Despite substantial animal evidence, cell therapy in humans remains in its infancy. The purpose of this study was to examine the potential therapeutic effects and safety of cell therapy in the treatment of tendon disorders. According to the PRISMA guideline, a systematic review was performed on clinical studies concerning cell therapy in tendon disorders. A comprehensive search including the 5 databases of MEDLINE, Embase, Scopus, Web of Science, and Cochrane Library until December 2021 was carried out and associated with hand searching. The quality of the eligible studies was assessed using the tools suggested by Cochrane recommendations. Qualitative synthesis was performed in 2 tables and discussed separately for rotator cuff, elbow, patella, Achilles, and gluteal tendons. Through 6017 records, 22 studies were included in the qualitative synthesis, including 658 patients. All the studies administered autologous cells, except one that used allogenic adipose-derived mesenchymal stem cells (Allogenic AD-MSC). Almost all studies demonstrated the safety of cell injection in their follow-up period with no serious side effects or immunologic reactions, with only a few related minor adverse events in some cases. The included studies showed the effectiveness of cell injection in tendinopathies of different sites, rotator cuff, elbow, patella, Achilles, and gluteal tendons. Among the rotator cuff studies, 4 comparative studies claimed that cell therapy is a more efficient treatment with a lower retear rate and pain level compared to the control group. However, one study found no differences between the groups. No controlled study has been performed on elbow tendinopathies, but 5 case series demonstrated the effectiveness of cell injection in elbow tendon disorders. For Achilles tendinopathies, only one randomized controlled trial (RCT) found that both cell therapy and control groups showed significant pain reduction and functional improvement with no statistical differences at the 6 months follow-up, but the cell therapy group had improved faster at earlier follow-ups. Patellar tendinopathy was studied in 2 RCTs, one did not show a significant difference and the other showed superior improvement compared to controls. Cell therapy showed promising results and the available evidence suggests that it is safe at several sites of tendon disease. Based on available evidence, cell therapy should be suggested in specific conditions at each site. To approve cell therapy for tendon diseases, randomized clinical trials are required with a large sample size and long-term follow-ups. IV

中文翻译：

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细胞疗法治疗肌腱疾病的疗效和安全性：临床研究的系统评价

尽管有大量的动物证据，但人类的细胞疗法仍处于起步阶段。本研究的目的是检查细胞疗法在治疗肌腱疾病中的潜在治疗效果和安全性。根据 PRISMA 指南，对肌腱疾病细胞疗法的临床研究进行了系统评价。进行了包括 MEDLINE、Embase、Scopus、Web of Science 和 Cochrane Library 的 5 个数据库在内的全面搜索，直至 2021 年 12 月，并与手动搜索相关联。使用 Cochrane 推荐建议的工具评估合格研究的质量。定性合成在 2 个表格中进行，并分别讨论肩袖、肘部、髌骨、跟腱和臀肌腱。通过6017条记录，定性综合纳入22项研究，包括658名患者。除一项使用同种异体脂肪来源的间充质干细胞 (Allogenic AD-MSC) 的研究外，所有研究均使用自体细胞。几乎所有研究都证明了细胞注射在随访期间的安全性，没有严重的副作用或免疫反应，在某些情况下只有少数相关的轻微不良事件。纳入的研究显示了细胞注射对不同部位、肩袖、肘部、髌骨、跟腱和臀肌腱的肌腱病的有效性。在肩袖研究中，有 4 项比较研究声称，与对照组相比，细胞疗法是一种更有效的治疗方法，再撕裂率和疼痛水平更低。然而，一项研究发现两组之间没有差异。尚未对肘部肌腱病进行对照研究，但 5 个病例系列证明了细胞注射在肘部肌腱疾病中的有效性。对于跟腱病，只有一项随机对照试验 (RCT) 发现，在 6 个月的随访中，细胞治疗组和对照组均显示出明显的疼痛减轻和功能改善，但无统计学差异，但细胞治疗组在早期随访时改善更快-UPS。在 2 项 RCT 中研究了髌腱病，其中一项没有显示出显着差异，另一项显示出与对照组相比有更好的改善。细胞疗法显示出有希望的结果，现有证据表明它在肌腱疾病的几个部位是安全的。根据现有证据，应在每个部位的特定条件下建议细胞治疗。为了批准肌腱疾病的细胞疗法，需要进行大样本量和长期随访的随机临床试验。四