Background: Intra-arterial (IA) mesenchymal stem cells (MSCs) delivery in ischemic stroke has high potential for clinical translation. Recently, we demonstrated safety and efficacy of IA-MSCs at 24h in a reversible middle cerebral artery occlusion (rMCAo) rodent model. Given the trophic mechanism of action of cell therapy in stroke, a second dose of cells may be beneficial. Therefore, we aimed to evaluate administration of two doses of IA-MSCs in the rodent stroke model.

Methods: Female ovariectomized Sprague–Dawley rats were exposed to MCAo for 90 min. Rats were treated with IA-MSCs (1x105 cells) or phosphate-buffered saline (PBS) at 1 and 6 days (1D-6D) after MCAo. To test neurological and motor function, the standardized neurobehavioral test battery and the rotarod test were performed. The mean duration (in seconds) on the device was recorded from 3 rotarod measurements. The rats were tested at 7, 15 and 30 days after MCAo. Rats were sacrificed at 30 days for infarct volume measurement using histology.
Results: There were no neurological worsening or mortality seen in either treatment group. The 1D-6D MSCs group showed significant reduction in infarct volume (21 ± 15mm3; n=5) compared to the PBS-treated group (86 ± 19 mm3; n=8, p<0.05) and improvement in rotarod test results (16.8 ± 5.8% vs 7.9 ± 3.4%, p=0.075) at 30 days and neurological scores (5.6 ± 1.2 vs 7.75 ± 0.6, p=0.15) at 15 days. 
Conclusions: Double dose IA-MSCs at 1D-6D post rMCAo is safe and reduces ischemic brain injury in female rats, with a trend towards functional improvement.

Multiple Intra-arterial Dosing of the Mesenchymal Stem Cells Reduces Ischemic Brain Injury in a Rat Stroke Model