Effects of Cord Blood Serum (CBS) on viability of retinal Müller glial cells under in vitro injury

Safety Results for Geographic Atrophy Associated with Age-Related Macular Degeneration Using Subretinal Cord Blood Platelet-Rich Plasma

Purpose

To evaluate the safety of subretinal injection of cord blood platelet-rich plasma (CB-PRP) and its possible effect in eyes affected by geographic atrophy (GA) associated with dry age-related macular degeneration (d-AMD).

Design

Interventional, open-label study started in January 2021 with follow-up at 12 months (the Si.Cord Study). This study was a single-center, nonrandomized, sequential-assigned clinical trial conducted in Rome, Italy, at Fondazione Policlinico Universitario Agostino Gemelli IRCCS (ClinicalTrials.gov NCT04636853).

Participants

Thirteen patients (26 eyes) with bilateral d-AMD-related GA were enrolled. One eye from each patient (with more advanced GA) underwent CB-PRP treatment, and the fellow eye was considered the control. All patients participated in follow-up at 12 months.

Intervention

All 13 eyes received 23-gauge (G) vitrectomy and subretinal injection of CB-PRP using a 41-gauge needle.

Main Outcomes and Measures

Best-corrected visual acuity (BCVA) with ETDRS letters, central macular thickness using OCT, and atrophic area measured on en face OCT images were assessed at baseline, 1, 3, 6, and 12 months.

Results

The BCVA in the treated group was 34.46 ± 20.8 ETDRS at baseline, 40.84 ± 20.52 at 1 month, 40.07 ± 20.34 at 3 months, 39.38 ± 19.84 at 6 months, and 35.84 ± 18.38 at 12 months. In the untreated group, the BCVA was 53 ± 21.1 ETDRS letters at baseline, 51.54 ± 20.99 at 1 month, 46.62 ± 19.47 at 3 months, 46.85 ± 18.58 at 6 months, and 43.92 ± 17.97 at 12 months (2-way analysis of variance: interaction of treatment by eye or time, P = 0.084). Central macular thickness did not show a significant intereye difference at 12 months (P = 0.97). The atrophic geographic areas tended to increase in both treated and fellow eyes at 12 months (P < 0.0001). No inflammatory reaction, endophthalmitis, retinal detachment, uveitis, or other complications due to the subretinal injection of CB-PRP were observed during the follow-up.

Conclusions

Subretinal injection of CB-PRP could be safely used for d-AMD in its GA form. Despite its safety, a larger cohort of patients, and probably a new way of administration, will be needed to understand whether the CB-PRP could have a role in the GA treatment.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Human glial müller and umbilical vein endothelial cell coculture as an in vitro model to investigate retinal oxidative damage. A morphological and molecular assessment

The aim of this study was to optimize a coculture in vitro model established between the human Müller glial cells and human umbilical vein endothelial cells, mimicking the inner blood-retinal barrier, and to explore its resistance to damage induced by oxidative stress. A spontaneously immortalized human Müller cell line MIO-M1 and human umbilical vein endothelial cells (HUVEC) were plated together at a density ratio 1:1 and maintained up to the 8th passage (p8). The MIO-M1/HUVECs p1 through p8 were treated with increasing concentrations (range 200-800 μM) of H₂ O₂ to evaluate oxidative stress induced damage and comparing data with single cell cultures. The following features were assayed p1 through p8: doubling time maintenance, cell viability using MTS assay, ultrastructure of cell-cell contacts, immunofluorescence for Vimentin and GFAP, molecular biology (q-PCR) for GFAP and CD31 mRNA. MIO-M1/HUVECs cocultures maintained distinct cell cytotype up to p8 as shown by flow cytometry analysis, without evidence of cross activation, displaying cell-cell tight junctions mimicking those found in human retina, only acquiring a slight resistance to oxidative stress induction over the passages. This MIO-M1/HUVECs coculture represents a simple, reproducible and affordable model for in vitro studies on oxidative stress-induced retinal damages.

Impact of Freeze-Drying on Cord Blood (CB), Serum (S), and Platelet-Rich Plasma (CB-PRP) Preparations on Growth Factor Content and In Vitro Cell Wound Healing

Blood-based preparations are used in clinical practice for the treatment of several eye disorders. The aim of this study is to analyze the effect of freeze-drying blood-based preparations on the levels of growth factors and wound healing behaviors in an in vitro model. Platelet-rich plasma (PRP) and serum (S) preparations from the same Cord Blood (CB) sample, prepared in both fresh frozen (FF) and freeze-dried (FD) forms (and then reconstituted), were analyzed for EGF and BDNF content (ELISA Quantikine kit). The human MIO-M1 glial cell line (Moorfield/Institute of Ophthalmology, London, UK) was incubated with FF and FD products and evaluated for cell migration with scratch-induced wounding (IncuCyte S3 Essen BioScience), proliferation with cyclin A2 and D1 gene expression, and activation with vimentin and GFAP gene expression. The FF and FD forms showed similar concentrations of EGF and BDNF in both the S and PRP preparations. The wound healing assay showed no significant difference between the FF and FD forms for both S and PRP. Additionally, cell migration, proliferation, and activation did not appear to change in the FD forms compared to the FF ones. Our study showed that reconstituted FD products maintained the growth factor concentrations and biological properties of FF products and could be used as a functional treatment option.

