Shanghai Children's Medical Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
Shanghai Changzheng Hospital, Shanghai, China.
Kidney Blood Press Res. 2020;45(1):95-108. doi: 10.1159/000504368. Epub 2020 Jan 10.
BACKGROUND/AIMS: Acute kidney injury (AKI) is a common clinical condition that can lead to chronic kidney failure. Although mesenchymal stem cell-derived extracellular vesicles (MSC EVs) are regarded as a potent AKI treatment, the mechanisms underlying their beneficial effects remain unclear. Oct-4 may play an important role in tissue injury repair. We thus hypothesized that oct-4 overexpression might enhance the therapeutic effects of MSC EVs in AKI treatment.
Renal tubular epithelial cells were cultured in a low oxygen environment, then cocultured with MSC EVs or control medium for 48 h. BrdU and transferase-mediated dUTP nick-end labeling (TUNEL) staining were used to assess cell proliferation and apoptosis. Mice subjected to ischemia reperfusion were randomly divided into 4 groups, then injected with either phosphate-buffered saline (vehicle), EVs, EVs overexpressing oct-4 (EVs+Oct-4), and EVs not expressing Oct-4 (EVs-Oct-4). Blood creatinine (CREA) and urine nitrone levels were assessed 48 h and 2 weeks after injection. After ischemia reperfusion, renal tissues from each group were stained with TUNEL and proliferating cell nuclear antigen (PCNA) to determine the degree of apoptosis and proliferation. Masson trichrome staining was used to evaluate renal fibrosis progression. Snail gene expression was assessed using polymerase chain reaction (PCR).
At 48 h after hypoxic treatment, TUNEL and BrdU staining indicated that the EVs+Oct-4 group had the least apoptosis and the most proliferation, respectively. Treatment with EVs overexpressing Oct-4 significantly decreased serum Crea and blood urea nitrogen levels and rescued kidney fibrosis, as indicated by the low proportion of Masson staining, high number of PCNA-positive cells, and low number of TUNEL-positive cells. PCR analysis indicated that Snail was most upregulated in the vehicle group and least upregulated in the EVs+Oct-4 group.
MSC EVs had a pronounced therapeutic effect on ischemic reperfusion injury-related AKI, and Oct-4 overexpression enhanced these therapeutic effects. Our results may inspire a new direction for AKI treatment with MSC EVs.
背景/目的：急性肾损伤（AKI）是一种常见的临床病症，可导致慢性肾衰竭。尽管间充质干细胞衍生的细胞外囊泡（MSC EVs）被认为是一种有效的 AKI 治疗方法，但它们的有益作用的机制尚不清楚。Oct-4 可能在组织损伤修复中发挥重要作用。因此，我们假设过表达 Oct-4 可能增强 MSC EVs 在 AKI 治疗中的治疗效果。
将肾小管上皮细胞在低氧环境中培养，然后与 MSC EVs 或对照培养基共培养 48 小时。BrdU 和转铁蛋白介导的 dUTP 末端标记（TUNEL）染色用于评估细胞增殖和凋亡。将缺血再灌注的小鼠随机分为 4 组，然后分别注射磷酸盐缓冲盐水（对照）、EVs、过表达 Oct-4 的 EVs（EVs+Oct-4）和未表达 Oct-4 的 EVs（EVs-Oct-4）。注射后 48 小时和 2 周评估血肌酐（CREA）和尿硝酮水平。缺血再灌注后，用 TUNEL 和增殖细胞核抗原（PCNA）染色评估各组肾组织的凋亡和增殖程度。Masson 三色染色评估肾纤维化进展。用聚合酶链反应（PCR）评估 Snail 基因表达。
缺氧处理后 48 小时，TUNEL 和 BrdU 染色表明 EVs+Oct-4 组的凋亡最少，增殖最多。过表达 Oct-4 的 EVs 治疗可显著降低血清 CREA 和血尿素氮水平，并挽救肾纤维化，Masson 染色比例低、PCNA 阳性细胞数多、TUNEL 阳性细胞数少。PCR 分析表明，Snail 在对照组中上调最明显，在 EVs+Oct-4 组中上调最少。
MSC EVs 对缺血再灌注损伤相关 AKI 有明显的治疗作用，过表达 Oct-4 增强了这些治疗效果。我们的研究结果可能为 MSC EVs 治疗 AKI 提供新的方向。
