Electrical stimulation through conductive membranes enhanced different wound healing genes including CCL7, KGF, and TIMP2 but reduced MMP2 in normal human dermal fibroblasts

Park, Hyun Jin (Groupe de Recherche en Écologie Buccale, Centre de recherche du CHU de Québec, Université Laval)
Zhang, Ze (Centre de recherche du CHU de Québec, Département de chirurgie, Faculté de médecine, Université Lava)
Rouabhia, Mahmoud (Groupe de Recherche en Écologie Buccale, Faculté de Médecine Dentaire, Université Laval)

Introduction

Cutaneous wound healing is a complex process involving the reconstitution of the epidermis and dermis of the skin [1]. Fibroblasts in the dermis are an important cell type during wound healing process by participating in inflammation, proliferation, and remodelling [1]. The secretion of various growth factors and cytokines by fibroblasts has a direct impact on keratinocyte proliferation and differentiation during wound healing process [2]. This involves different genes, which are grouped into different but complementary control pathways for collagen production, cell adhesion, remodelling and spreading, cytoskeleton proteins, inflammatory cytokines and chemokines, and growth factors and signalling pathways [3]. These genes can be affected by various conditions, such as diabetes [4] or an exposure to exogenous stimuli, such as ultraviolet light [5] and electrical stimulation (ES). ES in its various forms has been shown to promote wound healing by increasing the migration of keratinocytes and macrophages [6], enhancing angiogenesis [7], and stimulating dermal fibroblasts [8,9]. Therefore, the objective of this study was to determine the effect of ES on the gene expression profiles involved in the wound healing process in normal human dermal fibroblasts using electrically conductive polypyrrole/heparin/polylactide (PPy/HE/PLLA) membranes.

Materials and Methods

The conductive member was made of PLLA matrix and HE doped PPy nanoparticles. Normal human dermal fibroblasts were seeded on the 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 total RNA for gene profiling. The culture supernatants were used to measure the level of the different wound healing mediators.

Results

A total of 50 genes were affected (activated/repressed) by ES; among these, 42 were up-regulated and 8 were down-regulated. The two different ES intensities (50 and 200 mV/mm) we tested did not activate/repress the same genes at the same time. ITGA2 and AGA2 were upregulated at 200 mV/mm. COL3A1, VTN, TIMP2, EGF, KGF, CCL7 and MAPK1 were significantly activated following ES (50 and 200 mV/mm). Finally, CTSL2 and PDGFA were down-regulated in response to ES. ES modulated the genes involved in cell adhesion, remodelling and spreading, cytoskeletal activity, extracellular matrix, inflammatory cytokines and chemokines, and growth factors, as well as the molecules participating in signalling pathways. The expression of several genes was supported by protein production. Protein levels in the culture supernatant showed that ES significantly increased CCL7, KGF, and TIMP2 but reduced MMP2.

Discussion and Conclusion

This study demonstrated that the two ES protocols were able to modulate the genes involved in the wound healing process, confirming that ES can become a useful tool in regenerative medicine.

Acknowledgements

This work was supported by The Canadian Institutes of Health Research (http://www.cihr-irsc.gc.ca/e/193.html). The grant number is 106555. The authors thank Dr. Denis Lavertu from the Department of Surgery of Saint François d’Assise Hospital for skin biopsies collection.

References

[1] Broughton G 2nd, Janis JE, Attinger CE. Plast Reconstr Surg 2006: 117: 12S–34S. [2] Wong T, McGrath JA, Naysaria H. Br J Dermatol 2007: 156: 1149-1155. [3] Velasquez LS, Sutherland LB, Liu Z et al. Proc Natl Acad Sci USA 2013: 110: 16850–16855. [4] Peplow PV, Chatterjee MP. Cytokine 2013: 62: 1–21. [5] Houreld NN, Ayuk SM, Abrahamse H. J Photochem Photobiol B 2013: 130C: 146–152. [6] Wang E, Zhao M, Forrester JV et al. Exp Eye Res 2003: 76: 29–37. [7] Zhao M, Bai H, Wang E et al. J Cell Sci 2004: 117: 397–405. [8] Shi GX, Zhang Z, Rouabhia M. Biomaterials 2008: 29: 3792–3798. [9] Rouabhia M, Park H, Meng S et al. PLoS One 2013: 8: e71660.

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