Pretreating mesenchymal stem cells with electrical stimulation causes sustained long-lasting pro-osteogenic effects

Abstract

BackgroundElectrical stimulation (ES) has a long history of successful use in the clinical treatment of refractory, non-healing bone fractures and has recently been proposed as an adjunct to bone tissue-engineering treatments to optimize their therapeutic potential. This idea emerged from ES’s demonstrated positive effects on stem cell migration, proliferation, differentiation and adherence to scaffolds, all cell behaviors recognized to be advantageous in Bone Tissue Engineering (BTE). In previous in vitro experiments we demonstrated that direct current ES, administered daily, accelerates Mesenchymal Stem Cell (MSC) osteogenic differentiation. In the present study, we sought to define the optimal ES regimen for maximizing this pro-osteogenic effect.MethodsRat bone marrow-derived MSC were exposed to 100 mV/mm, 1 hr/day for three, seven, and 14 days, then osteogenic differentiation was assessed at Day 14 of culture by measuring collagen production, calcium deposition, alkaline phosphatase activity and osteogenic marker gene expression.ResultsWe found that exposing MSC to ES for three days had minimal effect, while seven and 14 days resulted in increased osteogenic differentiation, as indicated by significant increases in collagen and calcium deposits, and expression of osteogenic marker genes Col1a1, Osteopontin, Osterix and Calmodulin. We also found that cells treated with ES for seven days, maintained this pro-osteogenic activity long (for at least seven days) after discontinuing ES exposure.DiscussionThis study showed that while three days of ES is insufficient to solicit pro-osteogenic effects, seven and 14 days significantly increases osteogenic differentiation. Importantly, we found that cells treated with ES for only seven days, maintained this pro-osteogenic activity long after discontinuing ES exposure. This sustained positive osteogenic effect is likely due to the enhanced expression of RunX2 and Calmodulin we observed. This prolonged positive osteogenic effect, long after discontinuing ES treatment, if incorporated into BTE treatment protocols, could potentially improve outcomes and in doing so help BTE achieve its full therapeutic potential.

Electrical stimulation-induced osteogenesis of human adipose derived stem cells using a conductive graphene-cellulose scaffold

“…We present here the fabrication and utility of a miniaturized, multi-chamber ES device that incorporates our previously described cell supporting G-C scaffold. The as-developed ES device can be employed for in vitro ADSC proliferation and osteogenic differentiation without [13][14][15]. The device may be useful in research for tissue engineering and modelling, as well as prospective therapeutics, including preclinical assays for drug screening and tissue development for regenerative medicine.…”

“…Electrical stimulation (ES) has been shown to promote migration, proliferation and differentiation of stem cells, including neural stem cells, bone marrow stromal cells, and ADSCs through modulation of intracellular signalling [7][8][9][10][11][12]. Previous studies have shown that intracellular calcium/calmodulin pathway, downstream calcineurin/NFAT signalling pathway, and master osteogenic transcription factor runt-related transcription factor 2 can be activated by ES, resulting in enhanced osteogenic differentiation of stem cells [13][14][15]. Notwithstanding the putative benefits of ES, there is a need for advanced biocompatible ES devices that omit the use of conventional electrodes such as metal electrodes for more optimal cell-compatibility, avoiding, for example, unwanted biochemical effects of corrosion and poor physical integration with cells and tissues [7].…”

Electrical stimulation in bone tissue engineering treatments

“…Previous in vitro experiments that exposed cells and/or scaffolds to EStim, demonstrated its ability to influence cell functions associated with enhanced bone healing [7][8][9][10][11][12][13][14]. These experiments were conducted on a variety of different cell types; bone marrow-derived mesenchymal stem cells (BM-MSC), from human and animal origin [10,11,[15][16][17][18][19][20][21][22][23][24][25]; adipose-derived mesenchymal stem cells (AT-MSC) [11,20,[26][27][28][29][30], mouse osteoblast-like cells [31][32][33] and more recently, human dental pulp stem cells (DPSC) [34]. The above cell types are commonly studied for use in BTE applications.…”

“…For decades, electrical stimulation (EStim) has been studied and used successfully in clinical practice to stimulate bone healing (reviewed in [6]). While the detailed mechanisms by which EStim promotes healing are poorly understood, several recently published in vitro studies suggest that EStim's pro-healing effect is due to its influence on the behavior and/or function of bone-forming stem cells, such as migration [7,8], proliferation [9], differentiation [10,11], mineralization [12], extracellular matrix deposition [13], and attachment to scaffold materials [14]. Importantly, all these cell behaviors/functions that are central to healing could potentially be used to optimize outcomes in BTE treatments.…”

Electroactive 3D Printed Scaffolds Based on Percolated Composites of Polycaprolactone with Thermally Reduced Graphene Oxide for Antibacterial and Tissue Engineering Applications

“…In particular, these biomaterials take advantage of the effect of a direct current (DC) or an electrical field on both cell proliferation and differentiation, stimulating, for instance, the regeneration of muscles, organs, and/or bones [3][4][5][6][7][8]. Moreover, ES has been studied as a potential tool in tissue regeneration to increase the proliferation and differentiation of human stem cells [5,[9][10][11][12][13]. There are several reports in the literature on the use of ES for fracture treatments and tissue repairs using electrical stimulation methodologies, particularly DC or electromagnetic fields [14].…”