构建功能基团修饰的树形高分子库筛选高效的蛋白质胞内递送载体

The therapeutic potential of protein-based genome editing in clinic is limited by the genetic toxicity using viral vector and gene. Therefore, developing new strategies to improve the clinical application of genome-editing system is essentially required. Previous studies have found that chemically modified nanocarriers can intracellularly deliver multiple proteins with advantages of biosafety. Whilst more and more efforts have been documented towards improving the intracellular protein delivery efficiency of polymer via chemical modifications, the efficiency of these polymers are not satisfaction. In this study, we systemically prepare a library of surface-engineered dendrimers as the screening pool which can exclude the differences of polymer structure, conformation and polydispersity to discover efficient and low-toxic protein carriers. A second-generation library designed based on the structure of the best ligand modified polymer to further study the structure-function relationship of these polymers. And efficiency of these polymers for gene-editing proteins delivery are validated in vivo and in vitro. The aim of this project is to identify the best nanocarrier among these ligands modified polymer for delivery of genome-editing protein into mammalian cells and to understand the structure-function relationship of ligands modified polymer. And the results of the study may enable the future rational design of potent genome-editing proteins nanocarriers.

基因编辑在临床上具有广阔的应用前景，利用常用的病毒载体递送核酸进行基因编辑容易导致机体产生免疫原性和遗传毒性，这极大的限制了基因编辑系统的使用。所以急需开发新的递送系统以满足基因编辑在临床上的应用需求。前期研究发现，化学改性的纳米载体能够胞内递送蛋白质但是其递送效率较低无法满足基因编辑的要求。在本项目的研究中，（1）我们通过构建多种功能基团修饰的树形高分子库，最大程度排除高分子的空间结构、组成、多分散性等因素的影响，筛选高效、低毒的蛋白质胞内递送载体；（2）针对能够提高树形高分子递送效率的表面功能基团二次建库，研究功能基团结构及其蛋白质递送效率之间的关系；（3）体内外验证功能基团修饰的树形高分子胞内递送基因编辑蛋白质的效率。通过该项目的开展，我们将从中筛选出高效的基因编辑蛋白质胞内递送载体，厘清高分子表面功能基团结构与材料递送效率的关系，为合理设计基因编辑蛋白质胞内递送载体提供理论依据。

阳离子高分子作为基因、蛋白质载体在分子生物学，遗传学，生物医学等领域具有广泛的应用前景。但是阳离子树形高分子转染效率低，限制了其在生物领域的应用。本项目采用表面修饰苯胍的方法，显著地提高阳离子树形高分子的转染效率。胍基可以和核酸中磷酸形成氢键，也可以和蛋白质的氨基酸之间形成多重氢键，除此之外还可以通过静电相互作用结合核酸或蛋白质，从而形成稳定的转染复合物。苯环结构增加了材料的输水性，能够帮助复合物快速的从内涵体中逃逸，避免了材料被溶酶体降解。该研究为合理设计高效的核酸、蛋白质载体提供了新的思路。