title: Macrophage and osteoblast responses to biphasic calcium phosphate microparticles.
abstract: The aim of this work was to investigate in vitro the biological events leading to ectopic bone formation in contact with microporous biphasic calcium phosphate (BCP) ceramics. After implantation, microparticles may arise from their degradation and induce an inflammatory response involving macrophages. The secretion of pro-inflammatory cytokines may affect the differentiation of osteoblasts. Mouse macrophage-like (J774) and osteoblast-like (MC3T3-E1) cells were cultured in the presence of BCP microparticles of different sizes (<20, 40-80, or 80-200 microm). The smallest microparticles decreased the viability of both cell types as measured with LDH and methyl tetrazolium salt assays, and enhanced the secretion of pro-inflammatory cytokines (IL-6 and TNF-alpha) by macrophages after 24 h, as revealed by ELISA. Osteoblastic cells were then cultured for 96 h in the presence of these pro-inflammatory cytokines and their differentiation studied by RT-PCR. MC3T3-E1 cells cultured with TNF-alpha showed a decrease in osterix, PTH receptor (PTHR1), and osteocalcin gene expression. On the contrary, IL-6 enhanced the expression of osterix, Runx2, alkaline phosphatase, and osteocalcin compared with plastic. In conclusion, this study shows that the inflammatory response initiated by BCP microparticles may have both detrimental and beneficial effects on osteogenesis.
authors.affiliation: Inserm, U791, Laboratory for Osteoarticular and Dental Tissue Engineering, Faculty of Dental Surgery, University of Nantes, 1 Place Alexis Ricordeau, 44042 Nantes, France. borhane.fellah@univ-nantes.fr
authors.forename: Borhane Hakim
authors.initials: BH
authors.lastname: Fellah
authors.forename: Bruno
authors.initials: B
authors.lastname: Delorme
authors.forename: Jérôme
authors.initials: J
authors.lastname: Sohier
authors.forename: David
authors.initials: D
authors.lastname: Magne
authors.forename: Pierre
authors.initials: P
authors.lastname: Hardouin
authors.forename: Pierre
authors.initials: P
authors.lastname: Layrolle
mesh_terms: D016475:3T3 Cells; D000469:Alkaline Phosphatase / Q000096:biosynthesis; D000818:Animals; D002130:Calcium Phosphates / Q000737:chemistry*; D050659:Core Binding Factor Alpha 1 Subunit / Q000096:biosynthesis; D016207:Cytokines / Q000378:metabolism*; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D007249:Inflammation; D008264:Macrophages / Q000166:cytology*; D051379:Mice; D008863:Microspheres; D010006:Osteoblasts / Q000166:cytology*; D015675:Osteocalcin / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000076182:Sp7 Transcription Factor; D014157:Transcription Factors / Q000096:biosynthesis
chemical_list: D002130:Calcium Phosphates; D050659:Core Binding Factor Alpha 1 Subunit; D016207:Cytokines; D000076182:Sp7 Transcription Factor; C479466:Sp7 protein, mouse; D014157:Transcription Factors; D015675:Osteocalcin; C020243:calcium phosphate; D000469:Alkaline Phosphatase