Rezaei Ramazan, Baghaei Kaveh, Hashemi Seyed Mahmoud, Zali Mohammad Reza, Ghanbarian Hossein, Amani Davar
Department of Immunology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Gastroenterology and Liver Diseases Research Center, Research Institute for Gastroenterology and Liver Diseases, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Front Med (Lausanne). 2021 Apr 27;8:619939. doi: 10.3389/fmed.2021.619939. eCollection 2021.
Exosomes have been introduced as a new alternative delivery system for the transmission of small molecules. Tumor-derived exosomes (TEXs) not only contain tumor-associated antigens to stimulate antitumor immune responses but also act as natural carriers of microRNAs. The aim of the current study was to evaluate the efficacy of miR-124-3p-enriched TEX (TEXomiR) as cell-free vaccine in the induction of antitumor immune responses in a mouse model of colorectal cancer. Briefly, the exosomes were isolated from cultured CT-26 cell line, and modified calcium chloride method was used to deliver miR-124-3p mimic into the exosomes. We used a CT-26-induced BALB/c mouse model of colorectal cancer and analyzed the effect of TEXomiR on survival, tumor size, spleen and tumor-infiltrated lymphocytes, and splenocyte proliferation. Furthermore, intra-tumor regulatory T cells, cytotoxic activity of the splenocytes, and cytokine secretion was also evaluated to describe the anti-tumor immune response. When the tumor size reached 100 mm, the mice were injected with TEXomiR, TEX, and/or phosphate-buffered saline (PBS) subcutaneously three times with 3-day interval, and then tumor size was monitored every 2 days. The results indicated that TEXs could efficiently deliver functional miR-124-3p mimic. The evaluation in tumor-bearing mice showed that treatment with TEXomiR can elicit a stronger anti-tumor immune response than unloaded TEX and PBS. Significant tumor growth inhibition and increased median survival time was achieved in tumor-bearing mice treated with TEXomiR. A significant decrease in CD4/CD8 and Treg/CD8 ratio in tumor tissue was demonstrated. Moreover, increased cytotoxicity and proliferation of splenocytes in the TEXomiR group compared to the TEX and PBS groups were identified. Taken together, our data demonstrated that tumor-derived exosomes efficiently deliver miR-124-3p mimic, and TEXomiR promotes anti-tumor immune responses.
外泌体已作为一种用于小分子传递的新型替代递送系统被引入。肿瘤来源的外泌体（TEXs）不仅含有肿瘤相关抗原以刺激抗肿瘤免疫反应，还作为微小RNA的天然载体。本研究的目的是评估富含miR-124-3p的TEX（TEXomiR）作为无细胞疫苗在结直肠癌小鼠模型中诱导抗肿瘤免疫反应的疗效。简要地说，从培养的CT-26细胞系中分离出外泌体，并使用改良的氯化钙方法将miR-124-3p模拟物递送至外泌体中。我们使用CT-26诱导的BALB/c结直肠癌小鼠模型，分析了TEXomiR对生存、肿瘤大小、脾脏和肿瘤浸润淋巴细胞以及脾细胞增殖的影响。此外，还评估了肿瘤内调节性T细胞、脾细胞的细胞毒性活性和细胞因子分泌，以描述抗肿瘤免疫反应。当肿瘤大小达到100mm时，给小鼠皮下注射TEXomiR、TEX和/或磷酸盐缓冲盐水（PBS），每隔3天注射一次，共注射三次，然后每2天监测一次肿瘤大小。结果表明，TEXs能够有效地递送功能性miR-124-3p模拟物。对荷瘤小鼠的评估表明，与未负载的TEX和PBS相比，用TEXomiR治疗可引发更强的抗肿瘤免疫反应。用TEXomiR治疗的荷瘤小鼠实现了显著的肿瘤生长抑制并延长了中位生存时间。肿瘤组织中CD4/CD8和Treg/CD8比值显著降低。此外，与TEX和PBS组相比，TEXomiR组脾细胞的细胞毒性和增殖增加。综上所述，我们的数据表明肿瘤来源的外泌体能够有效地递送miR-124-3p模拟物，并且TEXomiR可促进抗肿瘤免疫反应。
