Adhesion of retinal cells to gold surfaces by biomimetic molecules.

Background: Neural cell-electrode coupling is crucial for effective neural and retinal prostheses. Enhancing this coupling can be achieved through surface modification and geometrical design to increase neuron-electrode proximity. In the current research, we focused on designing and studying various biomolecules as a method to elicit neural cell-electrode adhesion via cell-specific integrin mechanisms.

A novel GCaMP6f-RCS rat model for studying electrical stimulation in the degenerated retina.

Retinal prostheses aim to restore vision by electrically stimulating the remaining viable retinal cells in Retinal Degeneration (RD) cases. Research in this field necessitates a comprehensive analysis of retinal ganglion cells' (RGCs) responses to assess the obtained visual acuity and quality. Here we present a novel animal model which facilitates the optical recording of RGCs activity in an RD rat.

Optimizing the fabrication of a 3D high-resolution implant for neural stimulation.

Background: Tissue-integrated micro-electronic devices for neural stimulation hold great potential in restoring the functionality of degenerated organs, specifically, retinal prostheses, which are aimed at vision restoration. The fabrication process of 3D polymer-metal devices with high resolution and a high aspect-ratio (AR) is very complex and faces many challenges that impair its functionality.

Approach: Here we describe the optimization of the fabrication process of a bio-functionalized 3D high-resolution 1mm circular subretinal implant composed of SU-8 polymer integrated with dense gold microelectrodes (23μm pitch) passivated with 3D micro-well-like structures (20μm diameter, 3μm resolution).

Electrophysiologic Characterization of Developing Human Embryonic Stem Cell-Derived Photoreceptor Precursors.

Purpose: Photoreceptor precursor cells (PRPs) differentiated from human embryonic stem cells can serve as a source for cell replacement therapy aimed at vision restoration in patients suffering from degenerative diseases of the outer retina, such as retinitis pigmentosa and AMD. In this work, we studied the electrophysiologic maturation of PRPs throughout the differentiation process.

Methods: Human embryonic stem cells were differentiated into PRPs and whole-cell recordings were performed for electrophysiologic characterization at days 0, 30, 60, and 90 along with quantitative PCR analysis to characterize the expression level of various ion channels, which shape the electrophysiologic response.

Carbon nanostructures as a scaffold for human embryonic stem cell differentiation toward photoreceptor precursors.

Carbon nanomaterials have been introduced as a scaffold for various biological applications due to their unique physical and electrical properties. Here we studied carbon nanotubes (CNTs) and carbon nanofibers (CNFs) as scaffold materials for the differentiation of human embryonic stem cells (hESCs) towards photoreceptor precursor cells (PRPs). We report on their cytoxicity, their effect on cell morphology, cell-surface interface and the differentiation process.

Anti-VEGF-Aptamer Modified C-Dots-A Hybrid Nanocomposite for Topical Treatment of Ocular Vascular Disorders.

The vascular endothelial growth factor (VEGF) induces pathological angiogenetic ocular diseases. It is a scientific challenge to develop carriers for the controlled release of inhibitors for VEGF present in the back of the eye domain. Carbon dots (C-dots) functionalized with the VEGF aptamer are introduced and the hybrid nanoparticles are used for ocular nanomedicine.

Gold nanoparticles for multimodal high-resolution imaging of transplanted cells for retinal replacement therapy.

Longitudinal tracking of transplanted cells in clinical and experimental setups is crucial for evaluating the efficiency of retinal cell replacement therapies. Gold nanoparticle-labeled photoreceptor precursors were transplanted in the vitreous and subretinal space of rats and were longitudinally tracked for over a month using optical coherence tomography, computed tomography and fluorescence fundus imaging. This multimodal imaging approach enabled high-resolution long-term tracking and estimation of cell survival in the retina and vitreous, while displaying no toxic effects on the cells or the retina.

SEM/FIB Imaging for Studying Neural Interfaces.

Tissue and neural engineering for various regenerative therapies are rapidly growing fields. Of major interest is studying the complex interface between cells and various 3D structures by scanning electron microscopy with focused ion beam. Notwithstanding its unrivaled resolution, the optimal fixation, dehydration, and staining protocols of the samples while preserving the complex cell interface in its natural form, are highly challenging.

