Osteogenic differentiation is selectively promoted by morphogenetic signals from chondrocytes and synergized by a nutrient rich growth environment.
Cartilage formation always precedes that of bone during endochondral skeletal development. To determine if chondrocytes provide inductive signals for osteogenesis, C3H10T(1/2) mesenchymal stem cells were co-cultured in membrane separated transwell culture chambers with chondrocytes, osteoblasts, or fibroblasts. Osteogenesis, as assessed by the expression of osteocalcin mRNAs, was strongly induced in the C3H10T(1/2) cells co-cultured with chondrocytes but not induced by co-culture with either osteoblasts or fibroblasts. Interestingly, while only osteogenic differentiation was observed in the C3H10T(1/2) cells co-cultured with chondrocytes, bone morphogenetic protein (BMP)-7 treatment induced an ordered endochondral progression of skeletal cell differentiation in which chondrogenic differentiation preceded osteogenesis by 2 to 4 days. A nutrient enriched growth environment enhanced osteogenic differentiation induced by either co-culture or BMP-7 treatment 2- to 5-fold. Nutrient enhanced osteogenic differentiation was associated with an activation of the retinoblastoma-mediated signal transduction pathways. In summary, these results show that osteogenesis is selectively induced by morphogenetic signals produced by chondrocytes and that a nutrient rich environment enhances both BMP-7- and co-culture-induced osteogenic differentiation.
Gerstenfeld
L C
LC
Orthopaedic Research Laboratory, Department of Orthopaedic Surgery, Boston University Medical Center, Boston, Massachusetts 02118, USA. lgersten@bu.edu
Barnes
G L
GL
Shea
C M
CM
Einhorn
T A
TA
D000818:Animals; D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins / Q000378:metabolism* / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D002642:Chick Embryo; D019902:Chondrocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D018920:Coculture Techniques; D003470:Culture Media / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D008648:Mesoderm / Q000166:cytology; D051379:Mice; D008809:Mice, Inbred C3H; D020411:Oligonucleotide Array Sequence Analysis; D015675:Osteocalcin / Q000096:biosynthesis / Q000235:genetics; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D015398:Signal Transduction; D013234:Stem Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016212:Transforming Growth Factor beta
D055419:Bone Morphogenetic Protein 7; D019485:Bone Morphogenetic Proteins; D003470:Culture Media; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D015675:Osteocalcin