Abstract
Background: This study tested the optimal time point for left intra-carotid arterial (LICA) administration of circulatory-derived autologous endothelial progenitor cells (EPCs) for improving the outcome in rat after acute ischemic stroke (IS). Methods and Results: Adult-male SD rats (n=70) were equally categorized into group 1 (sham-operated control), group 2 (IS), group 3 (IS+EPCs/1.2x106 cells/by LICA administration 3h after IS), group 4 (IS+EPCs/LICA administration post-day-3 IS), group 5 (IS+EPCs/LICA administration post-day-7 IS), group 6 (IS+EPCs/LICA administration post-day-14 IS) and group 7 (IS+EPCs/LICA administration post-day-28 IS). The brain-infarct volume (BIV) (at day 60/MRI) was lowest in group 1, highest in group 2 and significantly progressively increased from groups 3 to 7, whereas among the IS animals, the neurological function was significantly preserved in groups 3 to 6 than in groups 2 and 7 post-day-60 IS (all p<0.0001). By day 60, the endothelial cell markers at protein and cellular levels, and number of small vessels exhibited an opposite pattern of BIV among the groups (all p<0.0001). The protein and cellular levels of inflammation, and protein levels of oxidative stress, autophagy and apoptosis, were highest in group 2, lowest in group 1 and progressively increased from groups 3 to 7 (all p<0.0001). The angiogenesis biomarkers at protein and cellular levels were significantly progressively increased from groups 1 to 3, then significantly progressively decreased from groups 4 to 7 (all p<0.0001). Conclusion: Early EPC administration provided better benefits on improving functional/image/molecular-cellular outcomes after acute IS in rat.