The effect of pulsed electric field on expression of ECM proteins: Collagen, elastin, and MMP1 in human dermal fibroblasts

Abstract

Electrical stimulation of tissues has many uses in pain management, antibacterial treatment, and wound healing. The electric field stimulates epidermal migration and increases fibroblast cell proliferation. Here we show the effects of electrical field (EF) stimulation of human dermal fibroblasts (HDF) on the expression of collagen, elastin, and collagenase (MMP1; matrix metalloproteinase 1). The effects of EF stimulation are evaluated in terms of changes in cell morphology and extracellular matrix (ECM) protein expression, defined as intracellular concentration of collagen, elastin, and MMP1. HDF are stimulated in a bioreactor using square wave voltage pulses for up to 24 h. The pulse voltage (0-10 V), pulse bias (0, +), pulse time (10–1000 ms), and rest time (0.1–10 s) were varied. We show that expression of collagen, elastin, and MMP1 increases in response to applied EF. The intracellular concentration of ECM proteins more than doubles depending on stimulation conditions with a threshold of effective stimulation above 3 V/cm. The short time voltage pulses used for EF stimulation are more effective, while the rest time between pulses has a small effect on intracellular concentration of collagen, MMP1 and elastin. The previously studied HDF stimulation with chemical factors (i.e. TNF-α, TGF-β) shows negative correlation between concentration of collagen and MMP1. Contrary to that observation, we show that EF stimulation causes increase in the intracellular concentration of both collagen and MMP1. We also demonstrate that the transdermal stimulation of HDF in subcutaneous tissue is possible, thus it might be utilized in the future to improve the wound healing and tissue regeneration process.