Early Choriocapillaris Loss in a Porcine Model of RPE Cell Debridement Precedes Pathology That Simulates Advanced Macular Degeneration.

Purpose: No large-mammal surgical models exist for geographic atrophy (GA), choroidal neovascularization (CNV), and pachychoroidal vascular remodeling. Our goal was to develop a porcine RPE debridement model of advanced macular degeneration to study photoreceptor cell loss and choroidal remodeling.

Methods: Seven 2-month-old female domestic pigs were used for this study.

Methodological Approach to Improve Surgical Outcomes of a Pig Subretinal Implantation Model.

Purpose: To improve outcomes for subretinal implantation surgery in pigs.

Methods: Analysis of variables affecting the success of subretinal implantation surgery was performed on videos of 37 surgeries. Ex vivo experiments were conducted to measure intraocular pressure (IOP) and test various prototyped implanters for effectiveness at maintaining IOP.

Alteration of fibrin hydrogel gelation and degradation kinetics through addition of azo dyes.

Fibrin is a degradable biopolymer with an excellent clinical safety profile. Use of higher mechanical strength fibrin hydrogels is limited by the rapid rate of fibrin polymerization. We recently demonstrated the use of higher mechanical strength (fibrinogen concentrations >30 mg/ml) fibrin scaffolds for surgical implantation of cells.

Fibrin hydrogels are safe, degradable scaffolds for sub-retinal implantation.

Retinal pigment epithelium (RPE) transplantation for the treatment of macular degeneration has been studied for over 30 years. Human clinical trials have demonstrated that RPE monolayers exhibit improved cellular engraftment and survival compared to single cell suspensions. The use of a scaffold facilitates implantation of a flat, wrinkle-free, precisely placed monolayer.

Perfusion Bioreactor Culture of Bone Marrow Stromal Cells Enhances Cranial Defect Regeneration.

Background: Cell-seeded biomaterial scaffolds have been proposed as a future option for reconstruction of bone tissue. The ability to generate larger, functional volumes of bone has been a challenge that may be addressed through the use of perfusion bioreactors. In this study, the authors investigated use of a tubular perfusion bioreactor system for the growth and differentiation of bone marrow stromal (mesenchymal stem) cells seeded onto fibrin, a highly angiogenic biomaterial.

Human Fibrinogen for Maintenance and Differentiation of Induced Pluripotent Stem Cells in Two Dimensions and Three Dimensions.

Human fibrin hydrogels are a popular choice for use as a biomaterial within tissue engineered constructs because they are biocompatible, nonxenogenic, autologous use compatible, and biodegradable. We have recently demonstrated the ability to culture induced pluripotent stem cell (iPSC)-derived retinal pigment epithelium on fibrin hydrogels. However, iPSCs themselves have relatively few substrate options (e.

A Model to Study Thermal Energy Delivery to the Choroid: A Comparison of Surgical Devices.

Purpose: We measure and compare surgical devices using an ex vivo, temperature-controlled, choroidal incision model during thermal energy transfer with a high-resolution infrared camera.

Methods: Ex vivo porcine choroidal tissue specimens ( = 516) were isolated and placed on a temperature-regulated (37°C) perfusion platform. We tested the pulsed electron avalanche knife (PEAK), micropulse laser (MpL), continuous laser (CL), and bipolar cautery (BpC) at three energy settings (11 [low], 45 [medium], and 134 [high] mJ/mm).

Mutant Best1 Expression and Impaired Phagocytosis in an iPSC Model of Autosomal Recessive Bestrophinopathy.

Autosomal recessive bestrophinopathy (ARB) is caused by mutations in the gene BEST1 which encodes bestrophin 1 (Best1), an anion channel expressed in retinal pigment epithelial (RPE) cells. It has been hypothesized that ARB represents the human null phenotype for BEST1 and that this occurs due to nonsense mediated decay (NMD). To test this hypothesis, we generated induced pluripotent stem cells (iPSCs) from a patient with ARB and her parents.

Fibrin hydrogels as a xenofree and rapidly degradable support for transplantation of retinal pigment epithelium monolayers.

Unlabelled: Recent phase 1 trials of embryonic stem cell and induced pluripotent stem cell (iPSCs) derived RPE transplants for the treatment of macular degeneration have demonstrated the relative safety of this process. However, there is concern over clumping, thickening, folding, and wrinkling of the transplanted RPE. To deliver a flat RPE monolayer, current phase 1 trials are testing synthetic substrates for RPE transplantation.

