| Hypertension is a common disease in the elderly, the prevalence rate of this desease isclose to20%in our country. Most patients of dental restoration and implantation are middleaged and elderly people, so the proportion of patients with high blood pressure is larger.Calcium antagonist is one of the most commonly used medicine in the treatment ofhypertensive disease, including nifedipine, amlodipine, etc. Whether the calcium antagonistwould cause osteoporosis and further affect oral treatment, or the drug could promote boneformation and prevent osteoporosis. These issues are worthy of attention and exploration.Benidipine (BD) is the second generation of dihydropyridine calcium antagonist, whichis often used for hypertension and angina pectoris. Previous studies have demonstrated thatBD has a positive effect on bone metabolism. Inspired by this promoting phenomenon, thepresent study investigated the effects of BD on osteoblast function in vitro. We preparedmagnesium silicate nanospheres (MSNs) and used it as nanocarriers to make BD-MSNs drugdelivery system for promoting the function of osteoblasts. The preparation of BD-MSNs drugdelivery system improved the stability of the drug, and also provided a theoretical basis forthe further clinical application.In addition we used MSNs as the chemotherapy drug carrier for the first time to preparethe drug delivery system of doxorubicin (DOX), evaluated its drug loading capacity and drugrelease property. We also explored the effects of DOX-MSNs drug delivery system on theinhibition of tumor in vitro and in vivo, which provided a theoretical basis for the clinicalapplication of DOX-MSNs drug delivery system.1. Effects of benidipine on osteoblast function in vitroObjective: To investigate the effects of benidipine (BD) on osteoblast function in vitro.Methods: A solution of BD was prepared by dissolving solid BD in DMSO solvent.Experiments were designed and performed, including an MTT assay, reverse transcription- polymerase chain reaction, western blot analysis, alkaline phosphatase activity measurementsand alizarin red staining.Results: BD promoted proliferation of MC3T3-E1cells at concentrations of10-9~10-6mol/L. The higher concentrations of BD inhibited cell proliferation whereas no significantdifference from the control was observed when the lower concentrations of BD were applied.So the concentrations of10-9~10-6mol/L was chosen for further experiments. Followingtreatment of the drug, BMP2, OCN and Runx2mRNA and protein levels were markedlyupregulated compared with those in the control group. ALP activity was enhancedsignificantly in a time dependent manner when osteoblasts were treated with BD. BD alsopromoted the formation of mineralized matrix nodules in the MC3T3-E1cells.Conclusion: BD promoted cell proliferation and osteogenic differentiation atconcentrations of10-9~10-6mol/L by upregulating BMP2, OCN and Runx2gene expressionlevels. BD promoted osteogenesis most markedly at concentrations of10-7mol/L.2. The preparation of magnesium silicate nanospheres and evaluation of theirbiocompatibilityObjective: To investigate morphological and structural features of magnesium silicatenanospheres (MSNs) and evaluate their biocompatibility in vitro and in vivo.Methods: Monodispersed silica colloidal spheres were synthesized in accordance withthe St ber method and then were used for the preparation of MSNs. Detailed morphologicaland structural features of MSNs were examined via scanning electron microscopy (SEM) andtransmission electron microscopy (TEM). Energy dispersive spectroscopy (EDS) analysisconfirmed the elements of our product. The N2adsorption and desorption analysis wasintroduced to investigate the pore properties of MSNs. Cellular modality, hemolysis assay andMTT assay were used to evaluate the cytotoxicity of MSNs in vitro. Body weightmeasurements, histology analysis, hematology analysis and blood biochemical assay wereused to detect the biocompatibility of MSNs in vivo.Results: The MSNs were uniform hollow spheres, the average diameter was nearly400nm and the specific surface area was498m2/g. MSNs were mesoporous materials, an averagediameter width of pores was4.32nm. In vitro experiment no obvious differences in the cell morphology and cell viability for the cells treated with MSNs were observed at theconcentration of200μg/ml. No hemolysis of RBCs could be detected upon the maximalconcentration of200μg/ml. There was nearly no difference in body weight measurements,histology analysis, hematology analysis and blood biochemical assay between test andcontrol groups in vivo.Conclusion: The MSNs had good biocompatibility and low biological toxicity, thus itcould be used as a practical and powerful nanocarrier for drugs. Nanocarriers based on MSNscould serve meeting the criteria as a high performance biomedical material.3. Effects of benidipine-loaded magnesium silicate nanospheres on osteoblast function invitroObjective: To investigate the effects of benidipine-loaded magnesium silicatenanospheres (BD-MSNs) on osteoblast function in vitro.Methods: Prepared BD-MSNs and evaluated the drug loading capacity. Theconcentration of BD was10-7mol/L in this experiment. Cell morphology was observed, MTTassay, alkaline phosphatase activity measurements and alizarin red staining were used toevaluate the effect of BD-MSNs on cell proliferation and osteogenic differentiation.Results: The BD loading capacity of BD-MSNs was450mg/g. No obvious differencesin the cell morphology for the cells treated with BD-MSNs were observed at the experimentalconcentration. BD-MSNs had a better effect on proliferation and osteogenic differentiation ofMC3T3-E1cells compared to BD at the concentration of10-7mol/L.Conclusion: BD-MSNs prepared in our experiment had good biocompatibility. Thisdrug delivery system had a better effect on proliferation and osteogenic differentiation ofMC3T3-E1cells compared to BD at the concentration of10-7mol/L.4. Uniform magnesium silicate nanospheres as high drug-loading nanocarriers forcancer therapyObjective: To evaluate drug loading capacity and drug release property of drug deliverysystem of doxorubicin (DOX-MSNs), and to explore the effects of DOX-MSNs on theinhibition of tumor in vitro and in vivo.Methods: MSNs (200μg/mL) at different pH values ranging from5to8was dispersed in various concentrations of DOX solution and stirred overnight to get the DOX-MSNs. TheUV-vis absorbance method was used to determine the loading and releasing amount of DOX.Endocytosis study was used to detect the accumulation of MSNs in tumer cells. MTT assay,tumer size measurement and TUNEL assay were used to evaluate the effects of DOX-MSNson the inhibition of tumor.Results: The drug-loading capacity was2140mg/g upon optimum conditions (pH8anda DOX concentration of500μg/ml). Approximately70%of the drug was released within24hat pH5.0, whereas at pH7.4, about32%of the drug was released. Most DOX-MSNsmolecules accumulated in lysosomes of tumer cells. DOX-MSNs had a better effect oninhibiting tumor cell proliferation in vitro compared to DOX at the same concentration.Tumer size measurement and TUNEL assay showed the same effect of DOX-MSNs in vivo.Conclusion：MSNs exhibited a significantly high storage capacity of DOX (2140mg/g)and held a sustained release property, showing more potential for cancer therapy. MSNs weremostly accumulated in lysosome, indicating their pH-dependent release character.DOX-MSNs could effectively suppress tumor growth and induce cancer cell destruction. |
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