Ocular Adverse Effects of Intravitreal Bevacizumab Are Potentiated by Intermittent Hypoxia in a Rat Model of Oxygen-Induced Retinopathy

Abstract

Intravitreal bevacizumab (Avastin) use in preterm infants with retinopathy of prematurity is associated with severe neurological disabilities, suggesting vascular leakage. We examined the hypothesis that intermittent hypoxia (IH) potentiates intravitreal Avastin leakage. Neonatal rats at birth were exposed to IH from birth (P0)–P14. At P14, the time of eye opening in rats, a single dose of Avastin (0.125 mg) was injected intravitreally into the left eye. Animals were placed in room air (RA) until P23 or P45 for recovery (IHR). Hyperoxia-exposed and RA littermates served as oxygen controls, and equivalent volume saline served as the placebo controls. At P23 and P45 ocular angiogenesis, retinal pathology and ocular and systemic biomarkers of angiogenesis were examined. Retinal flatmounts showed poor peripheral vascularization in Avastin-treated and fellow eyes at P23, with numerous punctate hemorrhages and dilated, tortuous vessels with anastomoses at P45 in the rats exposed to IH. These adverse effects were associated with robust increases in systemic VEGF and in both treated and untreated fellow eyes. Histological analysis showed severe damage in the inner plexiform and inner nuclear layers. Exposure of IH/IHR-induced injured retinal microvasculature to anti-VEGF substances can result in vascular leakage and adverse effects in the developing neonate.

Comparative Effects of Coenzyme Q10 or n-3 Polyunsaturated Fatty Acid Supplementation on Retinal Angiogenesis in a Rat Model of Oxygen-Induced Retinopathy

“…Episodes of reoxygenation following an IH event may occur in normoxia or hyperoxia. The two IH paradigms and confirmation of oxygen saturation have been previously described [ 40 , 41 , 42 , 43 , 44 , 45 , 46 ].…”

Oxygen-Induced Retinopathy from Recurrent Intermittent Hypoxia Is Not Dependent on Resolution with Room Air or Oxygen, in Neonatal Rats

“…It mimics a preterm newborn with brief, recurrent apnea and desaturations, and simulates babies who are bagged with oxygen during an IH episode. Reoxygenation in 50% O 2 followed each clustered IH event for 2.4 h for a total of eight clustered IH episodes per day for 14 days, as previously described [ 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ]; and (2) consisting of an initial exposure of normoxia (21% O 2 ) for 30 min followed by three brief, 1 min, clustered hypoxic events (12% O 2 ), with a 10 min recovery in 21% O 2 between each IH event ( Figure 8 C). This model simulates preterm infants who are bagged with room air during an IH event and recover in normoxia.…”

“…VEGF, sVEGFR-1, and IGF-I levels in the serum, vitreous fluid, and retinal and choroid homogenates were assayed using commercially-available quantikine ELISA kits from R&D Systems (Minneapolis, MN, USA), as previously described [ 45 , 47 , 51 , 52 , 53 ]. All assays were conducted according to the manufacturer’s protocol.…”

“…However, many of these models fail to incorporate the features of recurrent neonatal IH experienced by extremely immature neonates born at <28 weeks gestation, who are at the highest risk for severe ROP. Our rat model of neonatal IH-induced retinopathy has repeatedly produced many characteristics consistent with severe ROP, including vascular tufts, neovascularization, hemorrhage, dilated and tortuous vessels, photoreceptor degeneration, choroidal ruptures, and, more recently, astrocyte and Müller cell activation [ 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ]. This model, which recapitulates frequent, brief, arterial oxygen desaturations experienced by ELGANs, showed that neonatal IH induces mechanisms that regulate both Phase 1 and Phase 2, within minutes of each other, with minimal recovery time between phases.…”

Human retinal endothelial cells and astrocytes cultured on 3-D scaffolds for ocular drug discovery and development

“…For the IH profile, oxygen was set at 50% for 30 minutes, followed by three 1-minute hypoxia (5% O 2 ) episodes, each 10 minutes apart, for a total of eight clustered IH episodes/day [23]. This profile consistently produces severe OIR in our rat model [19, 24–26]. The oxygen content in the media was continuously monitored using an oxyvalidator with an oxygen sensor (BioSpherix) inserted directly into the media of a sacrificial well with cells.…”