The Analysis of Embryoid Body Formation and Its Role in Retinal Organoid Development.

Within the last decade, a wide variety of protocols have emerged for the generation of retinal organoids. A subset of studies have compared protocols based on stem cell source, the physical features of the microenvironment, and both internal and external signals, all features that influence embryoid body and retinal organoid formation. Most of these comparisons have focused on the effect of signaling pathways on retinal organoid development. In this study, our aim is to understand whether starting cell conditions, specifically those involved in embryoid body formation, affect the development of retinal organoids in terms of differentiation capacity and reproducibility. To investigate this, we used the popular 3D floating culture method to generate retinal organoids from stem cells. This method starts with either small clumps of stem cells generated from larger clones (clumps protocol, CP) or with an aggregation of single cells (single cells protocol, SCP). Using histological analysis and gene-expression comparison, we found a retention of the pluripotency capacity on embryoid bodies generated through the SCP compared to the CP. Nonetheless, these early developmental differences seem not to impact the final retinal organoid formation, suggesting a potential compensatory mechanism during the neurosphere stage. This study not only facilitates an in-depth exploration of embryoid body development but also provides valuable insights for the selection of the most suitable protocol in order to study retinal development and to model inherited retinal disorders in vitro.

"Palliative care is so much more than that": a qualitative study exploring experiences of hospice staff and bereaved carers during the COVID-19 pandemic.

Background: The way in which end-of-life care was provided changed significantly during the first 2 years of the COVID-19 pandemic. The national lockdown restrictions reduced formal care support services and increased the burden on many carers taking on the caring role for the first time. We aimed to explore decision-making about the place of care during the COVID-19 pandemic and the impact on experience from the perspectives of carers and hospice staff caring for people at the end-of-life. Methods: A qualitative study using virtual interviews was conducted between October 2020 and April 2021. Data were analyzed thematically using framework analysis, an analytical framework that enables qualitative research to be organized into defined themes derived from the research question. Findings were presented to stakeholders in policy roundtables between March 2022 and March 2023 and discussed collaboratively with staff, stakeholders, and the public to inform policy and practice change. Findings: A total of 37 participants (15 bereaved carers and 22 staff) were recruited via hospice services in England and Scotland. Four key themes were identified: (1) changing preferences relating to decision-making about the place of care and the impact at the time of death and into bereavement; (2) missed opportunities related to not being there, not having others around, and being robbed of memory-making; (3) the lone carer during a period of high intensity and reduced home support; (4) process vs. person-centered care resulting from changing rules and restrictions and prioritization of regulations over essential palliative care. Conclusion: The study provides valuable global implications for all involved in end-of-life care. Despite great efforts to provide dignified, quality care, palliative care during the pandemic changed, focusing on essential 'physical care'. The psychological suffering experienced by staff and carers may need longer-term support mechanisms put in place, which will benefit from a public health approach. Policymakers should consider improving carer identification and resources for wider end-of-life care education to support the needs of carers, health and social care staff, and citizens.

The Experiences of Informal Carers during the COVID-19 Pandemic: A Qualitative Systematic Review.

OBJECTIVES: To identify, critically appraise and synthesise the qualitative literature on the experiences of informal carers of people with long-term conditions during the COVID-19 pandemic. DESIGN: A qualitative systematic literature review. DATA SOURCES: Eight electronic databases were systematically searched (Medline, Embase, CINAHL, PubMed, PsychINFO, Web of Science, Nursing and Allied Health and ASSIA) along with Google Scholar and handsearching via secondary sources. STUDY SELECTION: Eligible studies had to include the experiences of informal carers (adults who are 65 or older), use a qualitative methodology and had to be written in English. DATA EXTRACTION AND SYNTHESIS: Retrieved papers were quality assessed using the Critical Appraisal Skills Programme qualitative checklist and ranked for quality. Thematic analysis was used to synthesise the findings. RESULTS: Fourteen studies were included, all from medical or nursing journals (n = 5 specifically gerontology). Four main themes were identified: (i) fear, (ii) uncertainty, (iii) burden and (iv) staying connected. Caregiving demands have increased for carers during the pandemic, as well as negative emotions such as fear and uncertainty. At the same time, less social support has been available, leading to concerns about carers' wellbeing and ability to cope. CONCLUSION: Carers' needs have been exacerbated by the COVID-19 pandemic. Greater practical and emotional support is needed for carers from both formal services and community sources that considers their changing needs and offers educational and emotional support for long-term wellbeing. Strengths and Limitations: (1) This is the first systematic review to explore in depth the experiences of informal carers caring for people with a range of long-term conditions and from an international context. (2) The review includes an analysis of the quality of the studies, as well as a study of their relative contributions. (3) Further research is needed to explore the physical, emotional and financial impact of the pandemic for bereaved carers which is not captured in this review due to the lack of empirical data available at the time of review.

