Electrical Stimulation Activates Fibroblasts through the Elevation of Intracellular Free Ca²⁺: Potential Mechanism of Pelvic Electrical Stimulation Therapy

Abstract

Ca2+ is an important ion in response to electrical stimulation (ES) and acts as second messenger in the regulation of various physiological processes. Pelvic floor electrical stimulation (PES) is a low-voltage clinical application, available for urinary incontinence (UI) treatment. Fibroblasts, as the main cellular component of vaginal wall and pelvic ligament, play an important role in the maintenance of pelvic health. We studied the effect of ES on fibroblasts in this study. ES was conducted with electrotaxis chambers on L929 fibroblast and the ES parameter was 100 mV/mm×2h. The results showed that ES increased intracellular Ca2+ concentration, promoted the expression of PCNA, CyclinB1, and CyclinD1, and increased the proportion of cells in S and G2 phages. After ES, fibroblasts get activated and proliferated. Besides, BAPTA-AM, a membrane permeated chelator for intracellular free Ca2+, partially inhibited the effect of ES on fibroblasts activation and proliferation promotion. Furthermore, we elucidated that Ca2+, as a second messenger and upstream signal for Smads and Akt signaling, regulated ES-induced nuclear translocation of smad2/3, phosphorylation of smad2/3, Akt, and GSK3β. Finally, we validated the effect of ES on PES mouse model. The results indicated that PES promoted the activation and proliferation of fibroblasts in vivo. In conclusion, we verify that ES can elevate the concentration of intracellular Ca2+ and activate its downstream signaling and then promote the activation of fibroblasts, which may be one of the mechanisms of PES therapy.

Electrical stimulation in bone tissue engineering treatments

“…Electroactive smart polymeric biomaterials could be used to build scaffolds that offer precise control over the amount, duration, and localization of the electrical stimulus, thus obviating the need for bone stimulators. These materials have already been tested in vitro, where they have demonstrated the ability to improve cell proliferation and differentiation [151][152][153]. If in addition to promoting these pro-osteogenic activities, these smart biomaterials can also be designed to biodegrade after a given useful time period, this would be yet another benefit [154].…”

CACNA1H downregulation induces skeletal muscle atrophy involving endoplasmic reticulum stress activation and autophagy flux blockade

“…Extensor digitorum longus from adult mice were digested in type I collagenase at 37°C for 2-3 h, and dissociated into single fibers. These single fibers and myotubes fixed with 4% paraformaldehyde for 15 min at 4°C and then performed as described previously 36 . The primary antibody information was as follows: anti-MyHC (1:50, RND, MAB4470), anti-SQSTM1 (1:150, MBL, M162-3), anti-LC3 (1:100, Proteintech, 14600-1-AP).…”

“…Myotubes were harvested, incubated with Fluo-3AM (10 μM) for 30 min in the incubator and then performed as described previously 36 . The Geo Mean fluorescence intensity was used to compare differences of Ca 2+ concentration between groups.…”

Electric field stimulation for tissue engineering applications

“…In a similar manner, electrodes were inserted in a rat brain and stimulated transplanted human neural progenitor cells, resulting in directed migration and increased motility [ 129 ]. Furthermore, transvaginal electric stimulation in female mice has shown activation and proliferation of fibroblasts [ 130 ].…”