ABSTRACT
Objective To investigate whether the low-frequency pulsed electromagnetic fields (LF-PEMFs) can enhance the osteogenic differentiation of human periodontal ligament stem cells (hPDLSCs) induced by bone morphogenetic protein 9 (BMP9). Methods We isolated CD146＋/STRO-1＋ cells (namely PDLSC) from periodontal ligament cells of healthy human premolars, transfected the PDLSC with BMP9-overexpressing recombinant adenoviruses (Ad-GFP-BMP9), exposed the cells to the different intensities of PEMF stimulation (15 Hz, 0.6，1.2，1.8，2.4，3.0 mT, 1 h/12 h), and then detected the expression of runt-related transcription factor 2 (Runx2), alkaline phosphatase (ALP), osteopontin (OPN) and osteocalcin (OCN) by qRT-PCR and Western blotting. Results Overexpression of BMP9 significantly promoted the expression of osteogenic markers (Runx2, ALP, OCN and OPN) in PDLSC (P0.05). After the intervention with 1.2, 1.8, 2.4 and 3.0 mT PEMF, the expression levels of osteogenic markers in PDLSC were significantly higher than those exposed to BMP9 alone (P0.05), and reached the peak at 2.4 mT (P0.05), indicating that LF-PEMFs enhanced BMP9-induced osteogenic differentiation of PDLSC, and there was a “window effect”. Conclusion LF-PEMFs stimulation (15 Hz, 1.8 to 3.0 mT) can enhance BMP9-induced osteogenesis of hPDLSCs in vitro.
ABSTRACT
Objective To observe the effects of low-frequency pulsed electromagnetic fields (LFPEMFs) on microcirculation angiogenesis in the hindlimbs of diabetic rats with acute ischemia. Methods Models of acute hindlimb ischemia were established in 60 male Sprague-Dawley diabetic rats. The diabetes model was established using 60 mg/kg intraperitoneal injections of streptozotocin (STZ). Fasting blood glucose levels were greater than 300 mg/dL. The rats were randomly divided into experimental and control groups. The rats in the experimental group were exposed to low-frequency pulsed electromagnetic fields for 2 hours each day, while the control group was not given any treatment. Laser-Doppler perfusion was used to measure blood flow in the ischemic hindlimb on days 0,7, 14 and 28 after the operation. The immunofluorescence of rat endothelial cell antigen-1 ( RECA-1) was used to evaluate the changes in angiogenesis. The levels of vascular endothelial growth factor (VEGF) and fibroblast growth factor-2 (FGF-2) were determined by both Western blotting and ELISA, and VEGFR2 and FGFR1 levels in the ischemic skeletal muscle were determined by Western blotting on days 7, 14 and 28 after the operation. Results The average perfusion ratio was significantly greater in the experimental group at days 14 and 28 compared with the control group. RECA-1 density in the tissues had increased significantly in the experimental group at the 14th and 28th day. The same was observed for FGF-2 and its receptor, but there was no significant difference for VEGF or its receptor in either group. Conclusions LFPMEFs can promote angiogenesis in acute hindlimb ischemia of diabetic rats by up-regulating FGF-2. This suggests that LFPMEFs may be useful for preventing and treating lower limb ischemia in diabetic humans.
ABSTRACT
Objective To study the effects of uhrashortwave and low frequency pulsed electromagnetic fields on the expression of vascular endothelial growth factor(VEGF) in fracture healing. Methods Fifty-six New Zeal-and rabbits with artificial fractures were randomly divided into 4 groups:a control group,an ultrashortwave group,a low frequency pulsed electromagnetic field group and an ultrashortwave combined with low frequency pulsed electro-magnetic field group(combined group),with 14 in each group.Radiographic evaluation of callus formation and frac-ture healing,pathohistological examination and detection of VEGF expression through immunohistochemical staining were performed at the 1 st,2nd,4th and 6th week after the operation. Results Radiographic examination showed that there was significantly greater callus formation in the combined group than in the other groups throughout the healing process. Pathohistological examination also revealed significantly more cartilage islets and callus formation in the combined group.At the 1 st,2nd and 4th week after the operation,VEGF positive indexes in the combined group were significantly higher than in the other groups. Conclusion Uhrashortwave combined with low frequency pulsed electromagnetic field exposure can up-regulate the expression of VEGF and thus can accelerate fracture healing.