Contribution of marrow stromal cells to the regulation of osteoblast proliferation in rats: evidence for the involvement of insulin-like growth factors.
Fibroblast-like marrow stromal cells are believed to play a role in the maintenance of osteoblast populations at the marrow-bone interface. We now report that this interaction may be very specific. Stromal cell conditioned medium (SC-CM) stimulated DNA synthesis and proliferation in culture of neonatal rat calvarial osteoblasts at low concentrations (1.25-5%), but was inhibitory at 10%. At growth promoting effective concentrations, the activity of osteoblast alkaline phosphatase was decreased. This action was selective since SC-CM failed to promote the growth of rat calvarial fibroblasts. Characterization of the SC-CM indicated the cells produced IGF-I and -II and a wide range of molecular weight fractions with putative stimulatory action (FPLC analysis using Superose 12 and 6 gel permeation columns). HPAE-PAD analysis showed that some elements were glycosylated, and the composition suggested the presence of N- and O-linked oligosaccharide chains. Because rat marrow stromal fibroblast-like cells produce a number of osteotropic factors which affect calvarial osteoblast growth, these interactions may be important to considerations about the etiology of the osteoporoses.
Zhang
R W
RW
University of Texas Medical Branch, Department of Surgery, Galveston 77550.
Simmons
D J
DJ
Crowther
R S
RS
Mohan
S
S
Baylink
D J
DJ
D000469:Alkaline Phosphatase / Q000378:metabolism; D000818:Animals; D001853:Bone Marrow / Q000378:metabolism; D001854:Bone Marrow Cells; D002452:Cell Count; D002478:Cells, Cultured; D002845:Chromatography; D003470:Culture Media; D004247:DNA / Q000096:biosynthesis; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis*; D007335:Insulin-Like Growth Factor II / Q000096:biosynthesis*; D008970:Molecular Weight; D009844:Oligosaccharides / Q000032:analysis; D010006:Osteoblasts / Q000166:cytology* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
D003470:Culture Media; D009844:Oligosaccharides; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D004247:DNA; D000469:Alkaline Phosphatase