Electric stimulation induced by polarized hydroxyapatite regulates osteoblast proliferation through ERK activation

Abstract

Event Abstract Back to Event Electric stimulation induced by polarized hydroxyapatite regulates osteoblast proliferation through ERK activation Akiko Nagai1, Takaaki Masutani1, 2, Kosuke Nozaki1 and Kimihiro Yamashita2* 1 Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Material BIofunctions, Japan 2 Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Inorganic Biomaterials, Japan Introduction: It was shown that electric polarization treatment on hydroxyapatite (HAp) can produce electric fields around the material and induced surface charges in previous reports. The electric energies induce osteoblast attachment and proliferation in vitro studies and enhance new bone formation in animal studies. Although stimuli from mechanical loads regulate osteoblast response via MAPK pathways, which signaling pathways to regulate the cell behaviors after received electric stimuli remains not fully elucidated. In the present study, we examined the effects of electric energy of polarized apatite on osteoblast proliferation and its molecular mechanism. Materials and Methods: HAp powders synthesized by a wet method were uniaxially pressed into pellets. They were sintered at 1250°C for 2 h under a water vapor stream. The disks were electrically polarized in a d.c. field of 5 kv·cm-1 in air at 400°C for 1 h, and then cooled to room temperature under the applied d.c. voltage. A non-polarized specimen was heated in air at 400°C for 1 h. To characterize of the polarized specimens, the thermally stimulated depolarization currents of the polarized specimen were measured using a picoampere meter. The human osteosarcoma cell lines, MG63, were cultured on HAp with or without polarization. Cell proliferation was quantitatively analyzed by using an MTT assay 1 d and 3 d after seeding. Cell spreading was assessed by measuring the cell-covered area, as determined by actin cytoskeleton staining. Total protein extracted from the cells on the specimens was applied in western immunoblot assays. Results and Discussion: The stored charges of the polarized specimen were around 2 µC·cm-2. The proliferation of MG63 cells cultured on polarized HAp increased compared to the cells on non-polarized HAp. The total actin-stained areas of cells spread on the polarized surface were significantly greater than the areas on the non-polarized surfaces, suggesting that the polarized surface favored cell adhesion. The results of western immunoblot assays were shown that the ERK activity was correlated with the proliferation of MG63 cells cultured on the polarization-treated surfaces (Fig. 1). Fig. 1. Electric stimulation activates ERK in MG63 cells. The protein expression of ERK phosphorylation was detected by Western blotting. GAPDH was used as an internal control. Data are represented as the mean ± SD, * P<0.05. Conclusion: Surface charges produced by the polarized HAp promoted osteoblast proliferation through ERK activation. The findings indicated that the signal pathway of osteoblast proliferation induced by electric stimulation was similar to the pathway in response to mechanical strain. Keywords: Cell Proliferation, Gene Expression, biomaterial, Surface modification Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: Poster Topic: Mechanobiology of cells on biomaterials Citation: Nagai A, Masutani T, Nozaki K and Yamashita K (2016). Electric stimulation induced by polarized hydroxyapatite regulates osteoblast proliferation through ERK activation. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.01125 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. * Correspondence: Dr. Kimihiro Yamashita, Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Inorganic Biomaterials, Tokyo, Japan, yama-k.bcr@tmd.ac.jp Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Akiko Nagai Takaaki Masutani Kosuke Nozaki Kimihiro Yamashita Google Akiko Nagai Takaaki Masutani Kosuke Nozaki Kimihiro Yamashita Google Scholar Akiko Nagai Takaaki Masutani Kosuke Nozaki Kimihiro Yamashita PubMed Akiko Nagai Takaaki Masutani Kosuke Nozaki Kimihiro Yamashita Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.