The retinal pigmentation pathway in human albinism: Not so black and white.

Albinism is a pigment disorder affecting eye, skin and/or hair. Patients usually have decreased melanin in affected tissues and suffer from severe visual abnormalities, including foveal hypoplasia and chiasmal misrouting. Combining our data with those of the literature, we propose a single functional genetic retinal signalling pathway that includes all 22 currently known human albinism disease genes. We hypothesise that defects affecting the genesis or function of different intra-cellular organelles, including melanosomes, cause syndromic forms of albinism (Hermansky-Pudlak (HPS) and Chediak-Higashi syndrome (CHS)). We put forward that specific melanosome impairments cause different forms of oculocutaneous albinism (OCA1-8). Further, we incorporate GPR143 that has been implicated in ocular albinism (OA1), characterised by a phenotype limited to the eye. Finally, we include the SLC38A8-associated disorder FHONDA that causes an even more restricted "albinism-related" ocular phenotype with foveal hypoplasia and chiasmal misrouting but without pigmentation defects. We propose the following retinal pigmentation pathway, with increasingly specific genetic and cellular defects causing an increasingly specific ocular phenotype: (HPS1-11/CHS: syndromic forms of albinism)-(OCA1-8: OCA)-(GPR143: OA1)-(SLC38A8: FHONDA). Beyond disease genes involvement, we also evaluate a range of (candidate) regulatory and signalling mechanisms affecting the activity of the pathway in retinal development, retinal pigmentation and albinism. We further suggest that the proposed pigmentation pathway is also involved in other retinal disorders, such as age-related macular degeneration. The hypotheses put forward in this report provide a framework for further systematic studies in albinism and melanin pigmentation disorders.

Abstracts from the 2022 European Association for Vision and Eye Research Festival, 13-15 October 2022, Valencia.

PURPOSE: Albinism refers to a group of genetic disorders typically characterized by a loss/reduction of melanin in the hair, skin and eyes of affected patients. Apart from pigment changes, all albinism patients present with foveal hypoplasia and optic nerve misrouting, and have blurred vision. The molecular mechanisms that link this lack of pigment with neural retinal development are poorly understood, with foveal and optic tract development being difficult to model. To advance our knowledge, we developed a novel retinal organoid model of albinism, and characterized the development and outgrowth of retinal ganglion cells affected during albinism as a model for future studies. METHODS: Human oculocutaneous albinism 1 (OCA1) patient-derived stem cells were differentiated alongside controls into retinal organoids, as published previously1,2 . Early retinal ganglion cells develop in the first 4 weeks of differentiation, at which point whole organoids could be plated to allow for optic nerve-like outgrowth. Whole organoids were also fixed and analysed with immunohistochemistry (IHC) to visualize contralateral and ipsilateral ganglion cells present in the organoid. RESULTS: IHC analysis showed differences in the number of ipsilateral and contralateral retinal ganglion cells between the healthy control and albinism organoids, in line with in vivo observations. Further, optic nerve-like outgrowth could be achieved with both models, allowing for future research into optic nerve misrouting in albinism. CONCLUSIONS: We generated a novel retinal organoid model of oculocutaneous albinism, and characterized the retinal ganglion cell development and outgrowth. This will allow us in the future to study a different and sometimes overlooked aspect of albinism; optic nerve misrouting. References 1. Wagstaff, P. E., Ten Asbroek, A., Ten Brink, J. B., Jansonius, N. M. & Bergen, A. A. B. An alternative approach to produce versatile retinal organoids with accelerated ganglion cell development. Sci Rep 11, 1101, doi:10.1038/s41598-020-79651-x (2021). 2. Ohlemacher, S. K. et al. Stepwise Differentiation of Retinal Ganglion Cells from Human Pluripotent Stem Cells Enables Analysis of Glaucomatous Neurodegeneration. Stem Cells 34, 1553-1562, doi:10.1002/stem.2356 (2016).

The Role of Small Molecules and Their Effect on the Molecular Mechanisms of Early Retinal Organoid Development.

