College of Life Science, Northwest University, Xi'an, 710069, China.
The State Laboratory of Cancer Biology, Department of Biochemistry and Molecular Biology, Air Force Medical University, Changlexi Road No.169Th, Xi'an, 710032, China.
J Nanobiotechnology. 2022 Oct 29;20(1):463. doi: 10.1186/s12951-022-01668-3.
Exosome mediated mRNA delivery is a promising strategy for the treatment of multiple diseases. However, the low yield of exosomes is a bottleneck for clinical translation. In this study, we boosted exosome production via simultaneously reducing the expression of genes inhibiting exosome biogenesis and supplementing the culture medium with red cell membrane components.
Among the candidate genes, knocking down of Rab4 was identified to have the highest efficacy in promoting exosome biogenesis while without any obvious cytotoxicity. Additionally, supplementing red cell membrane particles (RCMPs) in the culture medium further promoted exosome production. Combination of Rab4 knockdown and RCMP supplement increased exosome yield up to 14-fold. As a proof-of-concept study, low-density lipoprotein receptor (Ldlr) mRNA was forced expressed in the exosome donor cells and passively encapsulated into the exosomes during biogenesis with this strategy. Though exosome production per cell increased, the booster strategy didn't alter the loading efficiency of therapeutic Ldlr mRNA per exosome. Consistently, the therapeutic exosomes derived by the strategy alleviated liver steatosis and atherosclerosis in Ldlr mice, similar as the exosomes produced by routine methods.
Together, the proposed exosome booster strategy conquers the low yield bottleneck to some extent and would certainly facilitate the clinical translation of exosomes.
外泌体介导的 mRNA 递呈是治疗多种疾病的一种很有前途的策略。然而，外泌体的产量低是临床转化的一个瓶颈。在这项研究中，我们通过同时降低抑制外泌体生物发生的基因的表达并在培养基中补充红细胞膜成分来提高外泌体的产量。
在候选基因中，敲低 Rab4 被鉴定为在促进外泌体生物发生方面最有效，而没有明显的细胞毒性。此外，在培养基中补充红细胞膜颗粒（RCMPs）进一步促进了外泌体的产生。Rab4 敲低和 RCMP 补充的组合将外泌体的产量提高了 14 倍。作为概念验证研究，在这项策略中，通过将低密度脂蛋白受体（Ldlr）mRNA 强制表达在供体细胞的外泌体中，并在生物发生过程中外泌体被动地包裹该 mRNA。虽然每个细胞的外泌体产量增加了，但该增强剂策略并没有改变每个外泌体中治疗性 Ldlr mRNA 的装载效率。一致地，该策略衍生的治疗性外泌体减轻了 Ldlr 小鼠的肝脂肪变性和动脉粥样硬化，与常规方法产生的外泌体相似。
总之，所提出的外泌体增强策略在一定程度上克服了产量低的瓶颈，肯定会促进外泌体的临床转化。
