Development of stromal differentiation patterns in heterotypical models of artificial corneas generated by tissue engineering.

Purpose: We carried out a histological characterization analysis of the stromal layer of human heterotypic cornea substitutes generated with extra-corneal cells to determine their putative usefulness in tissue engineering. Methods: Human bioartificial corneas were generated using nanostructured fibrin-agarose biomaterials with corneal stromal cells immersed within. To generate heterotypical corneas, umbilical cord Wharton's jelly stem cells (HWJSC) were cultured on the surface of the stromal substitutes to obtain an epithelial-like layer. These bioartificial corneas were compared with control native human corneas and with orthotypical corneas generated with human corneal epithelial cells on top of the stromal substitute. Both the corneal stroma and the basement membrane were analyzed using histological, histochemical and immunohistochemical methods in samples kept in culture and grafted in vivo for 12 months in the rabbit cornea. Results: Our results showed that the stroma of the bioartificial corneas kept ex vivo showed very low levels of fibrillar and non-fibrillar components of the tissue extracellular matrix. However, in vivo implantation resulted in a significant increase of the contents of collagen, proteoglycans, decorin, keratocan and lumican in the corneal stroma, showing higher levels of maturation and spatial organization of these components. Heterotypical corneas grafted in vivo for 12 months showed significantly higher contents of collagen fibers, proteoglycans and keratocan. When the basement membrane was analyzed, we found that all corneas grafted in vivo showed intense PAS signal and higher contents of nidogen-1, although the levels found in human native corneas was not reached, and a rudimentary basement membrane was observed using transmission electron microscopy. At the epithelial level, HWJSC used to generate an epithelial-like layer in ex vivo corneas were mostly negative for p63, whereas orthotypical corneas and heterotypical corneas grafted in vivo were positive. Conclusion: These results support the possibility of generating bioengineered artificial corneas using non-corneal HWJSC. Although heterotypical corneas were not completely biomimetic to the native human corneas, especially ex vivo, in vivo grafted corneas demonstrated to be highly biocompatible, and the animal cornea became properly differentiated at the stroma and basement membrane compartments. These findings open the door to the future clinical use of these bioartificial corneas.

Successful restoration of corneal surface integrity with a tissue-engineered allogeneic implant in severe keratitis patients.

OBJECTIVES: Corneal diseases are among the main causes of blindness, with approximately 4.6 and 23 million patients worldwide suffering from bilateral and unilateral corneal blindness, respectively. The standard treatment for severe corneal diseases is corneal transplantation. However, relevant disadvantages, particularly in high-risk conditions, have focused the attention on the search for alternatives. METHODS: We report interim findings of a phase I-II clinical study evaluating the safety and preliminary efficacy of a tissue-engineered corneal substitute composed of a nanostructured fibrin-agarose biocompatible scaffold combined with allogeneic corneal epithelial and stromal cells (NANOULCOR). 5 subjects (5 eyes) suffering from trophic corneal ulcers refractory to conventional treatments, who combined stromal degradation or fibrosis and limbal stem cell deficiency, were included and treated with this allogeneic anterior corneal substitute. RESULTS: The implant completely covered the corneal surface, and ocular surface inflammation decreased following surgery. Only four adverse reactions were registered, and none of them were severe. No detachment, ulcer relapse nor surgical re-interventions were registered after 2 years of follow-up. No signs of graft rejection, local infection or corneal neovascularization were observed either. Efficacy was measured as a significant postoperative improvement in terms of the eye complication grading scales. Anterior segment optical coherence tomography images revealed a more homogeneous and stable ocular surface, with complete scaffold degradation occurring within 3-12 weeks after surgery. CONCLUSIONS: Our findings suggest that the surgical application of this allogeneic anterior human corneal substitute is feasible and safe, showing partial efficacy in the restoration of the corneal surface.

Treatment of neovascular age-related macular degeneration within 48 h from diagnosis improves long-term functional outcome.

