title: Motile chondrocytes from newborn calf: migration properties and synthesis of collagen II.
abstract: OBJECTIVE
  To determine whether differentiated chondrocytes are motile.
  
  
  METHODS
  Calf articular chondrocytes isolated from six animals were cultured in spinner flasks and removed on days 3 and 7. Boyden chamber assays and time-lapse videomicroscopy were performed to monitor and quantify cell migration. A novel method for selectively harvesting and metabolically labeling the migrated cells was developed, based on cell movement to the underside of the Boyden chamber membranes. The 3H-collagen synthesized by these cells was purified and analyzed by SDS-PAGE and autoradiography either before or after cyanogen bromide cleavage.
  
  
  RESULTS
  In Boyden chambers, locomotion of day 3 chondrocytes on fibronectin-coated membranes was approximately 3-fold higher than on bovine serum albumin-coated controls (39+/-15 vs 12+/-8 cells/mm(2), respectively (P=0.005)). Insulin-like growth factor-I (IGF-I, 10 ng/ml) was chemotactic, increasing motility to 87+/-16 cells/mm(-) (difference from fibronectin alone: P=0.0003). A similar response was observed for day 7 cells, but IGF-I activation was not as pronounced (P=0.055). The collagen patterns produced by the migrated cells closely resembled those of standard collagen type II, without any evidence of collagen I production. In videotracking experiments, motile cells attached on fibronectin exhibited typical lamellipodia and filopodia, and approximately 30% of attached cells were motile (speed >1 micro m/h and directional persistence >1h). Typical cell path lengths were 30-50 micro m, substantially greater than a full cell length displacement.
  
  
  CONCLUSIONS
  A population of well-differentiated chondrocytes capable of matrix (COL II) synthesis are motile in vitro. This original finding opens new avenues to study the potential of motile cells for cartilage repair.
authors.affiliation: Division of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02114, USA. tmorales@partners.org
authors.forename: C
authors.initials: C
authors.lastname: Chang
authors.forename: D A
authors.initials: DA
authors.lastname: Lauffenburger
authors.forename: T I
authors.initials: TI
authors.lastname: Morales
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001345:Autoradiography / Q000379:methods; D002358:Cartilage, Articular / Q000166:cytology*; D002417:Cattle; D002454:Cell Differentiation / Q000502:physiology; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D002633:Chemotaxis / Q000187:drug effects / Q000502:physiology; D019902:Chondrocytes / Q000502:physiology*; D024043:Collagen Type II / Q000096:biosynthesis*; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D013997:Time Factors
chemical_list: D024043:Collagen Type II; D007334:Insulin-Like Growth Factor I