Mesenchymal stem cell therapy for laryngotracheal stenosis: A systematic review of preclinical studies

Background
Laryngotracheal stenosis (LTS) can be either congenital or acquired. Laryngeal stenosis is most often encountered after prolonged intubation. The mechanism for stenosis following intubation is believed to be hypertrophic scarring. Mesenchymal stem cells (MSCs) therapy has shown promising results in regenerative medicine. We aimed to systematically review the literature on MSC therapy for stenosis of the conductive airways.
Methods
PubMed, EMBASE, Google Scholar and the Cochrane Library were systematically searched from January 1980–January 2017 with the purpose of identifying all studies addressing the effect of MSC therapy on the airway. We assessed effect on inflammation, fibrosis, and MSC as a component in tissue engineering for treating defects in the airway.
Results
We identified eleven studies (n = 256 animals) from eight countries evaluating the effect of MSCs as a regenerative therapy in the upper airways. The studies indicate that MSC therapy may lead to a more constructive inflammatory response as well as support tissue regeneration.
Conclusion
There may be a favorable effect of MSCs in inhibiting inflammation and as a component in tissue engineering. Given the heterogeneous nature of the included animal studies, any clear conclusion regarding the effect of tracheal stenosis in human subjects cannot be drawn. The included preclinical studies are however encouraging for further research.

研究背景
喉气管狭窄（Laryngotracheal stenosis, LTS）可分为先天性与获得性两类。喉狭窄最常见于长期气管插管术后，目前认为其发病机制为插管后增生性瘢痕形成。间充质干细胞（Mesenchymal stem cells, MSCs）疗法在再生医学领域已展现出良好应用前景。本研究旨在对间充质干细胞疗法治疗传导气道狭窄的相关文献进行系统综述。

研究方法
本研究于1980年1月至2017年1月期间，系统检索PubMed、EMBASE、Google Scholar及Cochrane图书馆数据库，以筛选所有探讨间充质干细胞疗法对气道影响的相关研究。本研究评估了该疗法对炎症、纤维化的作用，以及间充质干细胞作为组织工程组分用于修复气道缺损的效果。

研究结果
本研究从8个国家共筛选出11项相关研究（共纳入256只实验动物），均评估了间充质干细胞作为再生疗法在上气道中的应用效果。研究结果显示，间充质干细胞疗法可诱导更具建设性的炎症反应，并可促进组织再生。

研究结论
间充质干细胞在抑制炎症及作为组织工程组分方面或具有积极作用。但由于纳入的动物研究存在异质性，目前尚无法明确其对人类气管狭窄的治疗效果。不过，纳入的临床前研究结果为后续研究提供了良好的研究前景。