Background: Stem cells have attracted the researchers interest, due to their applications in regenerative medicine. Their self-renewal capacity for multipotent differentiation, and immunomodulatory properties make them unique to significantly contribute to tissue repair and regeneration applications. Recently, stem cells have shown increased proliferation when irradiated with low-level laser therapy or Photobiomodulation Therapy (PBMT), which induces the activation of intracellular and extracellular chromophores and the initiation of cellular signaling. The purpose of this study was to evaluate this phenomenon in the literature.

Methods: The literature investigated the articles written in English in four electronic databases of PubMed, Scopus, Google Scholar and Cochrane up to April 2019. Stem cell was searched by combining the search keyword of "low-level laser therapy" OR "low power laser therapy" OR "low-intensity laser therapy" OR "photobiomodulation therapy" OR "photo biostimulation therapy" OR "LED". In total, 46 articles were eligible for evaluation.

Results: Studies demonstrated that red to near-infrared light is absorbed by the mitochondrial respiratory chain. Mitochondria are significant sources of reactive oxygen species (ROS). Mitochondria play an important role in metabolism, energy generation, and are also involved in mediating the effects induced by PBMT. PBMT may result in the increased production of (ROS), nitric oxide (NO), adenosine triphosphate (ATP), and cyclic adenosine monophosphate (cAMP). These changes, in turn, initiate cell proliferation and induce the signal cascade effect.

Conclusion: The findings of this review suggest that PBMT-based regenerative medicine could be a useful tool for future advances in tissue engineering and cell therapy.

背景：干细胞由于其在再生医学中的应用而吸引了研究人员的兴趣。它们具有多种能力的自我更新能力以及免疫调节特性，使其独特地显着有助于组织修复和再生应用。最近，干细胞在接受低水平激光疗法或光生物调节疗法（PBMT）照射时显示出增加的增殖，这会诱导细胞内和细胞外生色团的活化以及细胞信号传导的启动。这项研究的目的是评估文献中的这种现象。

方法：截至2019年4月，文献研究了PubMed，Scopus，Google Scholar和Cochrane的四个电子数据库中用英语撰写的文章。通过结合“低水平激光疗法”或“低功率激光”的搜索关键字来搜索干细胞。疗法”或“低强度激光疗法”或“光生物调制疗法”或“光生物刺激疗法”或“ LED”。共有46篇文章符合评估条件。

结果：研究表明，线粒体呼吸链吸收了红色至近红外光。线粒体是活性氧（ROS）的重要来源。线粒体在代谢，能量产生中起重要作用，并且还参与介导PBMT诱导的作用。PBMT可能导致（ROS），一氧化氮（NO），三磷酸腺苷（ATP）和环状单磷酸腺苷（cAMP）的产生增加。这些变化继而引发细胞增殖并诱导信号级联效应。

结论：这篇综述的结果表明，基于PBMT的再生医学可能是组织工程和细胞疗法未来发展的有用工具。