title: Normal proliferation and differentiation of Hoxc-8 transgenic chondrocytes in vitro.
abstract: BACKGROUND
  Hox genes encode transcription factors that are involved in pattern formation in the skeleton, and recent evidence suggests that they also play a role in the regulation of endochondral ossification. To analyze the role of Hoxc-8 in this process in more detail, we applied in vitro culture systems, using high density cultures of primary chondrocytes from neonatal mouse ribs.
  
  
  RESULTS
  Cultured cells were characterized on the basis of morphology (light microscopy) and production of cartilage-specific extracellular matrix (sulfated proteoglycans and type II Collagen). Hypertrophy was demonstrated by increase in cell size, alkaline phosphatase activity and type X Collagen immunohistochemistry. Proliferation was assessed by BrdU uptake and flow cytometry. Unexpectedly, chondrocytes from Hoxc-8 transgenic mice, which exhibit delayed cartilage maturation in vivo 1, were able to proliferate and differentiate normally in our culture systems. This was the case even though freshly isolated Hoxc-8 transgenic chondrocytes exhibited significant molecular differences as measured by real-time quantitative PCR.
  
  
  CONCLUSIONS
  The results demonstrate that primary rib chondrocytes behave similar to published reports for chondrocytes from other sources, validating in vitro approaches for studies of Hox genes in the regulation of endochondral ossification. Our analysis of cartilage-producing cells from Hoxc-8 transgenic mice provides evidence that the cellular phenotype induced by Hoxc-8 overexpression in vivo is reversible in vitro.
authors.affiliation: Samuel C, Johnson Medical Research Center, Mayo Clinic Scottsdale, Scottdale, AZ 85259, USA. cormier.stephania@mayo.edu
authors.forename: Stephania A
authors.initials: SA
authors.lastname: Cormier
authors.forename: Maria Alice
authors.initials: MA
authors.lastname: Mello
authors.forename: Claudia
authors.initials: C
authors.lastname: Kappen
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002455:Cell Division / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D019902:Chondrocytes / Q000737:chemistry / Q000166:cytology* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology; D018398:Homeodomain Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008822:Mice, Transgenic; D012272:Ribs / Q000166:cytology
chemical_list: D018398:Homeodomain Proteins; C489816:Hoxc8 protein, mouse