Liu Min, Guo You-min, Wu Qi-fei, Yang Jun-le, Wang Peng, Wang Si-cen, Guo Xiao-juan, Qiang Yong-qian, Duan Xiao-yi
Imaging Center, The 2nd Affliated Hospital of Medical School, Xi'An Jiao Tong University, Xi'An City ShaanXi Province, China.
Biochem Biophys Res Commun. 2006 Aug 18;347(1):133-40. doi: 10.1016/j.bbrc.2006.06.081. Epub 2006 Jun 22.
The ability to track the distribution and differentiation of stem cells by high-resolution imaging techniques would have significant clinical and research implications. In this study, a model cell-penetrating peptide was used to carry gadolinium particles for magnetic resonance imaging of the mesenchymal stem cells. The mesenchymal stem cells were isolated from rat bone marrow by Percoll and identified by osteogenic differentiation in vitro. The cell-penetrating peptides labeled with fluorescein-5-isothiocyanate and gadolinium were synthesized by a solid-phase peptide synthesis method and the relaxivity of cell-penetrating peptide-gadolinium paramagnetic conjugate on 400 MHz nuclear magnetic resonance was 5.7311 +/- 0.0122 m mol(-1) s(-1), higher than that of diethylenetriamine pentaacetic acid gadolinium (p < 0.05). Fluorescein imaging confirmed that this new peptide could internalize into the cytoplasm and nucleus. Gadolinium was efficiently internalized into mesenchymal stem cells by the peptide in a time- or concentration-dependent fashion, resulting in intercellular T1 relaxation enhancement, which was obviously detected by 1.5 T magnetic resonance imaging. Cytotoxicity assay and flow cytometric analysis showed the intercellular contrast medium incorporation did not affect cell viability and membrane potential gradient. The research in vitro suggests that the newly constructed peptides could be a vector for tracking mesenchymal stem cells.
通过高分辨率成像技术追踪干细胞的分布和分化能力具有重大的临床和研究意义。在本研究中，一种模型细胞穿透肽被用于携带钆颗粒以对间充质干细胞进行磁共振成像。间充质干细胞通过Percoll从大鼠骨髓中分离出来，并通过体外成骨分化进行鉴定。用异硫氰酸荧光素和钆标记的细胞穿透肽通过固相肽合成方法合成，细胞穿透肽-钆顺磁共轭物在400 MHz核磁共振上的弛豫率为5.7311±0.0122 mmol(-1) s(-1)，高于二乙三胺五乙酸钆（p < 0.05）。荧光成像证实这种新肽能够内化到细胞质和细胞核中。钆通过该肽以时间或浓度依赖性方式有效地内化到间充质干细胞中，导致细胞内T1弛豫增强，这可通过1.5 T磁共振成像明显检测到。细胞毒性测定和流式细胞术分析表明细胞内造影剂的掺入不影响细胞活力和膜电位梯度。体外研究表明，新构建的肽可能是追踪间充质干细胞的载体。
