DC Electric Fields Induce Distinct Preangiogenic Responses in Microvascular and Macrovascular Cells

Abstract

Objective-Electrical stimulation induces significant angiogenesis in vivo. We have shown recently that electrical stimulation induces directional migration, reorientation, and elongation of macrovascular endothelial cells. Because angiogenesis occurs mainly in the microvasculature, we have extended this observation to include human microvascular endothelial cells and compared the responses with that of vascular fibroblasts and smooth muscle cells and human umbilical vein endothelial cells. Methods and Results-Four types of vascular cells were cultured in electric fields (EFs). Dynamic cell behaviors were recorded and analyzed with an image analyzer. EFs of 150 to 400 mV/mm induced directed migration, reorientation, and elongation of all the vascular cells. HMEC-1s showed the greatest directional migration (migration rate of 11 m/h and directedness of 0.35 at 200 mV/mm). Most intriguingly, HMEC-1s migrated toward the cathode, whereas the other cell types migrated toward the anode. Conclusions-Endothelial cells derived from angiogenic microvascular as opposed to nonangiogenic macrovascular tissues were more responsive to electrical stimulation. This intriguing directional selectivity indicates that a DC electrical signal as a directional cue may be able to play a role in the spatial organization of vascular structure. Key Words: vascular cells Ⅲ electrical stimulation Ⅲ angiogenesis Ⅲ heterogeneity Ⅲ cell migration Ⅲ alignment Ⅲ orientation M odulation of new blood vessel formation, either to increase the blood supply to ischemic tissue or to inhibit blood supply to undesired neoplasm such as cancer, offers great hope for treatment of a vast spectrum of diseases. 1 Electrical stimulation has emerged recently as a novel approach to induce angiogenesis in vivo, and this is mediated by enhanced local expression of vascular endothelial growth factor (VEGF) by muscle cells. [2][3][4] More recently, we and others have shown that electrical stimulation also has significant direct effects on endothelial cells to induce reorientation of the long axis of the cell, directional cell migration, and to stimulate cell elongation. [5][6][7][8] This may be of physiological significance because endogenous electric fields (EFs) have been found to be associated with circulation, tissue damage, and abnormal cell proliferation. 9 -14 Endogenous EFs are widespread, have been measured directly in animals and in humans, and may be important for development and wound healing. [15][16][17] For example, a steady DC EF of 450 to 1600 mV/mm has been measured across the wall of the amphibian neural tube during early neuronal development, 16 and disrupting this perturbs neural development. 18 At surface wounds, a steady DC EF of at least 40 mV/mm in bovine cornea and 100 to 200 mV/mm in guinea pig skin arises as soon as the wound occurs, and this persists until re-epithelialization is complete. 19 -21 This laterally oriented EF is attributable to the immediate flow of current driven by the transepithelial potential difference, which is susta...

Laserterapia e microcorrente na cicatrização de queimadura em ratos: terapias associadas ou isoladas?

“…The endothelial cells of the micro vessels seem to be sensitive to laser stimulation through the expression of gene proteins that regulate the cell cycle and the proliferation of these cells 27 . Bai et al 28 describe that electric fields of 150 to 400 mV/mm also perform migration, reorientation, and extension of the endothelial cells of micro-circulation vessels. The endothelial cells of micro-circulation present different behaviors when compared to macrovascular tissues, which suggests that each cellular type has a distinct disposition of receptors, and tolerance to different electric fields, contributing or not contributing to the activation of the vascular endothelial growth factor 28 .…”

“…Bai et al 28 describe that electric fields of 150 to 400 mV/mm also perform migration, reorientation, and extension of the endothelial cells of micro-circulation vessels. The endothelial cells of micro-circulation present different behaviors when compared to macrovascular tissues, which suggests that each cellular type has a distinct disposition of receptors, and tolerance to different electric fields, contributing or not contributing to the activation of the vascular endothelial growth factor 28 . Even with the positive action of laser and microcurrent upon the healing process in the various model types, such as skin 1 , diabetic ulcers 6 , and temperature burns 5,16,24 , their associated use still deserves more discussion.…”

“…It is possible that the electric stimulation might have hampered the occurrence of cellular and molecular reactions involved in the healing process, such as the gene expression of cellular growth factors, errors in the process of cell differentiation, and alteration in the behavior of receptors and ionic channels. Considering that these act upon the cellular metabolism, we point to the hypothesis of cellular fatigue, and alterations in cellular signalization or in the metabolic ways of the cells 27,28 . Laser and microcurrent seem to act directly upon the expression of cellular growth factors in several types of cell (fibroblast, vascular endothelium, epithelial cells) related to the healing process.…”

Hormetic Electric Field Theory of Pattern Formation

“…Migration and alignment: In vitro, electrical fields can induce directional migration and elongation of vascular cells and align the cells with their long axis perpendicular to electrical field vectors ( Bai et al 2004). Sato et al (2009) demonstrated that genes can control the direction of electrotaxis and field-strength-dependent direction of cell migration, i.e., the hormetic cell response to external direct current electrical fields.…”

“…Here, I propose that the ATP gradients modulate export of H + by vacuolar H + -ATPase (V-ATPase) located on the surface of field cells and generate extracellular ion concentration gradients, ion currents and electrical fields along the paths of morphogen gradients. In vitro, electrical fields can induce directional migration and elongation of vascular cells and align the cells with their long axis perpendicular to electrical field vectors ( Bai et al 2004). I suggest that likewise, in vivo vascular transmural electrical fields induced by hormetic morphogen concentration gradients can modulate cell shape i.e.…”