双耐药基因导入脐血干/祖细胞降低联合化疗骨髓毒性作用的临床前研究

Improvement of combination chemotherapy tolerance of human umbilical cord blood CD_(34)^+ cells transducted with double drug resistance genes by a bicistronic retroviral vector

目的 探讨转染醛脱氢酶基因 (ALDH3)和多药耐药基因 (mdr 1)的人脐血CD3 4+ 细胞能否同时增强对活性环磷酰胺 (4 HC)和mdr 1基因靶药的抗性。方法 构建含ALDH3和mdr 1双耐药基因的逆转录病毒表达质粒G1Na ALDH3 IRES MDR1,经LipofectAMINE介导转染包装细胞 ,采用含 4 HC和长春新碱 (VCR)的培养基克隆选择后收集重组病毒上清于单向型GP +E86与双嗜型PA317包装细胞行乒乓交互感染 ,将含ALDH3和mdr 1双耐药基因重组病毒的上清在细胞生长因子刺激下重复感染经免疫磁珠分离系统 (MACS)纯化后的人脐血CD3 4+ 细胞 ,用PCR、RT PCR、Southernblot、Northernblot、FACS和MTT等方法检测外源ALDH3与mdr 1基因在CD3 4+ 细胞中的转移和表达。结果 MACS分离纯化后的人脐血CD3 4+ 细胞纯度平均达 91% ,回收率为 72 % ,含双耐药基因重组病毒的上清最高滴度为 6 .5× 10 5CFU/ml,应用集落计数、PCR和FACS方法测定基因转导效率分别为 18.0 %、2 0 .0 %和16 7% ,未检测到辅助病毒存在 ,有P170功能的细胞占 16 0 % ,经双耐药基因修饰的脐血CD3 4+ 细胞对 4 HC的IC50 较对照组提高 3.5倍 ,对VCR和柔红霉素的IC50 较未转染细胞分别高 6 .8和 5 .5倍。结论 逆转录病毒载体介导双耐药基因转导脐血造血干

Objective To explore whether human umbilical cord blood hematopoietic progenitor cells transduced with human aldehyde dehydrogenase class 3 (ALDH3) and multidrug resistance gene (MDR1) could increase resistance to 4 hydroxycyclophosphamide (4 HC) and P glycoprotein effluxed drugs. Methods A bicistronic retroviral vector G1Na ALDH3 IRES MDR1 cDNA was constructed and transfected the packaging cell lines GP+E86 and PA317 by LipofectAMINE method , using the medium containing VCR and 4 HC for cloning selection and ping ponging supernatant infection between ecotropic producer clone and amphotropic producer clone, cord blood CD 34 + cells were enriched with a high gradient magnetic cell sorting system(MACS), and then repeatedly transfected with supernatant of retrovirus containing human ALDH3 and MDR1 cDNA under stimulation of hematopoietic growth factors. PCR , RT PCR, Southern blot, Northern blot, FACS and MTT assay were used to evaluate the transfection and expression of the double genes. Results The purity of cord blood CD 34 + cells was approximately 91% and the recovery rate was 72%. The highest titer of recombinant amphotropic retrovirus in the supernatant was up to 6.5×10 5 CFU/ml. The efficiency of gene transduction was 18%,20% and 16.7% tested by colony formation, PCR and FACS, respectively. Rhodamine 123 efflux showed 16% transduced cells with P gp function. No helper virus was found by both nested PCR and rescue assay. The MTT analysis showed a 3.5 to 6.8 fold increase of resistance of transducted cells to cyclophosphamide and P glycoprotein effluxes drug as compared with the nontransduced cells. Conclusion The efficiency and co expression of this dual genes transfer system provided a foundation for ameliorating combination chemotherapy toxicity in clinical trial.