Thrombospondin gene expression by endothelial cells in culture is modulated by cell proliferation, cell shape and the substratum

Canfield, Ann E.; Boot-Handford, RP; Schor, Ana M.

doi:10.1042/bj2680225

Cited by 44 publications

(17 citation statements)

References 41 publications

(51 reference statements)

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“…Since endothelial cells that are incorporated into tubes tend to be less active mitotically than the population from which they are derived (6)(7)(8), these findings are consistent with earlier data indicating an inverse relationship between the rate of growth and TSP production by endothelial cells in culture (29). The findings are also consistent with the more recent studies of Canfield et al (30), who reported that the level of TSP synthesis by BAEC correlated more precisely with cell shape than with rate of growth. In particular, these workers showed that BAEC cultured within collagen gels, a condition that promoted an elongated morphology similar to that displayed by sprouts, produced low levels of TSP mRNA and protein, regardless of the proliferative state of the cells.…”

Section: Discussionsupporting

confidence: 83%

Thrombospondin exerts an antiangiogenic effect on cord formation by endothelial cells in vitro.

Iruela‐Arispe

Börnstein

Sage

1991

Proc. Natl. Acad. Sci. U.S.A.

250

147

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The response of endothelial cells to angiogenic stimuli has been shown to be influenced by the extracellular microenvironment. We tested whether thrombospondin, an extraceilular matrix protein, modulated the spontaneous formation of cords by endothelial cells in vitro. Despite continued proliferation, a decrease in secreted thrombospondin was detected in cord-containing, as compared with subconfluent, cultures of both aortic and microvascular endothelial cells. Consistent with this trend, mRNA levels of thrombospondin decreased by factors of 16 in aortic and 60 in microvascular cultures that contained endothelial cords. Since thrombospondin was immunolocalized to fibrillar arrays that appeared to be associated with endothelial cords, we added anti-thrombospondin IgG to cord-forming cultures to limit the availability of the protein during this process. In the presence of antithrombospondin antibodies, there was a 33-50% increase in cord formation. These results suggest that thrombospondin is an inhibitor of angiogenesis in vitro and are consistent with its proposed roles as a destabilizer of endothelial cell focal contacts and as an inhibitor of endothelial cell proliferation.Endothelial cells from both large vessels and capillaries demonstrate a tendency to form branching tubular networks, a process that has been termed "angiogenesis in vitro" (1). The factors that influence tube formation by endothelial cells in culture are complex and include the availability and activity of mitogens such as basic fibroblast growth factor and the synthesis and interaction of endothelial cells with components of the extracellular matrix (ECM) (2, 3). Ingber and Folkman (4, 5) have stressed the importance of an appropriate degree of adhesion of endothelial cells to components of the ECM in the formation of cords and tubes and have related this adhesivity to the transduction of mechanical forces between cells and their extracellular environment. At a molecular level, the interactions that are important in this process include the recognition of ECM macromolecules by integrins and other cell-surface receptors and the ability of such complexes to affect cytoskeletal organization and to generate intracellular chemical signals.

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Section: Discussionsupporting

confidence: 83%

Thrombospondin exerts an antiangiogenic effect on cord formation by endothelial cells in vitro.

Iruela‐Arispe

Börnstein

Sage

1991

Proc. Natl. Acad. Sci. U.S.A.

250

147

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“…TSP1 expression in endothelial cells is also regulated by cell-cell contact (Mumby et al, 1984;Canfield et al, 1990). Cells without mature cell-cell contacts produce more TSP1 than confluent cells (Mumby et al, 1984).…”

Section: Discussionmentioning

confidence: 99%

Cell Contact–dependent Activation of α3β1 Integrin Modulates Endothelial Cell Responses to Thrombospondin-1

Chandrasekaran

Al-Barazi

et al. 2000

MBoC

137

129

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Thrombospondin-1 (TSP1) can inhibit angiogenesis by interacting with endothelial cell CD36 or proteoglycan receptors. We have now identified ␣3␤1 integrin as an additional receptor for TSP1 that modulates angiogenesis and the in vitro behavior of endothelial cells. Recognition of TSP1 and an ␣3␤1 integrin-binding peptide from TSP1 by normal endothelial cells is induced after loss of cell-cell contact or ligation of CD98. Although confluent endothelial cells do not spread on a TSP1 substrate, ␣3␤1 integrin mediates efficient spreading on TSP1 substrates of endothelial cells deprived of cell-cell contact or vascular endothelial cadherin signaling. Activation of this integrin is independent of proliferation, but ligation of the ␣3␤1 integrin modulates endothelial cell proliferation. In solution, both intact TSP1 and the ␣3␤1 integrin-binding peptide from TSP1 inhibit proliferation of sparse endothelial cell cultures independent of their CD36 expression. However, TSP1 or the same peptide immobilized on the substratum promotes their proliferation. The TSP1 peptide, when added in solution, specifically inhibits endothelial cell migration and inhibits angiogenesis in the chick chorioallantoic membrane, whereas a fragment of TSP1 containing this sequence stimulates angiogenesis. Therefore, recognition of immobilized TSP1 by ␣3␤1 integrin may stimulate endothelial cell proliferation and angiogenesis. Peptides that inhibit this interaction are a novel class of angiogenesis inhibitors. INTRODUCTIONAngiogenesis under normal and pathological conditions is regulated by both positive and negative signals received from soluble growth factors and components of the extracellular matrix (reviewed by Folkman, 1995;Polverini, 1995;Hanahan and Folkman, 1996). Thrombospondins are a family of extracellular matrix proteins that have diverse effects on cell adhesion, motility, proliferation, and survival (reviewed by Bornstein, 1992Bornstein, , 1995Roberts, 1996). Two members of this family, thrombospondin-1 (TSP1) and thrombospondin-2, are inhibitors of angiogenesis (Good et al., 1990;Volpert et al., 1995). TSP1 inhibits growth, sprouting, and motility responses of endothelial cells in vitro (Good et al., 1990;Taraboletti et al., 1990;Iruela Arispe et al., 1991;Canfield and Schor, 1995;Tolsma et al., 1997) and, under defined conditions, induces programmed cell death in endothelial cells (Guo et al., 1997b). TSP1 inhibits angiogenesis in vivo in the rat corneal pocket and chick chorioallantoic membrane (CAM) angiogenesis assays (Good et al., 1990;Iruela-Arispe et al., 1999). The ability of TSP1 overexpression to suppress tumor growth and neovascularization in several tumor xenograft models provides further evidence for an antiangiogenic activity of TSP1 (Dameron et al., 1994;Weinstat-Saslow et al., 1994;Sheibani and Frazier, 1995;Hsu et al., 1996). Circulating TSP1 may also inhibit neovascularization of micrometastases in some cancers (Morelli et al., 1998;Volpert et al., 1998). A few studies, however, have concluded that TSP1 also has p...

