title: The effects of velvet antler polypeptides on the phenotype and related biological indicators of osteoarthritic rabbit chondrocytes.
abstract: OBJECTIVE
  To study the effects of velvet antler polypeptides (VAPs) on osteoarthritic chondrocytes (OCs) in rabbits.
  
  
  METHODS
  An osteoarthritic rabbit model was established according to Hulth's method. OCs were isolated and cultured for observation of the cell cycle. Cell proliferation was detected by MTT assay and the cell cycle was monitored by flow cytometry. The phenotype was determined by toluidine blue staining as well as immunohistochemical staining for collagen type II. The expression of MMP-1, MMP-3, MMP-13, TIMP-1, and collagen I and X mRNA by chondrocytes was assayed by RT-PCR.
  
  
  RESULTS
  The VAPs had no obvious proliferative effect on OCs and did not affect the cell cycle. However, they significantly reduced the proportion of early apoptotic cells in a dose-dependent manner. Further, VAPs inhibited the expression of collagen I and X mRNA and induced abnormal expression of MMP-1 and MMP-13 mRNA. VAPs had no significant effect on MMP-3 and TIMP-1 mRNA levels. The toluidine blue and collagen type II immunohistochemical staining intensities of VAP-treated chondrocytes were positively correlated with the concentration of VAPs used.
  
  
  CONCLUSIONS
  VAPs had no significant effect on OC proliferation and the cell cycle, but did increase the glycosaminoglycan (GAG) and collagen type II expression levels in the extracellular matrix, and down-regulated collagen I and X mRNA expression. Treatment of cartilage cells with VAPs maintained their normal phenotype, inhibited matrix metalloproteinases (MMPs) secretion, kept the balance of cartilage matrix metabolism, and sustained an external environment where the cartilage cells could survive. Moreover, VAPs reduced the proportion of early apoptotic cells, suggesting that they may block the apoptotic pathway in OCs.
authors.affiliation: Department of Biopharmacy, School of Pharmaceutical Sciences, Jilin University, Jilin, PR China.
authors.forename: Zhengyao
authors.initials: Z
authors.lastname: Zhang
authors.forename: Xiaofeng
authors.initials: X
authors.lastname: Liu
authors.forename: Lengxin
authors.initials: L
authors.lastname: Duan
authors.forename: Xia
authors.initials: X
authors.lastname: Li
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Qiuli
authors.initials: Q
authors.lastname: Zhou
mesh_terms: D000818:Animals; D000999:Antlers / Q000737:chemistry*; D017209:Apoptosis / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D019902:Chondrocytes / Q000187:drug effects* / Q000473:pathology; D024042:Collagen Type I / Q000235:genetics; D024121:Collagen Type X / Q000235:genetics; D005260:Female; D005786:Gene Expression Regulation; D008297:Male; D020781:Matrix Metalloproteinase 1 / Q000235:genetics; D053509:Matrix Metalloproteinase 13 / Q000235:genetics; D019278:Matrix Metalloproteinase 3 / Q000235:genetics; D010003:Osteoarthritis / Q000188:drug therapy* / Q000473:pathology*; D010455:Peptides / Q000494:pharmacology*; D010641:Phenotype; D011817:Rabbits; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics
chemical_list: D024042:Collagen Type I; D024121:Collagen Type X; D010455:Peptides; D019715:Tissue Inhibitor of Metalloproteinase-1; D053509:Matrix Metalloproteinase 13; D019278:Matrix Metalloproteinase 3; D020781:Matrix Metalloproteinase 1