Stem Cell Ophthalmology Treatment Study (SCOTS): Bone Marrow-Derived Stem Cells in the Treatment of Age-Related Macular Degeneration

Atrophic Macular Degeneration and Stem Cell Therapy: A Clinical Review

Age-related macular degeneration (AMD) is one of the leading causes of visual loss in older patients. No effective drug is available for this pathology, but studies about therapy with stem cells replacing the damaged retinal cells with retinal pigment epithelium (RPE) were described. The documentation of AMD progression and the response to stem cell therapy have been performed by optical coherence tomography, microperimetry, and other diagnostic technologies.This chapter reports a clinical review of the most important clinical trials and protocols regarding the use of stem cells in AMD.

Cell therapy for retinal degenerative disorders: a systematic review and three-level meta-analysis

BACKGROUND

Retinal degenerative disorders (RDDs) cause vision loss by damaging retinal neurons and photoreceptors, affecting individuals of all ages. Cell-based therapy has emerged as an effective approach for the treatment of RDDs with promising results. This meta-analysis aims to comprehensively evaluate the efficacy of cell therapy in treating age-related macular degeneration (AMD), retinitis pigmentosa (RP), and Stargardt macular degeneration (SMD) as the most prevalent RDDs.

METHODS

PubMed, Scopus, Web of Science, and Embase were searched using keywords related to various retinal diseases and cell therapy treatments until November 25th, 2023. The studies' quality was evaluated using the Joanna Briggs Institute's (JBI) checklist for quasi-experimental studies. Visual acuity measured as LogMAR score was used as our main outcome. A three-level random-effect meta-analysis was used to explore the visual acuity in patients who received cell-based therapy. Heterogeneity among the included studies was evaluated using subgroup and sensitivity analyses. Moreover, meta-regression for the type of cells, year of publication, and mean age of participants were performed.

RESULTS

Overall, 8345 studies were retrieved by the search, and 39 met the eligibility criteria, out of which 18 studies with a total of 224 eyes were included in the meta-analysis. There were 12 studies conducted on AMD, 7 on SMD, and 2 on RP. Cell therapy for AMD showed significant improvement in LogMAR (p < 0.05). Also, cell therapy decreased the LogMAR score in SMD and RP (p < 0.01 and p < 0.0001, respectively). Across all conditions, no substantial publication bias was detected (p < 0.05).

CONCLUSION

The findings of the study highlight that the application of cell therapy can enhance the visual acuity in AMD, SMD, and RP.

Beyond Vision: An Overview of Regenerative Medicine and Its Current Applications in Ophthalmological Care

Regenerative medicine (RM) has emerged as a promising and revolutionary solution to address a range of unmet needs in healthcare, including ophthalmology. Moreover, RM takes advantage of the body's innate ability to repair and replace pathologically affected tissues. On the other hand, despite its immense promise, RM faces challenges such as ethical concerns, host-related immune responses, and the need for additional scientific validation, among others. The primary aim of this review is to present a high-level overview of current strategies in the domain of RM (cell therapy, exosomes, scaffolds, in vivo reprogramming, organoids, and interspecies chimerism), centering around the field of ophthalmology. A search conducted on clinicaltrials.gov unveiled a total of at least 209 interventional trials related to RM within the ophthalmological field. Among these trials, there were numerous early-phase studies, including phase I, I/II, II, II/III, and III trials. Many of these studies demonstrate potential in addressing previously challenging and degenerative eye conditions, spanning from posterior segment pathologies like Age-related Macular Degeneration and Retinitis Pigmentosa to anterior structure diseases such as Dry Eye Disease and Limbal Stem Cell Deficiency. Notably, these therapeutic approaches offer tailored solutions specific to the underlying causes of each pathology, thus allowing for the hopeful possibility of bringing forth a treatment for ocular diseases that previously seemed incurable and significantly enhancing patients' quality of life. As advancements in research and technology continue to unfold, future objectives should focus on ensuring the safety and prolonged viability of transplanted cells, devising efficient delivery techniques, etc.

