Rabbit rubeosis iridis induced by intravitreal latex-derived angiogenic fraction

Natural latex serum: characterization and biocompatibility assessment using Galleria mellonella as an alternative in vivo model

Natural latex serum (NLS) is one of the natural rubber latex fractions from Hevea brasiliensis tree, which is formed by centrifuged serum and is composed of proteins, acids, nucleotides, salts and carbohydrates. The proteins present in NLS have demonstrated several interesting biological properties, including angiogenic, healing, osteogenic, anti-inflammatory, antimicrobial, in addition to inducing neovascularization, bone formation and osseointegration. Thus, we proposed to characterize NLS by physicochemical techniques and to investigate the biocompatibility by toxicological assays and safety test in Galleria mellonella. Infrared spectrum showed vibrational bands characteristic of amide I, II and III that are linked to the protein content, which was confirmed by the High Performance Liquid Chromatography profile and by the Electrophoresis analysis. This material did not exhibit hemolytic (rate <0.5%) and cytotoxic effects (viability >70%) and was able to enhance the proliferation of fibroblasts (>600%) after 3 days. The pronounced proliferative effect observed in fibroblast cells can be explained by the presence of the fibroblast growth factor (FGF) like protein revealed by the Western blot test. Moreover, NLS did not provoke toxic effects (survival ∼ 80%) on the G. mellonella model, indicating that it is a biocompatible and safe material.

Puncture-Induced Iris Neovascularization as a Mouse Model of Rubeosis Iridis

We describe a model of puncture-induced iris neovascularization as a general model for noninvasive evaluation of angiogenesis. The model is also relevant for targeting neovascular glaucoma, a sight-threatening complication of diabetic retinopathy. This method is based on the induction of iris vascular response by a series of self-sealing uveal punctures on BALB/c mice and takes advantage of the postpartum maturation of mouse ocular vasculature. Mouse pups undergo uveal punctures from postnatal day 12.5, when the pups naturally open their eyes, until postnatal day 24.5. Due to the transparency of the cornea, iris vasculature can be analyzed easily through time by noninvasive in vivo methods. Furthermore, the semitransparent iris of BALB/c mice can be flatmounted for detailed immunohistologic analysis with minimal non-specific background staining. In this model, angiogenesis is mainly driven by the inflammatory and plasminogen activating systems. The puncture-induced model is the first to induce iris neovascularization in small rodents, and has the advantage of allowing direct noninvasive in vivo analysis of the angiogenic process. Moreover, the model can be combined with angiogenic modulating substances, which highlights its potential in the study of angiogenesis with an in vivo perspective.

Establishment of an experimental glaucoma animal model: A comparison of microbead injection with or without hydroxypropyl methylcellulose

The present study aimed to compare microbead injection with and without hydroxypropyl methylcellulose (HPM) in order to establish an experimental animal model of glaucoma. This model was established in C57BL/6 mice and transgenic mice expressing cyan fluorescent protein (CFP) under the control of the Thy1 promoter in retinal ganglion cells (RGCs). C57BL/6 mice aged between 12 and 20 weeks old were randomly separated into three groups, which received different injections into the anterior chamber of the eye. Group A (microbead) received 2 µl microbeads (10×106 beads/ml) and 1 µl air. Group B (microbeads + HPM) received 2 µl microbeads and 1 µl HPM. Group C (control group) received 2 µl PBS and 1 µl air. The intraocular pressure (IOP) was measured with a tonometer under topical anesthesia daily for 1 month. A single injection of microbeads, with or without HPM, induced consistent IOP elevation when compared with the control group. Thy1-CFP mice received an injection of 2 µl microbeads and 1 µl HPM into the anterior chamber of the eyes, and the number of CFP+ RGCs was subsequently assessed in vivo by confocal scanning laser microscopy in the same area of the retina weekly for 6 weeks. The results from in vivo imaging of Thy1-CFP mice were comparable with the immunohistochemical staining results from the C57BL/6 mice. The combined injection of microbeads and HPM induced longer and higher peaks of IOP elevation when compared with the microbeads alone. The rate of RGC loss following the administration of microbeads alone was 25.0±1.3% 6 weeks after the initial IOP elevation, while it was 33.2±1.9% following the administration of microbeads + HPM. These results indicate that the injection of microbeads + HPM is a more effective method of establishing a mouse model with chronic elevation of IOP. In addition, the in vivo imaging that can be used with this technique provides an effective and noninvasive approach for monitoring the progress of RGC loss.