哺乳动物的指尖有超强的再生能力

海量资料下载 免费学习 www.englishvip.com/xinlw.htm （申请网址） Mammals possess the remarkable ability to regenerate a lost fingertip, including the nail, nerves and even bone. In humans, an amputated fingertip can sprout back in as little as two months, a phenomenon that has remained poorly understood until now. In a paper published today in the journal Nature, researchers at NYU Langone Medical Center shed light on this rare regenerative power in mammals, using genetically engineered mice to document for the first time the biochemical chain of events that unfolds in the wake of a fingertip amputation（截肢）. The findings hold promise for amputees who may one day be able to benefit from therapies that help the body regenerate lost limbs.    "Everyone knows that fingernails keep growing, but no one really knows why," says lead author Mayumi Ito, PhD, assistant professor of dermatology in the Ronald O. Perelman Department of Dermatology at NYU School of Medicine. Nor is much understood about the link between nail growth and the regenerative ability of the bone and tissue beneath the nail. Now, Dr. Ito and team have discovered an important clue in this process: a population of self-renewing stem cells in the nail matrix, a part of the nail bed rich in nerve endings and blood vessels that stimulate nail growth. Moreover, the scientists have found that these stem cells depend upon a family of proteins known as the "Wnt signaling network" -- the same proteins that play a crucial role in hair and tissue regeneration -- to regenerate bone in the fingertip.   "When we blocked the Wnt-signaling pathway in mice with amputated fingertips, the nail and bone did not grow back as they normally would," says Dr. Ito. Even more intriguing, the researchers found that they could manipulate the Wnt pathway to stimulate regeneration in bone and tissue just beyond the fingertip. "Amputations of this magnitude ordinarily do not grow back," says Dr. Ito. These findings suggest that Wnt signaling is essential for fingertip regeneration, and point the way to therapies that could help people regenerate lost limbs. An estimated 1.7 million people in the U.S. live with amputations.   The team's next step is to zoom in on the molecular mechanisms that control how the Wnt signaling pathway interacts with the nail stem cells to influence bone and nail growth. 哺乳动物具有非凡的能力，再生失去的指尖，包括指甲，神经甚至骨骼。在人类中，一个被截肢的指尖可以在短短两个月的萌芽，到现在为止，仍然知之甚少的现象。今天在“自然”杂志上发的一篇论文，在纽约大学Langone医学中心的研究人员揭示这在哺乳动物中罕见的再生能力，首次利用遗传工程小鼠文件生化一连串的事件之后，展现在指尖截肢（截肢）。发现持有的承诺为截肢者可能有一天谁能够从中受益，帮助身体失去肢体再生的疗法。    “每个人都知道，指甲保持增长，但没有人真正知道为什么，说：”主要作者伊藤真弓，博士，在纽约大学医学院皮肤科助理教授罗纳德澳佩雷尔曼皮肤科。指甲的生长和再生能力，指甲下面的骨骼和组织之间的联系，也不是非常了解。现在，伊藤博士和他的团队在这个过程中发现了一个重要线索：人口自我更新的干细胞在指甲基质，甲床的一部分，丰富的神经末梢和血管，刺激指甲的生长。此外，科学家们发现，这些干细胞依赖于一个家庭的蛋白质被称为“Wnt信号网络” - 相同的蛋白质，头发和组织再生中发挥了至关重要的作用 - 在指尖骨再生。   伊藤博士说：“当我们封锁的Wnt信号通路在小鼠截肢的指尖，指甲和骨骼不长，他们通常会”。更有趣的是，研究人员发现，他们可以操控Wnt信号通路刺激只是超出了指尖的骨头和组织再生。伊藤博士说：“这种规模的截肢通常不长回来了，”。这些发现表明，Wnt信号指尖再生，点的方式，可以帮助人们失去肢体再生的疗法是必不可少的。估计有1.7亿人在美国住了截肢手术。   该小组的下一步是进行放大控制Wnt信号通路如何用指甲干细胞相互作用的分子机制，影响骨骼和指甲生长。 “成千上万人疯狂下载。。。。。。 更多价值连城的绝密英语学习资料， 洛基内部秘密英语，技巧，策略 请在 网上 申请报名” 洛基国际英语 竭诚为您服务