Treatment of dry age-related macular degeneration: A review

Age-related macular degeneration is a global disease with a significant societal impact. The advent of anti-vascular endothelial growth factor therapy (anti-VEGF) has revolutionised the treatment of neovascular age-related macular degeneration (nAMD). Dry age-related macular degeneration (dAMD) is being investigated for possible therapeutic options. The therapeutic categories undergoing clinical trials include complement pathway inhibitors, visual cycle modulators, reduction of toxic byproducts, antioxidative therapy, neuroprotective agents, laser therapy, surgical options, gene therapy, stem cell therapy, and miscellaneous treatments. Two intravitreal anti-complement factors (pegcetacoplan and avacincaptad pegol) have recently shown phase 3 clinical trial evidence of a reduction in the growth of geographic atrophy. In this review, we provide an update on treatment options currently undergoing clinical research trials for the management of dAMD and preventing the progression of Geographic Atrophy (GA).

Intravitreal allogeneic mesenchymal stem cells: a non-randomized phase II clinical trial for acute non-arteritic optic neuropathy

BACKGROUND

An effective treatment for acute non-arteritic ischemic optic neuropathy (NA-AION) has not been known or proven yet. Previous studies have suggested a neuroprotective effect of allogeneic bone marrow-derived mesenchymal stem cells. This study aims to report the results of a clinical trial on patients with acute non-arteritic optic neuropathy (NA-AION) treated with an intravitreal injection of allogeneic bone marrow-derived mesenchymal stem cells (BM-MSCs) (MSV®).

METHODS

We conducted a prospective, non-randomized, clinical phase-II study (Eudra CT number 2016-003029-40; ClinicalTrials.gov Registry NCT03173638) that included 5 patients with acute unilateral NA-AION diagnosed within 2 weeks after symptom onset and who received an intravitreal injection of allogeneic BM-MSCs (0.05 ml; cell concentration: 1.5 × 106cells/mL). The patients underwent regular ophthalmological examinations and were followed for one year.

RESULTS

In this trial, allogeneic BM-MSCs appeared to be safe as no patients developed signs of acute nor chronic intraocular inflammation or a significant change in intraocular pressure, although an epiretinal membrane was developed in one patient. A retrolental aggregate formed shortly after the injection spontaneously disappeared within a few weeks in another phakic patient, leaving a subcapsular cataract. Visual improvement was noted in 4 patients, and amplitudes of P100 on the visually evoked potentials recordings increased in three patients. The retinal nerve fiber layer and macular ganglion cell layer thicknesses significantly decreased during the follow-up.

CONCLUSIONS

Besides the development of an epiretinal membrane in one patient, the intravitreal application of allogeneic BM-MSCs appeared to be intraocularly well tolerated. Consequently, not only NA-AION but also BM-MSCs deserve more clinical investigational resources and a larger randomized multicenter trial that would provide stronger evidence both about safety and the potential therapeutic efficacy of intravitreally injected allogeneic BM-MSCs in acute NA-AION.

TRIAL REGISTRATION

Safety Assessment of Intravitreal Mesenchymal Stem Cells for Acute Non-Arteritic Anterior Ischemic Optic Neuropathy (NEUROSTEM). NCT03173638. Registered June 02, 2017 https://clinicaltrials.gov/ct2/show/NCT03173638 .

