Perimysial fibroblasts of extraocular muscle, as unique as the muscle fibers.
OBJECTIVE
Extraocular muscle (EOM) has a distinct skeletal muscle phenotype. The hypothesis for the study was that fibroblasts support the unique EOM phenotype and that perimysial fibroblasts derived from EOM have properties that distinguish them from fibroblasts derived from other skeletal muscle.


METHODS
Perimysial fibroblasts from leg muscle (LM-Fibro) and EOM (EOM-Fibro) of mice were derived and maintained in culture. EOM- and LM-Fibro were assessed morphologically and for vimentin, smooth muscle actin, and Thy-1 immunoreactivity. DNA microarray analysis was performed on LM- and EOM-Fibro grown in conditions that support myoblast differentiation. To assess trophic interactions, co-cultures of myoblasts from established cell lines, CL-EOM and CL-LM with, EOM- or LM-Fibro were performed in direct contact and in a permeable filter support culture. The degree of myotube maturation was assessed by the percentage of myotubes with more than three myonuclei per myotube.


RESULTS
EOM- and LM-Fibro cells exhibited distinct morphologies. Both cell types proliferated as a monolayer and expressed vimentin. Fifty-five percent (SD 4.4%) of EOM-Fibro were Thy-1 positive compared with only 24% (SD 4.4%) of LM-Fibro. DNA microarray analysis demonstrated differential expression of structural, immune response, and metabolism-related genes between EOM- and LM-Fibro. Co-cultures demonstrated that mature myotube formation in EOM-derived cell lines was supported to a greater extent by EOM-Fibro than by LM-Fibro, compared with CL-EOM grown with LM-Fibro.


CONCLUSIONS
Fibroblasts from EOM demonstrate distinct properties that distinguish them from leg muscle-derived fibroblasts. The distinct properties of EOM-Fibro may support the unique EOM phenotype and contribute to their differential involvement in disease.
Kusner
Linda L
LL
Department of Ophthalmology, Saint Louis University, St. Louis, Missouri 63104, USA. lkusner@slu.edu
Young
Andrew
A
Tjoe
Steven
S
Leahy
Patrick
P
Kaminski
Henry J
HJ
D000199:Actins / Q000378:metabolism; D000818:Animals; D002454:Cell Differentiation; D002478:Cells, Cultured; D018920:Coculture Techniques; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism; D005434:Flow Cytometry; D019084:Fluorescent Antibody Technique, Indirect; D020869:Gene Expression Profiling; D006614:Hindlimb / Q000166:cytology; D051379:Mice; D008810:Mice, Inbred C57BL; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000378:metabolism; D032446:Myoblasts / Q000166:cytology; D009801:Oculomotor Muscles / Q000166:cytology* / Q000378:metabolism; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D018800:Thy-1 Antigens / Q000378:metabolism; D014746:Vimentin / Q000378:metabolism
C558396:Acta2 protein, mouse; D000199:Actins; D018800:Thy-1 Antigens; D014746:Vimentin