Scars are the normal outcome of wound repair and involve a co-ordinated inflammatory and fibrotic process. When a scar does not resolve, uncontrolled chronic inflammation can persist and elicits excessive scarring that leads to a range of abnormal phenotypes such as hypertrophic and keloid scars. These pathologies result in significant impairment of quality of life over a long period of time. Existing treatment options are generally unsatisfactory, and there is mounting interest in innovative cell-based therapies. Despite the interest in mesenchymal stem cells (MSCs), there is yet to be a human clinical trial that investigates the potential of MSCs in treating abnormal scarring. A synthesis of existing evidence of animal studies may therefore provide insight into the barriers to human application. The aim of this PRISMA systematic review was to evaluate the effectiveness of MSC transplantation in the treatment of hypertrophic and keloid scars in in vivo models. A total of 11 case-control studies were identified that treated a total of 156 subjects with MSCs or MSC-conditioned media. Ten studies assessed hypertrophic scars, and one looked at keloid scars. All studies evaluated scars in terms of macroscopic and histological appearances and most incorporated immunohistochemistry. The included studies all found improvements in the above outcomes with MSC or MSC-conditioned media without complications. The studies reviewed support a role for MSC therapy in treating scars that needs further exploration. The transferability of these findings to humans is limited by factors such as the reliability and validity of the disease model, the need to identify the optimal MSC cell source, and the outcome measures employed.

中文翻译：

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间充质干细胞治疗肥厚性疤痕和疤痕疙瘩

疤痕是伤口修复的正常结果，涉及协调的炎症和纤维化过程。当疤痕无法消退时，不受控制的慢性炎症可能会持续存在，并引起过度疤痕，从而导致一系列异常表型，例如肥厚性疤痕和疤痕疙瘩。这些病症会导致长期生活质量严重受损。现有的治疗方案通常不能令人满意，人们对创新的细胞疗法越来越感兴趣。尽管人们对间充质干细胞 (MSC) 很感兴趣，但尚未开展人体临床试验来研究 MSC 治疗异常疤痕的潜力。因此，对现有动物研究证据的综合可能有助于深入了解人类应用的障碍。本次 PRISMA 系统评价的目的是评估 MSC 移植在体内模型中治疗肥厚性疤痕和疤痕疙瘩的有效性。总共确定了 11 项病例对照研究，使用 MSC 或 MSC 条件培养基治疗了总共 156 名受试者。十项研究评估了增生性疤痕，其中一项研究研究了疤痕疙瘩。所有研究都从宏观和组织学外观以及大多数结合的免疫组织化学方面评估了疤痕。纳入的研究均发现 MSC 或 MSC 条件培养基可改善上述结果，且无并发症。回顾的研究支持 MSC 疗法在治疗疤痕方面的作用，需要进一步探索。这些发现向人类的转移受到疾病模型的可靠性和有效性、确定最佳 MSC 细胞来源的需要以及所采用的结果测量等因素的限制。