Rhodopsin-associated retinal dystrophy: Disease mechanisms and therapeutic strategies

Rhodopsin is a light-sensitive G protein-coupled receptor that initiates the phototransduction cascade in rod photoreceptors. Mutations in the rhodopsin-encoding gene RHO are the leading cause of autosomal dominant retinitis pigmentosa (ADRP). To date, more than 200 mutations have been identified in RHO. The high allelic heterogeneity of RHO mutations suggests complicated pathogenic mechanisms. Here, we discuss representative RHO mutations as examples to briefly summarize the mechanisms underlying rhodopsin-related retinal dystrophy, which include but are not limited to endoplasmic reticulum stress and calcium ion dysregulation resulting from protein misfolding, mistrafficking, and malfunction. Based on recent advances in our understanding of disease mechanisms, various treatment methods, including adaptation, whole-eye electrical stimulation, and small molecular compounds, have been developed. Additionally, innovative therapeutic treatment strategies, such as antisense oligonucleotide therapy, gene therapy, optogenetic therapy, and stem cell therapy, have achieved promising outcomes in preclinical disease models of rhodopsin mutations. Successful translation of these treatment strategies may effectively ameliorate, prevent or rescue vision loss related to rhodopsin mutations.

The expression of NOTUM in replantation of severed fingers may be an important treatment factor

BACKGROUND

After years of development, digital replantation has become a mature treatment. Although the NOTUM gene has been shown to be involved in the formation of vertebrate nerves, whether it contributes to the osteogenic mechanism of severed finger replantation remains unknown. In response to this, this study investigates the specific details of NOTUM involvement in replantation of severed fingers.

METHODS

The experimental subjects are patients with replantation of severed fingers from Shulan International Medical College of Shulan (Hangzhou) Hospital affiliated to Zhejiang Shuren University. In addition to using bone marrow mesenchymal stem cells (BMSCs) as an in vitro system, this experiment also involves quantitative polymerase chain reaction, microarray analysis, cell counting Kit-8, ethynyl deoxyuridine staining and Western blot analysis.

RESULTS

The expression level of NOTUM in the severed finger replantation group is lower than that in the normal group. NOTUM inhibits cell growth and cell transfer, osteogenic differentiation and β-catenin gene expression in BMSCs. Luciferase reporter assay illustrated that β-catenin wild type closely correlated with NOTUM. The inhibition of β-catenin increases the effects of NOTUM on cell growth, cell transfer and osteogenic differentiation of BMSCs.

CONCLUSIONS

Considering that NOTUM can inhibit cell growth, cell transfer, osteogenic differentiation of BMSCs, as well as the gene expression of β-catenin, it may be a biomarker of osteogenic differentiation and a potential therapeutic target for replantation of severed fingers.

New frontiers of retinal therapeutic intervention: a critical analysis of novel approaches

A recent wave of pharmacologic and technologic innovations has revolutionized our management of retinal diseases. Many of these advancements have demonstrated efficacy and can increase the quality of life while potentially reducing complications and decreasing the burden of care for patients. Some advances, such as longer-acting anti-vascular endothelial growth factor agents, port delivery systems, gene therapy, and retinal prosthetics have been approved by the US Food and Drug Administration, and are available for clinical use. Countless other therapeutics are in various stages of development, promising a bright future for further improvements in the management of the retinal disease. Herein, we have highlighted several important novel therapies and therapeutic approaches and examine the opportunities and limitations offered by these innovations at the new frontier. KEY MESSAGESNumerous pharmacologic and technologic advancements have been emerging, providing a higher treatment efficacy while decreasing the burden and associated side effects.Anti-vascular endothelial growth factor (anti-VEGF) and its longer-acting agents have dramatically improved visual outcomes and have become a mainstay treatment in various retinal diseases.Gene therapy and retinal prosthesis implantation in the treatment of congenital retinal dystrophy can accomplish the partial restoration of vision and improved daily function in patients with blindness, an unprecedented success in the field of retina.

