Synovial fibroblasts self-direct multicellular lining architecture and synthetic function in three-dimensional organ culture.
OBJECTIVE
To define the intrinsic capacity of fibroblast-like synoviocytes (FLS) to establish a 3-dimensional (3-D) complex synovial lining architecture characterized by the multicellular organization of the compacted synovial lining and the elaboration of synovial fluid constituents.


METHODS
FLS were cultured in spherical extracellular matrix (ECM) micromasses for 3 weeks. The FLS micromass architecture was assessed histologically and compared with that of dermal fibroblast controls. Lubricin synthesis was measured via immunodetection. Basement membrane matrix and reticular fiber stains were performed to examine ECM organization. Primary human and mouse monocytes were prepared and cocultured with FLS in micromass to investigate cocompaction in the lining architecture. Cytokine stimuli were applied to determine the capacity for inflammatory architecture rearrangement.


RESULTS
FLS, but not dermal fibroblasts, spontaneously formed a compacted lining architecture over 3 weeks in the 3-D ECM micromass organ cultures. These lining cells produced lubricin. FLS rearranged their surrounding ECM into a complex architecture resembling the synovial lining and supported the survival and cocompaction of monocyte/macrophages in the neo-lining structure. Furthermore, when stimulated by cytokines, FLS lining structures displayed features of the hyperplastic rheumatoid arthritis synovial lining.


CONCLUSIONS
This 3-D micromass organ culture method demonstrates that many of the phenotypic characteristics of the normal and the hyperplastic synovial lining in vivo are intrinsic functions of FLS. Moreover, FLS promote survival and cocompaction of primary monocytes in a manner remarkably similar to that of synovial lining macrophages. These findings provide new insight into inherent functions of the FLS lineage and establish a powerful in vitro method for further investigation of this lineage.
Medical University of Vienna, Vienna, Austria.
Hans P
HP
Kiener
Gerald F M
GF
Watts
Yajun
Y
Cui
John
J
Wright
Thomas S
TS
Thornhill
Markus
M
Sköld
Samuel M
SM
Behar
Birgit
B
Niederreiter
Jun
J
Lu
Manuela
M
Cernadas
Anthony J
AJ
Coyle
Gary P
GP
Sims
Josef
J
Smolen
Matthew L
ML
Warman
Michael B
MB
Brenner
David M
DM
Lee
D000818:Animals; D005109:Extracellular Matrix / Q000648:ultrastructure; D005347:Fibroblasts / Q000502:physiology*; D006023:Glycoproteins / Q000096:biosynthesis; D006801:Humans; D007249:Inflammation / Q000503:physiopathology; D008264:Macrophages / Q000166:cytology; D051379:Mice; D009924:Organ Culture Techniques; D013582:Synovial Fluid / Q000737:chemistry*; D013583:Synovial Membrane / Q000033:anatomy & histology / Q000166:cytology*; D000099158:Proteoglycan 4
D006023:Glycoproteins; D000099158:Proteoglycan 4