Endothelial Effects and Angiogenesis

Bioelectromagnetics. 2010 May;31(4):296-301.

Effects of weak static magnetic fields on endothelial cells.

Martino CF, Perea H, Hopfner U, Ferguson VL, Wintermantel E.

Department of Mechanical Engineering, University of Colorado at Boulder, Boulder, Colorado, USA. martino@colorado.edu

Abstract

Pulsed electromagnetic fields (PEMFs) have been used extensively in bone fracture repairs and wound healing. It is accepted that the induced electric field is the dose metric. The mechanisms of interaction between weak magnetic fields and biological systems present more ambiguity than that of PEMFs since weak electric currents induced by PEMFs are believed to mediate the healing process, which are absent in magnetic fields. The present study examines the response of human umbilical vein endothelial cells to weak static magnetic fields. We investigated proliferation, viability, and the expression of functional parameters such as eNOS, NO, and also gene expression of VEGF under the influence of different doses of weak magnetic fields. Applications of weak magnetic fields in tissue engineering are also discussed. Static magnetic fields may open new venues of research in the field of vascular therapies by promoting endothelial cell growth and by enhancing the healing response of the endothelium.

Br J Dermatol. 2010 Feb 1;162(2):258-66. Epub 2009 Oct 3.

Extremely low frequency electromagnetic fields modulate expression of inducible nitric oxide synthase, endothelial nitric oxide synthase and cyclooxygenase-2 in the human keratinocyte cell line HaCat: potential therapeutic effects in wound healing.

Patruno A, Amerio P, Pesce M, Viazio S, Tulli A, Franceschelli S, Grilli A, Muraro R, Reale M.nale G, Di Lu

Department of Drug Sciences, University ‘G. d’Annunzio’ of Chieti-Pescara, Via dei Vestini, 66100 Chieti, Italy.

Abstract

BACKGROUND: Extremely low frequency (ELF) electromagnetic fields (EMF) are known to produce a variety of biological effects. Clinical studies are ongoing using EMF in healing of bone fractures and skin wounds. However, little is known about the mechanisms of action of ELF-EMF. Several studies have demonstrated that expression and regulation of nitric oxide synthase (NOS) and cyclooxygenase-2 (COX-2) are vital for wound healing; however, no reports have demonstrated a direct action of ELF-EMF in the modulation of these inflammatory molecules in human keratinocytes.

OBJECTIVES: The present study analysed the effect of ELF-EMF on the human keratinocyte cell line HaCaT in order to assess the mechanisms of action of ELF-EMF and to provide further support for their therapeutic use in wound healing.

METHODS: Exposed HaCaT cells were compared with unexposed control cells. At different exposure times, expression of inducible NOS (iNOS), endothelial NOS (eNOS) and COX-2 was evaluated by Western blot analysis. Modulation of iNOS and eNOS was monitored by evaluation of NOS activities, production of nitric oxide (NO) and O(2)(-) and expression of activator protein 1 (AP-1). In addition, catalase activity and prostaglandin (PG) E(2) production were determined. Effects of ELF-EMF on cell growth and viability were monitored.

RESULTS: The exposure of HaCaT cells to ELF-EMF increased iNOS and eNOS expression levels. These ELF-EMF-dependent increased expression levels were paralled by increased NOS activities, and increased NO production. In addition, higher levels of AP-1 expression as well as a higher cell proliferation rate were associated with ELF-EMF exposure. In contrast, ELF-EMF decreased COX-2 expression, PGE(2) production, catalase activity and O(2)(-) production.

CONCLUSIONS: Mediators of inflammation, such as reactive nitrogen and PGE(2), and keratinocyte proliferation are critical for the tissue regenerative processes. The ability of ELF-EMF to upmodulate NOS activities, thus nitrogen intermediates, as well as cell proliferation, and to downregulate COX-2 expression and the downstream intermediate PGE(2), highlights the potential therapeutic role of ELF-EMF in wound healing processes.

Bioelectromagnetics. 2009 Apr;30(3):189-97.

Osteoblasts stimulated with pulsed electromagnetic fields increase HUVEC proliferation via a VEGF-A independent mechanism.

Hopper RA, VerHalen JP, Tepper O, Mehrara BJ, Detch R, Chang EI, Baharestani S, Simon BJ, Gurtner GC.

