title: Gene expression analyses of subchondral bone in early experimental osteoarthritis by microarray.
abstract: Osteoarthritis (OA) is a degenerative joint disease that affects both cartilage and bone. A better understanding of the early molecular changes in subchondral bone may help elucidate the pathogenesis of OA. We used microarray technology to investigate the time course of molecular changes in the subchondral bone in the early stages of experimental osteoarthritis in a rat model. We identified 2,234 differentially expressed (DE) genes at 1 week, 1,944 at 2 weeks and 1,517 at 4 weeks post-surgery. Further analyses of the dysregulated genes indicated that the events underlying subchondral bone remodeling occurred sequentially and in a time-dependent manner at the gene expression level. Some of the identified dysregulated genes that were identified have suspected roles in bone development or remodeling; these genes include Alp, Igf1, Tgf β1, Postn, Mmp3, Tnfsf11, Acp5, Bmp5, Aspn and Ihh. The differences in the expression of these genes were confirmed by real-time PCR, and the results indicated that our microarray data accurately reflected gene expression patterns characteristic of early OA. To validate the results of our microarray analysis at the protein level, immunohistochemistry staining was used to investigate the expression of Mmp3 and Aspn protein in tissue sections. These analyses indicate that Mmp3 protein expression completely matched the results of both the microarray and real-time PCR analyses; however, Aspn protein expression was not observed to differ at any time. In summary, our study demonstrated a simple method of separation of subchondral bone sample from the knee joint of rat, which can effectively avoid bone RNA degradation. These findings also revealed the gene expression profiles of subchondral bone in the rat OA model at multiple time points post-surgery and identified important DE genes with known or suspected roles in bone development or remodeling. These genes may be novel diagnostic markers or therapeutic targets for OA.
authors.affiliation: Department of Orthopaedics, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou, China.
authors.forename: RongKai
authors.initials: R
authors.lastname: Zhang
authors.forename: Hang
authors.initials: H
authors.lastname: Fang
authors.forename: YuXian
authors.initials: Y
authors.lastname: Chen
authors.forename: Jun
authors.initials: J
authors.lastname: Shen
authors.forename: HuaDing
authors.initials: H
authors.lastname: Lu
authors.forename: Chun
authors.initials: C
authors.lastname: Zeng
authors.forename: JianHua
authors.initials: J
authors.lastname: Ren
authors.forename: Hua
authors.initials: H
authors.lastname: Zeng
authors.forename: Zhifu
authors.initials: Z
authors.lastname: Li
authors.forename: ShaoMing
authors.initials: S
authors.lastname: Chen
authors.forename: DaoZhang
authors.initials: D
authors.lastname: Cai
authors.forename: Qing
authors.initials: Q
authors.lastname: Zhao
mesh_terms: D000818:Animals; D001835:Body Weight; D016723:Bone Remodeling; D001842:Bone and Bones / Q000378:metabolism; D002356:Cartilage / Q000378:metabolism / Q000473:pathology; D016000:Cluster Analysis; D004195:Disease Models, Animal; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D010003:Osteoarthritis / Q000235:genetics / Q000378:metabolism*; D010010:Osteoclasts / Q000166:cytology; D051381:Rats; D017207:Rats, Sprague-Dawley; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D013997:Time Factors