Induction of angiogenic response by chemically stable prostacyclin analogs

Effect of topical application of a stable prostacyclin analogue, SM-10902 on wound healing in diabetic mice

The mechanism of wound healing induced by topical application of an ointment containing a new stable prostacyclin analogue, SM-10902 ((+)-methyl[2-[(2R,3aS,4R,5R, 6aS)-octahydro-5-hydroxy-4-[(E)-(3S,5S)-3-hydroxy-5-methyl-1- nonenyl]-2-pentalenyl] ethoxy] acetate), was investigated in the full-thickness wounds of genetically diabetic mice (db/db mice). The db/db mice treated with SM-10902 ointment (1, 10 and 100 micrograms/g) showed greater decrease in wound lesion area not covered with epidermis and fewer complete healing days than those treated with ointment base, and the effects of this prostacyclin analogue were greater than those of lysozyme chloride ointment (50 mg/g, Reflap ointment). SM-10902 ointment increased skin blood flow in the central site of the wound with development of wound healing. Histological evaluation of wounds revealed that SM-10902 ointment increased the capillary number during the early stage of the wound-healing process. These results suggest that SM-10902 ointment promotes wound healing through the stimulation of angiogenesis and the improvement of blood flow in neovascularization of repairing wound and may be useful in the treatment of skin ulcers caused by peripheral circulatory insufficiency.

Tumour vasculature--a potential therapeutic target

The tumour vasculature is vital for the establishment, growth and metastasis of solid tumours. Its physiological properties limit the effectiveness of conventional anti-cancer strategies. Therapeutic approaches directed at the tumour vasculature are reviewed, suggesting the potential of anti-angiogenesis and the targeting of vascular proliferation antigens as cancer treatments.

Angiostasis and vascular regression in chronic granulomatous inflammation induced by diclofenac in combination with hyaluronan in mice

Angiostasis and vascular regression in chronic granulomatous inflammation was assessed in mice induced with diclofenac in combination with hyaluronan. The local injection of 0.1 mL HYAL EX-0001 (0.18% diclofenac in 2.5% hyaluronan) reduced granulomatous development after six days treatment from 150.4 +/- 13.8 (0.18 saline) to 117.1 +/- 17.8 mg (dry weight, n = 10), but not significantly when compared with 0.1 mL 2.5% hyaluronan alone or diclofenac in 0.1 mL saline. Diclofenac administered in saline had no significant effect when compared with saline control. The vascular density, expressed as carmine content per mg dry weight tissue, in those animals treated with HYAL EX-0001 was also significantly reduced to 5.27 +/- 0.55 micrograms mg-1 (P < 0.1, n = 10) when compared with saline control (7.99 +/- 1.0), hyaluronan alone (7.20 +/- 1.0), and diclofenac in saline. (7.36 +/- 1.28). A similar profile of activity was seen on topical application except that all treatments did not affect granulomatous tissue development. On therapeutic dosing of mice daily with HYAL EX-0001 from day 7 after induction of the granulomatous tissue, the granulomatous tissue development was dramatically reduced from 111.67 +/- 4.40 mg (n = 14 on day 7) to 60.23 +/- 7.22 (P < 0.001, n = 8 on day 14) and 54.98 +/- 7.88 (P < 0.001, n = 8 on day 21). HYAL EX-0001 after 14 days of application significantly reduced granulomatous tissue mass when compared with the hyaluronan-dosed control on day 21 (89.58 +/- 7.49, P = 0.01, n = 8).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of isocarbacyclin, a stable prostacyclin analogue, on monkey isolated cerebral and peripheral arteries

1. The effects of isocarbacyclin (TEI 7165), a stable prostacyclin analogue, were examined in monkey isolated cerebral and peripheral arteries. 2. Addition of TEI 7165 (0.1 nM-10 microM) produced a dose-dependent relaxation in cerebral arteries pre-contracted with 1 microM 5-hydroxytryptamine (5-HT). High concentrations (more than 1 microM) of TEI 7165 elicited a transient contraction followed by a sustained relaxation. 3. TEI 7165 also elicited a dose-dependent relaxation in the peripheral (except popliteal) arteries. The maximum relaxation induced by 10 microM TEI 7165 was greater (P < 0.05) in the mesenteric artery than in the cerebral artery. The negative logarithm of the EC50 value for the mesenteric, 7.6 +/- 0.3, was greater (P < 0.05) than that for the cerebral artery, 6.4 +/- 0.3. The decreasing order of potency for the TEI 7165-induced relaxation was as follows: mesenteric > renal > cerebral > coronary > popliteal. 4. Removal of the endothelium did not significantly affect TEI 7165-induced relaxations. 5. The transient contraction produced by high concentrations of TEI 7165 was not observed in cerebral arteries precontracted with 1 nM U46619, a stable analogue of thromboxane A2 (TXA2). Furthermore, the TEI 7165-induced contraction was markedly suppressed (P < 0.05) by treatment with 10 nM S1452, a TXA2 blocking agent. 6. These results suggest that TEI 7165 causes an endothelium-independent relaxation in monkey cerebral and peripheral arteries, and that there is a marked regional difference in the TEI 7165-induced relaxations. A high concentration of TEI 7165 also produces a transient contraction which is probably through activation of TXA2 (TP-) receptors.

