A tissue-engineered human trabecular meshwork hydrogel for advanced glaucoma disease modeling

Abnormal human trabecular meshwork (HTM) cell function and extracellular matrix(ECM) remodeling contribute to HTM stiffening in primary open-angle glaucoma (POAG). Most current cellular HTM model systems do not sufficiently replicate the complex native three dimensional (3D) cell-ECM interface, limiting their use for investigating POAG pathology. Tissue-engineered hydrogels are ideally positioned to overcome shortcomings of current models. Here, we report a novel biomimetic HTM hydrogel and test its utility as a POAG disease model. HTM hydrogels were engineered by mixing normal donor-derived HTM cells with collagen type I, elastin-like polypeptide and hyaluronic acid, each containing photoactive functional groups, followed by UV crosslinking. Glaucomatous conditions were induced with dexamethasone (DEX), and effects of the Rho-associated kinase (ROCK) inhibitor Y27632 on cytoskeletal organization and tissue-level function, contingent on HTM cell-ECM interactions, were assessed. DEX exposure increased HTM hydrogel contractility, f-actin and alpha smooth muscle actin abundance and rearrangement, ECM remodeling, and fibronectin deposition - all contributing to HTM hydrogel condensation and stiffening consistent with glaucomatous HTM tissue behavior. Y27632 treatmentproduced precisely the opposite effects and attenuated the DEX-induced pathologic changes, resulting in HTM hydrogel relaxation and softening. For model validation, confirmed glaucomatous HTM (GTM) cells were encapsulated; GTM hydrogels showed increased contractility, fibronectin deposition, and stiffening vs. normal HTM hydrogels despite reduced GTM cell proliferation. We have developed a biomimetic HTM hydrogel model for detailed investigation of 3D cell-ECM interactions under normal and simulated glaucomatous conditions. Its bidirectional responsiveness to pharmacological challenge and rescue suggests promising potential to serve as screening platform for new POAG treatments with focus on HTM biomechanics

A tissue-engineered human trabecular meshwork hydrogel for advanced glaucoma disease modeling.

Abnormal human trabecular meshwork (HTM) cell function and extracellular matrix (ECM) remodeling contribute to HTM stiffening in primary open-angle glaucoma (POAG). Most current cellular HTM model systems do not sufficiently replicate the complex native three dimensional (3D) cell-ECM interface, limiting their use for investigating POAG pathology. Tissue-engineered hydrogels are ideally positioned to overcome shortcomings of current models. Here, we report a novel biomimetic HTM hydrogel and test its utility as a POAG disease model. HTM hydrogels were engineered by mixing normal donor-derived HTM cells with collagen type I, elastin-like polypeptide and hyaluronic acid, each containing photoactive functional groups, followed by UV crosslinking. Glaucomatous conditions were induced with dexamethasone (DEX), and effects of the Rho-associated kinase (ROCK) inhibitor Y27632 on cytoskeletal organization and tissue-level function, contingent on HTM cell-ECM interactions, were assessed. DEX exposure increased HTM hydrogel contractility, f-actin and alpha smooth muscle actin abundance and rearrangement, ECM remodeling, and fibronectin deposition - all contributing to HTM hydrogel condensation and stiffening consistent with glaucomatous HTM tissue behavior. Y27632 treatment produced precisely the opposite effects and attenuated the DEX-induced pathologic changes, resulting in HTM hydrogel relaxation and softening. For model validation, confirmed glaucomatous HTM (GTM) cells were encapsulated; GTM hydrogels showed increased contractility, fibronectin deposition, and stiffening vs. normal HTM hydrogels despite reduced GTM cell proliferation. We have developed a biomimetic HTM hydrogel model for detailed investigation of 3D cell-ECM interactions under normal and simulated glaucomatous conditions. Its bidirectional responsiveness to pharmacological challenge and rescue suggests promising potential to serve as screening platform for new POAG treatments with focus on HTM biomechanics

Calculation of Intralocular Lens Power Using Orbscan II Quantitative Area Topography After Corneal Refractive Surgery

PURPOSE: To present the prospective application of the Orbscan II central 2-mm total-mean corneal power obtained by quantitative area topography in intraocular lens (IOL) calculation after refractive surgery.METHODS: Calculated and achieved refraction and the difference between them were studied in 77 eyes of 61 patients with previous radial keratotomy (RK), RK and additional surgeries, myopic LASIK, myopic photo-refractive keratectomy (PRK), or hyperopic LASIK who underwent phacoemulsification without complications in 3 eye centers. All IOL calculations used the average from the central 2-mm Orbscan II total-mean power of maps centered on the pupil without the use of previous refractive data. Six IOL styles implanted within the bag were used.RESULTS: Using the SRK-T formula, the overall calculated refraction was -0.64 +/- 0.93 diopters (D). the overall achieved spherical equivalent refraction (-0.52 +/- 0.79 D; range: -3.12 to 1.25 D; 95% confidence interval [Cl]: -0.70/-0.34 D) was +/- 0.50 D in 53% of eyes, +/- 1.00 D in 78% of eyes and +/- 2.00 D in 99% of eyes the over-all difference between the calculated and achieved refraction (0.12 +/- 0.93 D, P=.27; range: -2.18 to 2.62 D; 95% Cl: 0.09/0.33 D) was +/- 0.50 D in 39% of eyes, +/- 1.00 D in 77% of eyes, and +/- 2.00 D in 96% of eyes. This difference was +/- 1.00 D in 77% of eyes with RK (P=.70), 82% of eyes with myopic LASIK (P=.34) and, 90% of eyes with myopic PRK (P=.96). in eyes with RK followed by LASIK, a trend toward undercorrection was noted (P=.03). in eyes with hyperopic LASIK, a trend toward overcorrection was noted (P=.005).CONCLUSIONS: in eyes with previous corneal refractive surgery, IOL power calculation can be performed with reasonable accuracy using the Orbscan II central 2-mm total-mean power. This method had better outcomes in eyes with previous RK, myopic LASIK, and myopic PRK than in eyes with hyperopic LASIK or RK with LASIK [J Refract Surg. 2009;25:1061-1074.] doi: 10.3928/1081597X-20091117-05Universidade Federal de São Paulo, Paulista Sch Med, Dept Ophthalmol, Inst Vis,Ocular Bioengn Sector, São Paulo, BrazilUniversidade Federal de São Paulo, Paulista Sch Med, Dept Ophthalmol, Inst Vis,Refract Surg Sector, São Paulo, BrazilSUNY Syracuse, Upstate Med Ctr, Dept Ophthalmol, Syracuse, NY USAPiedmont Better Vis LLC, Atlanta, GA USAUniversidade Federal de São Paulo, Paulista Sch Med, Dept Ophthalmol, Inst Vis,Cataract Sector, São Paulo, BrazilUniversidade Federal de São Paulo, Paulista Sch Med, Dept Ophthalmol, Inst Vis,Ocular Bioengn Sector, São Paulo, BrazilUniversidade Federal de São Paulo, Paulista Sch Med, Dept Ophthalmol, Inst Vis,Refract Surg Sector, São Paulo, BrazilUniversidade Federal de São Paulo, Paulista Sch Med, Dept Ophthalmol, Inst Vis,Cataract Sector, São Paulo, BrazilWeb of Scienc