Abstract
Mesenchymal stem cells (MSCs) are among the major stem cells used for cell therapy and regenerative medicine. In-vivo cell-tracking by magnetic resonance imaging (MRI) is crucial for regenerative medicine, allowing verification that the transplanted cells reach the targeted sites. Cellular MRI combined with superparamagnetic iron-oxide (SPIO) contrast agents is an effective cell-tracking method. Here, we are reporting a new “bio-mimicry” method by making use of the “in-vivo environment” of MSCs to prepare native MSCs, so that (i) the phagocytic activity of cultured MSCs can be recovered and expanded MSCs can be ex-vivo labeled with Ferumoxytol, which is currently the only FDA approved SPIO nanoparticles for human use. Using our new method, 7-day cultured MSCs regain the capability to take up Ferumoxytol and exhibit an intracellular iron concentration of 2.50 ± 0.50 pg/MSC, comparable to that obtained by using Ferumoxytol-heparin-protamine nanocomplex; and (ii) cells can be re-sized to more native size, reducing from 32.0 ± 7.2 μm to 19.5 ± 5.2 μm. Our method can be very useful for expanding MSCs and labeling with Ferumoxytol, without the need for transfection agents and/or electroporation, allowing cell-tracking by MRI in both pre-clinical and clinical studies.
Highlights
Mesenchymal stem cells (MSCs) are important multipotent cells and have been registered in over 360 clinical trials for at least 12 kinds of pathological conditions[14,24,25]
If we can recover the phagocytic capability of expanded MSCs, MSCs can be labeled with Ferumoxytol in cell culture, without the need for transfection agents and/or electroporation
The purity and phenotype of MSCs prepared through this method have been investigated in our previous publication[43]
Summary
Mesenchymal stem cells (MSCs) are important multipotent cells and have been registered in over 360 clinical trials for at least 12 kinds of pathological conditions[14,24,25]. MSCs were labeled in vivo by injecting rats with a dose of 28 mg of iron per kilogram of Ferumoxytol 48 hrs before extraction, resulting in an iron content of 4.28 ± 0.19 pg/MSC This method reduces the risk of contamination and biologic alterations of the stem cells between harvest and transplantation. Our hypothesis is that the “in-vivo cellular environment” is important for MSC functions and can recover the “changes” of the ex-vivo expanded MSCs. If we can recover the phagocytic capability of expanded MSCs, MSCs can be labeled with Ferumoxytol in cell culture, without the need for transfection agents and/or electroporation. If we can recover the phagocytic capability of expanded MSCs, MSCs can be labeled with Ferumoxytol in cell culture, without the need for transfection agents and/or electroporation It can be very useful for cell-tracking by MRI in both clinical and pre-clinical studies
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