RESUMEN
Background In vitro study showed that chemotaxis consist of chemotaxis factor 4(CXCR4)and stromal cells derived factor-1(SDF-1)and may play a role in the orientation and migration of retinal progenitor cells (RPCs)toward lesion.Overexpression of CXCR4 in RPCs can enhance the chemotaxis activity.Objective This work was to explore the feasibility and underlying mechanism of up-regulation of CXCR4 on RPCs induced by hypoxia.Methods RPCs were retained in an incubator with normal O2volume(16％)or hypoxia condition(10％ O2)for 12 hours and 24 hours respectively.Flow cytometer cell analysis screening(FACS)was conduced to measure the proportion of CXCR4-expressing cells,and CXCR4,HIF-1 mRNA were analyzed by reverse transcription-polymerse chain reaction(RT-PCR).The chemotical effect of 30 mg/L SDF-1 to RPCs cultured under the hypoxia condition was assessed using Boyden chamber.Results The expression level of CXCR4(CXCR4 mRNA/β-actin mRNA)inRPCs cultured by 10％ O2 for 12 and 24 hours were 0.28+0.07and 0.48+0.17 and increased by 1.75 and 3.00 fold more than that of 16％ O2 culture group(0.16+0.02)(P＜0.01).The expression level of HIF-1 mRNA(HIF-1 mRNA/β-actin mRNA)in RPCs cultured by 10％ O2 for 12 and 24 hours were 0.18 ±0.07and 0.38 ±0.13 and increased by 3.00 and 6.30 fold more than that of 16％ O2 culture group(0.06±0.01)(P＜0.01).The chemotical effect of 30 μg/L SDF-1 to RPCs increased from 13.00％ in 16％ O2 culture group to 36.00％ and 46.00％ in the cells cultured by 10％ O2for 12 and 24 hours.FACS revealed that the proportion of CXCR4+ cells in hypoxia-exposure for 12 and 24 hours were 26.90％ and 46.10％,respectively,but that in 16％ O2 culture group was 9.10％,showing a statistically significant difference(P ＜ 0.01).Conclusions RPCs induced by hypoxia can enhance the expression of CXCR4 in RPE cells and the chemotaxia to SDF-1.The overexpression of H1F-1 in RPCs may be involved in the up-regulation of CXCR4 expression.