In vivo Tracking of Transplanted Neural Stem Cells Using Oatp1a1-Enhanced Magnetic Resonance Imaging in a Mouse Model...

Neural stem cells (NSCs) represent a promising therapeutic avenue for ischemic stroke. A critical barrier to their clinical application is the challenge of monitoring their survival and location post-transplantation. While iron-based magnetic resonance imaging (MRI) is widely used for cell tracking, its utility is limited by ambiguous contrast due to endogenous sources like hemosiderin and potential compromises to cell safety from iron's biological activity. This study aimed to achieve precise, specific, and longitudinal tracking of NSCs in ischemic stroke using a novel positive reporter gene system.

We first generated organic anion transporting polypeptide 1a1 (Oatp1a1)-overexpressing NSCs using lentiviral vectors and confirmed their biosafety and efficient uptake of gadolinium-ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA). Subsequently, these pre-labeled cells were transplanted into mice with photothrombotic ischemia under MRI guidance. Finally, in vivo tracking was performed via 3.0 T MRI, supported by ex vivo histological and elemental analyses.

Stable Oatp1a1 expression in transduced NSCs and biosafety of Oatp1a1 overexpression were confirmed. In vitro, overexpression of Oatp1a1 promoted Gd-EOB-DTPA uptake, significantly reducing the longitudinal relaxation time. Following the injection of Gd-EOB-DTPA-labeled NSCs into the area of cerebral infarction, these NSCs appeared as hyperintense signals on T1W images for up to 21 days of follow-up, as confirmed by histology.

The Oatp1a1-based positive-contrast MRI strategy enables safe and specific in vivo tracking of stem cells, facilitating the clinical translation of therapies for ischemic stroke.