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Angiostatin inhibits and regresses corneal neovascularization
Balamurali K Ambati1, Antonia M Joussen, Jayakrishna Ambati
1Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Boston, MA 02114, USA.
Objective:
To determine the ability of angiostatin and the angiostatin-producing low-metastatic (LM) clone of Lewis lung carcinoma (LLC) to inhibit and regress corneal neovascularization, as compared with the non-angiostatin-producing high-metastatic (HM) clone.
Methods:
Three groups of C57BL6/J mice underwent chemical and mechanical denudation of corneal and limbal epithelium. One group remained tumor free while the other 2 were implanted with LLC cells (either the HM or LM clones) subcutaneously the day before, 2 weeks after, or 4 weeks after denudation. Corneas were harvested 2 weeks after tumor implantation (at 2, 4, and 6 weeks after denudation for tumor-free mice). Neovascularization was quantified by CD31 immunostaining. In a second experiment, recombinant angiostatin was delivered continuously for 2 weeks via an osmotic pump in mice with established corneal neovascularization.
Results:
The mean percentages of neovascularized corneal area in mice 2 weeks after LM-LLC implantation were 4.6%, 3.7%, and 37.0%, at 2, 4, and 6 weeks after scraping, respectively. In contrast, in the mice implanted with HM-LLC, the corresponding values were 45.4% (P =.01), 90.1% (P =.03), and 80.3% (P =.005). For tumor-free mice, the corresponding values were 62.0% (P =.003), 68.9% (P =.03), and 59.3% (P =.06). Mice implanted with angiostatin pumps had a 37.7% neovascularized corneal area 2 weeks after implantation and 4 weeks after scraping while mice implanted with sham pumps had 60.5% (P =.007).
Conclusion:
Angiostatin inhibits and regresses corneal neovascularization induced by mechanical and alkali corneal injury.
Clinical Relevance:
This appears to be the first evidence of biologically induced regression of corneal neovascularization, and the first direct demonstration of angiostatin-induced regression of neovascularization in any tissue.
Insights
Angiostatin effectively inhibits and regresses corneal neovascularization. This study provides the first evidence of biologically induced regression of corneal neovascularization using angiostatin.
Area of Science:
- Ophthalmology
- Oncology
- Vascular Biology
Background:
- Corneal neovascularization (CNV) is a significant cause of vision loss.
- Tumor cells can induce CNV, and Lewis lung carcinoma (LLC) has high-metastatic (HM) and low-metastatic (LM) clones.
- Angiostatin is a known inhibitor of angiogenesis.
Purpose of the Study:
- To evaluate the efficacy of angiostatin and the LM clone of LLC in inhibiting and regressing CNV.
- To compare the effects of LM and HM clones of LLC on CNV.
- To assess the direct impact of recombinant angiostatin on established CNV.
Main Methods:
- C57BL6/J mice underwent corneal denudation and were implanted with either LM or HM LLC clones.
- Corneal neovascularization was quantified using CD31 immunostaining.
- Recombinant angiostatin was administered via osmotic pumps to mice with established CNV.
Main Results:
- LM-LLC implantation resulted in significantly less CNV compared to HM-LLC.
- HM-LLC implantation led to extensive CNV (45.4%–90.1%) compared to LM-LLC (3.7%–37.0%).
- Mice treated with angiostatin pumps showed reduced CNV (37.7%) compared to sham pumps (60.5%).
Conclusions:
- Angiostatin, both endogenously produced by LM-LLC and exogenously administered, inhibits and regresses CNV.
- This study presents the first evidence of biologically induced regression of CNV.
- This is the first direct demonstration of angiostatin-induced regression of neovascularization in any tissue.