Effect of hydroxyapatite and beta-tricalcium phosphate nanoparticles on promonocytic U937 cells.
OBJECTIVE
Nanoparticles from implanted materials are reported as the main cause of implant failure. Monocytes are among the first cells to colonize the inflammatory site. We evaluated the biological effects of bone substitutes presented to U937 cells in vitro as micron- or nanometer-sized particles.


METHODS
The HA (550 nm) and beta-TCP (550 nm) nanoparticles were incubated with U937 cells. Cell cycle modification, specific antigens expression, and the extent of cell death were determined.


RESULTS
Firstly, by using the sulforhodamine B (SRB) test and the annexin V-FITC analysis by flow cytometry, our results provide evidence of the absence of cytotoxicity, and show that nanoparticles do not induce more apoptosis than microparticles in U937 cells. Secondly, although morphologic evidence of stimulation of U937-cells was found by confocal microscopy, neither bone substitute altered the distribution of the cells into different phases of the cell cycle (Kit Cycle Test Plus DNA). These results suggest that nanoparticles do not cause promonocyte maturation in macrophages. Thirdly, the flow cytometry results showed no differences in the expression of the adherence and activation markers.


CONCLUSIONS
The results suggest that nanoparticles do not promote the differentiation of promonocytic U937 cells into macrophages and do not induce an enhanced inflammatory response.
Jeanne
Sylvie
S
Equipe de Biomatériaux en Site Osseux, UMR CNRS 6226, Sciences Chimiques de Rennes, Faculté d'Odontologie, Université de Rennes 1, Université Européenne de Bretagne, 2 Avenue du Professeur Léon Bernard, Bâtiment 15, 35043 Rennes Cedex, France.
Sylvie
Jeanne
J
Tricot-Doleux
Sylvie
S
Sylvie
Tricot-Doleux
TD
Pellen-Mussi
Pascal
P
Pascal
Pellen-Mussi
PM
Perez
Fabienne
F
Fabienne
Perez
P
Oudadesse
Hassane
H
Hassane
Oudadesse
O
Cathelineau
Guy
G
Guy
Cathelineau
C
D000704:Analysis of Variance; D015703:Antigens, CD / Q000378:metabolism; D017209:Apoptosis / Q000187:drug effects*; D018786:Bone Substitutes / Q000494:pharmacology*; D002130:Calcium Phosphates / Q000494:pharmacology*; D002453:Cell Cycle / Q000187:drug effects; D003601:Cytotoxicity Tests, Immunologic / Q000379:methods*; D017886:Durapatite / Q000494:pharmacology*; D005434:Flow Cytometry; D006801:Humans; D018613:Microscopy, Confocal; D053758:Nanoparticles / Q000737:chemistry*; D010641:Phenotype; D012235:Rhodamines; D020298:U937 Cells
D015703:Antigens, CD; D018786:Bone Substitutes; D002130:Calcium Phosphates; D012235:Rhodamines; C485817:beta-tricalcium phosphate; C022027:lissamine rhodamine B; D017886:Durapatite