POSTER PRESENTATION Open Access

Osteoblast differentiation from synovial fluid cellsin juvenile idiopathic arthritis (JIA)Marija Jelusic-Drazic1*, Elvira Lazic Mosler2, Danka Grcevic2, Mandica Vidovic1, Ana Marusic2, Natasa Kovacic2

From 2011 Pediatric Rheumatology Symposium sponsored by the American College of RheumatologyMiami, FL, USA. 2-5 June 2011

PurposeJuvenile idiopathic arthritis (JIA) is one of the leadingcauses of disability in children characterized by destruc-tion of articular cartilage and underlying bone, as wellas synovial hyperplasia. Since synovia contains osteoblastprogenitors, hyperplastic changes may contribute tojoint destruction by inhibition of osteoblast differentia-tion. Osteoblasts are also immunoregulatory cells andtheir inhibited differentiation and function may affectjoint inflammation. The objective of this report is toexplore the osteoblastogenic potential of synovial fluidcells in JIA and to examine whether synovial fluid fromchildren with JIA effects osteoblast differentiation ofhuman bone marrow cells in vitro. Additionaly, weaimed to determine and compare the local and systemicexpression of osteoblast related genes in patients withJIA.

MethodsBlood samples were obtained from 21 children with oli-goarticular JIA (oJIA), 21 children with polyarticular JIA(pJIA), and 24 control children. Synovial fluid sampleswere collected from 21 children with oJIA and 6 childrenwith pJIA. Peripheral blood cells from healthy controlsand children with JIA, as well as synovial fluid cells fromchildren with JIA were used to analyze the gene expres-sion of Runx1, Runx2, Runx3, osteoprotegerin (OPG)and receptor activator of nuclear factor kappa-B ligand(RANKL) by quantitative polymerase chain reaction.Osteoblastogenesis from synovial cells was induced in a-MEM medium supplemented with 10% fetal bovineserum, 50 μg/ml ascorbic acid and 5 mmol b-glyceropho-sphate, and assessed by alkaline phospatase (AP) stainingof osteoblast colonies on culture day 21. The humanbone marrow cells from healthly donor were cultured for

17 days with 10% synovial fluid from children with JIA.Osteoblast differentiation was compared with non-trea-ted cells, assessed by AP activity.

ResultsSynovial cells from children with oJIA formed more APpositive colonies on culture day 21, in comparison tosynovial cells from children with pJIA (784.81±216.79 vs.257.21±68.13 arbitrary units, p<0.001, t-test). As assessedby AP activity synovial fluid from children both withoJIA and pJIA inhibited osteoblast differentiation ofhuman bone marrow cells (0.059±0.026 in oJIA; 0.068±0.019 in pJIA vs. 0,115 ± 0,023 in control cultures,p<0.05, t-test). Gene expression of Runx1, Runx2, Runx3and RANKL was higher in synovial fluid of children withpJIA than with oJIA.The expression of osteoblast relatedgenes in peripheral blood mononuclear cells from chil-dren with JIA was similar to healthy controls.

ConclusionOsteoblast differentiation is locally inhibited in childrenwith JIA, which is particularly pronounced in poliarticu-lar disease. Osteoblast differentiation potential of syno-vial cells may serve as an important prognostic andtherapeutic factor in JIA

DisclosureMarija Jelusic-Drazic: None; Elvira Lazic Mosler: None;Danka Grcevic: None; Mandica Vidovic: None; AnaMarusic: None; Natasa Kovacic: None.

Author details1University Hospital Center Zagreb, Zagreb, Croatia, Croatia. 2University ofZagreb School of Medicine, Zagreb, Croatia.

Published: 13 July 2012

1University Hospital Center Zagreb, Zagreb, Croatia, CroatiaFull list of author information is available at the end of the article

Jelusic-Drazic et al. Pediatric Rheumatology 2012, 10(Suppl 1):A115http://www.ped-rheum.com/content/10/S1/A115

© 2012 Jelusic-Drazic et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the CreativeCommons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, andreproduction in any medium, provided the original work is properly cited.

doi:10.1186/1546-0096-10-S1-A115Cite this article as: Jelusic-Drazic et al.: Osteoblast differentiation fromsynovial fluid cells in juvenile idiopathic arthritis (JIA). PediatricRheumatology 2012 10(Suppl 1):A115.

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Jelusic-Drazic et al. Pediatric Rheumatology 2012, 10(Suppl 1):A115http://www.ped-rheum.com/content/10/S1/A115

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