title: Aqueous humor enhances the proliferation of rat retinal precursor cells in culture, and this effect is partially reproduced by ascorbic acid.
abstract: Aqueous humor has been shown to influence the proliferation of various ocular cell types, but the effect on immature retinal cells is not known. Here, the effect of pig aqueous humor on the proliferation of rat retinal precursor cells (RPCs) was investigated. RPCs were prepared from embryonic day 19 Sprague-Dawley rats and cultured in the presence or absence of aqueous humor from healthy pigs along with a medium consisting of Dulbecco's modified Eagle's medium:Ham's F-12 medium, N2 supplement, and epidermal growth factor. Proliferation was quantified by [(3)H]thymidine incorporation under different treatment conditions, and any associated morphological changes were noted. Potential active components of porcine aqueous humor were partially characterized by gel filtration chromatography, and the effect on RPC proliferation was determined. Results showed that adding 20% aqueous humor increased [(3)H]thymidine incorporation by as much as 317%, as compared with controls. Aqueous supplementation also increased both the number and size of RPC spherical aggregates ("spheres") over the first 4 days, consistent with increased proliferative activity. Using gel filtration and the in vitro proliferation assay, the growth-promoting activity of aqueous humor was localized to two different molecular mass ranges, namely, around 30 kDa and less than 1 kDa. Ascorbic acid was present in the lower molecular mass fraction, and use of this molecule reproduced some, but not all, of the proliferative activity present in aqueous humor. These results highlight the potential role of soluble factors present in the cellular microenvironment with respect to modulation of endogenous progenitor cell activity.
authors.affiliation: Laboratory of Experimental Immunology, Department of Medical Anatomy, Panum Institute, University of Copenhagen, Copenhagen, Denmark. yangjingbell@hotmail.com
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.forename: Henry
authors.initials: H
authors.lastname: Klassen
authors.forename: Mette
authors.initials: M
authors.lastname: Pries
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Mogens H
authors.initials: MH
authors.lastname: Nissen
mesh_terms: D000818:Animals; D001082:Aqueous Humor / Q000187:drug effects / Q000378:metabolism*; D001205:Ascorbic Acid / Q000032:analysis / Q000494:pharmacology*; D015415:Biomarkers; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002850:Chromatography, Gel; D016895:Culture Media, Serum-Free; D004815:Epidermal Growth Factor / Q000494:pharmacology; D005260:Female; D005615:Freezing; D008970:Molecular Weight; D051381:Rats; D017207:Rats, Sprague-Dawley; D012160:Retina / Q000166:cytology* / Q000187:drug effects*; D013056:Spectrophotometry, Ultraviolet; D013234:Stem Cells / Q000166:cytology* / Q000187:drug effects*; D013552:Swine
chemical_list: D015415:Biomarkers; D016895:Culture Media, Serum-Free; D004815:Epidermal Growth Factor; D001205:Ascorbic Acid