bims-mideyd 2023-06-11 papers

Issue of 2023‒06‒11
three papers selected by
Rajalekshmy “Raji” Shyam, Indiana University Bloomington

BMJ Open Ophthalmol. 2022 Nov;7(Suppl 2): A9

21 Denuded descemet's membrane as potential tool to support human embryonic stem cell derived retinal pigment epithelial cells culture.

Miss Elena Daniele, Lorenzo Bosio, Stefano Ferrari, Vanessa Barbaro, Nicolò Rassu, Barbara Ferrari, Diego Ponzin.

INTRODUCTION: Recent clinical studies suggest that RPE-cell replacement therapy may preserve vision and restore retinal structure in retinal degenerative diseases. New developments enabled the differentiation of RPE cells from pluripotent stem cells. Scaffold-based methods are being tested in ongoing clinical trials for delivering these cells to the back of the eye. Borrowed materials from donor tissues can be used as cell supports in subretinal transplantation. These biological matrices resemble the extracellular matrix microenvironment of the native tissue. The Descemet's membrane (DM) is an example of high collagen-rich basement membrane (BM). The potential of this tissue in retinal repair remains to be uncovered.AIMS: To investigate human embryonic stem cell-retinal pigment epithelium (hESC-RPE) cells survival and behaviour on a decellularized DM, which may be of clinical relevance in retinal transplantation.
MATERIALS: DMs were isolated from human donor corneas and treated with thermolysin. The DM surface topology and the efficiency of the denudation method were evaluated by atomic force microscope and histology. hESC-RPE cells were seeded onto the endothelial-side surface of acellular DM in order to determine the potential of the membrane to support hESC-RPE cell culture, alongside maintaining their viability. Integrity of the hESC-RPE monolayer was assessed by measuring transepithelial resistance. RPE-specific gene, protein expression and growth factors secretion were assessed to confirm maturation and functionality of the cells over the new substrate.
RESULTS: Thermolysin treatment did not affect the integrity of the tissue, thus ensuring a reliable method to standardize the preparation of decellularized DM. hESC-RPE cell attachment 6 days post-seeding and proliferation rates over the acellular DM were similar to hESC-RPE cells cultured on tissue culture inserts.On the new matrix, hESC-RPE cells succeeded in forming an intact monolayer with mature tight junctions. The resulting cell graft showed the characteristic RPE morphology. The expression of typical RPE genes, proper protein localization and key growth factor secretion further confirmed the correct RPE phenotype. The viability of the cells was maintained for up to 4 weeks in culture.
CONCLUSION: Acellular DM was shown to be capable of sustaining hESC-RPE cells growth, thus confirming to be potentially a valid alternative to the Bruch's membrane.Further in vivo studies will need to verify if this product can represent a feasible tool to deliver RPE cells in the back of the eye.Our study highlights the possibility of recycling unsuitable corneal tissues, which would otherwise be discarded by the eye banks for clinical application.

DOI: https://doi.org/10.1136/bmjophth-2022-EEBA.21

JCI Insight. 2023 06 08. pii: e157654. [Epub ahead of print]8(11):

A versatile laser-induced porcine model of outer retinal and choroidal degeneration for preclinical testing.

Francesca Barone, Juan Amaral, Irina Bunea, Mitra Farnoodian, Rohan Gupta, Rishabh Gupta, Dara Baker, M Joseph Phillips, Richard J Blanch, Arvydas Maminishkis, David M Gamm, Kapil Bharti.

Over 30 million people worldwide suffer from untreatable vision loss and blindness associated with childhood-onset and age-related eye diseases caused by photoreceptor (PR), retinal pigment epithelium (RPE), and choriocapillaris (CC) degeneration. Recent work suggests that RPE-based cell therapy may slow down vision loss in late stages of age-related macular degeneration (AMD), a polygenic disease induced by RPE atrophy. However, accelerated development of effective cell therapies is hampered by the lack of large-animal models that allow testing safety and efficacy of clinical doses covering the human macula (20 mm2). We developed a versatile pig model to mimic different types and stages of retinal degeneration. Using an adjustable power micropulse laser, we generated varying degrees of RPE, PR, and CC damage and confirmed the damage by longitudinal analysis of clinically relevant outcomes, including analyses by adaptive optics and optical coherence tomography/angiography, along with automated image analysis. By imparting a tunable yet targeted damage to the porcine CC and visual streak - with a structure similar to the human macula - this model is optimal for testing cell and gene therapies for outer retinal diseases including AMD, retinitis pigmentosa, Stargardt, and choroideremia. The amenability of this model to clinically relevant imaging outcomes will facilitate faster translation to patients.

Keywords: Gene therapy; Ophthalmology; Retinopathy; Stem cell transplantation; Stem cells

DOI: https://doi.org/10.1172/jci.insight.157654

PNAS Nexus. 2023 Jun;2(6): pgad167

Vitamin A deficiency compromises the barrier function of the retinal pigment epithelium.

Jean Moon, Gao Zhou, Eckhard Jankowsky, Johannes von Lintig.

A major cause for childhood blindness worldwide is attributed to nutritional vitamin A deficiency. Surprisingly, the molecular basis of the ensuing retinal degeneration has not been well defined. Abundant expression of the retinoid transporter STRA6 in the retinal pigment epithelium (RPE) and homeostatic blood levels of retinol-binding protein delay vitamin A deprivation of the mouse eyes. Hence, genetic dissection of STRA6 makes mice susceptible to nutritional manipulation of ocular retinoid status. We performed RNA-seq analyses and complemented the data with tests of visual physiology, ocular morphology, and retinoid biochemistry to compare eyes with different vitamin A status. Mild ocular vitamin A deficiency decreased transcripts of photoreceptor transduction pathway-related genes and increased transcripts of oxidative stress pathways. The response was associated with impaired visual sensitivity and an accumulation of fluorescent debris in the retina. Severe vitamin A deficiency did not only impair visual perception but also decreased transcripts of genes encoding cell adhesion and cellular junction proteins. This response altered cell morphology, resulted in significant changes in transport pathways of small molecules, and compromised the barrier function of the RPE. Together, our analyses characterize the molecular events underlying nutritional blindness in a novel mouse model and indicate that breakdown of the outer blood-retinal barrier contributes to retinal degeneration and photoreceptor cell death in severe vitamin A deficiency.

Keywords: RPE; STRA6; deficiency; transcriptome; vitamin A

DOI: https://doi.org/10.1093/pnasnexus/pgad167