Department of Surgery, University of Washington, Seattle, WA 98105, USA. richard.hopper@seattlechildrens.org

Abstract

The clinically beneficial effect of low frequency pulsed electromagnetic fields (ELF-PEMF) on bone healing has been described, but the exact mechanism of action remains unclear. A recent study suggests that there is a direct autocrine mitogenic effect of ELF-PEMF on angiogenesis. The hypothesis of this study is that ELF-PEMF also has an indirect effect on angiogenesis by manipulation of vascular endothelial growth factor (VEGF)-A-based paracrine intercellular communication with neighboring osteoblasts. Conditioned media experiments measured fetal rat calvarial cell (FRC) and human umbilical vein endothelial cell (HUVEC) proliferation using tritiated thymidine uptake. We demonstrate that ELF-PEMF (15 Hz, 1.8 mT, for 8 h) has an indirect effect on the proliferation rate of both endothelial cells and osteoblasts in vitro by altering paracrine mediators. Conditioned media from osteoblast cells stimulated with ELF-PEMF increased endothelial proliferation 54-fold, whereas media from endothelial cells stimulated with ELF-PEMF did not affect osteoblast proliferation. We examined the role of the pro-angiogenic mediator VEGF-A in the mitogenic effect of ELF-PEMF-stimulated osteoblast media on endothelial cells. The production of VEGF-A by FRC as measured by ELISA was not changed by exposure to PEMF, and blocking experiments demonstrated that the ELF-PEMF-induced osteoblast-derived endothelial mitogen observed in these studies was not VEGF-A, but some other soluble angiogenic mediator.

Sheng Wu Yi Xue Gong Cheng Xue Za Zhi. 2008 Jun;25(3):694-8.

The influence of the pulsed electrical stimulation on the morphology and the functions of the endothelial cells.

[Article in Chinese]

Yue A, Yang G, Wu J, Lai Y, Huang H, Chen H.

Institute of Biomedical Engineering, West China Medical Center, Sichuan University, Chengdu 610041, China.

Abstract

The aim of this study is to explore the effects of the pulsed electrical stimulation (PES) on the morphology, the proliferation and the values of NO and ET-1 of the endothelial cells (ECs). We chose the different frequency PES (1, 5, 10, 20, 50, 100 Hz) with 25 mV to stimulate the ECs for 6 hours. We observed the cell’s morphous by the scanning electron microscope (SEM) and detected the values of MTT, NO and ET-1. The proliferation of the ECs was obviously rose up under the PES from 10 to 100 Hz. But the PES inhibited the proliferation with the frequency lower than 10 Hz. After stimulated with PES (20 – 100 Hz), the NO expression of ECs were increased obviously, and the peak value was appeared at 50 Hz. The peak value of ET-1 was appeared at 100 Hz. The PES has significant effects on the ECs’ morphology, proliferation and expression of NO and ET-1. Particularly, the 50 Hz PES plays a positive role to enhance the ECs’ function and to maintain the vascular biology.

Plast Reconstr Surg. 2008 Jan;121(1):130-41.

Pulsed electromagnetic fields accelerate normal and diabetic wound healing by increasing endogenous FGF-2 release.

Callaghan MJ, Chang EI, Seiser N, Aarabi S, Ghali S, Kinnucan ER, Simon BJ, Gurtner GC.

Stanford University Medical Center, Palo Alto, Calif, USA.

Abstract

BACKGROUND: Chronic wounds, particularly in diabetics, result in significant morbidity and mortality and have a profound economic impact. The authors demonstrate that pulsed electromagnetic fields significantly improve both diabetic and normal wound healing in 66 mice through up-regulation of fibroblast growth factor (FGF)-2 and are able to prevent tissue necrosis in diabetic tissue after an ischemic insult.

METHODS: Db/db and C57BL6 mice were wounded and exposed to pulsed electromagnetic fields. Gross closure, cell proliferation, and vascularity were assessed. Cultured medium from human umbilical vein endothelial cells exposed to pulsed electromagnetic fields was analyzed for FGF-2 and applied topically to wounds. Skin flaps were created on streptozocin-induced diabetic mice and exposed to pulsed electromagnetic fields. Percentage necrosis, oxygen tension, and vascularity were determined.

RESULTS: Pulsed electromagnetic fields accelerated wound closure in diabetic and normal mice. Cell proliferation and CD31 density were significantly increased in pulsed electromagnetic field-treated groups. Cultured medium from human umbilical vein endothelial cells in pulsed electromagnetic fields exhibited a three-fold increase in FGF-2, which facilitated healing when applied to wounds. Skin on diabetic mice exposed to pulsed electromagnetic fields did not exhibit tissue necrosis and demonstrated oxygen tensions and vascularity comparable to those in normal animals.

CONCLUSIONS: This study demonstrates that pulsed electromagnetic fields are able to accelerate wound healing under diabetic and normal conditions by up-regulation of FGF-2-mediated angiogenesis. They also prevented tissue necrosis in response to a standardized ischemic insult, suggesting that noninvasive angiogenic stimulation by pulsed electromagnetic fields may be useful to prevent ulcer formation, necrosis, and amputation in diabetic patients.

