Angiostatin and integrin ?v?3 in the feline, bovine, canine, equine, porcine and murine retina and cornea

Endothelial cells and angiogenesis in the horse in health and disease-A review

The cardiovascular system is the first functional organ in the embryo, and its blood vessels form a widespread conductive network within the organism. Blood vessels develop de novo, by the differentiation of endothelial progenitor cells (vasculogenesis) or by angiogenesis, which is the formation of new blood vessels from existing ones. This review presents an overview of the current knowledge on physiological and pathological angiogenesis in the horse including studies on equine endothelial cells. Principal study fields in equine angiogenesis research were identified: equine endothelial progenitor cells; equine endothelial cells and angiogenesis (heterogeneity, markers and assessment); endothelial regulatory molecules in equine angiogenesis; angiogenesis research in equine reproduction (ovary, uterus, placenta and conceptus, testis); angiogenesis research in pathological conditions (tumours, ocular pathologies, equine wound healing, musculoskeletal system and laminitis). The review also includes a table that summarizes in vitro studies on equine endothelial cells, either describing the isolation procedure or using previously isolated endothelial cells. A particular challenge of the review was that results published are fragmentary and sometimes even contradictory, raising more questions than they answer. In conclusion, angiogenesis is a major factor in several diseases frequently occurring in horses, but relatively few studies focus on angiogenesis in the horse. The challenge for the future is therefore to continue exploring new therapeutic angiogenesis strategies for horses to fill in the missing pieces of the puzzle.

Bigh3 silencing increases retinoblastoma tumor growth in the murine SV40-TAg-Rb model

BIGH3, a secreted protein of the extracellular matrix interacts with collagen and integrins on the cell surface. BIGH3 can have opposing functions in cancer, acting either as tumor suppressor or promoter by enhancing tumor progression and angiogenesis. In the eye, BIGH3 is expressed in the cornea and the retinal pigment epithelium and could impact on the development of retinoblastoma, the most common paediatric intraocular neoplasm. Retinoblastoma initiation requires the inactivation of both alleles of the RB1 tumor suppressor gene in the developing retina and tumor progression involves additional genomic changes. To determine whether BIGH3 affects retinoblastoma development, we generated a retinoblastoma mouse model with disruption of the Bigh3 genomic locus. Bigh3 silencing in these mice resulted in enhanced tumor development in the retina. A decrease in apoptosis is involved in the initial events of tumorigenesis, followed by an increased activity of the pro-survival ERK pathway as well as an upregulation of cyclin-dependent kinases (CDKs). Taken together, these data suggest that BIGH3 acts as a tumor suppressor in the retina.

Cyclic RGD peptides target human trabecular meshwork cells while ameliorating connective tissue growth factor-induced fibrosis

The major risk factor for primary open-angle glaucoma is increased intraocular pressure stemming from elevated outflow resistance in the trabecular meshwork (TM) region. Integrins play a pivotal role in the TM by influencing its biological properties and growth factor signaling. Pathologic changes in the TM are partially mediated by growth factors like connective tissue growth factor (CTGF). Specific targeting of TM cells could play a critical clinical role by increasing the therapeutic efficacy of nanoparticles, e.g. for nonviral gene delivery. Quantum dots with cyclo(RGDfC) covalently immobilized to their surface effectively targeted cultured TM cells and were rapidly and efficiently endocytosed by binding to α_vβ₃ and α_vβ₅ integrins. Compared to the integrin-overexpressing U87-MG cell line, the association of RGD-modified nanoparticles with the TM cells was significantly higher. Binding and uptake into TM cells was receptor-mediated and suppressible with free peptide. Soluble cyclic RGD peptides effectively attenuated CTGF-mediated effects and inhibited CTGF signaling. Due to their antagonism for αvβ3 and αvβ5 integrins, these cyclic RGD pentapeptides effectively ameliorated the CTGF-induced effects and strongly promoted specific nanoparticle association. Thus, cyclic RGD peptides are powerful multifunctional ligands for both addressing nanomaterials to the TM and interfering with pathologic CTGF signaling upon arrival.

