CHARACTERIZATION & MODIFICATION OF CARDIAC NEURAL CREST

对鸡胚胎的多学科研究表明，神经脊细胞在完整胚胎中到达心脏之前，心肌功能就会发生变化。在第一次可以看到心肌功能障碍的时候，心脏神经压迫细胞与咽背外侧缘接触。我们最近发现，分离的咽内皮细胞可以在培养的心肌中引起类似的变化。这种作用可被抗成纤维细胞生长因子的多克隆中和抗体阻断。这些观察结果导致假设：1)神经脊细胞与内胚层的相互作用需要抑制成纤维细胞生长因子样信号，该信号导致神经脊细胞中的心肌发育异常，从而抑制内胚层来源的信号。这些假说将首先通过定位成纤维细胞生长因子配体和受体在神经脊、内胚层和心肌中的表达，然后在神经脊和/或内胚层与心肌的组织重组中进行体外验证。在组织重组和外植体培养中，将使用各种技术来干扰成纤维细胞生长因子信号。在组织重组和外植体培养中，将使用各种技术来干扰成纤维细胞生长因子信号。在完整的胚胎中，神经脊切除和背部移植将被用来改变成纤维细胞生长因子的表达，并干扰成纤维细胞生长因子的信号。最后，我们将把过量的维甲酸应用于神经脊细胞，以改变神经脊调节成纤维细胞生长因子信号机制的能力。提出的实验将阐明心脏神经脊细胞以前未知的功能，并表征神经脊细胞与咽内皮细胞的相互作用。这些相互作用似乎对正常的心肌发育至关重要，如果没有它们，心肌发育史就会改变。我们认为，这可能会导致患有神经脊相关心脏缺陷的儿童即使在手术修复后仍有很高的死亡率。

Multi-disciplinary studies of chick embryos that neural crest ablation have shown that myocardial function is altered prior to the time that neural crest cells would be expected to reach the heart in intact embryos. At the time when myocardial dysfunction can first be seen, the cardiac neural cress cells are in contact with the dorsolateral margin of the pharynx. We have recently found that isolated pharyngeal endoderm can cause similar changes in cultured myocardium. The effect can be blocked by a polyclonal neutralizing antibody to FGF. These observations have led to the hypothesis that 1) an interaction of neural crest cells with endoderm is required for suppression of an FGF-like signal that leads to abnormal myocardial development in neural crest cells to suppress the endodermally-derived signal. The hypotheses will be tested first by localizing expression of FGF ligands and receptors in neural crest, endoderm, and myocardium and then in tissue recombinations of neural crest and/or endoderm with myocardium in vitro. Various techniques will be used to interfere with FGF signaling in the tissue recombinations and in explant cultures. Various techniques will be used to interfere with FGF signaling in the tissue recombinations and in explant cultures. Neural crest ablations and back-transplantations will be used to modify expression of FGF modulating factors and to interfere with FGF signaling in intact embryos. Finally, we will apply excess retinoic acid to neural crest cells to alter the ability of neural crest to modulate the FGF signaling mechanism. The experiments proposed will elucidate a previously unrecognized function of cardiac neural crest cells and characterize the interactions of neural crest cells with pharyngeal endoderm. These interactions appear to be critical for normal myocardial development and in their absence, myocardial developmental history is altered. We believe that this may lead to the high mortality in children with neural crest-related heart defects even after surgical repair.