Quantitative Analysis of Aggregated Human Mesenchymal Stem Cell Spheroids Applied to a Rodent Model of Ischemic Stroke Using 1H and 23Na MRI at 21.1 T

High field 1H and 23Na MRI provide sensitive metrics of quantifying ischemic stroke over time. In this work, the efficacy of human mesenchymal stem cells (hMSC) aggregated into 3D spheroids (a-hMSC) as a treatment method for ischemic stroke in a rat model was assessed. High resolution fast spin echo (FSE) 1H and gradient recalled echo (GRE) 23Na images were acquired using the 21.1-T, 900-MHz MRI scanner located at the National High Magnetic Field Laboratory in order to elucidate evolving volumetric changes as a result of a-hMSC versus control treatments following ischemic insult. Significant changes were observed in sodium with a-hMSC transplantation, which was supported by observed improvement trends in asymmetric behavior. Histology showed the a-hMSC treatment decreased astrocytic activity, preserved mature neurons and stimulated migration of neuroprogenitor cells differentiating primarily into neurons instead of other cell types. The work presented qualifies a-hMSC as a viable candidate for further study as an implant to treat ischemic stroke, and further validates 23Na MRI as an efficient and sensitive biological metric for evaluating therapeutic efficiency at the cellular level.