Objective  To investigate the apoptosis of neurons in the penumbra of cerebral ischemic rats transplanted with bone marrow derived-mesenchymal stem cells(BMSCs).

  Methods  Bone marrow of a healthy adult volunteer was collected, and BMSCs were cultivated and harvested.Adult rats subjected to 2 h middle cerebral artery occlusion(MCAO)were randomly assigned to the BMSCs-treated group(n=12)and the control group(n=12), in which rats were transplanted with 5×10⁵ BMSCs or saline, respectively, into the ipsilateral brain parenchyma on the 3rd post-MCAO day.The modified neurological severity scores(mNSS)was used to measure functional recovery.On the 14th post-MCAO day, apoptotic cells in the penumbra were detected by TUNEL analysis.On the 28th post-MCAO day, neurons were stained by immunoflu-orescence, and hematoxylin-eosin staining was used to evaluate the relative ischemic volume.

  Results  TUNEL-positive cells were significantly reduced(P=0.017), and in contrast, neuronal nuclei antigen(NeuN)-positive cells were significantly increased(P=0.015)in the penumbra in BMSCs-treated group compared with control group.The relative ischemic volume was decreased in the BMSCs-treated group(28.3±4.5)% compared with the control group(36.8±5.6)%(P=0.041).The mNSS was significantly decreased in BMSCs-treated group at each time point starting on the 14th post-MCAO day compared with control group(P < 0.05).

  Conclusion  BMSCs treatment can decrease ischemic volume and improve functional recovery after cerebral ischemia, which may, at least partially, attribute to the reduced apoptosis of neurons in the penumbra.