Transforming growth factor-beta 1 promotes contraction of collagen gel by bovine corneal fibroblasts through differentiation of myofibroblasts.
OBJECTIVE
To determine whether the ability of transforming growth factor-beta (TGF-beta) to influence the contractile activity of corneal fibroblasts depends on their differentiation into myofibroblasts.


METHODS
Bovine corneal fibroblasts were cultured on collagen gel in MED 5 medium (F-12 nutrient mixture supplemented with 5% fetal bovine serum) with or without TGF-beta 1 (0.01-10 ng/ml). To evaluate the corneal fibroblast-derived contraction of collagen gel, the thickness of the gel was measured daily for 6 days. The total number of cells on the gel was counted with a Coulter counter. The detection of alpha-smooth muscle actin (alpha-SMA); a marker for myofibroblasts, on these cells was performed immunocytochemically by using a mouse monoclonal antibody against alpha-SMA. The number of myofibroblasts (alpha-SMA-positive cells) was determined.


RESULTS
The control gels containing bovine corneal fibroblasts that were cultured with the MED 5 medium alone significantly contracted to 72.3 +/- 1.2% of their original thickness after 6 days. TGF-beta 1 increased the contraction of collagen gel mediated by bovine corneal fibroblasts in a dose-dependent manner. Approximately 0.2% of the cells on the control gels cultured with MED 5 medium alone were alpha-SMA positive. TGF-beta 1 significantly increased the expression of alpha-SMA in a dose-dependent manner. There was no significant correlation between the thickness of the collagen gel and the total number of cells. However, there was a significant negative correlation between the thickness of collagen gel and the number of myofibroblasts.


CONCLUSIONS
TGF-beta 1 increased the contractile activity of bovine corneal fibroblasts and their ability to differentiate into myofibroblasts. Because contractile activity was correlated with differentiation, the influence of TGF-beta 1 on corneal fibroblast-induced collagen gel contraction may depend on the promotion of myofibroblast differentiation.
Kurosaka
H
H
Department of Ophthalmology, Keio University, School of Medicine, Tokyo, Japan.
Kurosaka
D
D
Kato
K
K
Mashima
Y
Y
Tanaka
Y
Y
D000199:Actins / Q000378:metabolism; D000818:Animals; D000911:Antibodies, Monoclonal; D002417:Cattle; D002454:Cell Differentiation / Q000502:physiology; D002455:Cell Division; D002465:Cell Movement / Q000187:drug effects; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism*; D003315:Cornea / Q000166:cytology / Q000502:physiology*; D003470:Culture Media; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000166:cytology / Q000502:physiology; D005782:Gels; D007124:Immunoenzyme Techniques; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D000199:Actins; D000911:Antibodies, Monoclonal; D003470:Culture Media; D005782:Gels; D016212:Transforming Growth Factor beta; D003094:Collagen