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C Jefferiss

Publications and source records attributed to C Jefferiss.

4 recordsLinked to original sources
PubMed2002

Methotrexate in the treatment of rheumatoid arthritis. I. In vitro effects on cells of the osteoblast lineage.

OBJECTIVE: Low-dose methotrexate (MTX) is often used in the treatment of rheumatoid arthritis (RA). To be effective, treatment must be long-term, and there are concerns that MTX may impair bone formation in a population already predisposed to osteoporosis. The purpose of this investigation was to determine the direct effects of MTX at clinically relevant doses on the growth and differentiation of human cells of the osteoblast (bone-forming) lineage. METHODS: Cells derived from the marrow stroma (BMSC) and trabecular surfaces [human bone-derived cells (HBDC)] of adult ribs were cultured in the absence or presence of MTX (1-1000 nM). To promote the differentiation and further maturation of cells of the osteoblast lineage, one half of the cultures were treated additionally with 10 nM dexamethasone (Dx). RESULTS: In cultures of BMSC, treatment with MTX (+/-Dx) did not affect the total number of colonies that formed or the expression of the developmental markers STRO-1 and alkaline phosphatase (AP). At concentrations > or =10 nM, however, there was a statistically significant reduction in the number of cells harvested at the end of primary culture. In cultures of HBDC, treatment with MTX (in the presence of Dx) did not affect cell number or the expression of AP. CONCLUSIONS: At concentrations > or =10 nM, treatment with MTX inhibits the proliferation of primitive marrow stromal cells, but not their ability to undergo osteogenic differentiation. The proliferation and further maturation of cells of the osteoblast lineage is not affected by treatment with MTX. These findings are reassuring for clinicians using MTX in the treatment of RA.

ADP-ribosyl Cyclase↗
PubMed2001

High concentrations of dexamethasone suppress the proliferation but not the differentiation or further maturation of human osteoblast precursors in vitro: relevance to glucocorticoid-induced osteoporosis.

OBJECTIVE: The use of glucocorticoids (GCs) in the treatment of RA is a frequent cause of bone loss. In vitro, however, this same class of steroids has been shown to promote the recruitment and/or maturation of primitive osteogenic precursors present in the colony forming unit-fibroblastic (CFU-F) fraction of human bone and marrow. In an effort to reconcile these conflicting observations, we investigated the effects of the synthetic GC dexamethasone (Dx) on parameters of growth and osteogenic differentiation in cultures of bone marrow stromal cells derived from a large cohort of adult human donors (n=30). METHODS: Marrow suspensions were cultured in the absence and presence of Dx at concentrations between 10 pm and 1 microm. After 28 days we determined the number and diameter of colonies formed, the total number of cells, the surface expression of receptors for selected growth factors and extracellular matrix proteins and, based on the expression of the developmental markers alkaline phosphatase (AP) and the antigen recognized by the STRO-1 monoclonal antibody, the proportion of cells undergoing osteogenic differentiation and their extent of maturation. RESULTS: At a physiologically equivalent concentration, Dx had no effect on the adhesion of CFU-F or on their subsequent proliferation, but did promote their osteogenic differentiation and further maturation. These effects were independent of changes in the expression of the receptors for fibroblast growth factors, insulin-like growth factor 1, nerve growth factor, platelet-derived growth factors and parathyroid hormone/parathyroid hormone-related protein, but were associated with changes in the number of cells expressing the alpha(2) and alpha(4), but not beta(1), integrin subunits. At supraphysiological concentrations, the effects of Dx on the osteogenic recruitment and maturation of CFU-F and their progeny were maintained but at the expense of a decrease in cell number. CONCLUSIONS: A decrease in the proliferation of osteogenic precursors, but not in their differentiation or maturation, is likely to be a key factor in the genesis of GC-induced bone loss.

Adult↗
PubMed2000

Expression of the developmental markers STRO-1 and alkaline phosphatase in cultures of human marrow stromal cells: regulation by fibroblast growth factor (FGF)-2 and relationship to the expression of FGF receptors 1-4.

Autologous marrow stromal cells have been proposed as an adjuvant in the treatment of bone defects and diseases. This will require the development of culture conditions that permit their rapid expansion ex vivo while retaining their potential for further differentiation. Fibroblast growth factor (FGF)-2 has been proposed as a candidate for the ex vivo expansion of cells with enhanced osteogenic potential, and we have explored this possibility further using cells obtained from a large cohort of adult human donors. Treatment with FGF-2 (0.001-2.5 ng/mL) had no detectable effect on colony formation, but markedly increased their proliferative potential and that of their immediate progeny, as shown by the increases in colony size and cell number. Based on the observed increase in the expression of the developmental markers STRO-1 and alkaline phosphatase (AP), a major target for the actions of FGF-2 appears to be the more primitive cells of the osteoblast lineage, and that, when added in combination with the synthetic glucocorticoid dexamethasone (Dx), it interacts positively to promote further cell maturation. The maintenance of adequate levels of ascorbate was shown to be a critical component in determining the nature of the effect of FGF-2 on AP expression. Variation in the response (predominantly in the magnitude and/or sensitivity) of the cultured cell populations to treatment with FGF-2 was apparent, but a preliminary analysis indicated that this was not due to differences in the age or gender of the donors used. The cultured cell populations were found to express multiple FGF receptors (FGFRs; 1-4) and the observed changes in the spectrum and abundance of FGFRs expressed in relation to that of STRO-1 and AP are consistent with their expression being developmentally regulated during the process of osteogenic differentiation. These results provide novel insights into the mechanism of action of FGF-2 on human cells of the osteoblast lineage and support the use of this factor, alone or in combination with Dx, for the rapid, ex vivo expansion of cell populations with enhanced osteogenic potential.

Adult↗