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“…15 This large difference in production rates is consistent with a study of endothelial cell production of thrombospondin in 2D and 3D collagen-based cultures (no flow) in which the production rates were observed to be much higher in 2 than in 3 dimensions. 16 A related study of rabbit arterial SMCs in 2D and 3D collagen-based cultures (no flow) showed that the cell growth rate was greatly inhibited in 3D cultures relative to 2D cultures. 17 It seems that cells in 3 dimensions are in a more quiescent state than cells in 2 dimensions in terms of both growth rate and biochemical activity.…”

Section: Discussionmentioning

confidence: 99%

Effect of Fluid Flow on Smooth Muscle Cells in a 3-Dimensional Collagen Gel Model

Wang

Tarbell

2000

ATVB

123

117

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Abstract-A 3D collagen gel model was developed to simulate interstitial fluid flow and to assess the importance of this flow on the biochemical production rates of vascular smooth muscle cells (SMCs). Rat aortic SMCs were suspended in type I collagen, and the gel was supported by nylon fibers that allowed a 9-cm length of the SMC-gel model to withstand 90 cm H 2 O differential pressure over a 6-hour period without significant compaction. Up to 1 dyne/cm 2 shear stress on the suspended SMCs could be induced by the pressure-driven interstitial flow. The suspended SMCs were globular, had a diameter of Ϸ10 m, and were distributed uniformly throughout the gel. The collagen fibers formed a network that was connected randomly with the surface of SMCs and nylon fibers. The diameter of the collagen fibers was Ϸ100 nm, and the concentration of collagen was 2.5 mg/mL. Using these parameters, fiber matrix theory predicted a Darcy permeability coefficient (K p ) of 1.22ϫ10 Ϫ8 cm 2 , which was close to the measured value of K p . The production rates of prostaglandin (PG) I 2 and PGE 2 were used as markers of biochemical responsiveness of SMCs to fluid shear stress. Both PGI 2 and PGE 2 production rates under 1 dyne/cm 2 shear stress were significantly elevated relative to static (no-flow) controls. The production rates, however, were Ϸ10 times lower than observed when the same cells were plated on collagen-treated glass slides (2D model) and exposed to the same level of shear stress by use of a rotating disk apparatus. which affects their physiological function and is believed by many to play a role in the localization of atherosclerotic plaques in arteries. 1 Smooth muscle cells (SMCs) are not normally exposed directly to the fluid shear stresses of blood flow, because they lie beneath the intact intima. In the case of injury to the intima, as occurs, for example, in angioplasty, near the anastomoses of vascular grafts, and in atherosclerotic disease, the superficial layers of SMCs are exposed directly to blood flow shear stresses (order of magnitude, 10 dyne/cm 2 ). 2 Several groups have studied the effects of fluid shear stress on SMCs using cultured cells grown in monolayers on impermeable substrates. Using these 2D models, they have shown that vascular SMCs are responsive to shear stress in the range 1 to 25 dyne/cm 2 and increase their synthesis of transforming growth factor-␤ and tissue plasminogen activator, 3 heme oxygenase-1, 4 and nitric oxide. 5 Protease-activated receptor-1 and tissue plasminogen activator gene expression are also regulated by shear stress on SMCs. 6 A more subtle mechanism by which SMCs are exposed to fluid shear stress derives from the transmural pressure gradient (typically 100 mm Hg in an artery), which drives transmural interstitial flow across the vessel wall. Using the Brinkman model of porous medium flow, Wang and Tarbell 7 estimated that for an artery with an intact intima at normal physiological pressure, the transmural flow would induce a shear stress on the SMCs in the tunica media o...

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Thrombospondin gene expression by endothelial cells in culture is modulated by cell proliferation, cell shape and the substratum

Cited by 44 publications

References 41 publications

Thrombospondin exerts an antiangiogenic effect on cord formation by endothelial cells in vitro.

Thrombospondin exerts an antiangiogenic effect on cord formation by endothelial cells in vitro.

Cell Contact–dependent Activation of α3β1 Integrin Modulates Endothelial Cell Responses to Thrombospondin-1

Effect of Fluid Flow on Smooth Muscle Cells in a 3-Dimensional Collagen Gel Model

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