Fibroblast growth factor reversal of the corneal myofibroblast phenotype.
OBJECTIVE
Keratocytes give rise to fibroblasts and myofibroblasts in wounded cornea. It is well established that treatment of fibroblasts with transforming growth factor (TGF) beta will induce myofibroblast differentiation. We investigated whether this differentiation could be reversed by the administration of fibroblast growth factor (FGF).


METHODS
Cultured corneal myofibroblasts were plated at 200 cells/mm(2), and cells were grown in DMEM/F12 containing (1) 10% FBS or (2) 10% FBS with FGF and heparin or (3) 1% FBS or (4) 1% FBS with TGF-beta. As distinguished from the fibroblast phenotype, the myofibroblast phenotype was identified by the assembly of alpha-smooth muscle (SM) actin protein into the stress fiber cytoskeleton. To further characterize growth factor regulation of the two phenotypes, the phenotypic expression of TGF-beta receptor types I and II, cadherins, and connexin 43 by immunocytochemistry, Western blot analysis, and immunoprecipitation and of alpha-SM actin mRNA in Northern blot analysis were evaluated.


RESULTS
Corneal myofibroblasts replated and grown in the presence of FGF-1 or FGF-2 (20 ng/ml) plus heparin (5 microg/ml) in 10% FBS medium had decreased expression of alpha-SM actin protein, TGF-beta receptors, and cadherins. Thus, FGF-heparin decreased the myofibroblast phenotype and promoted the fibroblast phenotype. Administration of either 20 ng/ml FGF or 5 microg/ml heparin alone was not effective. Addition of TGF-beta further enhanced the expression of alpha-SM actin mRNA and protein and cell surface expression of TGF-beta receptors in myofibroblast cultures.


CONCLUSIONS
FGF-1 or -2 and heparin promoted the fibroblast phenotype and reversed the myofibroblast phenotype. This finding supports the idea that corneal myofibroblasts and fibroblasts are alternative phenotypes rather than terminally differentiated cell types.
Maltseva
O
O
Department of Ophthalmology, Mount Sinai School of Medicine of New York University, New York, New York 10029-6574, USA.
Folger
P
P
Zekaria
D
D
Petridou
S
S
Masur
S K
SK
D000199:Actins / Q000235:genetics / Q000378:metabolism; D030201:Activin Receptors, Type I; D000818:Animals; D015152:Blotting, Northern; D015153:Blotting, Western; D015820:Cadherins / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D002455:Cell Division; D002478:Cells, Cultured; D018031:Connexin 43 / Q000378:metabolism; D003315:Cornea / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D004338:Drug Combinations; D016220:Fibroblast Growth Factor 1; D016222:Fibroblast Growth Factor 2 / Q000494:pharmacology*; D005347:Fibroblasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D006493:Heparin / Q000494:pharmacology; D010641:Phenotype; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism
D000199:Actins; D015820:Cadherins; D018031:Connexin 43; D004338:Drug Combinations; D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; D016222:Fibroblast Growth Factor 2; D016220:Fibroblast Growth Factor 1; D006493:Heparin; D017346:Protein Serine-Threonine Kinases; D030201:Activin Receptors, Type I; D000077293:Receptor, Transforming Growth Factor-beta Type I; D000077294:Receptor, Transforming Growth Factor-beta Type II