Tgfbi/Bigh3 silencing activates ERK in mouse retina

BIGH3 is a secreted protein, part of the extracellular matrix where it interacts with collagen and integrins on the cell surface. BIGH3 can play opposing roles in cancer, acting as either tumor suppressor or promoter, and its mutations lead to different forms of corneal dystrophy. Although many studies have been carried out, little is known about the physiological role of BIGH3. Using the cre-loxP system, we generated a mouse model with disruption of the Bigh3 genomic locus. Bigh3 silencing did not result in any apparent phenotype modifications, the mice remained viable and fertile. We were able to determine the presence of BIGH3 in the retinal pigment epithelium (RPE). In the absence of BIGH3, a transient decrease in the apoptotic process involved in retina maturation was observed, leading to a transient increase in the INL thickness at P15. This phenomenon was accompanied by an increased activity of the pro-survival ERK pathway.

Equine deep stromal abscesses (51 cases - 2004-2009)--Part 2: the histopathology and immunohistochemical aspect with attention to the histopathologic diagnosis, vascular response, and infectious agents

PURPOSE

To investigate histopathologic and immunohistochemical aspects of equine deep stromal abscesses (DSA) with a focus on the histopathologic diagnosis, presumptive etiology, and the immunohistochemical expression of three angiogenesis-related factors: vascular endothelial growth factor-A (VEGF-A), pigment epithelium-derived factor (PEDF), and interleukin-1 receptor antagonist (IL-1ra).

SAMPLE POPULATION

Paraffin-embedded biopsy samples from 51 DSA. The biopsies were collected from full-thickness penetrating keratoplasty or split-thickness lamellar keratoplasty surgeries at the University of Florida Veterinary Medical Center in the period from 2004 to 2009.

PROCEDURE

The histopathologic and immunohistochemical findings were tested for association between each other. Prevalence calculation and test for association with qualitative data analysis was used for data evaluation.

RESULTS

Fungal hyphae were found histologically in 47.1% (n = 24) of the DSA cases. Histopathologically, most fungal DSA showed suppurative keratitis (n = 34; 66.7%) and little to no stromal vascularization infiltrating the abscess (negative association, P = 0.005). All three angiogenesis-related factors were expressed to some degree in DSA tissue. A negative association between VEGF-A and PEDF when compared to the presence of fungal hyphae (P < 0.001, P = 0.023) indicated that cases positive for these two factors will most probably not have fungal hyphae present.

CONCLUSION

Abnormally decreased VEGF-A expression is suggested as the reason for the slow vascularization and delayed resolution of fungal DSA, whereas PEDF and IL-ra did not seem to have any influence on the vascularization process. Clinical and histopathologic characteristics of DSA make it possible to suggest an etiology for an equine DSA with an unknown etiology.

A novel injectable chitosan/polyglutamate polyelectrolyte complex hydrogel with hydroxyapatite for soft-tissue augmentation

This study demonstrated a chitosan (CS)/polyglutamate (PG) polyelectrolyte complex (PEC) hydrogel combined with spherical hydroxyapatite (HAp) particles as an injectable dermal filler for soft-tissue augmentation. The CS/PG PEC hydrogel with oppositely charged ionic cross-linking, a high gel content, and low degradation rate was introduced as a carrier to achieve high shape and volume stability. An MTT assay indicated that the CS/PG PEC had satisfactory cell biocompatibility. This PEC/HAp hydrogel showed good structural integrity in a PBS solution for up to 60 days. Clinical manageability was indexed by an injection force measurement through sterile 27-gauge needles using a texture analyzer. In an animal study, 0.2 mL of the PEC and PEC/hydroxyapatite (HAp) were implanted within the dorsal dermis of a swine ear. Injected tissue areas were biopsied 2 weeks, and 2 and 6 months after the injection. According to the histomorphometric results, the PEC and PEC/HAp groups showed percentages of retention of the maximum height of the cross-section of about 44% and 73% at 6 months. New collagen was observed in the central position indicating a possible collagenesis effect. These results suggest that this PEC/HAp system can be used as an alternative for soft-tissue augmentation.

Porcine ophthalmology

Although there appears to have been an increase in literature about the anatomy and physiology of the pig eye because of an expansion in its use as a model for research, there has been little written about the development of veterinary medicine in the area. Pig eyes share many similarities with human eyes, having a holangiotic retinal vasculature, no tapetum, cone photoreceptors in the outer retina, and a similar scleral thickness, rendering them valuable in comparative research. It must not be forgotten, however, that pigs are intelligent sentient animals which use vision as an important sense. Thus, diseases such as congenital cataracts, which impede vision, are important from the perspective of pig welfare. In addition, ocular lesions in this species, as with many others, can be a significant sign of systemic disease.