| Rare earth elements are widely used in industry and agriculture due to their unique physical and chemical properties.With the rapid development of nanotechnology,rare earth nanomaterials have been widely developed and applied in recent years.With the increase of exposure to nanoparticles of rare earth elements,the biological safety has become a new issue that cannot be ignored.Many studies have reported that rare earth ions are similar to Ca2+,and are easy to accumulate in bone tissue,replacing calcium and disturbing bone metabolism.Therefore,rare earth ions and rare earth nanoparticles have been extensively studied in bone repair and bone disease treatment.Among them,La3+related research has the most reports and is the most representative.However,there are few studies on the effect of La?OH?3nanoparticles on bone metabolism.Therefore,it is very important to investigate the effect of La?OH?3 nanoparticles on osteogenic differentiation of bone marrow mesenchymal stem cells?BMSCs?.Based on these reasons,three different size La?OH?3 nanorods were firstly prepared by hydrothermal method,and their physical and chemical properties were characterized and analyzed by SEM,TEM,DLS,XRD,FT-IR and TGA.The cytotoxicity and blood compatibility of La?OH?3 nanorods were detected by MTT assay,live/dead staining and hemolysis test.In terms of osteogenic differentiation of BMSCs,by analyzing the expression of ALP,osteogenic marker genes?BMP2 and Runx2?and cell morphological changes,and mineralization experiments,the effects of different size La?OH?3 nanorods on osteogenic differentiation of BMSCs were comprehensively evaluated.Furthermore,the distribution of La?OH?3 nanorods in cells was analyzed by fluorescence co-localization,and the stability of La?OH?3 nanorods in lysosomal mimic solution?LSBF buffer?was discussed.The results show that the size of the prepared La?OH?3 nanorods is significantly different.Long-La?OH?3nanorod:length 643.09±123.78 nm,diameter 83.54±13.73 nm;medium-La?OH?3 nanorods:length 254.88±56.82 nm,diameter 38.84±7.19 nm;short-La?OH?3 nanorods:80.51±17.78nm in length and 33.64±5.39 nm in diameter.XRD,FTIR and TGA results show that the three La?OH?3 nanorods are hexagonal crystals and contain no other impurities.In the concentration range of 1.05.0?g/mL,La?OH?3 nanorods have good cell activity and blood compatibility.La?OH?3 nanorods with different sizes have different effects on osteogenic differentiation of BMSCs.Among them,the short-La?OH?3 nanorods promoted the expression of ALP and osteogenic marker gene BMP2.The cells had richer cell microfilament structure and more obvious pseudofoot extension,and the cell spreading area became larger than that of the control group.However,all La?OH?3 nanorods had no significant effect on the final mineralization of the cells.Fluorescence co-localization revealed that La?OH?3 nanorods would enter the lysosome after being taken up by the cells.By comparing the fluorescence intensity,it was found that there were more short-La?OH?3nanorods had being taken up by the cells.In the LSBF buffer,La?OH?3 nanorods were degraded and the concentration of free La3+was significantly reduced.At the same time,the morphology of these nanoparticles changed significantly.It is speculated that La?OH?3 may react with phosphate in the lysosome to form LaPO4,which may affect the osteogenic differentiation of BMSCs.This article provides some scientific basis for the design and development of lanthanum-based nanoparticles in bone repair materials. |
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