Fibroblast growth factor and epidermal growth factor differently affect differentiation of murine retinal stem cells in vitro.
OBJECTIVE
The developmental processes that mediate differentiation from retinal stem cells (RSC) to different retinal neuronal types remain unclear. During retinal development, progenitor cells modify expression of growth factor (GF) receptors and their differentiation potentials. Similarly, RSC in culture may exhibit alternative molecular characteristics in response to different GF stimuli.


METHODS
RSC were purified from the adult ciliary margin and exposed to fibroblast growth factor (FGF), epidermal growth factor (EGF), or FGF+EGF. Proliferation was analyzed by bromodeoxyuridine (BrdU) labeling. Differentiation was evaluated by immunofluorescence with antibodies recognizing specific markers of different retinal cell types.


RESULTS
In the absence of GF stimuli, RSC in culture expressed FGFR1, similar to early progenitors in vivo. Treatment with GFs up-regulated the expression of both fibroblast growth factor receptor 1 (FGFR1) and epidermal growth factor receptor (EGFR). Exposure to either FGF, EGF, or FGF+EGF strongly affected retinal stem cell-renewal and differentiation. Specifically, expression of progenitor/stem cell markers and stem cell-renewal was higher in the presence of FGF than in that of EGF. FGF favored differentiation of RSC into photoreceptor-like cells. Finally, we showed that the treatment of the primary culture with FGF+EGF imprinted the cells and limited plasticity in subsequent differentiation.


CONCLUSIONS
We provide evidence that conditions of the primary culture have a strong influence on cell-renewal and differentiation potentials of RSC.
Giordano
Francesca
F
Telethon Institute of Genetics and Medicine, Naples, Italy.
De Marzo
Anna
A
Vetrini
Francesco
F
Marigo
Valeria
V
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D004357:Drug Synergism; D004815:Epidermal Growth Factor / Q000494:pharmacology*; D066246:ErbB Receptors / Q000378:metabolism; D005346:Fibroblast Growth Factors / Q000494:pharmacology*; D051379:Mice; D008810:Mice, Inbred C57BL; D020419:Photoreceptor Cells, Vertebrate / Q000166:cytology; D051496:Receptor, Fibroblast Growth Factor, Type 1 / Q000378:metabolism; D012160:Retina / Q000166:cytology* / Q000378:metabolism; D013234:Stem Cells / Q000166:cytology* / Q000378:metabolism; D015854:Up-Regulation
D015415:Biomarkers; D005346:Fibroblast Growth Factors; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; C496349:Fgfr1 protein, mouse; D051496:Receptor, Fibroblast Growth Factor, Type 1