Mesenchymal-Stem-Cell-Based Strategies for Retinal Diseases

Perspectives and Limitations of Mesenchymal Stem Cell-Based Therapy for Corneal Injuries and Retinal Diseases

The eye represents a highly specialized organ, with its main function being to convert light signals into electrical impulses. Any damage or disease of the eye induces a local inflammatory reaction that could be harmful for the specialized ocular cells. Therefore, the eye developed several immunoregulatory mechanisms which protect the ocular structures against deleterious immune reactions. This protection is ensured by the production of a variety of immunosuppressive molecules, which create the immune privilege of the eye. In addition, ocular cells are potent producers of numerous growth and trophic factors which support the survival and regeneration of diseased and damaged cells. If the immune privilege of the eye is interrupted and the regulatory mechanisms are not sufficiently effective, the eye disease can progress and result in worsening of vision or even blindness. In such cases, external immunotherapeutic interventions are needed. One perspective possibility of treatment is represented by mesenchymal stromal/stem cell (MSC) therapy. MSCs, which can be administered intraocularly or locally into diseased site, are potent producers of various immunoregulatory and regenerative molecules. The main advantages of MSC therapy include the safety of the treatment, the possibility to use autologous (patient's own) cells, and observations that the therapeutic properties of MSCs can be intentionally regulated by external factors during their preparation. In this review, we provide a survey of the immunoregulatory and regenerative mechanisms in the eye and describe the therapeutic potential of MSC application for corneal damages and retinal diseases.

Advanced bioengineering strategies broaden the therapeutic landscape for corneal failure

The cornea acts as the eye foremost protective layer and is essential for its focusing power. Corneal blindness may arise from physical trauma or conditions like dystrophies, keratitis, keratoconus, or ulceration. While conventional treatments involve medical therapies and donor allografts-sometimes supplemented with keratoprostheses-these options are not suitable for all corneal defects. Consequently, the development of bioartificial corneal tissue has emerged as a critical research area, aiming to address the global shortage of human cornea donors. Bioengineered corneas hold considerable promise as substitutes, with the potential to replace either specific layers or the entire thickness of damaged corneas. This review first delves into the structural anatomy of the human cornea, identifying key attributes necessary for successful corneal tissue bioengineering. It then examines various corneal pathologies, current treatments, and their limitations. Finally, the review outlines the primary approaches in corneal tissue engineering, exploring cell-free, cell-based, and scaffold-based options as three emerging strategies to address corneal failure.

Mitochondrial transfer between BMSCs and Müller promotes mitochondrial fusion and suppresses gliosis in degenerative retina

Mitochondrial dysfunction and Müller cells gliosis are significant pathological characteristics of retinal degeneration (RD) and causing blinding. Stem cell therapy is a promising treatment for RD, the recently accepted therapeutic mechanism is cell fusion induced materials transfer. However, whether materials including mitochondrial transfer between grafted stem cells and recipient's cells contribute to suppressing gliosis and mechanism are unclear. In present study, we demonstrated that bone marrow mesenchymal stem cells (BMSCs) transferred mitochondria to Müller cells by cell fusion and tunneling nanotubes. BMSCs-derived mitochondria (BMSCs-mito) were integrated into mitochondrial network of Müller cells, improving mitochondrial function, reducing oxidative stress and gliosis, which protected visual function partially in the degenerative rat retina. RNA sequencing analysis revealed that BMSCs-mito increased mitochondrial DNA (mtDNA) content and facilitated mitochondrial fusion in damaged Müller cells. It suggests that mitochondrial transfer from BMSCs remodels Müller cells metabolism and suppresses gliosis; thus, delaying the degenerative progression of RD.

Mapping the current trends of autophagy in retinal diseases: A bibliometric analysis

Background

Several scholarly publications have thoroughly examined the significant role of autophagy in the pathogenesis, progression, and treatment of retinal diseases. This research utilized bibliometric analysis to identify the primary areas of focus and emerging trends within the discipline and offer a comprehensive summary.

Methods

The research articles and reviews regarding autophagy and retinal diseases from 2009-01-01 to 2022-12-31 were from the Web of Science Core Collection (WOSCC). The software VOSviewer and CiteSpace were applied to analyze and visualize maps of countries, organizations, authors, journals, keyword networks, and citations in the field of autophagy in retinal diseases.

