Abstract
Purpose :
To evaluate hemangiogenesis and VEGF ligand and receptor expression in young versus adult mice using a suture model of corneal neovascularization (NV)
Methods :
Three interrupted figure-of-eight intrastromal corneal sutures were placed in young (3.5 week old) and adult (8 week old) male BALB/c mice. Corneal NV was evaluated by slit-lamp microscopy at days 1,3,7 and 14 after suture implantation. mRNA levels of VEGFA, VEGFC, VEGFR1 and VEGFR2 were additionally evaluated on days 3, 7 and 14. The change in mRNA level in sutured corneas was compared to naive (unsutured) control corneas by calculating the following ratio: (Young-Naïve)/(Adult-Naïve) and then evaluating the expression of each ligand relative to its corresponding receptor (VEGFA/VEGFR1 and VEGFC/VEGFR2). Whole mount corneal immunohistochemistry (IHC) was performed on day 14. Corneal blood vessels were stained with anti-CD31 antibody
Results :
Young and adult mice demonstrated a significant induction of clinically apparent NV through day 14. At day 14, mRNA levels of VEGFA were significantly higher in young (3937±537 copies/106 GAPDH) versus adult mice (2167±292 copies/106GAPDH, p=0.011) and mRNA levels of VEGFR1 were also significantly higher in young (2703±389 copies/106GAPDH) versus adult mice (1541±331 copies/106 GAPDH, p=0.039). There was a trend towards significance for VEGFC (1417±323 copies/106 GAPDH versus 532±271 copies/106 GAPDH, p=0.05) and there was no difference in level of VEGFR2 (2029±486 versus 2021±549, respectively, p=0.99). In evaluating change in mRNA expression relative to naïve controls, we found a 1.48-fold increase in VEGFA compared to VEGFR1 and a 1.7-fold increase in VEGFC compared to VEGFR2. IHC revealed a difference in the pattern of NV between groups. Young mice demonstrated smaller caliber vessels with greater circumferential involvement. The extent of corneal NV in mean number of clock hours was 11±0.84 in young versus 6.6±4.28 in adult mice (p=0.046)
Conclusions :
We observed significantly greater mRNA expression of VEGFA and VEGFR1, and a greater increase in VEGFA and VEGFC in young versus adult mice, as well as differences in pattern of NV on IHC, with a significantly greater circumferential extent of corneal NV in young mice. These results suggest distinct hemangiogenic responses in young versus adult mice with potentially more robust responses to injury in young mice
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.