Advanced Therapy and Clinical Trials to Treat Patients with Optic Nerve Diseases

Optic nerve diseases include a wide variety of pathogenic conditions triggering injury or dysfunction of the optic nerves that lead to visual impairment or blindness in one or both eyes. Despite their pathogenic variety, most of them proceed through common mechanisms that allow them to investigate together. Nevertheless, roles of the cells, tissues, genes, growth factors, and proteins, and all underlying pathophysiological mechanisms need to be studied fully for better management of each optic nerve disease. This review presents a collection of information regarding ongoing and completed clinical trials (CT) of advanced therapies that deliver stem cell and gene therapy treatments as drugs to patients with optic nerve diseases as well as successes and failures achieved in treating these patients in the last few years. These drugs seem safe from creating neurotoxicity. It describes outcomes of a bibliographic search for stem cell therapy, gene therapy, and neuroprotection-based CT registered in the International ClinicalTrials.gov, the European EudraCT, and the Spanish REEC database, and related papers published in the PUBMED database by applying different search terminologies. This review overall informs the patients of optic neurodiseases that advanced therapies are progressing successfully in search of effective and safe treatments for them.

Current Status of Mesenchymal Stem/Stromal Cells for Treatment of Neurological Diseases

Neurological disorders include a wide spectrum of clinical conditions affecting the central and peripheral nervous systems. For these conditions, which affect hundreds of millions of people worldwide, generally limited or no treatments are available, and cell-based therapies have been intensively investigated in preclinical and clinical studies. Among the available cell types, mesenchymal stem/stromal cells (MSCs) have been widely studied but as yet no cell-based treatment exists for neurological disease. We review current knowledge of the therapeutic potential of MSC-based therapies for neurological diseases, as well as possible mechanisms of action that may be explored to hasten the development of new and effective treatments. We also discuss the challenges for culture conditions, quality control, and the development of potency tests, aiming to generate more efficient cell therapy products for neurological disorders.

Bone marrow-derived mononuclear stem cells in the treatment of retinal degenerations

Retinal degenerative diseases affecting the outer retina in its many forms (inherited, acquired or induced) are characterized by photoreceptor loss, and represent currently a leading cause of irreversible vision loss in the world. At present, there are very few treatments capable of preventing, recovering or reversing photoreceptor degeneration or the secondary retinal remodeling, which follows photoreceptor loss and can also cause the death of other retinal cells. Thus, these diseases are nowadays one of the greatest challenges in the field of ophthalmological research. Bone marrow derived-mononuclear stem cell transplantation has shown promising results for the treatment of photoreceptor degenerations. These cells may have the potential to slow down photoreceptor loss, and therefore should be applied in the early stages of photoreceptor degenerations. Furthermore, because of their possible paracrine effects, they may have a wide range of clinical applications, since they can potentially impact on several retinal cell types at once and photoreceptor degenerations can involve different cells and/or begin in one cell type and then affect adjacent cells. The intraocular injection of bone marrow derived-mononuclear stem cells also enhances the outcomes of other treatments aimed to protect photoreceptors. Therefore, it is likely that future investigations may combine bone marrow derived-mononuclear stem cell therapy with other systemic or intraocular treatments to obtain greater therapeutic effects in degenerative retinal diseases.

Progress of clinical therapies for dry age-related macular degeneration

Dry age-related macular degeneration (AMD) is a progressive blinding disease that currently affects millions of people worldwide with no successful treatment available. Significant research efforts are currently underway to develop therapies aimed at slowing the progression of this disease or, more notably, reversing it. Here the therapies which have reached clinical trial for treatment of dry AMD were reviewed. A thorough search of PubMed, Embase, and Clinicaltrials.gov has led to a comprehensive collection of the most recent strategies being evaluated. This review also endeavors to assess the status and future directions of therapeutics for this debilitating condition.

The Future of Stem Cells and Their Derivates in the Treatment of Glaucoma. A Critical Point of View

This review focuses on the clinical translation of preclinical studies, especially those that have used stem cells in the treatment of glaucoma, with an emphasis on optic nerve regeneration. The studies referred to in the review aim to treat optic nerve atrophy, while cell therapies targeting other sites in the eye, such as the trabecular meshwork, have not been addressed. Such complex and varied pathophysiological mechanisms that lead to glaucoma may explain the fact that although stem cells have a high capacity of neuronal regeneration, the treatments performed did not have the expected results and the promise offered by animal studies was not achieved. By analyzing the facts associated with failure, important lessons are to be learned: the type of stem cells that are used, the route of administration, the selection of patients eligible for these treatments, additional therapies that support stem cells transplantation and their mode of action, methods of avoiding the host’s immune response. Many of these problems could be solved using exosomes (EV), but also miRNA, which allows more targeted approaches with minimal side effects.