Results

854 qualified records (721 articles and 133 reviews) were retrieved in this research. The annual publication output of literature shows a growing trend. China is the most productive country, and the author with the most publications is Kai Kaarniranta. Journal Autophagy published the most articles in this field. Keywords analysis can effectively reflect the research hot spots and indicate that diabetic retinopathy and glaucoma have drawn more attention recently. Researchers have shifted the research emphasis on "AMPK", "angiogenesis", "mutation", and "inflammation".

Conclusions

With the bibliometric analysis approach, we presented the number of publications, countries, regions, authors, institutions, keywords, and citations, which further helps researchers understand the hot spots and trends in the field of autophagy in retinal diseases and explore the issues in the rapidly developing area.

Combined Light and Thermal Stimulation of Bone Marrow Stem Cells

Introduction: The purpose of this study is to achieve a significant increase in the proliferative activity of mesenchymal stem cells (MSCs) of the bone marrow (BM) at early passages after laser exposure to a suspension of these cells and to estimate the effect of light and heat components of laser radiation on the proliferation of BM MSCs. Methods: The studies were performed on rats BM MSCs. MSC suspension was placed into the wells and heated by using laser radiation (980 nm wavelength) or a water bath at 70 °C providing similar temperature dynamics. The studies were carried out in 3 comparison groups: (1) control suspension of MSCs, which was not subjected to heating in a water bath or laser exposure; (2) MSC suspension, which was heated for in a water bath; and (3) suspension of MSCs, which was subjected to laser exposure. The exposure times for the 2nd and 3rd experimental groups were 10- 50 seconds. Results: Under optimal parameters of laser action on the suspension of BM MSCs, a six-fold increase in the number of BM MSCs colonies was registered compared to the control. The role of the light and heat components of laser exposure to MSCs was determined by comparable heating of a suspension of BM MSCs in a water bath, at which only a twofold increase in the number of colonies was maximally obtained. Conclusion: The increase in the MSC proliferation activity occurs due to their Thermo-Photobiomodulation. The result obtained is important for practical use in cell transplantation in the treatment of traumatic injuries of bone, cartilage, and tendon tissues when a rapid and multiple increase in the initial number of autologous BM MSCs is required.

Smart Nanocarriers for the Treatment of Retinal Diseases

Retinal diseases, such as age-related macular degeneration, diabetic retinopathy, and retinoblastoma, stand as the leading causes of irreversible vision impairment and blindness worldwide. Effectively administering drugs for retinal diseases poses a formidable challenge due to the presence of complex ocular barriers and elimination mechanisms. Over time, various approaches have been developed to fabricate drug delivery systems for improving retinal therapy including virus vectors, lipid nanoparticles, and polymers. However, conventional nanocarriers encounter issues related to the controllability, efficiency, and safety in the retina. Therefore, the development of smart nanocarriers for effective or more invasive long-term treatment remains a desirable goal. Recently, approaches have surfaced for the intelligent design of nanocarriers, leveraging specific responses to external or internal triggers and enabling multiple functions for retinal therapy such as topical administration, prolonged drug release, and site-specific drug delivery. This Review provides an overview of prevalent retinal pathologies and related pharmacotherapies to enhance the understanding of retinal diseases. It also surveys recent developments and strategies employed in the intelligent design of nanocarriers for retinal disease. Finally, the challenges of smart nanocarriers in potential clinical retinal therapeutic applications are discussed to inspire the next generation of smart nanocarriers.

Classical and Innovative Evidence for Therapeutic Strategies in Retinal Dysfunctions

The human retina is a complex anatomical structure that has no regenerative capacity. The pathogenesis of most retinopathies can be attributed to inflammation, with the activation of the inflammasome protein platform, and to the impact of oxidative stress on the regulation of apoptosis and autophagy/mitophagy in retinal cells. In recent years, new therapeutic approaches to treat retinopathies have been investigated. Experimental data suggest that the secretome of mesenchymal cells could reduce oxidative stress, autophagy, and the apoptosis of retinal cells, and in turn, the secretome of the latter could induce changes in mesenchymal cells. Other studies have evidenced that noncoding (nc)RNAs might be new targets for retinopathy treatment and novel disease biomarkers since a correlation has been found between ncRNA levels and retinopathies. A new field to explore is the interaction observed between the ocular and intestinal microbiota; indeed, recent findings have shown that the alteration of gut microbiota seems to be linked to ocular diseases, suggesting a gut-eye axis. To explore new therapeutical strategies for retinopathies, it is important to use proper models that can mimic the complexity of the retina. In this context, retinal organoids represent a good model for the study of the pathophysiology of the retina.

