Bioconjugate approaches for the systemic delivery of proteins with the Feldan Shuttle

细胞膜是一个很难逾越的生物屏障，特别是对蛋白质来说。它的极性外部和非极性内部有效地阻止了这些分子的扩散，这限制了它们到达细胞内部的能力。这对治疗性蛋白质的输送是一个重大挑战，因为许多这些制剂必须到达细胞内空间才能起作用。费尔丹治疗公司开发了一个阳离子多肽文库(即费尔丹穿梭平台)，以促进蛋白质、蛋白质复合体和多肽(即货物)进入细胞。由于货物和航天飞机之间没有形成共价键，而且由于文库内有大量不同的多肽航天器，该平台适合于促进多种类别货物的细胞内递送。这一点已经在体外和实验动物研究中得到了证明。然而，这一过程是非特定的，将在遇到的第一个细胞中发生。虽然将蛋白质输送到细胞培养中不是问题，但这种非特异性意味着货物输送将被限制在注射部位的直接区域(即，无法针对患病组织和健康组织)。此外，尽管航天飞机和货物蛋白之间缺乏共价键被视为有利于细胞培养实验，但这在体内是一个重大挑战，因为注射时的高度稀释会导致航天飞机与货物蛋白解离。这个项目将建立在戈蒂尔教授和费尔丹已经确定的概念验证结果的基础上。目标是进一步推进航天飞机/聚乙二醇/货运生物结合物的原型设计，以：i)通过暂时停用其细胞穿透特性来增加其在体内的循环时间；ii)将货物蛋白质临时结合到航天飞机上，使两种成分(费尔丹航天飞机及其货物)到达体内的目标区域；iii)与航天飞机和货物的物理混合物相比，实现体内生物分布的改变。原型的预期开发将是迭代的，并将以在健康小鼠的细胞培养和动物实验中进行的性能评估为指导。

The cell membrane is a biological barrier that can be difficult to cross, especially for proteins. Its polar exterior and non-polar interior effectively block diffusion of these molecules, which limits their ability to reach the interior of the cell. This is a major challenge for the delivery of therapeutic proteins, because many of these agents must reach the intracellular space to be active. Feldan Therapeutics Inc. has developed a library of cationic peptides (i.e., the Feldan Shuttle platform) to facilitate the delivery of proteins, protein complexes, and peptides (i.e., the Cargos) into the cell. Because no covalent bond is formed between the cargo and the Shuttle, and because of the large number of different peptide Shuttles within the library, this platform is suitable for promoting the intracellular delivery of many categories of Cargos. This has been demonstrated in both ex vivo as well as in pilot animal studies. However, this process is non-specific and will occur in the first cells encountered. While not an issue for the delivery of proteins into cell cultures, this non-specificity implies that cargo delivery will be restricted to the immediate area at the site of injection (i.e., inability to target diseased vs. healthy tissue). Moreover, while the lack of covalent bond between the Shuttle and the cargo protein is seen as advantageous for cell culture experiments, this is a major challenge in vivo, due to high dilution upon injection that would cause the Shuttle to become dissociated from the cargo protein. This project will build upon proof-of-concept findings already established by Prof. Gauthier and Feldan. The objectives are to further advance the design of a prototype Shuttle/PEG/Cargo bioconjugate to: i) Increase its circulation time in the body by temporarily deactivating its cell-penetrating properties; ii) Temporarily conjugate a Cargo protein to the Shuttle so that both components (the Feldan Shuttle and its Cargo) reach the targeted area in the body; iii) Achieve altered biodistribution in vivo compared to a physical mixture of Shuttle and Cargo. The foreseen development of the prototype will be iterative and will be guided by performance assessed in both cell culture and animal experiments in healthy mice.