The Transcriptome Profile of Retinal Pigment Epithelium and Müller Cell Lines Protected by Risuteganib Against Hydrogen Peroxide Stress

Purpose:

Oxidative stress contributes to the pathogenesis of vision-impairing diseases. In the retina, retinal pigment epithelium (RPE) and Müller cells support neuronal homeostasis, but also contribute to pathological development under stressed conditions. Recent studies found that the investigational drug risuteganib (RSG) has a good safety profile, provided protection in experimental models, and improved visual acuity in patients. The present in vitro study evaluated the effects of RSG in RPE and Müller cell lines stressed with the oxidant hydrogen peroxide (H₂O₂).

Methods:

Human RPE (ARPE-19) and Müller (MIO-M1) cell lines were treated with various combinations of RSG and H₂O₂. Trypan blue assay was used to investigate the effect of compounds on cell viability. Gene expression was measured using RNA sequencing to identify regulated genes and the biological processes and pathways involved.

Results:

Trypan blue assay found RSG pre-treatment significantly protected against H₂O₂-induced cell death in ARPE-19 and MIO-M1 cells. Transcriptome analysis found H₂O₂ regulated genes in several disease-relevant biological processes, including cell adhesion, migration, death, and proliferation; ECM organization; angiogenesis; metabolism; and immune system processes. RSG pre-treatment modulated these gene expression profiles in the opposite direction of H₂O₂. Pathway analysis found genes in integrin, AP-1, and syndecan signaling pathways were regulated. Expression of selected RSG-regulated genes was validated using qRT-PCR.

Conclusions:

RSG protected cultured human RPE and Müller cell lines against H₂O₂-induced cell death and mitigated the associated transcriptome changes in biological processes and pathways relevant to the pathogenesis of retinal diseases. These results demonstrate RSG reduced oxidative stress-induced toxicity in two retinal cell lines with potential relevance to the treatment of human diseases.

Nerve Growth Factor Promotes Retinal Neurovascular Unit Repair: A Review

Purpose: The purpose of this paper is to investigate how the imbalance of neurogenic factor (NGF) and its precursor (pro-NGF) mediates structural and functional impairment of retinal neurovascular unit (RNVU) that plays a role in retinal degenerative diseases.Methods: A literature search of electronic databases was performed.Results: The pro-apoptotic effect of pro-NGF and the pro-growth effect of NGF are essential for the pathological and physiological activities of RNVU. Studies show that NGF-based treatment of retinal degenerative diseases, including glaucoma, age-related macular degeneration, retinitis pigmentosa, and diabetic retinopathy, has achieved remarkable efficacy.Conclusions: RNVU plays a complex and multifaceted role in retinal degenerative diseases. The exploration of the differential signaling expression of proNGF-NGF homeostasis under physiological and pathological conditions, and the corresponding pathological processes induced by its regulation, has prompted us to focus on earlier retinal neuroprotective therapeutic strategies to prevent retinal degenerative diseases.

Harnessing Astrocytes and Müller Glial Cells in the Retina for Survival and Regeneration of Retinal Ganglion Cells

Astrocytes have been associated with the failure of axon regeneration in the central nervous system (CNS), as it undergoes reactive gliosis in response to damages to the CNS and functions as a chemical and physical barrier to axon regeneration. However, beneficial roles of astrocytes have been extensively studied in the spinal cord over the years, and a growing body of evidence now suggests that inducing astrocytes to become more growth-supportive can promote axon regeneration after spinal cord injury (SCI). In retina, astrocytes and Müller cells are known to undergo reactive gliosis after damage to retina and/or optic nerve and are hypothesized to be either detrimental or beneficial to survival and axon regeneration of retinal ganglion cells (RGCs). Whether they can be induced to become more growth-supportive after retinal and optic nerve injury has yet to be determined. In this review, we pinpoint the potential molecular pathways involved in the induction of growth-supportive astrocytes in the spinal cord and suggest that stimulating the activation of these pathways in the retina could represent a new therapeutic approach to promoting survival and axon regeneration of RGCs in retinal degenerative diseases.