Objective   To investigate the value of imaging application to evaluate the therapeutic effect of mesenchymal stem cells (MSCs) transplantation in the treatment of ischemic stroke.    Methods   Totally 80 adult male Wistar rats were divided into sham operation group (n=5)

ischemic reperfusion (MCAO) group (

n

=25)

PBS treated group (

n

=25)and MSCs treated group (

n

=25). MSCs were isolated from the bone marrow of femur and tibia of male Wistar rats at the age of 4 to 6 weeks and identified with flow cytometry followed by SPIO labeling. MCSs of 2×10

6

were injected into ischemic reperfusion rats through tail vein to MSCs treated group 24 h after reperfusion

and 1 ml PBS were given to PBS group at the same time point. In 1

3

7

14 and 28 d after the establishment of experimental models

CT perfusion imaging (CTPI)

MR imaging

modified neurological severity scoring

2-3-5-triphenyltetrazolium (TTC) staining

HE staining and microvessel density analysis were carried out.    Results   There was no infarction and hemodynamic was normal at each time point in Sham group. In MCAO group

PBS group

and MSCs group

there was no significant difference in the volume of infarction among CBF and CBV values of CTPI

T

2

WI images and TTC staining.The infarction volume of MSCs group in 7

14 and 28 d was significantly smaller than MACO and PBS groups (

P

<

0.05). MSCs group had significantly increased rCBF compared with MCAO and PBS group in 7

14 and 28 d (

P

<

0.05). But neurological score was reduced

microvessel density raised

and HE staining showed cell degeneration and reduced necrosis.Long-T1

short-T2 signal was seen around the infarction in 3 and 7 d

and the low signal diffused to the direction of the infarction and the intensity reduced in MSCs group.    Conclusion   CTPI and MRI can be used to observe the effects of MSCs in the treatment of ischemic stroke about morphology and homodynamics

track the survival

migration and differentiation of magnetic labeled cells in living animal

and provide a broad platform for stem cell transplantation.