Study Design in Experiments 1 and 2.

Experiment 1 was conducted to identify the time point of human mesenchymal stem cell (MSC) transplantation that led to maximal neurological recovery in rats after middle cerebral artery occlusion (MCAO). In Experiment 2, MSCs were administered at 1 h after MCAO, the time point identified in Experiment 1 as being optimal for enabling maximal neurological recovery. Infarction volume, neurological recovery, MMP-2 and MMP-9 activity, and vascular density after MCAO were compared between the MSC 1-hour group and the control group.实验1旨在明确大鼠大脑中动脉闭塞（middle cerebral artery occlusion, MCAO）模型中，人间充质干细胞（human mesenchymal stem cell, MSC）移植可实现最大化神经功能恢复的时间节点。实验2中，研究人员于MCAO术后1小时移植MSC，该时间点为实验1筛选出的可实现最大神经功能恢复的最优移植时机。本研究比较了MSC 1小时移植组与对照组的脑梗死体积、神经功能恢复水平、基质金属蛋白酶-2（matrix metalloproteinase-2, MMP-2）与基质金属蛋白酶-9（matrix metalloproteinase-9, MMP-9）活性，以及MCAO术后的血管密度。