Therapeutic efficacy and promise of stem cell-derived extracellular vesicles in Alzheimer's disease and other aging-related disorders

The term extracellular vesicles (EVs) refers to a variety of heterogeneous nanovesicles secreted by almost all cell types, primarily for intercellular communication and maintaining cellular homeostasis. The role of EVs has been widely reported in the genesis and progression of multiple pathological conditions, and these vesicles are suggested to serve as 'liquid biopsies'. In addition to their use as biomarkers, EVs secreted by specific cell types, especially with stem cell properties, have shown promise as cell-free nanotherapeutics. Stem cell-derived EVs (SC-EVs) have been increasingly used as an attractive alternative to stem cell therapies and have been reported to promote regeneration of aging-associated tissue loss and function. SC-EVs treatment ameliorates brain and peripheral aging, reproductive dysfunctions and inhibits cellular senescence, thereby reversing several aging-related disorders and dysfunctions. The anti-aging therapeutic potential of SC-EVs depends on multiple factors, including the type of stem cells, the age of the source stem cells, and their physiological state. In this review, we briefly describe studies related to the promising effects of SC-EVs against various aging-related pathologies, and then we focus in-depth on the therapeutic benefits of SC-EVs against Alzheimer's disease, one of the most devastating neurodegenerative diseases in elderly individuals. Numerous studies in transgenic mouse models have reported the usefulness of SC-EVs in targeting the pathological hallmarks of Alzheimer's disease, including amyloid plaques, neurofibrillary tangles, and neuroinflammation, leading to improved neuronal protection, synaptic plasticity, and cognitive measures. Cell culture studies have further identified the underlying molecular mechanisms through which SC-EVs reduce amyloid beta (Aβ) levels or shift microglia phenotype from pro-inflammatory to anti-inflammatory state. Interestingly, multiple routes of administration, including nasal delivery, have confirmed that SC-EVs could cross the blood-brain barrier. Due to this, SC-EVs have also been tested to deliver specific therapeutic cargo molecule/s (e.g., neprilysin) to the brain. Despite these promises, several challenges related to quality control, scalability, and biodistribution remain, hindering the realization of the vast clinical promise of SC-EVs.

The New Era of Therapeutic Strategies for the Treatment of Retinitis Pigmentosa: A Narrative Review of Pathomolecular Mechanisms for the Development of Cell-Based Therapies

Retinitis pigmentosa, defined more properly as cone-rod dystrophy, is a paradigm of inherited diffuse retinal dystrophies, one of the rare diseases with the highest prevalence in the worldwide population and one of the main causes of low vision in the pediatric and elderly age groups. Advancements in and the understanding of molecular biology and gene-editing technologies have raised interest in laying the foundation for new therapeutic strategies for rare diseases. As a consequence, new possibilities for clinicians and patients are arising due to the feasibility of treating such a devastating disorder, reducing its complications. The scope of this review focuses on the pathomolecular mechanisms underlying RP better to understand the prospects of its treatment using innovative approaches.

Biodegradable Dual-Cross-Linked Hydrogels with Stem Cell Differentiation Regulatory Properties Promote Growth Plate Injury Repair via Controllable Three-Dimensional Mechanics and a Cartilage-like Extracellular Matrix

Recent breakthroughs in cell transplantation therapy have revealed the promising potential of bone marrow mesenchymal stem cells (BMSCs) for promoting the regeneration of growth plate cartilage injury. However, the high apoptosis rate and the uncertainty of the differentiation direction of cells often lead to poor therapeutic effects. Cells are often grown under three-dimensional (3D) conditions in vivo, and the stiffness and components of the extracellular matrix (ECM) are important regulators of stem cell differentiation. To this end, a 3D cartilage-like ECM hydrogel with tunable mechanical properties was designed and synthesized mainly from gelatin methacrylate (GM) and oxidized chondroitin sulfate (OCS) via dynamic Schiff base bonding under UV. The effects of scaffold stiffness and composition on the survival and differentiation of BMSCs in vitro were investigated. A rat model of growth plate injury was developed to validate the effect of the GMOCS hydrogels encapsulated with BMSCs on the repair of growth plate injury. The results showed that 3D GMOCS hydrogels with an appropriate modulus significantly promoted chondrogenic differentiation of BMSCs, and GMOCS/BMSC transplantation could effectively inhibit bone bridge formation and promote the repair of damaged growth plates. Accordingly, GMOCS/BMSC therapy can be engineered as a promising therapeutic candidate for growth plate injury.