Stem Cells in the Path of Light, from Corneal to Retinal Reconstruction

The future of eye reconstruction invariably includes stem cells transplantation. Corneal limbus, corneal stroma, trabeculum, retinal cells, optic nerve, and all structures that are irreversibly damaged and have no means to be repaired or replaced, through conventional treatment or surgery, represent targets for stem cell reconstruction. This review tries to answer the question if there is any clinical validation for stem therapies, so far, starting from the cornea and, on the path of light, arriving to the retina. The investigation covers the last 10 years of publications. From 2385 published sources, we found 56 clinical studies matching inclusion criteria, 39 involving cornea, and 17 involving retina. So far, corneal epithelial reconstruction seems well validated clinically. Enough clinical data are collected to allow some form of standardization for the stem cell transplant procedures. Cultivated limbal epithelial stem cells (CLET), simple limbal epithelial transplant (SLET), and oral mucosa transplantation are implemented worldwide. In comparison, far less patients are investigated in retinal stem reconstructions, with lower anatomical and clinical success, so far. Intravitreal, subretinal, and suprachoroidal approach for retinal stem therapies face specific challenges.

Stem Cell Ophthalmology Treatment Study (SCOTS): Bone Marrow-Derived Stem Cells in the Treatment of Stargardt Disease

Background: Stargardt Disease is the most common inherited macular degeneration, typically resulting in progressive central vision loss and legal blindness at an early age. We report regarding 34 eyes with Stargardt Disease treated in the Stem Cell Ophthalmology Treatment Study (SCOTS and SCOTS2). Methods: Autologous bone marrow was processed, separating the stem cell fraction which was provided Arms using retrobulbar, subtenons, intravitreal or subretinal and intravenous. The follow-up period was one year. Results: Of the 34 treated eyes, 21 (61.8%) improved, 8 (23.5%) remained stable, and 5 (14.7%) showed continued progression of their disease. Results were statistically significant with p = 0.0004. The average central vision improvement following treatment was 17.96% (95%CI, 16.39–19.53%) and ranged up to 80.5%. Of 17 patients treated, 13 (76.5%) showed visual acuity improvement in one or both eyes, 3 patients (17.6%) showed no net loss, and 1 worsened as a consequence of disease progression; 94.1% of patients had improved vision or remained stable. There were no adverse events. Conclusions: Patients with Stargardt Disease may potentially benefit from autologous bone marrow-derived stem cells (BMSC) as provided in SCOTS. Improvement or stabilization of vision was found to occur for the vast majority of reported patients and findings were highly statistically significant.

Gene, Cell and Antibody-Based Therapies for the Treatment of Age-Related Macular Degeneration

Here we discuss antibody, cell and gene-based therapies that are currently available and under investigation for both wet and dry age-related macular degeneration (AMD). We initially discuss ocular anatomy, AMD modelling as well as the underlying pathophysiology of AMD. The antibody-based trials which have revolutionised the management of wet AMD are reviewed. The latest concepts in antibody therapy for wet AMD such as the port delivery systems, bispecific antibodies, designed ankyrin repeat protein (DARPINs) and brolucizumab are explored. Furthermore, the antibody-based trials targeting the complement pathway to reduce progression of geographic atrophy (GA) in dry AMD are discussed. Stem cell therapy and gene therapy are novel treatment modalities with no established clinical use in wet or dry AMD. Here, we discuss their efficacy so far in clinical trials. Their benefits and risk in the treatment of both wet and dry AMD are evaluated.