The effects of platelet gel on cultured human retinal pigment epithelial (hRPE) cells.

The positive role of platelet gel (PG) in tissue regeneration is well known, however, other characteristics of PG still remain to be determined. We investigated cellular and molecular changes in cultured human retinal pigment epithelial (hRPE) cells when treated with different concentrations of PG named PG1, PG2, and PG3. hRPE cells were isolated from donor eyes of two newborn children, within 24 hours after their death. The cells were treated with three concentrations of PG for 7 days: 3 × 104/ml (PG1), 6 × 104/ml (PG2), and 9 × 104/ml (PG3). Fetal bovine serum was used as a control. Immunocytochemistry was performed with anti-RPE65 (H-85), anti-Cytokeratin 8/18 (NCL-5D3), and anti-PAX6 antibody. We used MTT assay to determine cell viability. Gene expressions of PAX6, MMP2, RPE65, ACTA2, MKI67, MMP9, and KDR were analyzed using real-time PCR. A significant increase in viability was observed for PG3-treated cells compared to control (p = 0.044) and compared to PG1 group (p = 0.027), on day 7. Cellular elongation together with dendritiform extensions were observed in PG-treated cells on days 1 and 3, while epithelioid morphology was observed on day 7. All cells were immunoreactive for RPE65, cytokeratin 8/18, and PAX6. No significant change was observed in the expression of MKI67 and PAX6, but the expressions of MMP2, MMP9, ACTA2, and KDR were significantly higher in PG2-treated cells compared to controls (p < 0.05). Our results indicate that increased concentration of PG and extended exposure time have positive effects on viability of hRPE cells. PG may be useful for hRPE cell encapsulation in retinal cell replacement therapy.