Pulsed electrical stimulation modulates fibroblasts' behaviour through the Smad signalling pathway.

The aim of this study was to investigate the healing characteristics and the underlying signalling pathway of human dermal fibroblasts under the influence of pulsed electrical stimulation (PES). Primary human dermal fibroblasts were seeded on polypyrrole-coated polyester fabrics and subjected to four different PES protocols. The parameters of the rectangular pulse included potential intensity (50 and 100 mV/mm) and stimulation time (pulse width 300 s within a period of 600 s, and pulse width 10 s within a period of 1200 s). Our study revealed that PES moderately improved the ability of the cells to migrate in association with a statistically significant (p < 0.05) increase of FGF2 secretion by the PES-exposed fibroblasts. These exposed fibroblasts were able to contract collagen gel matrix up to 48 h and this collagen gel contraction paralleled an increase in α-SMA mRNA expression and protein production from the PES-exposed fibroblasts. Interestingly, the effect of PES on the human fibroblasts involved the Smad signalling pathway, as we observed higher levels of phosphorylated Smad2 and Smad3 in the stimulated groups compared to the control groups. Overall, this study demonstrated that PES modulates fibroblast activities through the Smad signalling pathway, thus providing new mechanistic insights related to the use of PES to promote wound healing in humans. Copyright © 2015 John Wiley & Sons, Ltd.

Electrical Stimulation Modulates the Expression of Multiple Wound Healing Genes in Primary Human Dermal Fibroblasts.

This study profiled multiple human dermal fibroblast wound-healing genes in response to electrical stimulation (ES) by using an RT(2) profiler PCR-Array system. Primary human skin fibroblasts were seeded on heparin (HE)-bioactivated polypyrrole (PPy)/poly(l-lactic acid) (PLLA) conductive membranes, cultured, and subsequently exposed to ES of 50 or 200 mV/mm for 6 h. Following ES, the cells were used to extract RNA for gene profiling, and culture supernatants were used to measure the level of the different wound healing mediators. A total of 57 genes were affected (activated/repressed) by ES; among these, 49 were upregulated and 8 were downregulated. ES intensities at 50 and 200 mV/mm activated/repressed different genes. The ES-modulated genes are involved in cell adhesion, remodeling and spreading, cytoskeletal activity, extracellular matrix metabolism, production of inflammatory cytokines/chemokines and growth factors, as well as signal transduction. The expression of several genes was supported by protein production. Protein analyses showed that ES increased CCL7, KGF, and TIMP2, but reduced MMP2. This study demonstrated that ES modulates the expression of a variety of genes involved in the wound healing process, confirming that ES is a useful tool in regenerative medicine.

Spruce budworm impact, abundance and parasitism rate in a patchy landscape.

The hypothesis that vegetational diversity may lessen the impact of forest insect pests by favoring natural enemies is appealing to those who seek ecologically sound solutions to pest problems. We investigated the effect of forest diversity on the impact of the spruce budworm Choristoneurafumiferana following the last outbreak, as well as the budworm's current abundance and parasitism rate, in the boreal forest of northwestern Québec. Mortality of balsam fir caused by the budworm was greater in extensive conifer stands than either in "habitat islands" of fir surrounded by deciduous forest or on true islands in the middle of a lake. Adult spruce budworm abundance, assessed by pheromone traps, did not differ significantly between the three types of sites. Larval and pupal parasitism rates were examined by transferring cohorts of laboratory-reared larvae and pupae to trees in the three site types and later collecting and rearing them. The tachinid Actiainterrupta, a parasitoid of fifth and sixth instar larvae, as well as the ichneumonid pupal parasitoids Itoplectesconquisitor, Ephialtesontario and Phaeogenesmaculicornis, caused higher mortality in the habitat islands than on true islands or in extensive stands. Exochusnigripalpistectulum, an ichneumonid that attacks the larvae and emerges from the pupae, caused greater mortality in the extensive stands of conifers.