Effect of cryotherapy on the expression of vascular endothelial growth factor and pigment epithelium-derived factor

Background: Cryotherapy is a noninvasive technique that uses intense cold to freeze and destroy cancer tissues. There are no descriptions of its effects on the expression of vascular endothelial growth factor (VEGF) and pigment epithelium-derived factor (PEDF). Methods: We carried out a retrospective cross-sectional study. Cryogenic spots were applied in the right sclera of 12 pigs for 10 min. Another three pigs were used as controls. Animals were sacrificed at days 7, 14 and 21 and choroidal and retinal tissues were dissected in areas of similar to 1 cm(2) surrounding cryogenic spots. Expression levels of VEGF and PEDF were determined and analyzed using reverse transcription-polymerase chain reaction. Results: VEGF was significantly downregulated (24%, p < 0.05) 7 days post-treatment; meanwhile, PEDF levels increased 44.8% (p < 0.05) as compared to controls (untreated). Both VEGF and PEDF levels remained the same until day 14 but returned to basal expression at day 21. Discussion: This work demonstrates the relationship of cryotherapy with the expression of two angiogenesis-related factors. Results showed significant changes on the expression of VEGF and PEDF, illustrating that both proteins are regulated in response to cryogenic treatment in relatively short periods (21 days).