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Lens epithelial cells (LECs) is the key of lens pathophysiological study. Pigment epithelium derived factor (PEDF) is a multifaceted factor and exists in aqueous humor and lens tissue, but its biological effect on LECs needs further study.
To investigate the regulation effect of PEDF on the growth of human LECs and related mechanisms in vivo and in vitro.
In the part of in vivo study, 181 eyes of 181 patients with age-related cataract were included to collect the central lens anterior capsule during the surgery under the approval of Ethic Committee of Sun Yat-sen University and informed consent of patients. The selected specimens were divided into the LECs low density group and high density group based on hematoxylin and eosin staining results and 30 specimens for each. The relative expressing levels of PEDF mRNA in the LECs were detected by reverse transcription PCR. In the part of in vitro study, human lens epithelial cell line (HLE-B3) was cultured, and 50 ng/ml PEDF was added in media for 72 hours in the PEDF culture group, while normal cultured cells were used as the control group. The percentage of LECs in G0 and S phases and apoptotic rate of the cells were assayed using flow cytometry with AnnexinV-FITC/7-AAD double staining method. Intracellular expression of VEGF mRNA was detected by real-time fluorescence quantitative PCR.
The central anterior subcapsular LECs density and relative expression level of PEDF mRNA were (3 672±326)/mm2 and 0.43±0.05 in the low density group, which were lower than (4 857±350)/mm2 and 0.55±0.04 in the high density group, showing significant differences between the two groups (t=4.16, 3.82, both at P<0.05). The percentage of the cells in G2+S phase was (54.05±4.98)% in the PEDF culture group, and that in the control group was (28.54±4.27)%, with a significant difference between them (t=-6.32, P<0.01). The apoptotic rate in the PEDF culture group was significantly reduced in comparison with the control group ([2.08±0.48]% versus [13.50±0.72]%) (t=7.90, P<0.01). In addition, the expressing level of VEGF mRNA was lower in the PEDF culture group compared with the control group (6.1±2.2 versus 27.4±4.8) (t=5.48, P<0.01).
In human eyes, PEDF may function as cytotrophic factor to promote survival of LECs through anti-apoptosis and reducing-expression of VEGF. Decrease of PEDF content in LECs probably modulate the pathophysiological process of lens cells and further cataractogenesis.