PURPOSE: To evaluate long-term visual and anatomical outcomes in neovascular age-related macular degeneration (nAMD) patients treated with anti-vascular endothelial growth factor (VEGF) agents depending on the time delay from confirmed diagnosis to treatment initiation. MATERIALS AND METHODS: Seventy-three nAMD patients (73 eyes) treated with anti-VEGF agents for 12 months using the pro re nata regimen were included in this retrospective longitudinal study. Patients were split into 3 groups according to the time from diagnosis to first anti-VEGF injection: < 48 h (group 1); 48 h-7 days (group 2); > 7 days (group 3). Decimal best-corrected visual acuity (VA) and macular thickness (MT) were recorded at baseline and 1-2-, 3-4-, 6- and 12-month later. Furthermore, age, gender as well as the applied treatment and number of injections after 12 months of treatment were also registered and compared. RESULTS: Long-term effect of the treatment demonstrated enhanced VA in group 1 patients compared with the rest of groups after 1-2-, 6-, and 12-month follow-up (P < 0.05). Positive effects of early treatment were additionally corroborated by the augmented percentage of patients with normal VA in the group 1 respect to the rest of groups over studied time points (P < 0.05). Moreover, the VA gain in nAMD at group 1 was obtained with a mean of 3.7 intravitreal injections over 1-year follow-up period. Regarding MT, non-significant difference was observed among groups. CONCLUSIONS: An early initial treatment with VEGF inhibitors is critical to achieve the best functional benefits of this therapy in new-onset nAMD patients.

Retinal detachment in UGH Syndrome after cataract surgery.

Purpose: To report a case of retinal detachment (RD) in a UGH Syndrome after cataract surgery and to emphasize special aspects of the management, along with factors that must be considered. Methods: We present the case of a 56-year-old man who underwent cataract surgery with a capsulorhexis leak, but the implantation of the lens in the sac did not hinder. 8 months after surgery, he presented several episodes of hypertensive uveitis that produced a progression in the excavation of the optic nerve head from 3/10 to 9/10 despite the treatment with ocular hypotensive drugs. He went to the emergency department due to sudden loss of vision during which a complete hemovitreous with a zone of transillumination and atrophy of the temporal sector of the iris were observed. Echo-B showed inferior retinal detachment. The apposition of the intraocular lens over the temporal region of the iris was observed in anterior segment OCT. Scleral band pars plana vitrectomy surgery was performed. Results: Currently, the VA RE was 6/10 with controlled IOP without the need for treatment, the excavation was 9/10 and it preserved an island of inferior paracentral vision in the perimetry. Vitrectomy favored the posterior displacement of the lens, avoiding friction of the iris, thus eliminating outbreaks of hypertensive uveitis. Conclusions: It is important to be aware of the mechanisms of uveitis-glaucoma-hyphema (UGH) syndrome. It is necessary to identify postoperative signs to make a diagnosis as soon as possible. It is time to consider that UGH syndrome can be caused by any type of pseudophakic lens.

Acute retinal necrosis: time to consider double dose of Foscarnet in the first 72 hours.

Purpose: To report a case of acute retinal necrosis (ARN) and to emphasize special aspects of the management. Factors that must be considered. Methods: We present the case of an 83-year-old woman examined for acute vision loss in her left eye (LE). Background: diabetes, pseudophakic in her LE; subluxated intraocular lens (IOL) and advanced pseudoexfoliative glaucoma in her right eye (RE). The visual acuity (VA) was hand movements in both eyes. Funduscopic examination revealed vitritis, temporal area of retinal necrosis with peripapillary choroiditis spots and macular haemorrhages in her LE and OCT showed a cystic macular edema. Results: A positive polymerase chain reaction (PCR) test for Varicella Zoster Virus (VZV) in aqueous humor of her LE was found. She underwent intravenous Acyclovir 10 mg per kg every 8 hours. She received two doses of adjunctive intravitreal Foscarnet (2.4 mg/ 0.1 mL) in the first 3 days of treatment (2 days between doses). After 3 days of treatment, she started with intravenous prednisone 60 mg per day. The VA of her LE was 0,8 and the retinal necrosis activity was stationary. In fundoscopic examination, vitritis and retinal hemorrhages have disappeared. At that moment there were no foci of chorioretinitis or macular edema although retinal ischemia persisted at the inferior nasal level. Conclusions: The role of adjunctive intravitreal antiviral therapy in combination with systemic treatment revealed promising results. Corticosteroids can be used topically and orally to decrease the severe inflammatory response associated with ARN. Early treatment is crucial to optimize visual and anatomic outcomes.

Generation of a Biomimetic Substitute of the Corneal Limbus Using Decellularized Scaffolds.

