Effect of Insulin-Like Growth Factors 1 and 2, and Glucose on the Migration and Proliferation of Bovine Retinal Pigment Epithelial Cellsin vitro

Abstract

Background: The retinal pigment epithelium (RPE) has been implicated in the development of diabetic retinopathy and it has been suggested that insulin-like growth factors (IGF) and glucose may be among those factors which are responsible for the RPE changes in diabetics. The purpose of this study was to investigate the effect of IGF-1, IGF-2, and glucose on the migration and proliferation of bovine RPE cells in vitro. Methods: Primary cultures of bovine RPE cells were established from freshly enucleated eyes and passages 5–8 were used for these experiments. RPE cell migration was studied in confluent RPE cultures grown in multiwell plates. After inhibition of proliferation with mitomycin C (10 µg/ml) and partial denudation of the RPE in each well, the cells were incubated with IGF-1 (10 ng/ml), IGF-2 (10 ng/ml) or glucose (10 mM). Migration was measured as the number of cells that had entered the denuded area after 20 h. RPE cell proliferation was determined by [³H]-thymidine incorporation after incubation with IGF-1, IGF-2, and glucose for 24 h. Statistical analysis was performed with the paired Student’s t test. Results: Exposure of RPE cells to IGF-1, IGF-2, and glucose resulted in a significantly higher RPE cell migration as compared to the control medium (p < 0.008) with 21, 20, 17, and 9 cells/raster field, respectively. Additionally, IGF-1 (p = 0.004) and IGF-2 (p = 0.008) but not glucose caused a statistically significant stimulation of DNA synthesis with 761, 747, and 593 ccpm, respectively, as compared to the negative control (352 ccpm). Conclusion: This study indicates that IGF-1 and IGF-2 influence RPE cell migration and proliferation. This is further evidence that these factors are among those which have to be kept in mind when trying to modulate the development of diabetic eye diseases.

Autocrine effects of IGF-I-induced VEGF and IGFBP-3 secretion in retinal pigment epithelial cell line ARPE-19

“…In light of the fact that IGF-I upregulates the secretion of IGFBP-3 and VEGF in ARPE-19 cells and that their secretion occurs at the apical pole in polarized RPE cells (33,49), the ability of IGFBP-3 to reduce the bioavailability of IGF-I may play a major role in modulating VEGF secretion by RPE cells in the subretinal space (25,33,49). As such, fluctuations in IGF-I, IGF-II, or IGFBPs may have significant implications on RPE cell proliferation and migration after choroidal capillary invasion and the subsequent leakage of circulatory IGFs from choroidal vessels (41,48,52,58,66). Consequently, dysregulation of the IGF-I system at the level of the subretina may contribute to changes in RPE morphology and increases in angiogenic factor secretion, consistent with CNV.…”

Gene Expression ofIGF1,IGF1R, andIGFBP3in Epiretinal Membranes of Patients with Proliferative Diabetic Retinopathy: Preliminary Study

“…The IGF family is comprised of ligands: IGF1, IGF2, insulin; six binding proteins (IGFBP1 through -6); and cell surface receptors, including IGF1R, IGF2R, and insulin receptors [11]. Many recent studies suggested that IGF1 and IGF2 may be involved in the pathogenesis of PDR; however, the exact role has not been well understood yet [12, 13]. Recent reports suggest that increases in IGF1 activity may contribute to retinal neovascularization characteristic for PDR [14, 15].…”

Elongation and Secretion of Tissue Inhibitor of Metalloproteinases 1 by Human Microvascular Endothelial Cells Cultured in Collagen Gels is Stimulated by Mitomycin C

“…Although MMC has been the proliferation inhibitor of choice for many assays of cell behavior in vitro (Spraul et al 2000;Basu et al 2001;Miura et al 2003) including those involving ECs (e.g., Vernon and Sage 1999), previous studies have not reported that MMC influences biosynthetic processes. Thus, our finding that MMC stimulated the secretion of TIMP-1 by hmECs was unexpected.…”

“…For example, cell proliferation may confound quantification of cell movement and, therefore, is frequently inhibited in assays of EC migration in vitro. Proliferation is commonly suppressed with the compound mitomycin C (MMC) (Spraul et al 2000;Basu et al 2001;Miura et al 2003), which cross-links complementary strands of DNA, thereby inhibiting DNA replication and subsequent cell division. Although the effects of MMC on DNA synthesis are well documented, little is known about the potential influence of MMC on other cell processes.…”