title: Baculovirus transduction of rat articular chondrocytes: roles of cell cycle.
abstract: BACKGROUND
  We have previously demonstrated highly efficient baculovirus transduction of primary rat articular chondrocytes, thus implicating the possible applications of baculovirus in gene-based cartilage tissue engineering. However, baculovirus-mediated gene expression in the chondrocytes is transient.
  
  
  METHODS
  In this study, we attempted to prolong the expression by supertransduction, but uncovered that after long-term culture the chondrocytes became more refractory to baculovirus transduction. Therefore, the correlation between baculovirus-mediated enhanced green fluorescent protein (EGFP) expression and cell cycle was investigated by comparing the cycling chondrocytes and chondrocytes rich in quiescent cells, in terms of EGFP expression, virus uptake, cell cycle distribution, nuclear import and methylation of viral DNA.
  
  
  RESULTS
  We demonstrated, for the first time, that baculovirus-mediated transduction of chondrocytes is correlated with the cell cycle. The chondrocytes predominantly in G2/M phase were approximately twice as efficient in EGFP expression as the cycling cells, while the cells in S and G1 phases expressed EGFP as efficiently as the cycling cells. Notably, the chondrocyte populations rich in quiescent cells resulted in efficient virus uptake, but less effective nuclear transport of baculoviral DNA and higher degree of methylation, and hence poorer transgene expression.
  
  
  CONCLUSIONS
  These findings unravel the practical limitations when employing baculovirus in cartilage tissue engineering. The implications and possible solutions are discussed.
authors.affiliation: Department of Chemical Engineering, National Tsing Hua University, Hsinchu, Taiwan 300.
authors.forename: Hsiao-Ping
authors.initials: HP
authors.lastname: Lee
authors.forename: Yen-Lin
authors.initials: YL
authors.lastname: Chen
authors.forename: Heng-Chun
authors.initials: HC
authors.lastname: Shen
authors.forename: Wen-Hsin
authors.initials: WH
authors.lastname: Lo
authors.forename: Yu-Chen
authors.initials: YC
authors.lastname: Hu
mesh_terms: D021581:Active Transport, Cell Nucleus; D000818:Animals; D016367:Baculoviridae / Q000235:genetics*; D002358:Cartilage, Articular / Q000166:cytology*; D002453:Cell Cycle; D002478:Cells, Cultured; D019902:Chondrocytes / Q000166:cytology / Q000502:physiology*; D019175:DNA Methylation; D015870:Gene Expression; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D023822:Tissue Engineering; D014161:Transduction, Genetic; D019076:Transgenes
chemical_list: D049452:Green Fluorescent Proteins