Trzcking Of Transplantion Mesenchymal Stem Cells In Tail Vein After Cerebral Ischemia In Rats By Magnetic Resonance Imaging In Vivo

PART 1 AN IN VITRO STUDY ON MR IMAGING OF MESENCHYMAL STEM CELLS LABELED WITH SUPERPARAMAGNETIC IRON OXIDEObjective: To explore the proper concentration of superparamagnetic iron oxide(SPIO) labeling mesechymal stem cells(MSCs) and the influence on cellular biology under different labeling concentrations,and to evaluate the characteristics of magnetic resonance imaging by a 1.5T MR scanner.Methods: MSCs (5th) were incubated with different concentrations of SPIO particles. The location, distribution and the labeling ratio of SPIO particles in cells were observed. An optimal concentration of 28μg/ml was used, and the SPIO-labeled and unlabeled MSCs suspension in agar were imaged by MRI with T1WI, T2WI and T2*WI. The signal intensity were measured and analyzed statisticallyResults:Labeled SPIO particles were stained in cytoplasm. MSCs were efficiently labeled (92% to 97%) with 28 to 56μg Fe/ml particle concentrations after cultured for 24 hours. Compared with unlabeled cells,MSCs loaded with SPIO had similar viability and proliferation profiles at this proper range of labeling concentration. MR imaging demonstrated that with the increasing of cells quantity, the signal of labeled cells manifested the tendency of linearity decreasing.Conclusions:MSCs can be easily and efficiently labeled by SPIO without interfering on cell viability and proliferation, MRI visualization of SPIO-labeled MSCs is feasible, and provides useful data for next in vivo studies.PART 2 THE EFFECTS OF X-RAY RADIATION ON MESENCHYMAL STEM CELLS OF RAT UNDER CT CEBERAL PERFUSION IN VITROObjective: The aim of the present study is to investigate direct effect of X-ray radiation on cultured rat messenchymal stem cells under CT rat ceberal perfusion in vitro.Methods: Marrow mesenchyma was divided into control group and irradiation group, under the irradiation group cell distinction line of 1-5 scanning of rat brain CT perfusion. After irradiation, cellular growth curves of the two groups were recorded separately, and the changes of cell cycle were detected by FCM, as well as the changes of apoptosis of were detected by MTT examination.Results: The cellular activities and apoptosis of experimental group were not different from that of control.Conclusions: The scanning of conventional rat brain CT perfusion has not influence on the cell activities.PART 3 TRACKING OF MESENCHYMAL STEM CELLS BY MAGNETIC RESONANCE IMAGING WITH A TRANSPLANTATION BY TAIL VEIN AFTER CEREBRAL ISCHEMIA IN RATSObjective: To explore the feasibility of in vivo tracking of mesenchymal stem cells(MSCs) labeled with superparamagnetic iron oxide(SPIO) by magnetic resonance imaging(MRI) in rats after cerebral ischemic, and to analyze the influence of stem cell therapy on the area of cerebral infarction.Methods: MSCs were labeled with SPIO, which was mixed with poly-L-lysine. The labeling efficiency was evaluated by Prussian blue staining. Transient middle cerebral arterial occlusion (MCAo) was performed successfully in 50 adult Sprague-Dawley rats. The 50 rats were then randomly divided into two groups, which were cell transplanting group and control group. In cell transplanting group, MSCs were injected into the tail vein in 24 hours after MCAo. MRI was performed 1 day after MCAo, 1 day, 3 days, 1 week, 2 weeks and 4 weeks after transplantation. The volume of infarcted brain tissue was measured and analyzed.Results: The labeling efficiency of SPIO on MSCs was 92%, and the cell viability was 97%. MRI confirmed that the transplanted MSCs migrated to the ischemic area after transplanted for 1 week. The changes of infarction volume were significantly different between experimental group with control.Conclusions:MRI is feasible for in vivo tracking of MSCs labeled with SPIO in rats. The transplanted stem cell could be useful to decrease the volume of cerebral infarction.