Effect Of CdTe QDs On Proliferation And Neurogenic Potential Of Rat Bone Marrow Mescenchymal Stem Cells

Cadmium telluride (CdTe) quantum dots (QDs) is a kind of nano-material with uniquefluoresce characters, which provides them a promising future for live cell tracking.Differently sized CdTe QDs can be exited at a same source of light, and emitfluorescent lights of different wavelengths and colors, the wavelengths of which isnarrow enough so as to be distinguished conveniently. Besides, CdTe has a relativelyeasier way of synthesize and a higher yielding rate, and under the protection ofcoatings, they could be more stable under different conditions, all the above makingthem an ideal live cell tracking agent. However, CdTe QDs contain heavy metal Cd,which may well be toxic to organism and cells, that is why many researches haveaddressed the toxic effect of CdTe QDs, but the given studies were mostly performedon non-mammal cell lines, and about the effect on cell proliferation, there is a lack ofstudies on cell physiology biochemistry and biological properties. Bone marrowmescenchymal stem cells (BMSCs) is one kind of pluripotent stem cells, they can beinduced into nerve-like cells, osteoblast, adipose cells and myocardial cells and so onin vitro, meaning potential cure for many diseases. But most stem cell technologiesare still in the stage of experiment, and live cell fluoresce labeling is very useful intracking the locations and analyzing the translocating mechanism of the implantedstem cells. Thus, owing to the advantage of CdTe QDs as a living cell tracking agent,it would be of great importance if it could be used to track living cells. But it is notenough to just determine the dose by cytotoxicity, their effects on stem celldifferentiation should also be considered. This study chosed rat BMSCs as experimental objects, featuring their pluripotency, exploring the effect of CdTe QDson the proliferation and neurogenic protential of rat BMSCs, and provide furtherevidence for CdTe QDs applications at a safe and reasonable dose..The characherization of CdTe QDs soluted in DMEM/F-12was examined, rat BMSCswere purified and expanded by the method of adherent culturing, and hexadecadrol,sodium glycerophosphate and Vitamin C were used to induce osteogenesisdifferentiation.BMSCs were exposed under different concentrations of CdTe QDs,（0.00pM，3.05pM，6.10pM，12.21pM，24.41pM，48.83pM，97.66pM，195.31pM，390.63pM，781.25pM）. MTT assays were used to examine the cell viabilities of BMSCs, assessthe effect of QDs on the BMSCs proliferation. Then BMSCs were exposed under alower series of CdTe QDs concentrations（3.05pM，6.10pM，12.21pM，24.41pM，48.83pM）for48h, then the cells were subjected to induced neurogenic differentiation(bFGF, EGF for3d, RA for7d)Immunocytochemistry and immunocytofluorescentwere used to examine the expression of three neuronal marker proteins: MAP-2,NeuN, NSE and an astrocyte marker, GFAP. RT-PCR was used to detect thetranscription of to neuronal marker gene NSE and asteocyte marker gene GFAP, inorder to assess the effect of QDs on the BMSCs neurogenic potential.Phosphorescence spectrum and transmission electron microscope results showed thatCdTe QDs were well-dispersed into DMEM/F-12medium, no aggregation ordecomposition were implied. Upon7days of in vitro culturing, the rat BMSCs weregrowing fast and proliferating strong. After inducing into osteogenesis differentiation,alizarin red staining results showed obvious calcification knots, confirming theBMSCs have differentiated into osteoblasts. MTT assays showed that when BMSCsexposed under CdTe QDs for24h,48.83pM or more could cause significant impacton BMSCs proliferation(P＜0.05), while exposed for48h, it could impact BMSCsproliferation at24.41pM or more(P＜0.05). And the longer and heavier of exposuretime and concentration was, the more toxic CdTe QDs could be.Immunocytochemistry and immunocytofluorescent showed that, the expression of the three neuronal cell marker protein, MAP-2, NeuN, NSE and astrocyte marker peoteinGFAP were inhibited at12.21pM and more (P＜0.05). RT-PCR results showed thatthe transcription of NSE and GFAP were also inhibited at12.21pM and more(P＜0.05).Conclusion: Under certain dose, CdTe QDs could inhibit BMSCs cell viability,showing cytotoxicity. Under certain dose, CdTe QDs could block neural markerprotein expression of MAP-2, NeuN, NSE and GFAP. Under certain dose, CdTe QDscould weaken the gene transcription of NSE and GFAP. Under a dose that would notinhibit BMSCs viability, CdTe QDs could cause decrease to the neural differentiationof BMSCs.