Angiogenesis in P- and E-selectin-deficient mice

OBJECTIVES

Several observations reported earlier indicated that the selectins, in particular E-selectin, might be involved in angiogenesis; however, mice deficient in the endothelial selectins develop normally. To clarify the role of endothelial selectins in angiogenesis, we have studied experimentally induced angiogenesis in selectin-deficient mice.

METHODS

Hydron pellets containing either basic fibroblast growth factor or the inflammatory cytokine tumor necrosis factor alpha were implanted into the corneas of wild-type and P- and/or E-selectin-deficient mice.

RESULTS

The lengths and circumferential range of the newly formed blood vessels in the corneas of the endothelial selectin-deficient mice were similar to those of wild-type mice.

CONCLUSION

The endothelial selectins are not essential in experimentally induced angiogenesis in vivo.

Effects of thalidomide and related metabolites in a mouse corneal model of neovascularization

Thalidomide, when administered orally, is an inhibitor of angiogenesis in the basic fibroblast growth factor (bFGF)-induced rabbit cornea micropocket assay. We now show in the mouse that thalidomide given intraperitoneally but not orally significantly inhibits bFGF-induced and vascular endothelial growth factor (VEGF)-induced corneal neovascularization. We further demonstrate that this inhibition is independent from thalidomide's ability to suppress tumor necrosis factor-alpha (TNF-alpha) production. Experiments examining thalidomide's enantiomers reveal-that the S(-)-enantiomer has the strongest antiangiogenic activity in VEGF-induced and bFGF-induced corneal neovascularization. Structure activity studies suggest that thalidomide's anti-angiogenic activity is related to the open ring metabolites resulting from hydrolysis. Together these data support a correlation between thalidomide's antiangiogenic and teratogenic activities.

A model of angiogenesis in the mouse cornea

PURPOSE

The study of angiogenesis depends on reliable and reproducible models for the stimulation of a neovascular response. The purpose of this research was to develop such a model of angiogenesis in the mouse cornea.

METHODS

Uniformly sized Hydron pellets containing either basic fibroblast growth factor (bFGF) or vascular endothelial growth factor (VEGF) and sucralfate were prepared and implanted into the stroma mouse cornea adjacent to the temporal limbus.

RESULTS

Neovascularization of the corneal stroma began on day 3 and was sustained through day 8. The bFGF-induced neovascularization was consistent and dose dependent in C57B1/6, as well as in severe combined immune deficient, beige natural killer cell-deficient, and nude mouse strains. Biomicroscopic and histologic examination of bFGF- and VEGF-induced angiogenesis was notable for the absence of corneal edema or substantial inflammation.

CONCLUSIONS

This noninflammatory model of corneal neovascularization is especially advantageous because it is reproducible, economical, and facilitates investigation of angiogenesis in various murine tumor models as well as in genetically defined murine strains.

Inhibition of angiogenesis in vivo by interleukin 12

BACKGROUND

In previous animal studies, interleukin 12 (IL 12) was shown to inhibit the growth of a wide spectrum of tumors in vivo but to have no direct effect on tumor cells in vitro. Also, contrary to the expectation of a T-cell-mediated effect, the antitumor activity of IL 12 was not completely abrogated in tests of T-cell-deficient mice. These observations suggest that IL 12 may possess antiangiogenic properties that account for its tumor-inhibitory effects in vivo.

PURPOSE

Our goal was to investigate the hypothesis that IL 12 has antiangiogenic properties.

METHODS

A model of basic fibroblast growth factor-induced corneal neovascularization in mice was used to evaluate the effects of IL 12 and interferon gamma (IFN gamma) on angiogenesis in vivo. Different strains of male mice, e.g., immunocompetent C57BL/6 mice, severe combined immune-deficient (SCID) mice, natural killer cell-deficient beige mice, and T-cell-deficient nude mice, were treated with IL 12 (1 microgram/day) intraperitoneally for 5 consecutive days. The extent of neovascularization in response to a basic fibroblast growth factor pellet and the inhibition of neovascularization by IL 12 or IFN gamma were assessed by measuring the maximal vessel length and the corneal circumference involved in new blood vessel formation. The antitumor activities of IL 12 and of the angiogenesis inhibitor AGM-1470 were evaluated in Lewis lung carcinoma-bearing mice. In vitro proliferation studies were performed on bovine capillary endothelial cells, mouse pancreatic islet endothelial cells, and mouse hemangioendothelioma cells.

RESULTS

IL 12 treatment almost completely inhibited corneal neovascularization in C57BL/6, SCID, and beige mice. This potent suppression of angiogenesis was prevented by the administration of IFN gamma-neutralizing antibodies, suggesting that the suppression was mediated through IFN gamma. In addition, the administration of IFN gamma reproduced the antiangiogenic effects observed during treatment with IL 12. Treatment with IL 12 and AGM-1470 combined did not increase toxicity and showed a trend toward enhanced antitumor efficacy in Lewis lung carcinoma-bearing mice.

CONCLUSIONS

IL 12 strongly inhibits neovascularization. This effect is not mediated by a specific cell type of the immune system. Instead, IL 12 has been shown to induce IFN gamma, which, in turn, appears to play a critical role as a mediator of the antiangiogenic effects of IL 12.

IMPLICATIONS

Recognition of the mechanisms of the antiangiogenic properties of IL 12 may be crucial in planning its clinical applications, including a possibility of coadministration with other inhibitors of neovascularization.

Penetrating keratoplasty and anterior segment reconstruction for severe ocular trauma

The principles for management of acute ocular trauma are also applicable to the subsequent reconstruction of the anterior segment. As with the primary repair of ocular trauma, meticulous anatomical restoration during reconstructive surgery minimizes secondary complications and enhances the visual prognosis. Anterior segment reconstruction may then involve procedures such as stripping of corneal pannus, removal of lens and vitreous remnants, iris and angle reconstruction, intraocular lens implantation, and penetrating keratoplasty. A total of 39 consecutive cases of severe ocular trauma, which had undergone penetrating keratoplasty and anterior segment reconstruction, were evaluated for visual outcome, graft survival, and secondary complications. Post-operatively, 49% of eyes achieved > 20/100 as compared with 10% before surgery, and 72% improved by at least two Snellen lines. In all, 31 (80%) initial keratoplasties remained clear, as did all 4 subsequently regrafted corneas, for an overall keratoplasty success rate of 90%. Elevated intraocular pressure occurred postoperatively in 18 eyes (46%), and among these, 10 of 13 eyes (77%) had preoperative glaucoma, whereas 8 of 26 (31%) did not (P < 0.015). Peripheral anterior synechiae could be anatomically corrected at surgery in 80% of cases (24 of 30 eyes). Thus, despite major trauma and a high prevalence of glaucoma, both the visual and the anatomical improvements were highly satisfactory and without severe complications.