Mesenchymal stromal cells (MSCs) are a potential therapeutic tool for pulmonary fibrosis. However, ex vivo MSC expansion using serum poses risks of harmful immune responses or unknown pathogen infections in the recipients. Therefore, MSCs cultured in serum-free media (SF-MSCs) are ideal for clinical settings; however, their efficacy in pulmonary fibrosis is unknown. Here, we investigated the effects of SF-MSCs on bleomycin-induced pulmonary inflammation and fibrosis compared to those of MSCs cultured in serum-containing media (S-MSCs). SF-MSCs and S-MSCs were characterized in vitro using RNA sequence analysis. The in vivo kinetics and efficacy of SF-MSC therapy were investigated using a murine model of bleomycin-induced pulmonary fibrosis. For normally distributed data, Student’s t test and one-way repeated measures analysis of variance followed by post hoc Tukey’s test were used for comparison between two groups and multiple groups, respectively. For non-normally distributed data, Kruskal–Wallis and Mann–Whitney U tests were used for comparison between groups, using e Bonferroni’s correction for multiple comparisons. All tests were two-sided, and P < 0.05 was considered statistically significant. Serum-free media promoted human bone marrow-derived MSC expansion and improved lung engraftment of intravenously administered MSCs in recipient mice. SF-MSCs inhibited the reduction in serum transforming growth factor-β1 and the increase of interleukin-6 in both the serum and the bronchoalveolar lavage fluid during bleomycin-induced pulmonary fibrosis. SF-MSC administration increased the numbers of regulatory T cells (Tregs) in the blood and lungs more strongly than in S-MSC administration. Furthermore, SF-MSCs demonstrated enhanced antifibrotic effects on bleomycin-induced pulmonary fibrosis, which were diminished by antibody-mediated Treg depletion. SF-MSCs significantly suppressed BLM-induced pulmonary inflammation and fibrosis through enhanced induction of Tregs into the lungs and corrected the dysregulated cytokine balance. Therefore, SF-MSCs could be a useful tool for preventing pulmonary fibrosis progression without the demerits of serum use.

中文翻译：

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在无血清培养基中培养的人骨髓源性间充质基质细胞通过延长存活时间和在鼠博莱霉素诱导的肺纤维化中强调节性 T 细胞诱导，显示出增强的抗纤维化能力

间充质基质细胞 (MSCs) 是肺纤维化的潜在治疗工具。然而，使用血清进行体外 MSC 扩增会在接受者中带来有害免疫反应或未知病原体感染的风险。因此，在无血清培养基 (SF-MSCs) 中培养的 MSCs 是临床环境的理想选择；然而，它们对肺纤维化的疗效尚不清楚。在这里，我们研究了与在含血清培养基 (S-MSCs) 中培养的 MSCs 相比，SF-MSCs 对博来霉素诱导的肺部炎症和纤维化的影响。SF-MSCs 和 S-MSCs 在体外使用 RNA 序列分析进行表征。使用博来霉素诱导的肺纤维化的鼠模型研究了 SF-MSC 治疗的体内动力学和功效。对于正态分布的数据，Student's t 检验和单向重复测量方差分析随后进行事后 Tukey's 检验分别用于两组和多组之间的比较。对于非正态分布的数据，使用 Kruskal-Wallis 和 Mann-Whitney U 检验进行组间比较，使用 e Bonferroni 校正进行多重比较。所有测试都是双面的，P < 0.05 被认为具有统计学意义。无血清培养基促进了人骨髓来源的 MSC 扩增，并改善了受体小鼠静脉注射 MSC 的肺移植。在博来霉素诱导的肺纤维化过程中，SF-MSCs抑制血清转化生长因子-β1的减少和血清和支气管肺泡灌洗液中白细胞介素-6的增加。SF-MSC 给药比 S-MSC 给药更能增加血液和肺中调节性 T 细胞 (Treg) 的数量。此外，SF-MSC 对博莱霉素诱导的肺纤维化具有增强的抗纤维化作用，而抗体介导的 Treg 耗竭则减弱了这种作用。SF-MSCs 通过增强 Tregs 进入肺部的诱导作用显着抑制 BLM 诱导的肺部炎症和纤维化，并纠正失调的细胞因子平衡。因此，SF-MSCs 可以成为预防肺纤维化进展的有用工具，而没有血清使用的缺点。SF-MSCs 通过增强 Tregs 进入肺部的诱导作用显着抑制 BLM 诱导的肺部炎症和纤维化，并纠正失调的细胞因子平衡。因此，SF-MSCs 可以成为预防肺纤维化进展的有用工具，而没有血清使用的缺点。SF-MSCs 通过增强 Tregs 进入肺部的诱导作用显着抑制 BLM 诱导的肺部炎症和纤维化，并纠正失调的细胞因子平衡。因此，SF-MSCs 可以成为预防肺纤维化进展的有用工具，而没有血清使用的缺点。