Monophasic Pulsed Current Stimulation of Duty Cycle 10% Promotes Differentiation of Human Dermal Fibroblasts into Myofibroblasts

Pulsed electrical stimulation and amino acid derivatives promote collagen gene expression in human dermal fibroblasts

Several collagen types are important for maintaining skin structure and function. Previous reports show that l-hydroxyproline (Hyp), N-acetyl-l-hydroxyproline (AHyp), and l-alanyl-l-glutamine (Aln-Gln) are biological active substances with collagen synthesis-promoting effects. In this study, we combined the promotive effects of pulsed electrical stimulation (PES) with three amino acid derivatives in human dermal fibroblasts. Fibroblasts were exposed to PES with a 4,800 Hz pulse frequency and a voltage at 1 or 5 V for 15 min. The gene expression of type I and III collagen (fibrillar collagen), type IV and VII collagen (basement membrane collagen and anchoring fibril collagen) were measured by RT-PCR 48 h after PES. PES alone promoted the expression of COL1A1 and COL3A1 at 5 V but did not alter that of COL4A1 and COL7A1. Each AAD and the AAD mixture promoted the expression of COL4A1 and COL7A1 but either repressed, or did not alter, that of COL1A1 and COL3A1. Compared to treatment with each AAD, PES at 5 V with Hyp promoted the expression of COL1A1 and COL3A1, enhanced COL3A1 expression with AHyp, and stimulated COL3A1 expression with Aln-Gln, while COL4A1 and COL7A1 expressions were not affected. PES and the AAD mixture significantly promoted COL4A1 expression in a voltage-dependent manner, and COL1A1 and COL3A1 demonstrated a similar but nonsignificant trend, whereas COL7A1 expression was not affected. The combination of PES with each AAD or the AAD mixture may improve skin structure and function by increasing the expression of basement membrane collagen and dermal fibrillar collagen.

Electrical Shunting Prevents the Decline of Galvanotaxis After Monophasic Pulsed Microcurrent Stimulation in Human Dermal Fibroblasts

BACKGROUND

Electrical stimulation (ES) therapy is recommended for healing pressure injuries. Monophasic pulsed microcurrent stimulation promotes the migration of human dermal fibroblasts (HDFs) to the cathode, and ES potentially accelerates pressure injury healing. A reverse current is generated after ES in the human body; however, the effects of the electrical shunt in preventing the reverse current from migrating are unclear. Therefore, this study aimed to investigate the effects of an electrical shunt on the migration of HDFs.

METHODS

In the shunt groups, HDFs were electrically stimulated (0, 200, 400, and 600 µA) for 8 hours, and an electrical shunt was used to remove the electricity after ES. HDFs were observed under time-lapse microscopy for 24 hours. The migration ratio toward the cathode was calculated for each dish.

RESULTS

The migration ratio was significantly higher in the 200-µA group than in the other groups. HDFs migrated toward the anode after ES in the non-shunt groups with greater than 400 µA ES; however, HDFs did not migrate toward the anode with electrical shunting.

CONCLUSIONS

A post-ES electrical shunt is important in preventing a decline in the migration effect of ES.

Efficacy of Low-frequency Monophasic Pulsed Microcurrent Stimulation Therapy in Undermining Pressure Injury: A Double-blind Crossover-controlled Study

Objectives:

This double-blind crossover-controlled trial aimed to verify the effect of electrical stimulation therapy on pressure injuries with undermining.

Methods

: In this trial, we compared the healing rates between a sham period and a treatment period using monophasic pulsed microcurrent therapy. The participants were randomly assigned to the sham or treatment group and received stimulation for 2 weeks. All the participants, physical therapists, and researchers were blinded to the allocation. For the main analysis, data on the effect of the intervention on changes in weekly healing and contraction rates of the wound areas, including undermining, were analyzed based on a two-period crossover study design. The intervention effect was estimated by examining the mean treatment difference for each period using Wilcoxon’s signed-rank test.

Results

: The reduction of the entire wound area, including the undermining area, resulted in significantly higher healing and contraction rates in the treatment group (overall wound area reduction rate: contraction rate, P=0.008; period healing rate, P=0.002).

Conclusions

: Electrical stimulation therapy for pressure injuries, using conditions based on the findings of an in vivo culture study, was effective in reducing the wound area.

Wound Healing with Electrical Stimulation Technologies: A Review

Electrical stimulation (ES) is an attractive field among clinicians in the topic of wound healing, which is common yet complicated and requires multidisciplinary approaches. The conventional dressing and skin graft showed no promise on complete wound closure. These urge the need for the exploration of electrical stimulation to supplement current wound care management. This review aims to provide an overview of electrical stimulation in wound healing. The mechanism of galvanotaxis related to wound repair will be reviewed at the cellular and molecular levels. Meanwhile, different modalities of externally applied electricity mimicking a physiologic electric field will be discussed and compared in vitro, in vivo, and clinically. With the emerging of tissue engineering and regenerative medicine, the integration of electroconductive biomaterials into modern miniaturised dressing is of interest and has become possible with the advancing understanding of smart biomaterials.