自言自语：以后有蛀牙看牙医，再也不用担心那令人头皮发麻，汗毛竖立，菊花紧锁的钻牙声了。  

Scientists Use Lasers To Regrow Teeth From Stem Cells 科学家使用激光技术从干细胞中再生牙齿

原文：www.iflscience.com。 翻译：派大丽Pally

Imagine if a trip to the dentist to treat a cavity didn’t involve a filling, root canal, or crown. What if a simple light treatment could actually get your teeth to regrow themselves using stem cells? That’s the aim of a group of researchers at Harvard’s Wyss Institute, led by David Mooney, who have found success in regrowing rat teeth in this manner. The researchers have developed a technique using a low-power laser to coax stem cells into reforming dentin, which could have implications for dentistry, wound healing, and bone restoration. The results of the study have been published in the journal Science Translational Medicine.

试想一下你要去牙医那里治疗一颗蛀牙，但无需任何填补，根管治疗或是冠套。如果有种简单的光疗法以使用干细胞就能让牙齿再生会怎样？由大卫.慕尼带领的一支来自哈佛大学维斯研究所的研究团队正致力于此，目前他们已成功在老鼠身上实现这一设想。研究团队开发了一种技术，即使用低功率激光将干细胞慢慢再生成牙本质，而这对牙齿损伤、伤口愈合及骨质修复等情况都可能适用。这一研究成果已刊登在《科学转化医学》期刊上。

Proteins known as growth factors are what cause stem cells to differentiate into whatever type of cell they are bound to become. Introducing different growth factors force the cells to develop the desired type of tissue. Unfortunately, it isn’t quite as simple as it sounds. Most of the developments in using stem cells in regenerative medicine have regrown tissues in vitro and later need to be transplanted into the person. This involves a lot of technical care and is a highly regulated process, which slows down progress. Mooney’s team claims they have come up with a new technique that could streamline the process, making it a viable clinical option much more quickly.

蛋白质作为一种生长因子，能促成干细胞变成其它任何想要变成的细胞类型。导入不同的生长因子促使细胞发展成为需要的组织。可惜的是，这并没有听上去的那么容易。目前多数使用干细胞实现再生治疗的研究都是先进行体外重生组织再将其移植到人类身上。这就需要大量的技术支持，而严格的操作流程也同时会拖缓进程。慕尼团队声称他们已经找到新技术能将流程简化，并更快的将其实现成可行的医疗手段。

The team set up a miniature dentist office-like setting for the rodents used in the study. They drilled holes into the rats’ molars to simulate tooth decay. Next, adult stem cells were applied to the pulp of the tooth and a non-ionizing, low-level laser was used to stimulate the growth factors. The teeth were then sealed with a temporary cap to be worn over the next 12 weeks. The follow-up x-rays and microscopy analysis showed that the dentin, the layer under the visible enamel, had indeed begun to grow back due to the laser/stem cell therapy.

研究团队为研究使用的啮齿动物们建立了一个迷你牙防所。他们在老鼠的臼齿上钻洞以此模拟蛀牙，接着将成人干细胞注入牙髓，并用非电离的低功率激光刺激生长因子。在接下来的12周，臼齿上会用临时冠套套封起来。随后的x光和显微镜分析都说明，在肉眼可及的烤瓷冠套下，的确由于激光干细胞疗法而重新开始生长出牙本质。

“Our treatment modality does not introduce anything new to the body, and lasers are routinely used in medicine and dentistry, so the barriers to clinical translation are low,” Mooney said in a press release. “It would be a substantial advance in the field if we can regenerate teeth rather than replace them.”

“我们的治疗方法并不在身体上使用任何新东西，而且激光也长期应用于医疗和牙科，所以很容易实现为可行的治疗方法，”慕尼在一次新闻媒体中说到，“如果我们能实现再生牙齿而不是替换牙齿，这将是这个领域的重大突破。“

Of course, performing dentistry on rats was not without its challenges. While the dentin was incredibly similar to that which grows naturally, it wasn’t organized exactly the same way. Also, restored dentin forms what is known as a “dentin bridge” that covers the exposed dental pulp. While this is somewhat easy to detect in human teeth, it was very difficult to see in the tiny rat teeth. Mooney stated that “[t]his is one of those rare cases where it would be easier to do this work on a human.”

当然，对老鼠进行牙科治疗也不是没有难度。尽管那些再生牙本质和自然生长的牙齿惊人相似，但却并不是完全相同的组织。再者，再生牙本质形成一种叫“牙本质链”的物质覆盖在暴露的牙髓上，尽管这在人类牙齿上很容易被发现，但要在那么小的老鼠牙齿上却并非易事。慕尼说：“这是比较罕见的在人类身上实验更容易的案例之一。”

The team then sought to identify which molecular mechanisms were influenced by the laser. Transforming growth factor beta-1 (TGF-β1), a widely multifunctional protein that regulates cell proliferation and differentiation, was largely responsible for regrowing the dentin. The laser first stimulated reactive oxygen species (ROS), which has an important function in cell signaling and other cellular homeostatic processes. ROS then stimulated the then-dormant TGF-β1 into activating, which gave the stem cells the signal to differentiate into dentin. The researchers also noted that the reaction was dose-specific to the level of light received.

研究团队接着研究确认出了哪些分子机制受到了激光的影响，它们就是：转化生长因子beta-1 (TGF-β1)。这是一种控制细胞繁殖和差异的多功能蛋白质，就是它在再生牙本质过程中发挥了重大作用。激光先刺激活性氧（ROS），后者在细胞信号收发及其它自动调节过程中扮演重要角色，活性氧再接着将彼时休眠状态的转化生长因子beta-1激活，以此来给干细胞发出转化成牙本质的信号。研究人员同时指出转化数量取决于吸收激光的多少。

Anecdotal evidence about the power of low-level light therapy has been piling up for nearly 50 years, but this study was the first to nail down the molecular mechanism. This could open up a host of potential avenues of treatments that expand far beyond dentin. The team’s future research will include experimentation with other stem cells, and they also hope to begin human trials for restorative dentistry soon.

在坊间关于低功率激光疗法功能的逸事已盛传近50年，但这项研究却是首次确定了是哪种分子机制发挥了作用。这也将为除牙本质外其它领域的潜在治疗方法延伸出更多可能性。研究团队未来将对其它干细胞进行实验，并希望能尽快针对修复性牙科在人类身上进行试验。