| Objective: Prepare PLGA microparticles with Iron Oxide,and label tendon stem cells(TSCs)with the prepared particles,and discus the feasibility of tracking TSCs by using dual modal Photoacoustic and Magnetic Resonance imaging,for providing a new,effective,and valuable tracer technic to tracking stem cells in vitro and in vivo.Methods:1 Prepare PLGA microparticles with Iron Oxide(PLGA/IO MPs)by using double emulsion method,then the morphology and stability were observed;the size and Zeta potential were detected;and the Fe concentration of the PLGA/IO MPs was measured.2 The dual modal PA/MR of the PLGA/IO MPs with different Fe concentrations(25,50,100,200,400,600 mg Fe/ml)were performed.3 The TSCs were isolated and cultivated from the male SD rat Achilles tendon,and the properties of stem cells were identified.4 The TSCs were labeled with the PLGA/IO MPs,and the labeling situation were verified by using TEM,the methods of fluorescence dye and Prussian blue stain.5 The cytotoxicity of the TSCs labeled with different Fe concentrations(25,50,100,200,400 mg Fe/ml)PLGA/IO MPs were detected by applying CCK-8 method.6 The dual modal PA/MR imaging of the TSCs labeled with different Feconcentrations(25,50,100,200,400 m g Fe/ml)PLGA/IO MPs were operated.7 The statistical analysis was performed through SPSS13.0 software.The measurement data was showed as (?) ± S.One-way analysis of variance was applied in the comparisons of the PA and MR signal values of different Fe concentrations PLGA/IO MPs and labeled TSCs and the cell viability of the TSCs labeled with different Fe concentrations microparticles.Pearson’s correlation coefficient was used for analysis the Fe concentrations and PA and MR signal intensity.P < 0.05 was considered that the difference was statistically significant.Results:1 The prepared PLGA/IO MPs were present as claybank solution,and there were not any delamination and sedimentation in it.The optical microscopy showed that the microparticles were spherical,regular morphology,well distributed,stable in quality and no visible aggregation;Single microparticle was spherical,regular morphology,and there were large IO NPs loaded in the shell structure of the microparticle observed by TEM.The mean particle size was(801.5 ± 165.6)nm;the Zeta surface potentials of the microparticle without or with PLL were(-6.36 ± 3.36)mV and(3.16 ±3.69)mV respectively.The Fe content of the prepared 1.5 ml PLGA/IO MPs was 1.6 mg/ml measured by using atomic absorption spectrometry.2 The whole different Fe concentrations(25,50,100,200,400,600 mg Fe/ml)PLGA/IO MPs presented as corresponding PA signal and MR signal in PA and MR T2* WI imaging,which signal intensity enhancing with the increase of the Fe concentration of the PLGA/IO MPs(P < 0.05).3 The TSCs has been isolated and cultivated from the male SD ratAchilles tendon successfully,and the growth characteristic of TSCs: their CD44、CD90、SSEA4 and Nucleostemin were presented as positive.4 The results of the TEM,fluorescence staining and Prussian blue staining all showed that the PLGA/IO MPs were distributed in the cytoplasm of TSCs.5 The cytotoxicity detection: When the Fe concentration was 25,50,100,200 mg/ml respectively,the PLGA/IO MPs had no significant effect on the cell viability of TSCs;while the Fe concentration increased to 400 mg/ml,the cell viability decreased significantly(P <0.05)6 When the Fe concentration was 25,50,100,200 mg/ml respectively,the PA signal and MR T2* signal of the TSCs labeled with the PLGA/IO MPs were increased gradually;but,when the Fe concentration increased to 400m g/ml,the PA signal and MR T2* signal of the TSCs labeled with the PLGA/IO MPs were decreased obviously(P < 0.05).Conclusion:The following conclusions have been drew from experimental of the dual modal PA/MR imaging of the TSCs labeled with PLGA/IO MPs:1 The PLGA/IO MPs were stable quality,well distribution,which were a kind of multifunction molecular probe and could been detected by dual modal PA/MR imaging in vitro,which PA and MR signal intensity were increased with the increase of Fe concentration of PLGA/IO MPs.2 The TSCs could labeled with the PLGA/IO MPs effectively,which also could be tracking by dual modal PA/MR imaging.3 The 100 mg Fe/ml PLGA/IO MPs not only had no obvious effects on the viability of TSCs,but also could label the TSCs effectively and track the TSCs in vitro. |
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