Tamiya T, Wei M X, Chase M, Ono Y, Lee F, Breakefield X O, Chiocca E A
Department of Surgery, Massachusetts General Hospital, Boston, USA.
Gene Ther. 1995 Oct;2(8):531-8.
One strategy to achieve efficient gene delivery into brain tumors employs the stereotactic implantation of fibroblasts that express a foreign gene and produce a retroviral vector bearing that gene. Another method involves the grafting of fibroblasts genetically engineered to produce a foreign gene product of interest. It is not clear to what extent retrovirus production in vivo provides an advantage over the grafting of genetically engineered cells for the purpose of achieving transgene expression. These two methods of gene delivery were compared in vivo by using the following cell lines: CRIP-MFG-LacZ cells, which express the lacZ gene and produce retrovirus vectors that bear this gene, and CRIP-LacZ cells, which express the lacZ gene, but do not produce retrovirus. Gene delivery was assessed in C6 gliomas established in the righ frontal lobe of athymic mice. CRIP-MFG-LacZ or CRIP-LacZ cells were inoculated stereotactically into these tumors. When CRIP-MFG-LacZ cells were used, a relatively elevated level of lacZ gene expression was present in cells scattered throughout the tumor. Using a computerized imaging system, this expression occurred in approximately 10% of the tumor area at 1 week, 42% at 2 weeks, and 32% at 3 weeks. In contrast, with CRIP-LacZ cells, lacZ gene expression was much weaker and occurred in a more focal area within the tumor. This expression occupied approximately 5% of the tumor area at 1 and 2 weeks and had almost disappeared at 3 weeks. In both cases there was no notable expression of the transgene in normal brain cells. In conclusion, transgene expression in brain tumors was achieved in more cells, at higher levels, and for longer time periods with retroviral vector-producing cells than with genetically engineered fibroblasts. This efficiency of gene delivery likely results from direct in situ delivery of the transgene to tumor cells with subsequent inheritance of the reporter gene to progeny tumor cells.
一种将基因高效递送至脑肿瘤的策略是采用立体定向植入表达外源基因并产生携带该基因的逆转录病毒载体的成纤维细胞。另一种方法是移植经过基因工程改造以产生感兴趣的外源基因产物的成纤维细胞。就实现转基因表达而言，体内产生逆转录病毒相对于移植基因工程细胞在多大程度上具有优势尚不清楚。通过使用以下细胞系在体内比较了这两种基因递送方法：CRIP-MFG-LacZ细胞，其表达lacZ基因并产生携带该基因的逆转录病毒载体；以及CRIP-LacZ细胞，其表达lacZ基因，但不产生逆转录病毒。在无胸腺小鼠右额叶建立的C6胶质瘤中评估基因递送情况。将CRIP-MFG-LacZ或CRIP-LacZ细胞立体定向接种到这些肿瘤中。当使用CRIP-MFG-LacZ细胞时，在整个肿瘤中散在的细胞中存在相对较高水平的lacZ基因表达。使用计算机成像系统，这种表达在1周时出现在约10%的肿瘤区域，2周时为42%，3周时为32%。相比之下，对于CRIP-LacZ细胞，lacZ基因表达要弱得多，且出现在肿瘤内更局限的区域。这种表达在1周和2周时占据约5%的肿瘤区域，在3周时几乎消失。在两种情况下，正常脑细胞中均未观察到明显的转基因表达。总之，与基因工程改造的成纤维细胞相比，产生逆转录病毒载体的细胞在更多细胞中、以更高水平且在更长时间段内实现了脑肿瘤中的转基因表达。这种基因递送效率可能源于将转基因直接原位递送至肿瘤细胞，随后报告基因遗传给子代肿瘤细胞。
