目的 构建新型低相对分子质量聚乙烯亚胺(PEI)耦联载体，评估其对原代大鼠骨髓间充质干细胞（BMSCs）的细胞毒性及转染效率。方法 利用可降解的氨基甲酸酯化学键耦联相对分子质量为800的PEI 制备低相对分子质量的PEI （PEI 800）衍生物纳米非病毒载体，命名为PEI-Bu；进一步对PEI-Bu压缩DNA的能力、体外降解效率及对原代BMSCs的细胞毒性和基因转染效率进行生物学评价。结果 PEI-Bu能有效压缩质粒DNA并形成稳定的复合物，所形成的复合物粒径约50 nm。与实验室常用的已商品化的相对分子质量为25 000 的PEI （PEI 25 000）相比，PEI-Bu对大鼠原代BMSCs的细胞毒性较小，且基因转染效率更高。结论 作为一种新型的非病毒纳米载体，PEI-Bu能有效转染BMSCs，且安全性较高，具有进一步研发的价值。

Objective To construct the novel low molecular weight polyethylenimine (PEI) conjugates, and evaluate its toxicity and transfection efficiency on rat bone marrow mesenchymal stem cells (BMSCs). Methods Low molecular weight PEI derivative non-viral nano vector was developed by conjugation of PEI of 800 in molecular weight and degradable carbamate linkage, and was named as PEI-Bu. The DNA condensation capability, in vitro degradation efficiency as well as toxicity and transfection efficiency on primary BMSCs of PEI-Bu were investigated. Results PEI-Bu efficiently condensed plasmid DNA, and stable polyplexes were formed, with the size of polyplexes being about 50 nm. Compared with commercialized PEI 25 000 (PEI of 25 000 in molecular weight) commonly used in laboratories, PEI-Bu had lower toxicity and higher transfection efficiency on rat primary BMSCs. Conclusion As a novel non-viral nano vector, PEI-Bu can efficiently transfect BMSCs with favorable safety, which has a potential value for further development.