Differential Intraocular Pressure Measurements by Tonometry and Direct Cannulation After Treatment with Soluble Adenylyl Cyclase Inhibitors.

Purpose: To validate the increase in intraocular pressure (IOP) caused by soluble adenylyl cyclase (sAC) inhibitors and determine reasons behind variation in IOP measurements performed by tonometry.

Methods: C57BL/6J mice were administered DMSO solubilized sAC inhibitors (KH7 or LRE-1) by intraperitoneal injection. Two hours post-treatment, mice were anesthetized with avertin or ketamine/xylazine/acepromazine (KXA).

Enhanced Viability of Endothelial Colony Forming Cells in Fibrin Microbeads for Sensor Vascularization.

Enhanced vascularization at sensor interfaces can improve long-term function. Fibrin, a natural polymer, has shown promise as a biomaterial for sensor coating due to its ability to sustain endothelial cell growth and promote local vascularization. However, the culture of cells, particularly endothelial cells (EC), within 3D scaffolds for more than a few days is challenging due to rapid loss of EC viability.

Falciform macular folds and chromosome 22q11.2: evidence in support of a locus for familial exudative vitreoretinopathy (FEVR).

Background: Familial exudative vitreoretinopathy (FEVR) is a genetic disease caused by abnormal retinal vascular development. New additional genetic loci for FEVR have recently been identified. Microduplication of 22q11.

Alginate-based strategies for therapeutic vascularization.

Therapeutic stimulation of vessel growth to improve tissue perfusion has shown promise in many regenerative medicine and tissue engineering applications. Alginate-based biomaterial systems have been investigated for growth factor and/or cell delivery as tools for modulating vessel assembly. Growth factor encapsulation allows for a sustained release of protein and protection from degradation.

Soluble CD59 expressed from an adenovirus in vivo is a potent inhibitor of complement deposition on murine liver vascular endothelium.

Inappropriate activation of complement on the vascular endothelium of specific organs, or systemically, underlies the etiology of a number of diseases. These disorders include atypical hemolytic uremic syndrome, membranoproliferative glomerulonephritis, atherosclerosis, age-related macular degeneration, diabetic retinopathy, and transplant rejection. Inhibition of the terminal step of complement activation, i.

TNFalpha is required for late BRB breakdown in diabetic retinopathy, and its inhibition prevents leukostasis and protects vessels and neurons from apoptosis.

Purpose: Blood-retinal barrier [BRB] breakdown, characteristic of diabetic retinopathy (DR), is believed to depend on inflammation and apoptosis. Retinal inflammation is almost completely suppressed in the absence of TNFα, which is also associated with apoptosis. This study was conducted to determine the role of TNFα in these diabetic complications.

Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP): 24-month experience with telemedicine screening.

Purpose: To report the 24-month experience of the Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP) telemedicine initiative.

Methods: Retrospective analysis of the SUNDROP archival data gathered between 1 December 2005 and 30 November 2007 to evaluate this diagnostic technology for ROP screening. One hundred and sixty consecutively enrolled infants meeting ROP examination criteria were screened with the RetCam II and evaluated by the SUNDROP reading centre at Stanford University.

Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP): 18-month experience with telemedicine screening.

Purpose: To report the 18-month experience of the Stanford University Network for Diagnosis of Retinopathy of Prematurity (SUNDROP) telemedicine initiative.

Design: Retrospective analysis of the SUNDROP archival data between 1 December 2005 and 30 May 2007, evaluating this new diagnostic technology for ROP screening.

Participants: All 97 consecutively enrolled infants in the SUNDROP network.

High-resolution imaging with adaptive optics in patients with inherited retinal degeneration.

Purpose: To investigate macular photoreceptor structure in patients with inherited retinal degeneration using high-resolution images and to correlate the findings with clinical phenotypes and genetic mutations.

Methods: Adaptive optics scanning laser ophthalmoscopy (AOSLO) images of photoreceptors were obtained in 16 eyes: five with retinitis pigmentosa (RP), three with cone-rod dystrophy (CRD), and eight without retinal disease. A quadratic model was used to illustrate cone spacing as a function of retinal eccentricity.