Magneticiiy Labeling Of Rat Glioma Stem Cells And MR Tracking In Vitro

Backgrounds and PurposeNeurogliocytoma is the most common type solid tumors in central nervous system inadult,with the percentage of60in intracranial primarily tumor.Glioblastomas(WHOgrade Ⅳ gliomas),have the features of difficult to cure,easy to recur,high mortality andpoor prognosis, although treated with multimodel therapies including surgicalresection、chemotherapy and radiation.Since Ignatova reported neural stem-like cells incontex gliomas in2002,glioma stem cells have brought wide attention.Glioma stemcells share some critical characteristics with normal stem cells,such as mainteinedproliferation、self-renew and multi-potential differentiation.It may be the original cellsof gliomas and is the key to tumor recur.Its finding provides a new stratery for treatmentof gliomas.In this study, the serum-free medium culture method was used to isolate and cultureglioma stem cells from rat C6glioma and demonstrated their phenotypic characteristicsof stem cells.Then poly-L-lysine (PLL)-ultrasmall superparamagnetic iron oxide(USPIO) particles,as a intracelluer contrast agent,was inducted into glioma stem cells invitro and its effect on the biological characteristics of glioma stem cells was studied.Magnetic resonance imaging was performed to observe the magnetically labeled stemcells and look for the optimal sequence to provide a non-invasive technique to monitorthe migration and differentiation of injected glioma stem cells. Materials and methodsC6glioma cells were injected into the cerebral hemisphere of maleSprague–Dawley(SD) rats cerebral hemisphere,which weighing about250-300g.Fifteendays later,tumor were removed and tumor cells were dissotiated、cultured in serum-freemedium which contain growth factors.Poly-lysine (PLL)-ultrasmall superparamagneticiron oxide (USPIO) was inducted into glioma stem cells in vitro and positive labelingrate of stem cells was calculated, vitality was measured as well differrent days(1,3,5d)later. MTT assay method was used to evaluate the impact of magnetic labeling on theproliferation capacity of GSCs. T2and T2*maps sequences were utilized for MRscanning and measure the relaxation time and the relaxation rate at differentconcentrations of suspened cells were measured, and correlation between the relaxationrate and the cell concentration were analyzed as well.ResultsGlioma stem cells can be achieved from C6glioma after dissotiated and cultured inserum-free medium and were labeled by USPIO-PLL with efficiency as high as92%72hrs later.Trypan blue staining、MTT assay and intracranial inoculation in situ showedthat magnetic labeling had no significant harmful effect on the biological characteristicsof glioma stem cells.T2and T2*maps sepuences demonstrated that the singal intensityincreased with the decrease of cell concentration, and the relaxation rate decreased withthe cell concentration and there was a linear correlation. The slope of R2*effect was2.40times larger than the slope of R2effect.ConclusionGlioma stem cells can be achieved from rat with C6glioma.GSCs can be labeled byUSPIO effectively with the help of PLL as a transfection agent and had no significantharmful effect on glioma stem cells.T2*map sequence was sensitive to reflect the concentration of magnetically labeled glioma stem cells by signal change..