Early in vivo embryonic retinal development is a well-documented and evolutionary conserved process. The specification towards eye development is temporally controlled by consecutive activation or inhibition of multiple key signaling pathways, such as the Wnt and hedgehog signaling pathways. Recently, with the use of retinal organoids, researchers aim to manipulate these pathways to achieve better human representative models for retinal development and disease. To achieve this, a plethora of different small molecules and signaling factors have been used at various time points and concentrations in retinal organoid differentiations, with varying success. Additions differ from protocol to protocol, but their usefulness or efficiency has not yet been systematically reviewed. Interestingly, many of these small molecules affect the same and/or multiple pathways, leading to reduced reproducibility and high variability between studies. In this review, we make an inventory of the key signaling pathways involved in early retinogenesis and their effect on the development of the early retina in vitro. Further, we provide a comprehensive overview of the small molecules and signaling factors that are added to retinal organoid differentiation protocols, documenting the molecular and functional effects of these additions. Lastly, we comparatively evaluate several of these factors using our established retinal organoid methodology.

An alternative approach to produce versatile retinal organoids with accelerated ganglion cell development.

Genetically complex ocular neuropathies, such as glaucoma, are a major cause of visual impairment worldwide. There is a growing need to generate suitable human representative in vitro and in vivo models, as there is no effective treatment available once damage has occured. Retinal organoids are increasingly being used for experimental gene therapy, stem cell replacement therapy and small molecule therapy. There are multiple protocols for the development of retinal organoids available, however, one potential drawback of the current methods is that the organoids can take between 6 weeks and 12 months on average to develop and mature, depending on the specific cell type wanted. Here, we describe and characterise a protocol focused on the generation of retinal ganglion cells within an accelerated four week timeframe without any external small molecules or growth factors. Subsequent long term cultures yield fully differentiated organoids displaying all major retinal cell types. RPE, Horizontal, Amacrine and Photoreceptors cells were generated using external factors to maintain lamination.

A Systematic Review on Transplantation Studies of the Retinal Pigment Epithelium in Animal Models.

The retinal pigment epithelium (RPE) and the adjacent light-sensitive photoreceptors form a single functional unit lining the back of the eye. Both cell layers are essential for normal vision. RPE degeneration is usually followed by photoreceptor degeneration and vice versa. There are currently almost no effective therapies available for RPE disorders such as Stargardt disease, specific types of retinitis pigmentosa, and age-related macular degeneration. RPE replacement for these disorders, especially in later stages of the disease, may be one of the most promising future therapies. There is, however, no consensus regarding the optimal RPE source, delivery strategy, or the optimal experimental host in which to test RPE replacement therapy. Multiple RPE sources, delivery methods, and recipient animal models have been investigated, with variable results. So far, a systematic evaluation of the (variables influencing) efficacy of experimental RPE replacement parameters is lacking. Here we investigate the effect of RPE transplantation on vision and vision-based behavior in animal models of retinal degenerated diseases. In addition, we aim to explore the effect of RPE source used for transplantation, the method of intervention, and the animal model which is used. METHODS: In this study, we systematically identified all publications concerning transplantation of RPE in experimental animal models targeting the improvement of vision (e.g., outcome measurements related to the morphology or function of the eye). A variety of characteristics, such as species, gender, and age of the animals but also cell type, number of cells, and other intervention characteristics were extracted from all studies. A risk of bias analysis was performed as well. Subsequently, all references describing one of the following outcomes were analyzed in depth in this systematic review: a-, b-, and c-wave amplitudes, vision-based, thickness analyses based on optical coherence tomography (OCT) data, and transplant survival based on scanning laser ophthalmoscopy (SLO) data. Meta-analyses were performed on the a- and b-wave amplitudes from electroretinography (ERG) data as well as data from vision-based behavioral assays. RESULTS: original research articles met the inclusion criteria after two screening rounds. Overall, most studies were categorized as unclear regarding the risk of bias, because many experimental details were poorly reported. Twenty-three studies reporting one or more of the outcome measures of interest were eligible for either descriptive (thickness analyses based on OCT data; n = 2) or meta-analyses. RPE transplantation significantly increased ERG a-wave (Hedges' g 1.181 (0.471-1.892), n = 6) and b-wave (Hedges' g 1.734 (1.295-2.172), n = 42) amplitudes and improved vision-based behavior (Hedges' g 1.018 (0.826-1.209), n = 96). Subgroup analyses revealed a significantly increased effect of the use of young and adolescent animals compared to adult animals. Moreover, transplanting more cells (in the range of 105 versus in the range of 104) resulted in a significantly increased effect on vision-based behavior as well. The origin of cells mattered as well. A significantly increased effect was found on vision-based behavior when using ARPE-19 and OpRegen® RPE. CONCLUSIONS: This systematic review shows that RPE transplantation in animal models for retinal degeneration significantly increases a- and b- wave amplitudes and improves vision-related behavior. These effects appear to be more pronounced in young animals, when the number of transplanted cells is larger and when ARPE-19 and OpRegen® RPE cells are used. We further emphasize that there is an urgent need for improving the reporting and methodological quality of animal experiments, to make such studies more comparable.