RNA Therapeutics Institute, University of Massachusetts Medical School, Worcester, MA 01604, USA.
Program in Molecular Medicine, University of Massachusetts Medical School, Worcester, MA 01604, USA.
Nucleic Acids Res. 2019 Feb 20;47(3):1082-1096. doi: 10.1093/nar/gky1239.
Small interfering RNA (siRNA)-based therapies are proving to be efficient for treating liver-associated disorders. However, extra-hepatic delivery remains challenging, limiting therapeutic siRNA utility. We synthesized a panel of fifteen lipid-conjugated siRNAs and systematically evaluated the impact of conjugate on siRNA tissue distribution and efficacy. Generally, conjugate hydrophobicity defines the degree of clearance and the liver-to-kidney distribution profile. In addition to primary clearance tissues, several conjugates achieve significant siRNA accumulation in muscle, lung, heart, adrenal glands and fat. Oligonucleotide distribution to extra-hepatic tissues with some conjugates was significantly higher than with cholesterol, a well studied conjugate, suggesting that altering conjugate structure can enhance extra-hepatic delivery. These conjugated siRNAs enable functional gene silencing in lung, muscle, fat, heart and adrenal gland. Required levels for productive silencing vary (5-200 μg/g) per tissue, suggesting that the chemical nature of conjugates impacts tissue-dependent cellular/intracellular trafficking mechanisms. The collection of conjugated siRNA described here enables functional gene modulation in vivo in several extra-hepatic tissues opening these tissues for gene expression modulation. A systemic evaluation of a panel of conjugated siRNA, as reported here, has not previously been investigated and shows that chemical engineering of lipid siRNAs is essential to advance the RNA therapeutic field.
基于小干扰 RNA（siRNA）的疗法已被证明在治疗肝脏相关疾病方面非常有效。然而，肝外递送仍然具有挑战性，限制了治疗性 siRNA 的应用。我们合成了一组十五种脂质偶联的 siRNA，并系统地评估了偶联物对 siRNA 组织分布和疗效的影响。一般来说，偶联物的疏水性决定了清除程度和肝到肾的分布模式。除了主要的清除组织外，几种偶联物还能在肌肉、肺、心脏、肾上腺和脂肪中积累大量的 siRNA。一些偶联物将寡核苷酸递送到肝外组织的分布明显高于胆固醇，这是一种研究得很好的偶联物，这表明改变偶联物的结构可以增强肝外递送。这些偶联的 siRNA 能够在肺、肌肉、脂肪、心脏和肾上腺中实现功能性基因沉默。每个组织产生有效沉默所需的水平（5-200μg/g）不同，这表明偶联物的化学性质影响了组织依赖性的细胞/细胞内运输机制。这里描述的偶联 siRNA 集合使我们能够在几种肝外组织中进行体内功能性基因调节，为基因表达调节开辟了这些组织的应用。以前没有对脂质 siRNA 偶联物的系统评估，而本研究表明，脂质 siRNA 的化学工程对于推进 RNA 治疗领域至关重要。
