title: The promotion of bone regeneration by nanofibrous hydroxyapatite/chitosan scaffolds by effects on integrin-BMP/Smad signaling pathway in BMSCs.
abstract: In bone tissue engineering, a combination of biomimetic nanofibrous scaffolds with renewable stem cells has recently emerged as a new strategy for promoting bone regeneration. We have previously developed a biomimetic nanocomposite nanofibrous scaffold of hydroxyapatite/chitosan (nHAp/CTS) [1]. However, the mechanism behind the supportive function of the scaffolds has not yet been adequately explored. Here, we evaluated the effect of nHAp/CTS seeded with bone marrow mesenchymal stem cells (BMSCs) on bone regeneration and examined the underlying mechanism in vitro and in vivo. The scaffolds of nHAp/CTS induced higher proliferation of BMSCs than membranous hydroxyapatite/chitosan (mHAp/CTS) and electrospun nanofibrous chitosan (nCTS) did. Interestingly, regardless the nanfibrous effect, nHAp/CTS and mHAp/CTS supported the spindle-shaped morphology, in contrast to the spherical shape of BMSCs on nCTS, indicating that HAp supports cell adhesion. Furthermore, the levels of the mRNA for Smad1, BMP-2/4, Runx2, ALP, collagen I, integrin subunits together with myosins were significantly up-regulated on nHAp/CTS whereas these genes were expressed at markedly low levels on mHAp/CTS and nCTS even in osteogenic medium. In addition, the critical proteins pSmad1/5/8 in BMP pathway showed clear nuclear localization and osteocalcin were significantly elevated on nHAp/CTS than mHAp/CTS (P < 0.01) and nCTS (P < 0.01). Similarly, the cells exhibited higher ALP activity on nHAp/CTS than mHAp/CTS (P < 0.01) and nCTS (P < 0.05). Therefore, the findings indicated the activating of intergrin-BMP/Smad signaling pathway of BMSCs on nHAp/CTS. Finally, in vivo, nHAp/CTS/BMSCs had a superior ability of bone reconstruction than other groups for cranial bone defects. In conclusion, our results demonstrated that nHAp/CTS scaffold promotes bone regeneration by supporting the adhesion, proliferation and activating integrin-BMP/Smad signaling pathway of BMSCs both in vitro and in vivo.
authors.affiliation: Zhejiang Provincial Key Laboratory of Tissue Engineering and Regenerative Medicine, Hangzhou, China.
authors.forename: Huanhuan
authors.initials: H
authors.lastname: Liu
authors.forename: Hongju
authors.initials: H
authors.lastname: Peng
authors.forename: Yan
authors.initials: Y
authors.lastname: Wu
authors.forename: Can
authors.initials: C
authors.lastname: Zhang
authors.forename: Youzhi
authors.initials: Y
authors.lastname: Cai
authors.forename: Guowei
authors.initials: G
authors.lastname: Xu
authors.forename: Qin
authors.initials: Q
authors.lastname: Li
authors.forename: Xiao
authors.initials: X
authors.lastname: Chen
authors.forename: Junfeng
authors.initials: J
authors.lastname: Ji
authors.forename: Yanzhong
authors.initials: Y
authors.lastname: Zhang
authors.forename: Hong Wei
authors.initials: HW
authors.lastname: OuYang
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology / Q000187:drug effects / Q000648:ultrastructure; D019485:Bone Morphogenetic Proteins / Q000235:genetics / Q000378:metabolism; D001861:Bone Regeneration / Q000187:drug effects* / Q000235:genetics; D049109:Cell Proliferation / Q000187:drug effects; D002469:Cell Separation; D048430:Cell Shape / Q000187:drug effects; D048271:Chitosan / Q000494:pharmacology*; D017886:Durapatite / Q000494:pharmacology*; D005109:Extracellular Matrix / Q000187:drug effects / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D020007:Implants, Experimental; D016023:Integrins / Q000235:genetics / Q000378:metabolism; D008567:Membranes, Artificial; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure; D057139:Nanofibers / Q000737:chemistry* / Q000648:ultrastructure; D015675:Osteocalcin / Q000378:metabolism; D010012:Osteogenesis / Q000187:drug effects / Q000235:genetics; D011859:Radiography; D051381:Rats; D017207:Rats, Sprague-Dawley; D015398:Signal Transduction / Q000187:drug effects* / Q000235:genetics; D012886:Skull / Q000000981:diagnostic imaging / Q000473:pathology; D051785:Smad Proteins / Q000235:genetics / Q000378:metabolism; D054457:Tissue Scaffolds / Q000737:chemistry*
chemical_list: D019485:Bone Morphogenetic Proteins; D016023:Integrins; D008567:Membranes, Artificial; D051785:Smad Proteins; D015675:Osteocalcin; D048271:Chitosan; D017886:Durapatite; D000469:Alkaline Phosphatase