缺陷有关，但视黄酸诱导的颅缝早闭的确切机制尚不清楚。作者使用鼠颅缝衍生间充质细胞培养来探讨这种致畸剂的潜在细胞机制，以更好地阐明视黄酸诱导的缝融合机制。
通过定量实时聚合酶链反应检测融合（额眶缝）和开放（矢状缝、冠状缝）颅缝中与视黄酸信号相关的基因。从小鼠 4 天大的颅缝中分离出 posterofrontal 颅缝来源的间充质细胞进行培养。用全反式视黄酸（1 和 5 μM）培养细胞。评估增殖、成骨分化和特定基因表达。
通过定量实时聚合酶链反应（Raldh1、Raldh2、Raldh3 和 Rbp4）发现，鼠缝表达了合成、结合和信号转导视黄酸所需的基因。这些基因在体内融合与开放颅缝之间没有差异表达。视黄酸的加入增强了体外缝源性间充质细胞的成骨分化，包括碱性磷酸酶活性和 Runx2 表达的上调。同时，增殖细胞核抗原的表达表明细胞增殖受到抑制。视黄酸的促成骨作用伴随着几种 hedgehog 和骨形态发生蛋白配体基因表达的增加。
视黄酸抑制缝源性间充质细胞的增殖，增强其成骨分化。这些体外数据表明，视黄酸暴露可能通过增强成骨作用和 hedgehog 和骨形态发生蛋白信号导致颅缝过早融合。
