Roelants Véronique, Labar Daniel, de Meester Carole, Havaux Xavier, Tabilio Antonio, Gambhir Sanjiv S, Di Ianni Mauro, Bol Anne, Bertrand Luc, Vanoverschelde Jean-Louis
Université catholique de Louvain, Division of Cardiology, Brussels, Belgium.
J Nucl Med. 2008 Nov;49(11):1836-44. doi: 10.2967/jnumed.108.052175.
Mesenchymal stem cells (MSCs) are a promising cell line for the treatment of ischemic heart disease. To evaluate the success of their transplantation into living animals, noninvasive imaging techniques that are able to track the distribution and fate of those cells would be useful. The aim of this study was to investigate the feasibility of infecting rat MSCs with adenoviruses and retroviruses carrying the herpes simplex virus type 1 thymidine kinase (HSV1-tk) gene; to compare the level of transgene expression induced by the 2 viral vectors; to evaluate the effects of viral transduction on cell phenotype, viability, proliferation rates, and differentiation capabilities; and to test the possibility of noninvasively imaging transduced MSCs using 9-(4-18F-fluoro-3-[hydroxymethyl]butyl)guanine (18F-FHBG) and small-animal PET after their transplantation into living rats.
We infected rat bone marrow MSCs with adenoviruses carrying the HSV1 mutant tk (Ad-HSV1-sr39tk) PET reporter gene (PRG) or with a retroviral construct expressing the wild-type HSV1-tk PRG. The efficacy and intensity of HSV1-sr39tk and HSV1-tk gene expression were determined by a direct comparison of [8-3H]-penciclovir ([8-3H]-PCV) cell uptake in both infected MSC populations and noninfected control MSCs. Small-animal PET studies were performed on living rats after an intramuscular injection of infected MSCs. The MSCs either have been incubated in advance with 18F-FHBG or they were administered and 18F-FHBG was thereafter intravenously administered [corrected]
Both adenoviral and retroviral vectors can be used to introduce the tk PRG in MSCs. Neither adenovirus nor retrovirus infections significantly modify MSC phenotype, viability, proliferation, and differentiation capabilities. No significant 3H-PCV uptake was observed in noninfected MSCs. By contrast, after both adenoviral and retroviral infections, the infected MSC populations exhibited a similar, significantly higher, 3H-PCV accumulation. Small-animal PET images showed intense activity within the transplanted regions irrespective of the infected MSC population used.
Our results demonstrate the feasibility of infecting MSCs with adenoviruses and retroviruses expressing the HSV1-tk PRG and suggest that infected MSCs can be noninvasively imaged with 18F-FHBG and small-animal PET after their transplantation into living animals.
间充质干细胞（MSCs）是用于治疗缺血性心脏病的一种很有前景的细胞系。为了评估将其移植到活体动物体内是否成功，能够追踪这些细胞分布和命运的非侵入性成像技术将很有用。本研究的目的是探讨用携带单纯疱疹病毒1型胸苷激酶（HSV1 - tk）基因的腺病毒和逆转录病毒感染大鼠MSCs的可行性；比较这两种病毒载体诱导的转基因表达水平；评估病毒转导对细胞表型、活力、增殖率和分化能力的影响；并测试在将转导的MSCs移植到活体大鼠体内后，使用9 -（4 - 18F - 氟 - 3 - [羟甲基]丁基）鸟嘌呤（18F - FHBG）和小动物正电子发射断层扫描（PET）对其进行非侵入性成像的可能性。
我们用携带HSV1突变型tk（Ad - HSV1 - sr39tk）PET报告基因（PRG）的腺病毒或表达野生型HSV1 - tk PRG的逆转录病毒构建体感染大鼠骨髓MSCs。通过直接比较两种感染的MSCs群体以及未感染的对照MSCs中[8 - 3H] - 喷昔洛韦（[8 - 3H] - PCV）的细胞摄取情况，来确定HSV1 - sr39tk和HSV1 - tk基因表达的效率和强度。在对活体大鼠进行肌肉注射感染的MSCs后，进行小动物PET研究。MSCs要么预先与18F - FHBG孵育，要么先注射MSCs然后再静脉注射18F - FHBG[已校正]
腺病毒和逆转录病毒载体均可用于将tk PRG导入MSCs。腺病毒和逆转录病毒感染均未显著改变MSCs的表型、活力、增殖和分化能力。在未感染的MSCs中未观察到显著的3H - PCV摄取。相比之下，在腺病毒和逆转录病毒感染后，感染的MSCs群体均表现出相似的、显著更高的3H - PCV积累。小动物PET图像显示，无论使用哪种感染的MSCs群体，移植区域内均有强烈的活性。
我们的结果证明了用表达HSV1 - tk PRG的腺病毒和逆转录病毒感染MSCs的可行性，并表明在将转导的MSCs移植到活体动物体内后，可以用18F - FHBG和小动物PET对其进行非侵入性成像。