FASEB J. 2004 Aug;18(11):1231-3. Epub 2004 Jun 18.

Electromagnetic fields increase in vitro and in vivo angiogenesis through endothelial release of FGF-2.

Tepper OM, Callaghan MJ, Chang EI, Galiano RD, Bhatt KA, Baharestani S, Gan J, Simon B, Hopper RA, Levine JP, Gurtner GC.

New York University Medical Center, Institute of Reconstructive Plastic Surgery, New York, New York 10016, USA .

Abstract

Pulsed electromagnetic fields (PEMF) have been shown to be clinically beneficial, but their mechanism of action remains unclear. The present study examined the impact of PEMF on angiogenesis, a process critical for successful healing of various tissues. PEMF increased the degree of endothelial cell tubulization (sevenfold) and proliferation (threefold) in vitro. Media from PEMF cultures had a similar stimulatory effect, but heat denaturation ablated this activity. In addition, conditioned media was able to induce proliferative and chemotactic changes in both human umbilical vein endothelial cells and fibroblasts, but had no effect on osteoblasts. Angiogenic protein screening demonstrated a fivefold increase in fibroblast growth factor beta-2 (FGF-2), as well as smaller increases in other angiogenic growth factors (angiopoietin-2, thrombopoietin, and epidermal growth factor). Northern blot analysis demonstrated an increase in FGF-2 transcription, and FGF-2 neutralizing antibody inhibited the effects of PEMF. In vivo, PEMF exposure increased angiogenesis more than twofold. We conclude that PEMF augments angiogenesis primarily by stimulating endothelial release of FGF-2, inducing paracrine and autocrine changes in the surrounding tissue. These findings suggest a potential role for PEMF in therapeutic angiogenesis.

Vestn Khir Im I I Grek. 1996;155(5):37-9.

The potentials of laser and electromagnetic-laser therapy in the treatment of patients with arteriosclerosis obliterans of the vessels of the lower extremities.

[Article in Russian]

Galimzianov FV.

A comparative analysis of the laser and electromagnetic laser therapy was performed in the complex treatment of patients with obliterating atherosclerosis of the lower extremity vessels. Laser treatment exerts a therapeutic effect related with its influence upon microcirculation. The effectiveness of complex treatment becomes higher when using a combination of laser therapy with the impulse electromagnetic therapy of complex modulation at the expense of improvement of the regional blood circulation in all links of the vasculature.

Vopr Kurortol Fizioter Lech Fiz Kult. 1993 Sep-Oct;(5):22-5.

The use of magnetics and laser therapy in treating obliterating vascular disease of the extremities.

[Article in Russian]

Kirillov IuB, Shval’b PG, Lastushkin AV, Sigaev AA, Kachinskii AE, Shashkova SN.

The paper presents the results of treatment received by 60 patients suffering from lower limb vascular obliteration stage IIA-III. The treatment involved combined use of magnetic field and laser irradiation. Peripheral circulation and central hemodynamics were evaluated rheographically and using ultrasound Doppler sphygmomanometry. Combined application of the above two modalities produced a greater effect on central hemodynamics compared to them introduced alone.

J Cell Physiol. 1988 Jan;134(1):37-46.

Endothelial cell response to pulsed electromagnetic fields: stimulation of growth rate and angiogenesis in vitro.

Yen-Patton GP, Patton WF, Beer DM, Jacobson BS.

Department of Biochemistry, University of Massachusetts, Amherst 01003.

Abstract

The effects of pulsed electromagnetic fields on the repopulation rate of denuded regions of endothelial cell monolayers and on endothelial cell reorganization into complex vessellike structures was monitored in vitro by using human umbilical vein and bovine aortic endothelial cells. A small (20-40%) but statistically significant enhancement in growth rate of partially denuded endothelial cell monolayers as determined by tritiated thymidine incorporation was observed in the presence of pulsed electromagnetic fields. Morphologically, endothelial cells entering the denuded regions were observed to be elongated, often connecting end to end to form a mycelial or “sprouting” pattern when exposed to pulsed electromagnetic fields. This was in contrast to cells outside of the field which had a more cuboidal morphology. Complete disruption of the endothelial cell monolayer by passaging the cells with EDTA-trypsin resulted in reorganization of some of the cells into three-dimensional vessellike structures after as little as 5-8 hours in the presence of the pulsed electromagnetic field. This reorganization occurred in the presence of heparin, endothelial cell growth factor, and a competent fibronectin matrix. Vascularization for comparable cultures outside of the field did not occur during the time-course of the experiments. Discrete stages of neovascularization were observed in the presence of the field that were qualitatively similar to stages of angiogenesis observed in vivo.

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