Patients with severe limbal damage and limbal stem cell deficiency are a therapeutic challenge. We evaluated four decellularization protocols applied to the full-thickness and half-thickness porcine limbus, and we used two cell types to recellularize the decellularized limbi. The results demonstrated that all protocols achieved efficient decellularization. However, the method that best preserved the transparency and composition of the limbus extracellular matrix was the use of 0.1% SDS applied to the half-thickness limbus. Recellularization with the limbal epithelial cell line SIRC and human adipose-derived mesenchymal stem cells (hADSCs) was able to generate a stratified epithelium able to express the limbal markers p63, pancytokeratin, and crystallin Z from day 7 in the case of SIRC and after 14-21 days of induction when hADSCs were used. Laminin and collagen IV expression was detected at the basal lamina of both cell types at days 14 and 21 of follow-up. Compared with control native limbi, tissues recellularized with SIRC showed adequate picrosirius red and alcian blue staining intensity, whereas limbi containing hADSCs showed normal collagen staining intensity. These preliminary results suggested that the limbal substitutes generated in this work share important similarities with the native limbus and could be potentially useful in the future.

Long-Term in vivo Evaluation of Orthotypical and Heterotypical Bioengineered Human Corneas.

PURPOSE: Human cornea substitutes generated by tissue engineering currently require limbal stem cells for the generation of orthotypical epithelial cell cultures. We recently reported that bioengineered corneas can be fabricated in vitro from a heterotypical source obtained from Wharton's jelly in the human umbilical cord (HWJSC). METHODS: Here, we generated a partial thickness cornea model based on plastic compression nanostructured fibrin-agarose biomaterials with cornea epithelial cells on top, as an orthotypical model (HOC), or with HWJSC, as a heterotypical model (HHC), and determined their potential in vivo usefulness by implantation in an animal model. RESULTS: No major side effects were seen 3 and 12 months after implantation of either bioengineered partial cornea model in rabbit corneas. Clinical results determined by slit lamp and optical coherence tomography were positive after 12 months. Histological and immunohistochemical findings demonstrated that in vitro HOC and HHC had moderate levels of stromal and epithelial cell marker expression, whereas in vivo grafted corneas were more similar to control corneas. CONCLUSION: These results suggest that both models are potentially useful to treat diseases requiring anterior cornea replacement, and that HHC may be an efficient alternative to the use of HOC which circumvents the need to generate cornea epithelial cell cultures.

Controlling the 3D architecture of Self-Lifting Auto-generated Tissue Equivalents (SLATEs) for optimized corneal graft composition and stability.

Ideally, biomaterials designed to play specific physical and physiological roles in vivo should comprise components and microarchitectures analogous to those of the native tissues they intend to replace. For that, implantable biomaterials need to be carefully designed to have the correct structural and compositional properties, which consequently impart their bio-function. In this study, we showed that the control of such properties can be defined from the bottom-up, using smart surface templates to modulate the structure, composition, and bio-mechanics of human transplantable tissues. Using multi-functional peptide amphiphile-coated surfaces with different anisotropies, we were able to control the phenotype of corneal stromal cells and instruct them to fabricate self-lifting tissues that closely emulated the native stromal lamellae of the human cornea. The type and arrangement of the extracellular matrix comprising these corneal stromal Self-Lifting Analogous Tissue Equivalents (SLATEs) were then evaluated in detail, and was shown to correlate with tissue function. Specifically, SLATEs comprising aligned collagen fibrils were shown to be significantly thicker, denser, and more resistant to proteolytic degradation compared to SLATEs formed with randomly-oriented constituents. In addition, SLATEs were highly transparent while providing increased absorption to near-UV radiation. Importantly, corneal stromal SLATEs were capable of constituting tissues with a higher-order complexity, either by creating thicker tissues through stacking or by serving as substrate to support a fully-differentiated, stratified corneal epithelium. SLATEs were also deemed safe as implants in a rabbit corneal model, being capable of integrating with the surrounding host tissue without provoking inflammation, neo-vascularization, or any other signs of rejection after a 9-months follow-up. This work thus paves the way for the de novo bio-fabrication of easy-retrievable, scaffold-free human tissues with controlled structural, compositional, and functional properties to replace corneal, as well as other, tissues.