June 2023
Volume 64, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2023
Endomucin deletion leads to disorganized choroidal capillary fenestration and reduces laser-induced choroidal neovascularization in mice
Author Affiliations & Notes
  • Zhengping Hu
    Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, Massachusetts, United States
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
  • Issahy Cano
    Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, Massachusetts, United States
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
  • Anton Lennikov
    Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, Massachusetts, United States
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
  • Melissa Wild
    Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, Massachusetts, United States
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
  • Urvi Gupta
    School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States
  • Yin Shan Eric Ng
    EyeBio, London, United Kingdom
  • Patricia A D'Amore
    Schepens Eye Research Institute of Massachusetts Eye and Ear, Boston, Massachusetts, United States
    Ophthalmology, Harvard Medical School, Boston, Massachusetts, United States
  • Footnotes
    Commercial Relationships   Zhengping Hu None; Issahy Cano None; Anton Lennikov None; Melissa Wild None; Urvi Gupta None; Yin Shan Eric Ng Sayht Therapeutics, LLC, Code O (Owner); Patricia D'Amore Sayht Therapeutics, LLC, Code O (Owner)
  • Footnotes
    Support  5R01EY026539-05
Investigative Ophthalmology & Visual Science June 2023, Vol.64, 3005. doi:
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    • Get Citation

      Zhengping Hu, Issahy Cano, Anton Lennikov, Melissa Wild, Urvi Gupta, Yin Shan Eric Ng, Patricia A D'Amore; Endomucin deletion leads to disorganized choroidal capillary fenestration and reduces laser-induced choroidal neovascularization in mice. Invest. Ophthalmol. Vis. Sci. 2023;64(8):3005.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : The type I integral membrane glycoprotein endomucin (EMCN) is selectively expressed by capillary and venous endothelium. We have previously reported that knockdown of EMCN in vitro prevents VEGF165-induced VEGFR2 internalization and downstream activities. This study aims to investigate the effect of EMCN deletion on the choriocapillaris and angiogenesis in laser-induced model of choroidal neovascularization (CNV).

Methods : Global EMCN knock-out (EMCN-/-) mice were generated by crossing EMCN-floxed mice with ROSA26-Cre mice. Choroid, retina, kidney, lung, spleen, liver and thyroid were harvested and mRNA levels of EMCN were examined. Eyes from adult EMCN-/- mice and EMCN+/+ littermates were fixed for transmission electron microscopy (TEM). CNV was induced in EMCN+/+ and EMCN-/- mice (6-8 weeks old) using 532 nm laser photocoagulation. Mice were imaged using fluorescein angiography (FA) and optical coherence tomography (OCT) seven days after laser and then sacrificed. The lesion leakage was calculated by subtracting the integrated intensity of the earlier time point from the later time point. Expression of IB4, VEGF and Iba1 were examined on retinal pigment epithelium/choroid flat mounts using an SP8 confocal microscope.

Results : The choroid had the highest level of EMCN mRNA level of the tissues examined (n=4). The fenestrations of the choriocapillaris of EMCN-/- mice were disorganized and the endothelial cells were thickened compared to wildtype (n=3) on TEM. EMCN-/- mice had significantly reduced CNV leakage compared to EMCN+/+ mice (22.2 x 104 ± 2.2 x 104 pixels vs 41.06 x 104 ± 3.6 x 104 pixels, n=24, p<0.001, Student’s t-test). EMCN-/- mice had significantly smaller lesion area compared to EMCN+/+ mice on OCT (2.7 x 104 ± 841.2 um2 vs 3.5 x 104 ± 1119 um2, n=24, p<0.0001, Student’s t-test). Quantification of IB4-stained lesion area corroborated the OCT findings confirming that EMCN-/- mice had smaller lesions compared to EMCN+/+ mice(2.2 x 104 ± 1639 um2 vs 3.2 x 104 ± 2226 um2, n=23, p<0.001, Student’s t-test).

Conclusions : Lack of EMCN in vivo leads to disorganized fenestrations in choroidal endothelium, structures known to be dependent on continuous signaling. In addition, the absence of EMCN interferes with angiogenesis and permeability, processes that are driven by VEGF signaling, pointing to EMCN as an alternative therapeutic target.

This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.

 

 

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