STEM CELL GENE THERAPY USING LONG TERM BONE MARROW CULTURE TRANSDUCTION PROTOCOL

向造血干细胞(HSCs)导入基因的尝试 总体上令人失望，使用基于老鼠的逆转录病毒 在体外转导CD34+细胞的载体导致低水平 (01%-1%)在有限的时间内进行基因标记研究 犬证实逆转录病毒载体转导LTBMC 在体内给予更高水平的基因标记的好处是 技术是通过使用未分离的骨髓，没有 预选；干细胞和逆转录病毒能够共存于 间质；系统选择用于LTCIC；转导发生3次以上 喂养后21天，使细胞处于周期中，改善 转导效率我们研究了这项技术在 2只接受自体移植的动物中的猕猴 移植过程中，没有实施任何条件调节机制 用PA317LN对未分离的骨髓进行15-18天的移植 对以载体为基础的动物进行了标记基因neo的监测 外周血和骨髓中观察到1%到3%的基因 在外周血液中标记大约3个月的频率 骨髓中的neo含量普遍低于外周血 血液这项技术似乎令人鼓舞，因为我们的数据类似于 其他人已经遵守了什么，但我们的协议没有 最近的努力都集中在尝试 利用逆转录病毒载体转导绿色荧光蛋白的HSC 利用R Howley提供的逆转录病毒载体进行的初步实验 导致维护LTBMC失败，这似乎是由于 逆转录病毒产生细胞系提供的可溶性因子 结果表明，LTBMC技术可能很难 将这些研究的结果推广到其他逆转录病毒载体可能 在优化人类基因改造的努力中被证明是有用的 造血干细胞

Attempts to introduce genes into hematopoietic stem cells (HSCs) have been disappointing In general, using murine retroviral based vectors to transduce CD34+ cells in vitro have resulted in a low level (0 1-1%) of gene marking for a limited period of time Studies in canines demonstrated that LTBMC transduced with retroviral vectors gave higher levels of gene marking in vivo The advantage of this technique is that by using unfractionated marrow there is no preselection; stem cells and retrovirus are able to colocalize on the stroma; the system selects for LTCIC; transduction occurs 3 times over 21 days following feeding so that cells are in cycle, improving transduction efficiency We examined the utility of this technique in rhesus macaques In 2 animals that underwent this autologous transplantation procedure, no conditioning regime was implemented Unfractionated marrow was transduced for 15 - 18 days with a PA317LN based vector Animals were monitored f or "neo" the marker gene in peripheral blood and bone marrow We observed between 1% and 3% gene marking in peripheral blood for approximately 3 months The frequency of neo in bone marrow was generally lower than that in peripheral blood This technique appears encouraging as our data are similar to what has been observed by others, but our protocol is in the absence of any conditioning regimen Recent efforts have focused on attempts to use LTBMC to transduce HSC using a retroviral vector encoding GFP Initial experiments using a retroviral vector provided by R Howley resulted in a failure to maintain LTBMC, which appears to be due to soluble factors provided by the retroviral producer cell line These results suggest that the LTBMC technique may be difficult to generalize to other retroviral vectors Results of these studies may prove useful in efforts to optimize genetic modification of human hematopoietic stem cells