An optimized protocol for generating labeled and transplantable photoreceptor precursors from human embryonic stem cells.

Cell replacement therapy is a promising approach for treatment of retinal degenerative diseases. Several protocols for the generation of photoreceptor precursors (PRP) from human embryonic stem cells (hESC) have been reported with variable efficiency. Herein, we show the advantages of use of size-controlled embryoid bodies in the ESC differentiation process using two differentiation protocols.

Varicella-Zoster Virus Expresses Multiple Small Noncoding RNAs.

Many herpesviruses express small noncoding RNAs (sncRNAs), including microRNAs (miRNAs), that may play roles in regulating lytic and latent infections. None have yet been reported in varicella-zoster virus (VZV; also known as human herpesvirus 3 [HHV-3]). Here we analyzed next-generation sequencing (NGS) data for small RNAs in VZV-infected fibroblasts and human embryonic stem cell-derived (hESC) neurons.

An in vitro model of latency and reactivation of varicella zoster virus in human stem cell-derived neurons.

Varicella zoster virus (VZV) latency in sensory and autonomic neurons has remained enigmatic and difficult to study, and experimental reactivation has not yet been achieved. We have previously shown that human embryonic stem cell (hESC)-derived neurons are permissive to a productive and spreading VZV infection. We now demonstrate that hESC-derived neurons can also host a persistent non-productive infection lasting for weeks which can subsequently be reactivated by multiple experimental stimuli.

Cellular transcriptome analysis reveals differential expression of pro- and antiapoptosis genes by varicella-zoster virus-infected neurons and fibroblasts.

Transcriptional changes following varicella-zoster virus (VZV) infection of cultured human neurons derived from embryonic stem cells were compared to those in VZV-infected human foreskin fibroblasts. Transcription of 340 neuronal genes significantly altered by VZV infection included 223 transcript changes unique to neurons. Strikingly, genes inhibiting apoptosis were upregulated in neurons, while proapoptotic gene transcription was increased in fibroblasts.

Simple generation of neurons from human embryonic stem cells using agarose multiwell dishes.

Human embryonic stem cells (hESC) are potentially an unlimited source of neurons for study and therapy for human disease. Directed differentiation of hESC has been performed using many different methods, often via neural precursor intermediates generated from aggregates of hESC. We describe here a protocol based on commercially available reusable silicone micromolds and two small molecule growth factor inhibitors to simply and reproducibly generate human neurons from hESC.

ORF7 of varicella-zoster virus is a neurotropic factor.

Varicella-zoster virus (VZV) is the causative agent of chickenpox and herpes zoster (shingles). After the primary infection, the virus remains latent in sensory ganglia and reactivates upon weakening of the cellular immune system due to various conditions, erupting from sensory neurons and infecting the corresponding skin tissue. The current varicella vaccine is highly attenuated in the skin and yet retains its neurovirulence and may reactivate and damage sensory neurons.

Varicella-zoster virus infects human embryonic stem cell-derived neurons and neurospheres but not pluripotent embryonic stem cells or early progenitors.

Pluripotent human stem cells are a powerful tool for the generation of differentiated cells that can be used for the study of human disease. We recently demonstrated that neurons derived from pluripotent human embryonic stem cells (hESC) can be infected by the highly host-restricted human alphaherpesvirus varicella-zoster virus (VZV), permitting the interaction of VZV with neurons to be readily evaluated in culture. In the present study, we examine whether pluripotent hESC and neural progenitors at intermediate stages of differentiation are permissive for VZV infection.

Varicella-zoster virus (VZV) infection of neurons derived from human embryonic stem cells: direct demonstration of axonal infection, transport of VZV, and productive neuronal infection.

Study of the human neurotrophic herpesvirus varicella-zoster virus (VZV) and of its ability to infect neurons has been severely limited by strict viral human tropism and limited availability of human neurons for experimentation. Human embryonic stem cells (hESC) can be differentiated to all the cell types of the body including neurons and are therefore a potentially unlimited source of human neurons to study their interactions with human neurotropic viruses. We report here reproducible infection of hESC-derived neurons by cell-associated green fluorescent protein (GFP)-expressing VZV.