自言自語：以后有蛀牙看牙醫，再也不用擔心那令人頭皮發麻，汗毛豎立，菊花緊鎖的鉆牙聲了。 ?

Scientists Use Lasers To Regrow Teeth From Stem Cells 科學家使用激光技術從干細胞中再生牙齒

原文：www.iflscience.com。 翻譯：派大麗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.

試想一下你要去牙醫那里治療一顆蛀牙，但無需任何填補，根管治療或是冠套。如果有種簡單的光療法以使用干細胞就能讓牙齒再生會怎樣？由大衛.慕尼帶領的一支來自哈佛大學維斯研究所的研究團隊正致力于此，目前他們已成功在老鼠身上實現這一設想。研究團隊開發了一種技術，即使用低功率激光將干細胞慢慢再生成牙本質，而這對牙齒損傷、傷口愈合及骨質修復等情況都可能適用。這一研究成果已刊登在《科學轉化醫學》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.

蛋白質作為一種生長因子，能促成干細胞變成其它任何想要變成的細胞類型。導入不同的生長因子促使細胞發展成為需要的組織。可惜的是，這并沒有聽上去的那么容易。目前多數使用干細胞實現再生治療的研究都是先進行體外重生組織再將其移植到人類身上。這就需要大量的技術支持，而嚴格的操作流程也同時會拖緩進程。慕尼團隊聲稱他們已經找到新技術能將流程簡化，并更快的將其實現成可行的醫療手段。

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.

研究團隊為研究使用的嚙齒動物們建立了一個迷你牙防所。他們在老鼠的臼齒上鉆洞以此模擬蛀牙，接著將成人干細胞注入牙髓，并用非電離的低功率激光刺激生長因子。在接下來的12周，臼齒上會用臨時冠套套封起來。隨后的x光和顯微鏡分析都說明，在肉眼可及的烤瓷冠套下，的確由于激光干細胞療法而重新開始生長出牙本質。

“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.”

“我們的治療方法并不在身體上使用任何新東西，而且激光也長期應用于醫療和牙科，所以很容易實現為可行的治療方法，”慕尼在一次新聞媒體中說到，“如果我們能實現再生牙齒而不是替換牙齒，這將是這個領域的重大突破。“

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.”

當然，對老鼠進行牙科治療也不是沒有難度。盡管那些再生牙本質和自然生長的牙齒驚人相似，但卻并不是完全相同的組織。再者，再生牙本質形成一種叫“牙本質鏈”的物質覆蓋在暴露的牙髓上，盡管這在人類牙齒上很容易被發現，但要在那么小的老鼠牙齒上卻并非易事。慕尼說：“這是比較罕見的在人類身上實驗更容易的案例之一。”

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.

研究團隊接著研究確認出了哪些分子機制受到了激光的影響，它們就是：轉化生長因子beta-1 (TGF-β1)。這是一種控制細胞繁殖和差異的多功能蛋白質，就是它在再生牙本質過程中發揮了重大作用。激光先刺激活性氧（ROS），后者在細胞信號收發及其它自動調節過程中扮演重要角色，活性氧再接著將彼時休眠狀態的轉化生長因子beta-1激活，以此來給干細胞發出轉化成牙本質的信號。研究人員同時指出轉化數量取決于吸收激光的多少。

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.

在坊間關于低功率激光療法功能的逸事已盛傳近50年，但這項研究卻是首次確定了是哪種分子機制發揮了作用。這也將為除牙本質外其它領域的潛在治療方法延伸出更多可能性。研究團隊未來將對其它干細胞進行實驗，并希望能盡快針對修復性牙科在人類身上進行試驗。