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干细胞移植治疗各种组织损伤或退行性疾病是目前生命科学领域中的前沿和热点问题[1], 其应用前景广阔。监测移植干细胞的增殖、分布、迁移的方法虽然有多种, 但传统方法主要是在体外进行组织学分析, 耗力、耗时、具侵袭性, 如何在活体内监测移植干细胞及其发展, 是关系到这一治疗方法成败的至关重要的医学问题。1999年美国哈佛大学Weissleder等[2]首先提出了分子影像学后, 移植干细胞治疗的监测进入了崭新的阶段, 人类开始在细胞分子水平评价活体组织细胞的生物学过程。目前, 无创性监测体内移植细胞的分子影像学技术主要是通过转染报告基因间接显像。
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报告基因是一种编码可被检测的蛋白质或酶的基因, 也就是说, 是一种表达产物非常容易被鉴定的基因。把它的编码序列和基因表达调节序列相融合形成嵌合基因, 或与其他目的基因相融合, 在调控序列控制下进行表达, 从而利用其表达产物来标定目的基因的表达调控。作为报告基因, 在遗传选择和筛选检测方面必须具有以下3个条件: ①已被克隆且全序列已测定; ②其表达产物能进行定量测定; ③表达产物在受体细胞中本不存在, 即无背景, 在被转染的细胞中无相似的内源性表达产物。报告基因显像(reporter gene imaging, RGI)则是将报告基因转染给靶细胞后, 通过标记的报告探针与报告基因的特异性结合而显影。通过探针的聚集显示报告基因产物的活性水平, 从而间接提供报告基因表达水平及驱动报告基因表达的内源性信号或转录因子水平的信息, 了解体内特异性基因或蛋白质表达的部位、水平、迁徙及持续时间。RGI可以无创性研究活体移植细胞的定位、存活、分布及分化过程, 指导临床干细胞治疗的顺利进行。因此, RGI成为活体监测移植干细胞治疗的最佳手段之一。
RGI目前已有很大发展, 根据报告基因的编码产物不同, 可分为以酶为基础的报告基因和以受体或转运子为基础的报告基因, 已经形成了包括放射性核素显像、MRI和光学成像的完整体系[3](表 1)。
显像技术 报告基因 光学成像 荧光蛋白(红、绿)基因、焚光素酶(萤火虫、甲虫、海肾、长腹水蚤)基因 放射性核素成像 单纯疱疹病毒1型胸苷激酶基因、人类线粒体胸苷激酶基因、多巴胺2型受体基因、去甲肾上腺素转运体基因、钠碘同向转运体基因、雌激素受体、生长抑素受体2基因 MRI 转铁蛋白受体基因、β-半乳糖苷酶基因、酪氨酸酶基因、铁蛋白基因 表 1 报告基因在分子影像技术中的应用
报告基因显像监测干细胞治疗的研究进展
Advances of reporter gene imaging monitoring stem cell therapy
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摘要: 干细胞移植治疗各种组织损伤或退行性疾病是目前国内外研究热点,而对干细胞移植后的活体归巢、分化及功能表达等动态变化却所知甚少,影响了干细胞治疗的进一步发展。报告基因显像是分子影像技术的重要组成部分,通过间接监测转染报告基因的表达,可以动态监测移植干细胞活体内变化过程。该文简述报告基因显像活体监测移植干细胞治疗的最新研究进展和未来发展趋势。Abstract: Stem cell transplantation in the treatment of various tissue damage or degenerative diseases are research hotspots both at home and abroad.However, ignorance of the homing, differentiation and functional expression of the stem cell in vivo influence the further development of stem cell therapy.As an important component of molecular imaging technology, reporter gene imaging dynamically monitors the change of stem cell in vivo via monitoring the expression of transfected reporter gene.This paper briefly describes the latest research progress and the future development trend of the monitoring of reporter gene imaging in stem cell therapy in vivo.
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表 1 报告基因在分子影像技术中的应用
显像技术 报告基因 光学成像 荧光蛋白(红、绿)基因、焚光素酶(萤火虫、甲虫、海肾、长腹水蚤)基因 放射性核素成像 单纯疱疹病毒1型胸苷激酶基因、人类线粒体胸苷激酶基因、多巴胺2型受体基因、去甲肾上腺素转运体基因、钠碘同向转运体基因、雌激素受体、生长抑素受体2基因 MRI 转铁蛋白受体基因、β-半乳糖苷酶基因、酪氨酸酶基因、铁蛋白基因 -
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