Internalization of mesoporous silica nanoparticles induces transient but not sufficient osteogenic signals in human mesenchymal stem cells.
The biocompatibility of nanoparticles is the prerequisite for their applications in biomedicine but can be misleading due to the absence of criteria for evaluating the safety and toxicity of those nanomaterials. Recent studies indicate that mesoporous silica nanoparticles (MSNs) can easily internalize into human mesenchymal stem cells (hMSCs) without apparent deleterious effects on cellular growth or differentiation, and hence are emerging as an ideal stem cell labeling agent. The objective of this study was to thoroughly investigate the effect of MSNs on osteogenesis induction and to examine their biocompatibility in hMSCs. Uptake of MSNs into hMSCs did not affect the cell viability, proliferation and regular osteogenic differentiation of the cells. However, the internalization of MSNs indeed induced actin polymerization and activated the small GTP-bound protein RhoA. The MSN-induced cellular protein responses as believed to cause osteogenesis of hMSCs did not result in promotion of regular osteogenic differentiation as analyzed by cytochemical stain and protein activity assay of alkaline phosphatase (ALP). When the effect of MSNs on ALP gene expression was further examined by reverse transcriptase polymerase chain reaction, MSN-treated hMSCs were shown to have significantly higher mRNA expression than control cells after 1-hour osteogenic induction. The induction of ALP gene expression by MSNs, however, was absent in cells after 1-day incubation with osteogenic differentiation. Together our results show that the internalization of MSNs had a significant effect on the transient protein response and osteogenic signal in hMSCs, thereby suggesting that the effects of nanoparticles on diverse aspects of cellular activities should be carefully evaluated even though the nanoparticles are generally considered as biocompatible at present.
Huang
Dong-Ming
DM
Center for Nanomedicine Research, National Health Research Institutes, Miaoli 350, Taiwan. dmhuang@nhri.org.tw
Chung
Tsai-Hua
TH
Hung
Yann
Y
Lu
Fang
F
Wu
Si-Han
SH
Mou
Chung-Yuan
CY
Yao
Ming
M
Chen
Yao-Chang
YC
D000199:Actins / Q000378:metabolism; D000469:Alkaline Phosphatase / Q000378:metabolism; D001672:Biocompatible Materials / Q000378:metabolism*; D002454:Cell Differentiation; D002470:Cell Survival; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000378:metabolism; D015870:Gene Expression; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000378:metabolism*; D053758:Nanoparticles; D010012:Osteogenesis; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D012822:Silicon Dioxide / Q000378:metabolism*; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
D000199:Actins; D001672:Biocompatible Materials; D012333:RNA, Messenger; D012822:Silicon Dioxide; D000469:Alkaline Phosphatase; D020742:rhoA GTP-Binding Protein