Using C-arm x-ray imaging to guide local reporter probe delivery for tracking stem cell engraftment.
Using C-arm x-ray imaging to guide local reporter probe delivery for tracking stem cell engraftment.
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DOI：
10.7150/thno.6943
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发表时间：
2013
期刊：
影响因子：
12.4
通讯作者：
Kraitchman DL
中科院分区：
文献类型：
--
作者：
Kedziorek DA;Solaiyappan M;Walczak P;Ehtiati T;Fu Y;Bulte JW;Shea SM;Brost A;Wacker FK;Kraitchman DL
细胞存活率差和细胞递送可视化困难是当前细胞移植方法的主要问题。为了保护细胞免受早期破坏，已经开发了微囊化方法。向微胶囊中添加造影剂还可以通过MR、超声和X射线成像进行跟踪。然而，确定微胶囊内的细胞活力仍然是一个问题。报告基因成像提供了一种确定细胞活力的方法，但在缺血性疾病中，通过全身注射递送报告探针可能会受到阻碍。在本研究中，骨髓间充质干细胞（MSCs）转染的三重融合报告基因包含红色荧光蛋白，截短胸苷激酶（SPECT/PET报告）和萤火虫荧光素酶（生物发光报告）。将转染的细胞微囊化在未标记的或全氟辛基溴（PFOB）浸渍的藻酸盐中。PFOB的添加提供了射线不透性，使得能够通过X射线成像可视化微胶囊。将微囊植入兔大腿肌肉内，与D-精氨酸孵育后，立即进行生物发光成像（BLI）。移植后24小时和48小时，使用C型臂CT将BLI蛋白靶向X射线可见的微胶囊，用于BLI细胞活力评估，而不是全身报告探针注射。与未包封的裸MSC相比，不仅证实了来自PFOB包封的MSC的生物发光信号发射，而且在C臂CT上可以看到PFOB包封的MSC的超过90%的注射部位。后者有助于使用常规X射线成像将报告探针成功靶向注射部位，以确定移植后1-2天的细胞活力。盲法注射到未标记微胶囊的近似位置导致仅18%的注射成功检测到BLI信号。总之，报告基因探针可以更精确地靶向使用C型臂CT在体内移植的生存能力评估，从而避免了大量和昂贵的系统注射的报告探针。
Poor cell survival and difficulties with visualization of cell delivery are major problems with current cell transplantation methods. To protect cells from early destruction, microencapsulation methods have been developed. The addition of a contrast agent to the microcapsule also could enable tracking by MR, ultrasound, and X-ray imaging. However, determining the cell viability within the microcapsule still remains an issue. Reporter gene imaging provides a way to determine cell viability, but delivery of the reporter probe by systemic injection may be hindered in ischemic diseases. In the present study, mesenchymal stem cells (MSCs) were transfected with triple fusion reporter gene containing red fluorescent protein, truncated thymidine kinase (SPECT/PET reporter) and firefly luciferase (bioluminescence reporter). Transfected cells were microencapsulated in either unlabeled or perfluorooctylbromide (PFOB) impregnated alginate. The addition of PFOB provided radiopacity to enable visualization of the microcapsules by X-ray imaging. Before intramuscular transplantation in rabbit thigh muscle, the microcapsules were incubated with D-luciferin, and bioluminescence imaging (BLI) was performed immediately. Twenty-four and forty-eight hours post transplantation, c-arm CT was used to target the luciferin to the X-ray-visible microcapsules for BLI cell viability assessment, rather than systemic reporter probe injections. Not only was the bioluminescent signal emission from the PFOB-encapsulated MSCs confirmed as compared to non-encapsulated, naked MSCs, but over 90% of injection sites of PFOB-encapsulated MSCs were visible on c-arm CT. The latter aided in successful targeting of the reporter probe to injection sites using conventional X-ray imaging to determine cell viability at 1-2 days post transplantation. Blind luciferin injections to the approximate location of unlabeled microcapsules resulted in successful BLI signal detection in only 18% of injections. In conclusion, reporter gene probes can be more precisely targeted using c-arm CT for in vivo transplant viability assessment, thereby avoiding large and costly systemic injections of a reporter probe.