Surface functionalization of titanium implants with chitosan-catechol conjugate for suppression of ROS-induced cells damage and improvement of osteogenesis
BIOMATERIALS
Authors: Chen, Weizhen; Shen, Xinkun; Hu, Yan; Xu, Kui; Ran, Qichun; Yu, Yonglin; Dai, Liangliang; Yuan, Zhang; Huang, Ling; Shen, Tingting; Cai, Kaiyong
Abstract
Oxidative stress induced by reactive oxygen species (ROS) overproduction would hinder bone healing process at the interface of bone/implant, yet underlying mechanism remains to be explored. To endow titanium (Ti) substrates with antioxidant activity for enhanced bone formation, multilayered structure composing of chitosan-catechol (Chi-C), gelatin (Gel) and hydroxyapatite (HA) nanofibers was constructed on Ti substrates. Surface wettability and topography of multilayer coated Ti substrates were characterized by water contact angle measurement, scanning electron microscopy and atomic force microscopy, respectively. Chi-C containing multilayer on Ti surface effectively protected osteoblasts from ROS damage, which was revealed by high level of intracellular ROS scavenging activity and reduced oxidative damage on cellular level by regulating the expression of cell adhesion related genes (integrin alpha v, (beta 3, CDH11 and CDH2). Moreover, it regulated the production of cell adhesive and anti-apoptotic related proteins (p-MYPT1, p-FAK, p-Akt and Bcl-2) and pro-apoptotic critical executioners (Bax and cleaved caspase 3). Beside, the composite multilayer of Chi-C/Gel/HA nanofibers on Ti substrates promoted osteoblasts differentiation, which was evidenced by high expression levels of alkaline phosphatase activity, collagen secretion, ECM mineralization and osteogenesis-related genes expression in vitro. The in vivo experiments of mu-CT analysis, push out test and histochemistry staining further confirmed that Chi-C multilayered implant had great potential for improved early bone healing. Overall, the study offers an effective strategy for the exploration of high quality Ti implants for orthopedic applications. (C) 2016 Elsevier Ltd. All rights reserved.
Down-regulation of transcription factor OVOL2 contributes to epithelial-mesenchymal transition in a noninvasive type of trophoblast implantation to the maternal endometrium
FASEB JOURNAL
Authors: Bai, Rulan; Kusama, Kazuya; Nakamura, Keigo; Sakurai, Toshihiro; Kimura, Koji; Ideta, Atsushi; Aoyagi, Yoshito; Imakawa, Kazuhiko
Abstract
Embryo implantation into the uterine endometrium is required for pregnancy establishment in most mammals. By using global expression analysis, we investigated the molecules that are related to epithelial- mesenchymal transition (EMT) in noninvasive bovine trophoblasts and found that the transcription factor, ovo-like zinc finger 2 (OVOL2), which is essential for mesenchymal-epithelial transition in various cancers, was down-regulated after trophoblast attachment to the endometrial epithelium in utero. In cultured bovine trophoblast cells, OVOL2 down-regulation occurred only when cells were allowed to attach to bovine endometrial epithelial cells via the TEAD3/YAP signaling pathway. This resulted in the up-regulation of the EMT-associated transcription factors, ZEB1 and SNAI2, and the mesenchymal cell markers, N-cadherin (CDH2) and vimentin (VIM), whereas epithelial cell marker, E-cadherin (CDH1), was down-regulated. In contrast, OVOL2 overexpression in bovine trophoblast cells exhibited a decrease in ZEB1 transcripts and an increase in E-cadherin. These observations revealed that ovo-like protein (OVOL)2 down-regulation occurred concurrently with conceptus implantation into the uterine endometrium via the YAP/TEAD3 signaling pathway, and suggest that the down-regulation of OVOL2 expression contributes to the up-regulation of EMT-related transcription factor expression, which enables EMT progression in the noninvasive bovine trophectoderm postimplantation.