Multifunctional lipids based on a molecular switch for the improved delivery of nucleic acids

50年前，当DNA的结构刚刚被发现的时候，谁能想到基因可以被用作药物呢？由于整个科学界的协同努力，这一概念已经从实验室走向临床，两种基因产品现在可以在市场上买到。然而，这些新疗法仍处于初级阶段，需要优化。通过使用精心设计的载体来提高它们的效率是可能的，这些载体能够携带遗传物质通过它们需要跨越的每一个生物屏障。特别是，进入细胞内部是一个主要的挑战，因为这些亲水核酸必须穿过富含脂质的质和/或内体膜，才能降解成溶酶体。设计一种能够在特定刺激下破坏膜稳定性的脂质载体，将有助于核酸到达目标细胞的细胞质。本研究计划的重点是设计和评估多功能脂质，具有DNA结合亲和力和ph触发的膜不稳定特性。DNA的结合亲和力将由可变的阳离子头基提供。pH敏感性将基于先前开发的分子镊子单元的使用，该单元已显示出适合内体逃逸的pH范围。这项研究计划将分三个阶段进行。在第一阶段，将合成和表征20种脂质的文库。筛选过程将根据它们的ph触发释放和对不同核酸的亲和力来选择最佳的6个候选物。第二阶段将确认膜不稳定特性，并评估转染效率和细胞毒性。两种最佳候选药物将进入III期，在此阶段将对核酸的胞质输送进行成像。最后，将在小鼠中进行概念验证，以评估这些生物反应性脂质纳米颗粒在体内提高遗传物质传递效率的潜力。

Who could have envisaged it would be possible to use a gene as a drug 50 years ago, when the structure of DNA has just been discovered? Thanks to synergistic efforts of a whole scientific community, the concept has gone from bench to bedside, and two gene products are now available on the market. However, these new therapeutics are still in their first stages and require optimization. It is possible to improve their efficiency by the use of carefully engineered vectors, able to carry the genetic material through each of the biological barriers they need to cross. In particular, getting inside the cell is a major challenge, because these hydrophilic nucleic acids have to cross the lipid-rich plasmatic and/or endosomal membrane, before being degraded into lysosomes. Designing a lipidic vector able to destabilize the membrane upon a specific stimulus would facilitate nucleic acids to reach the cytoplasm of the targeted cell. This research program is focused on the design and evaluation of multifunctional lipids, bearing DNA binding affinity and pH-triggered membrane destabilization properties. The DNA binding affinity will be provided by variable cationic headgroups. The pH-sensitivity will be based on the use of previously developed molecular tweezer units, which have shown the suitable pH range for endosomal escape. This research program will process in three phases. In phase I, a library of 20 lipids will be synthesized and characterized. A selection process, based on their pH-triggered release and affinity for diverse nucleic acids, will be applied to select the best 6 candidates. The phase II will confirm the membrane-destabilizing properties and assess the transfection efficiency and cytotoxicity. The two best candidates will access to phase III, where the cytosolic delivery of nucleic acids will be imaged. Finally, a proof of concept in mice will evaluate the potential of these bioresponsive lipid nanoparticles to improve the efficiency of genetic material delivery in vivo.