Abstract
ObjectiveThe aim of the present work was to verify whether adenoviral vector mediated ferritin over-expression in mesenchymal stem cells could be detected by 7T MRI device, and to explore the relationship between ferritin content and MRI signal intensities.MethodsA recombined adenoviral vector (rAdV) encoding ferritin heavy chain (FTH1) subunit was specially designed for the aim of infecting bone marrow mesenchymal stem cells (BMSCs). Ferritin over-expression in BMSCs was determined by cell immunocytochemistry and the ferritin content in cells was determined by ELISA assay. BMSCs were subjected to cell viability, proliferation and multi-differentiation analyses as well as 7T MRI test using fast spin-echo pulse sequence. The R2 value andδR2 were calculated according to T2 mapping images.ResultsAs was confirmed by cell immunocytochemistry and ELISA assay, rAdV mediated ferritin was over-expressed in BMSCs. Ferritin over-expression did not interfere with stem cell viability or pluripotent differentiation but slowed cell proliferation. The R2 value of BMSCs-FTH1 vs control BMSCs from 1–4 weeks was16.65±1.28 s-1 vs 13.99±0.80 s-1, (t = 3.94, p = 0.004), 15.63±1.37 s-1 vs 13.87±0.83 s-1 (t = 2.47, p = 0.039), 15.53±0.88 s-1 vs 14.25±0.53 s-1 (t = 2.80, p = 0.023) and 14.61±1.28 s-1 vs 13.69±1.03 s-1 (t = 1.25, p = 0.24), respectively. δR2 gradually decreased from 1–4 weeks and the difference between the groups had statistical significance (F = 12.45, p<0.01).δR2 was positively correlated with OD value (r = 0.876, p<0.01) and ferritin concentration (r = 0.899, p<0.01) as determined by Pearson correlation.ConclusionsOur study confirms that ferritin could be over-expressed in BMSCs as a result of rAdV mediated infection and could be quantitatively detected by 7T MRI device. The differences in T2 signal intensities and R2 values stem from internal contrast generated by endogenous ferritin over-expression. The correlation between δR2, OD and ferritin concentration suggests that MRI can detect ferritin signal change accurately.
Highlights
Bone marrow mesenchymal stem cells (BMSCs) are pluripotent progenitors and keep the ability of multi-differentiation [1,2,3]
As was confirmed by cell immunocytochemistry and ELISA assay, recombined adenoviral vector (rAdV) mediated ferritin was over-expressed in BMSCs
The R2 value of BMSCs-FTH1 vs control BMSCs from 1–4 weeks was16.65±1.28 s-1 vs 13.99±0.80 s-1, (t = 3.94, p = 0.004), 15.63±1.37 s-1 vs 13.87±0.83 s-1 (t = 2.47, p = 0.039), 15.53±0.88 s-1 vs 14.25±0.53 s-1 (t = 2.80, p = 0.023) and 14.61±1.28 s-1 vs 13.69±1.03 s-1 (t = 1.25, p = 0.24), respectively. δR2 gradually decreased from 1–4 weeks and the difference between the groups had statistical significance (F = 12.45, p
Summary
Bone marrow mesenchymal stem cells (BMSCs) are pluripotent progenitors and keep the ability of multi-differentiation [1,2,3]. Stem cell transplantation has shown great prospects in damage repair and tissue engineering, and can help avoid several ethical and technical issues [4]. One problem hindering stem cell application in clinic is the lack of an appropriate way to monitor cell status after transplantation. For a long period of time, superparamagnetic iron oxides (SPIOs), which can decrease T2 relaxation time, has been considered as a novel exogenous contrast medium for stem cell labeling [5, 6]. It was found that cell survival time may be overestimated by MRI when labeled with SPIOs [9]. This well recognized exogenous contrast has shown some defects and limitations. New strategies for cell labeling are badly in need
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