Coordinated regulation of vascular endothelial cell growth and prostacyclin production by epidermal growth factor: evidence of clonal variations among rat aortic endothelial cells

Rat aortic endothelial cells were found to exhibit clonal variations in response to EGF stimulation in cell growth and prostacyclin synthesis. EGF-induced growth and prostacyclin synthesis appeared to be regulated in a coordinated manner in that a clone with a higher response to EGF growth stimulation also exhibited a higher response to EGF-stimulated prostacyclin synthesis. This observation implies a possible involvement of prostacyclin synthesis in some of the biological effects of EGF on vascular endothelial cells.

Eicosapentaenoic acid inhibits tube formation of vascular endothelial cells in vitro

We previously have described a quantitative angiogenesis in vitro model, in which endothelial cells are cultured between two layers of type I collagen gel and become organized into tube-like structures. Using this model, the effect of eicosapentaenoic acid (20:5n-3) on tube formation was investigated. When the endothelial cells isolated from bovine carotid artery were treated for 2 days with 5 micrograms/mL of arachidonic acid (20:4n-6), eicosapentaenoic acid or docosahexaenoic acid (22:6n-3), these polyunsaturated fatty acids were extensively incorporated into cellular phospholipids. The context of arachidonic, eicosapentaenoic and docosahexaenoic acid increased from 9.58% to 23.29%, from 0.98% to 11.76% and from 6.88% to 18.40%, respectively. When the eicosapentaenoic acid-treated cells were cultured between collagen gels, the tube-forming ability of the cell was markedly inhibited. The inhibition was dose-dependent between 1.0 and 5.0 micrograms/mL of eicosapentaenoic acid. At 5.0 micrograms/mL of eicosapentaenoic acid the inhibition reached 76%. By contrast, arachidonic acid increased tube formation, and docosahexaenoic acid had no effect. To elucidate the mechanism of eicosapentaenoic acid induced inhibition of in vitro tube formation, we examined the effect of the acid on the proliferation of endothelial cells. Eicosapentaenoic acid at any dose (less than 5.0 micrograms/mL) had no effect on the proliferation of endothelial cells cultured on plastic plates without collagen gel. However, when the cells were cultured between collagen gels, eicosapentaenoic acid inhibited cell growth in a dose-dependent manner with maximum inhibition being observed at 2.5 micrograms/mL. These data suggest that eicosapentaenoic acid suppresses tube formation of endothelial cells,at least in part, via its inhibitory effect on cellular proliferation.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of growth factors on human vascular endothelial cell prostacyclin production

Prostacyclin (PGI2) is an antithrombotic factor, which may prevent the initiation and the complications of arteriosclerosis. The most important site of PGI2 production is the vascular endothelium, but little is known about how this process is regulated. In this connection, there is special interest in the roles of various growth factors released from platelets, macrophages, vascular smooth muscle cells, and the endothelial cells themselves. We investigated the effects of transforming growth factor-beta (TGF-beta), platelet-derived growth factor (PDGF), and acidic and basic fibroblast growth factors (aFGF and bFGF) on the PGI2 production of cultured human umbilical vein endothelial cells by measuring the stable metabolite of PGI2, 6-keto-prostaglandin F1 alpha, by radioimmunoassay. TGF-beta induced dose- and time-dependent stimulation of PGI2 production. The lowest stimulatory concentration of TGF-beta was 0.1 ng/ml, and the maximal response, a 2.1-fold rise, was obtained with 1.0 ng/ml. The effect of TGF-beta lasted 48 hours and was blocked by inhibitors of transcription, translation, and cyclooxygenase. Maximal stimulation by TGF-beta was enhanced by epidermal growth factor. PDGF and bFGF had no effect on PGI2 production, but aFGF inhibited it. This is the first demonstration that TGF-beta enhances PGI2 production by human vascular cells, and this phenomenon may be part of negative feedback mechanisms that prevent thrombosis and arteriosclerosis.

Transforming growth factor alpha stimulates prostacyclin production by cultured human vascular endothelial cells more potently than epidermal growth factor

Transforming growth factor alpha (TGF alpha) induces dose- and time-dependent stimulation of prostacyclin (PGI2) production by cultured human umbilical vein endothelial cells. The lowest stimulatory concentration of TGF alpha was 0.1 ng/ml and the maximal response, a 2.7-fold rise, was obtained with 10 ng/ml. The stimulation, which lasted at least 24 h, was blocked by cycloheximide and by indomethacin. TGF alpha induced PGI2 production at 10-100 times lower concentrations than did epidermal growth factor (EGF), although in stimulating endothelial cell growth the two factors were equipotent. This is the first demonstration that TGF alpha enhances PGI2 production by human cells. Moreover, this is the first evidence that it acts as both an agonist (growth) and a superagonist (PGI2 production) of EGF in the same cell type. I suggest that this phenomenon may be involved with the angiogenic activity of TGF alpha.