[Effects of pulsed electromagnetic fields on high-glucose-induced inhibition of HUVEC proliferation and its underlying mechanisms].

Objective: To investigate the effects of pulsed electromagnetic fields (PEMFs) on high-glucose (HG)-induced inhibition of human umbilical vein endothelial cells (HUVECs) proliferation and its underlying mechanisms. Methods: This study was an experimental research involving grouping design and factorial design. HUVECs were divided into a conventionally cultured control group, a PEMF group with conventional culture exposed to PEMF stimulation at frequency of 15 Hz, intensity of 0.5 mT, and duration of 0.5 h/d for 2 consecutive days, a HG group cultured with final molarity of 30 mmol/L glucose (hereinafter referred to as HG culture), and a HG+PEMF group received the aforementioned PEMF stimulation while under HG culture. Cell proliferation was assessed using cell counting kit-8 (CCK-8) after 24, 36, and 48 h of culture. After the optimal PEMF stimulation duration 1.0 h/d was screened out, HUVECs were collected and grouped as before. Except for the PEMF stimulation duration of 1.0 h/d, all other treatments were the same as before. Western blotting was employed to detect the protein expression levels of Wnt-3a and β-catenin in cells in each group after 48 h of culture, transcriptomic sequencing was performed on cells in HG and HG+PEMF groups after 48 h of culture to screen for differentially expressed genes (DEGs) with significant differential expression, and Western blotting was used to detect the protein expression level of adenomatous polyposis coli (APC) in cells in each group after 48 h of culture. HUVECs were divided into a HG group, a HG+PEMF group, and an APC overexpression group. The cells in HG group were cultured in HG medium; the cells in HG+PEMF group were cultured in HG medium while receiving PEMF stimulation with frequency of 15 Hz, intensity of 0.5 mT, and duration of 1.0 h/d for 2 consecutive days; the cells in APC overexpression group were transfected using a plasmid to overexpress APC gene, and then subjected to the same treatment as that in HG+PEMF group. Cell proliferation was detected by CCK-8 after 36 and 48 h of culture, and protein expression levels of APC, β-catenin, and Wnt-3a in cells were detected by Western blotting after 48 h of culture. The sample size for the experiments was three. Results: After 24, 36, and 48 h of culture, cell proliferation levels in HG group were all significantly lower than those in control group (P<0.05). After 36 and 48 h of culture, the cell proliferation levels in HG+PEMF group were significantly increased compared with those in HG group (P<0.05). After 48 h of culture, the protein expression levels of Wnt-3a and β-catenin in HG group of cells were significantly lower than those in control group and HG+PEMF group (P<0.05). Transcriptomic sequencing showed that after 48 h of culture,compared with those in HG group, there were 573 DEGs significantly expressed in the cells of HG+PEMF group, among which the gene expression of APC, the key regulatory protein of the Wnt pathway, was significantly downregulated. After 48 h of culture, the protein expression level of APC in HG group of cells was significantly higher than that in control group and HG+PEMF group (with P values both <0.05). After 36 and 48 h of culture, the cell proliferation levels in HG+PEMF group were 0.479±0.016 and 0.552±0.029, respectively, which were significantly higher than 0.363±0.019 and 0.437±0.010 in HG group and 0.358±0.005 and 0.439±0.020 in APC overexpression group (with P values all <0.05). After 48 h of culture, the protein expression level of APC in cells of HG+PEMF group was significantly lower than that in HG group and APC overexpression group (with P values both <0.05), and the protein expression levels of Wnt-3a and β-catenin were significantly higher than those in HG group and APC overexpression group (P<0.05). Conclusions: PEMF stimulation at the frequency of 15 Hz, intensity of 0.5 mT, and duration of 1.0 h/d for 2 consecutive days can alleviate the inhibitory effect of HG on HUVEC proliferation. The mechanism involves the downregulation of APC protein expression in cells by PEMF, which attenuates the suppression of the Wnt/β-catenin pathway and subsequently modulates the expressions of Wnt-3a and β-catenin.