Comparison of the effects of unfractionated heparin, low molecular weight heparin and hirudin (revasc™) on the fibrinolytic potential of cultured human umbilical vein endothelial cells

SummaryCultured human umbilical vein endothelial cells (HUVEC) have been reported to produce extrinsic pathway inhibitor (EPI), the factor Xa-dependent inhibitor of factor VHa/tissue factor (TF). We examined the release of this inhibitor from HUVEC as a function of their growth state and in response to the induction of endothelial cell TF activity. HUVEC constitutively produced significant amounts of EPI at all stages of their growth in culture including the post-confluent state. Rate of release varied over a 3-fold range for primary cultures from 12 different batches of pooled umbilical cord cells. Constitutive EPI release was unaltered during a 6 hour period of induction of TF activity with thrombin or phorbol ester but slowed during longer incubation of the cells with phorbol ester. Whereas plasma contains two molecular weight forms of EPI, only the higher of these two molecular weight forms was demonstrable by Western analysis of HUVEC supernatants with 125I-factor Xa as the ligand.

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HEPARIN STIMULATES FIBROBLAST GROWTH INDUCED BY PDGF

10.1055/s-0038-1643750 ◽

1987 ◽

Author(s):

E Dupuy ◽

P S Rohrlich ◽

G Tobelem

Keyword(s):

Molecular Weight ◽

Endothelial Cells ◽

Smooth Muscle ◽

Smooth Muscle Cells ◽

Unfractionated Heparin ◽

Low Molecular Weight Heparin ◽

Muscle Cells ◽

Low Molecular Weight ◽

Thymidine Uptake ◽

Fibroblast Proliferation

Heparin binds to smooth muscle cells and endothelial cells. It inhibits the proliferation of the smooth muscle cells and modulates the growth of endothelial cells. Fibroblasts which represent an other cell type belonging to the vascular wall could also have their growth modified by heparin. We have at first, demonstrated that 125I unfractionated heparin bigds to cultured human skin fibroblasts with a Kd of 1.16 10 M.A low molecular weight heparin fraction (PK 10169) competed (50 %)with I unfractionated heparin, but at aless extent than cold unfractionated heparin(90%).As it has been reported with endothelial and smooth muscle cells, about 30% of the bound unfractionated heparin was internalized bythe fibroblasts. Heparin alone at the concentration ranges from 0 to 10-5M has no effect on fibroblast proliferation measured by the H thymidine uptake. When the cellproliferation was induced by pure PDGF, heparin potentiated markedly the fibroblast growth.The effgct started at 10-8 M heparinand reached a plateau from 10-6 M to 10-5 M. Similar stimulationwas observed when the growth was induced by FGF or EGF. Low molecular weight heparin enhanced the fibroblast proliferation induced by PDGF but at a less extent than unfractionated heparin, chondroltin sulfate has no effect. When added during the cell culture growth withhuman serum (5%), unfractionated heparin increased by 48 the cell proliferation as measured bycell counting at the 6th day of the culture. PDGF did not modify the heparin binding on fibroblast cultures either at 4°C or 37°C and did not alter the process of heparin internalization. JDGF binding to the cultured fibroblast (Kd 10.1 ± 3.4 10-10 M)was not modified by the presence of heparin when studied at 4°C.In conclusion : i) cultured human fibroblasts bind and internalize heparin, ii) heparinand heparin fraction stimulate the fibroblastgrowth induced by PDGF, iii) since the binding of PDGF is not modified by bound heparin, the mechanism of stimulation remains unknown.

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